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S. epidermidis is an ocular pathogen and a leading cause of keratitis. It produces hemolysins and at least 3 proteases. The purpose of the present study is to compare the secretion of hemolysins and proteases between 28 ocular isolates and one non-ocular strain and to determine their relationship to ocular virulence in selected strains using a rabbit model of infection. Culture supernatants were compared for protease production and hemolysis. Selected strains were injected into rabbit corneas and their virulence and pathology recorded. The major protease activity in a virulent strain was identified and the gene was cloned and expressed as a recombinant protein. The corneal toxicity of this protease was determined. Antibodies to the native protease were generated and tested for neutralizing activity in vivo and in vitro. The corneal pathology of the S. epidermidis protease was compared to the pathology of S. aureus V8 protease. Strains that exhibited the least protease activity in vitro caused significantly less ocular pathology in vivo (p ≤ 0.003). Strains that were hemolytic and secreted a major protease had numerically higher SLE scores. This protease was identified as the serine protease Esp. The recombinant Esp protease caused extensive pathology when injected into the corneal stroma (7.62 ± 0.33). Antibody generated against native Esp did not neutralize the activity of the protease in vivo or in vitro. The antibody reacted with Esp proteases secreted by other S. epidermidis strains. S. epidermidis Esp protease and its homologue in S. aureus caused similar ocular pathology when injected in the rabbit corneal stroma. Hemolysins and proteases seem to be important in corneal pathology caused by S. epidermidis infections. The Esp protease mediates significant corneal damage. S. epidermidis Esp and S. aureus V8 protease caused similar and extensive edema in rabbit corneas. [ABSTRACT FROM AUTHOR]

Purpose: Both borneol and danshensu are bioactive substances derived from traditional Chinese medicine. In this paper, the effect of borneol on the distribution of danshensu to the eyes in rabbits via oral administration was investigated. Methods: The rabbits were injected danshensu (1.0 g/kg) into the auris dextra vein 15 min after intragastric administration of borneol and the danshensu concentrations in plasma, aqueous humor, and vitreous humor were measured by high-performance liquid chromatography. Draize test was used to examine the eye irritation. Results: Compared with the administration of danshensu alone, danshensu concentrations co-administrated with borneol in plasma were between 60.99 and 722.90 μg/ml. Peak times ( Tmax) in both groups appeared at 0 min; however, compared with the control group, the values were not statistically significant although they differ ( P > 0.05). The concentrations of danshensu in aqueous humor and vitreous humor in test group are higher than that in control group. The difference was statistically significant ( P < 0.05). Tmax in both groups appeared at 25 min. Neither irritation nor inflammatory reaction was found during the examinations. Conclusion: The results suggest that the promoting effect of borneol on the permeability of drugs through the blood–ocular barrier in vivo is obvious, which indicates that borneol has the potential to be used as an ocular penetration enhancer. [ABSTRACT FROM AUTHOR]

Several older studies on rabbits indicated that the pre-corneal tear film was unusually stable and this perspective was revisited recently. However, the methods used for these studies were very different from those generally used in human studies. A literature search was undertaken for the time period of 1965 through 2017, mainly using PubMed, to identify studies where values for the tear break up time (TBUT) were reported for the eyes of nominally normal (healthy) laboratory rabbits regardless of breed or age and where the methods were more similar to those routinely used in human clinical studies. For 20 reports identified where sodium fluorescein was used, the average TBUT values in any particular study ranged from 1.9 to 51 s, with a group mean of 21.8 ± 11.9 s (SD), with the inter-study variability in TBUT (as the coefficient of variation) being 19.4%. For four studies not using fluorescein, the mean break up time reported was 32.7 ± 16.2 s, while a separate study (also not using fluorescein) reported an average break up time of 1788 s. Most reports of the pre-corneal tear film stability in laboratory rabbits, especially as reported over the last 10 years, indicate break up times of less than 60 s have been observed, although has been little consistency in the methods used. Overall, this outcome is not consistent with a perspective that the rabbit (as routinely used in experimental studies) has an extraordinarily stable tear film. [ABSTRACT FROM AUTHOR]

Purpose: This study analyzed the toxicity of purified gamma-toxin fromStaphylococcus aureusand the protectiveness of antisera to gamma-toxin in the rabbit cornea. Materials and methods: Gamma-toxin was purified from cultures of alpha-toxin deficientS. aureusstrain NewmanΔhla. Antisera to native gamma-toxin (Hlg) were produced in rabbits. These antisera and a commercial polyclonal antibody to recombinant HlgB (rHlgB) were analyzed for specificity and toxin neutralization. Heat-inactivated gamma-toxin, active gamma-toxin either alone or with antisera or with commercial antibody to rHlgB, was injected into the rabbit cornea to observe the pathological effects using slit lamp examination scoring (SLE) and histological analyses. Results: Eyes with intrastromal injection of gamma-toxin developed SLE scores that were significantly higher than eyes injected with heat-inactivated gamma-toxin (p≤ 0.003). Slit lamp and histological examination of eyes revealed that gamma-toxin injected into the cornea mediated conjunctival injection and chemosis, iritis, fibrin accumulation in the anterior chamber, and polymorphonuclear neutrophil infiltration of the cornea and iris. Also, eyes injected with gamma-toxin plus antisera to native whole gamma-toxin or HlgB, but not with commercial antibody to rHlgB, yielded significantly lower SLE scores than eyes injected with gamma-toxin alone (p≤ 0.003). Conclusions: This study illustrates thatS. aureusgamma-toxin is capable of causing significant corneal pathology. Furthermore, the use of polyclonal antisera specific for native gamma-toxin was found to inhibit the damaging effects of the toxin in the rabbit cornea. [ABSTRACT FROM PUBLISHER]

Purpose: Evaluate toxicity of acai fruit (Euterpe oleracea) dye concentrations in a rabbit model. Methods: Rabbits were injected intravitreously with 10%, 25%, and 35% acai dye concentrations. Control eyes received balanced salt solution (BSS). Electroretinogram (ERG), fundus imaging, fluorescein angiography (FA), optical coherence tomography (OCT), and light and transmission electron microscopy (LM/TEM) were performed. Results: Fundus imaging showed increased vitreous opacity with increased dye concentrations. FA and OCT showed normality with all concentrations. Comparisons between BSS and dye concentrations were analyzed using Kruskal–Wallis and Mood’s median test (p< 0.05). At 24 h, ERGs showed reduced amplitudes from baseline in all eyes. Median b-wave amplitudes nonsignificantly decreased and latency increased with 10% and 25%; findings were significant (p< 0.05) for 35%. LM and TEM showed no abnormalities for 10% and 25%. With 35%, TEM showed ganglion cell edema at 24 h that resolved after 7 days. Vacuolization, multilamellar bodies, and nerve bundle damage occurred at 24 h/7 days in the inner nuclear layer. Mitochondrial cristae disruption occurred in the inner photoreceptor segment at 24 h that decreased by 7 days. Conclusion: Ten and twenty-five percent concentrations were safe and may improve identification of the posterior hyaloid and internal limiting membrane during chromovitrectomy in humans. [ABSTRACT FROM PUBLISHER]

Purpose: To evaluate the safety and efficacy of a membrane-tube-type glaucoma shunt device (MT-device), which was developed to control intraocular pressure (IOP) with a lower chance of complications than conventional glaucoma surgery, in a rabbit model. Materials and Methods: The MT-device consists of an expanded polytetrafluoroethylene membrane (thickness 0.2 mm, area 2.5 × 2.5 mm2) and a tube (internal diameter 76 µm, external diameter 175.5 µm, length 7 mm) attached to the membrane. The device was implanted into the left eyes of nine New Zealand white rabbits. The tube was placed in the anterior chamber through paracentesis, and the membrane was fixated on the scleral surface; this induces aqueous drainage from the anterior chamber to the subconjunctival space. IOP, filtering bleb morphology, depth and inflammation of the anterior chamber, and possible complications were evaluated periodically for 8 weeks after surgery. Histological sections were analyzed at 2 and 8 weeks after the surgery. Results: Mean IOP decreased from a preoperative value of 8.7 ± 1.2–4.7 ± 0.6 mmHg at postoperative 8 weeks (p < 0.05). The filtering bleb was maintained during the study period. There were no major postoperative complications. Histologic assessment revealed that 2 weeks after the surgery, fibrous encapsulation, inflammatory cells, and fibroblasts were observed around the MT-device; however, 8 weeks after the surgery, minimal inflammation was observed. Conclusions: The MT-device showed good biocompatibility and effective IOP reduction with a low risk of complications in a rabbit model. [ABSTRACT FROM AUTHOR]

Purpose: Several studies showed that repeated topical administration of brimonidine tartrate ophthalmic solution reached the human vitreous concentration above 2 nM, which is the concentration necessary to activate the α2-adrenergic receptor. The purpose of this study was to elucidate the relationship of the brimonidine concentration in the vitreous body to the free concentration in the retina/choroid which is the target site of brimonidine on neuroprotective effect after topical administration. Materials and methods: Brimonidine concentrations in the eye tissues of pigmented rabbits were determined following single ocular administration of 0.1% brimonidine tartrate ophthalmic solution at pH 7.3. Binding affinity of brimonidine to melanin and melanin content in the retina/choroid of pigmented rabbits was also examined. The concentration of free brimonidine which did not bind to melanin in the retina/choroid was calculated using the binding parameters to melanin. Results: Topically applied brimonidine rapidly distributed to intraocular tissues. The elimination rate from melanin-containing tissues such as the iris/ciliary body and retina/choroid was slower than the aqueous humor and vitreous body in pigmented rabbits. In both the anterior and posterior retina/choroid, the free brimonidine concentrations were over 100-fold lower than the total concentrations. The concentrations in the vitreous body closely matched to the free concentrations in the posterior retina/choroid. Simulated free concentrations in the posterior retina/choroid were gradually increased when 0.1% solution was instilled twice daily. Conclusion: The present data indicated that the brimonidine concentration in the vitreous body was comparable to the free concentration in the posterior retina/choroid. This suggests that the vitreous concentration can be a surrogate indicator of the free brimonidine concentration in the posterior retina/choroid. From the present findings, it is expected that multiple instillation of brimonidine tartrate ophthalmic solution may produce the sufficient free concentration for activation of the α2-adrenergic receptor in the retina/choroid in human. [ABSTRACT FROM PUBLISHER]

Purpose: To compare the safety and efficacy of intravitreal anidulafungin injection with voriconazole and amphotericin B (Amp B) in an experimentalCandidaendophthalmitis (CE) model. Methods: Intravitreal 1 × 105CFU/0.1 mlCandida albicanswas injected into the right eyes of 24 New Zealand rabbits, which were divided into 4 groups. Voriconazole 50 μg/0.1 ml, Amp B 10 μg/0.1 ml, and Anidulafungin 50 μg/0.1 ml were injected by intravitreal injection 72 h after inoculation. The control group was injected with 0.1 ml 0.9% NaCl. Clinical scoring was performed by assessing the cornea, conjunctiva, iris, and vitreous on days 3 and 7 of therapy. At the end of the study, the right eyes of all rabbits were enucleated and histopathological evaluation was performed. Therapy groups were compared according to the clinical, histopathological, and microbiological analysis scores. Results: Total clinical scores were significantly different between treatment groups and the control group (p< 0.05). On day 7 of the therapy, clinical scores of the anidulafungin group were found to be significantly lower when compared with the other therapy groups, while a significant improvement was observed in the eyes of rabbits in the anidulafungin group (p< 0.05). Also, microbiological scores of the anidulafungin group were lower than those of the control group (p< 0.05). Histopathological scores of the anidulafungin treatment group were significantly better than the voriconazole and control groups. Inflammation was evidently suppressed and marked retinal toxicity was not observed with anidulafungin. Conclusions: This is the first study comparing the efficacy of anidulafungin with other antifungal agents. In this CE model, an intravitreal single dose of anidulafungin was shown to be noninferior to voriconazole and Amp B. As an alternative to Amp B or voriconazole, intravitreal anidulafungin is suggested as an effective antifungal agent for the treatment of CE. [ABSTRACT FROM PUBLISHER]

Purpose: We attempted to develop anti-glaucoma eye drops using 0.5% disulfiram (DSF), 5% 2-hydroxypropyl-β-cyclodextrin, 0.1% hydroxypropylmethylcellulose, and 2% methylcellulose (MC) (DSF eye drops with MC), and tested the ability of a DSF eye drops with MC to reduce intraocular pressure (IOP) in rabbit models. Methods: Elevated IOP was induced by the rapid infusion of 5% glucose solution (15 ml/kg of body weight) through the marginal ear vein or by keeping rabbits in the dark for 5 h. IOP and the nitric oxide (NO) level in the aqueous humor were measured with an electronic tonometer and by a microdialysis method, respectively. ΔIOP and ΔNO values were analyzed as the differences in IOP and NO in rabbits instilled with saline or eye drops, respectively. Results: Increased IOP in rabbit models was reduced by the instillation of DSF eye drops with or without MC, and a close relationship was observed between IOP and NO levels in rabbit receiving a rapid infusion of isotonic glucose. We present kinetic parameters [secondaryAUC(prolonged drug effect) and secondaryMRT(prolonged effective time)] analyzed as the area under the curve (AUC) of ΔIOP or ΔNO versus time using rabbits instilled with eye drops 10, 50, or 90 min prior to the infusion of the isotonic glucose solution. The elevations in IOP and NO level were reduced by the instillation of DSF eye drops with or without MC; the addition of MC increased the secondaryAUCandMRTof DSF eye drops. Conclusions: The present study demonstrates that 0.5% DSF eye drops suppress increased IOP in rabbit models, probably by inhibiting the elevation in NO levels. In addition, we propose a kinetic analysis method to predict drug effects and effective time. These findings suggest that a low-substituted MC-based drug delivery system promotes drug effectiveness and effective time. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the involvement of VEGF in corneal neovascularization (CNV) following sulfur mustard (SM) exposure and to test the therapeutic effects of bevacizumab (Avastin) in respect to dose, route of administration and timing. Materials and methods: Topical bevacizumab (6 or 25 mg/ml, ×2/day) was applied to rabbit eyes, before or after appearance of NV, following SM vapor exposure, and was compared with subconjunctival injection (25 mg/ml, ×2/week) and topical dexamethasone (1%, ×4/day). Treatments were given for 3 weeks. VEGF levels were monitored by immunohistochemistry and ELISA assay. Clinical evaluations included slit-lamp examination, impression cytology for diagnosis of Limbal Stem Cell Deficiency (LSCD), pachymetry, measurement of NV length and histology. Results: Corneal NV was developed, as early as 2 weeks after exposure, in 50-70% of the eyes, associated with increased levels of VEGF. Topical bevacizumab treatment with both doses, starting at 4 weeks, reduced vascularization. Subconjunctival injection and topical dexamethasone were more potent. A combined treatment of dexamethasone and bevacizumab improved the anti-angiogenic efficacy, yet, there was no effect on LSCD. Topical bevacizumab treatment starting at 1 week, when VEGF was elevated but before appearance of NV, had no effect. Conclusions: VEGF was involved in corneal angiogenesis in SM-induced ocular injury. Bevacizumab was beneficial in reducing CNV by both, topical or subconjunctival injection, when given as a symptomatic therapy with or without dexamethasone, however with no effect on SC deficiency. Further studies on the pathological mechanism of SM-induced ocular surface disorder may direct towards improved therapy. [ABSTRACT FROM AUTHOR]

Aim: To study the effects of intravitreally injected triamcinolone acetonide (TA) and/or its preservative benzyl alcohol (BA) in healthy rabbit retina. Methods: Forty-eight rabbits (aged 4 months, body weight ≈3 kg) were randomized into four groups ( n = 12). They were examined with electroretinography (ERG) prior to drug exposure, and then injected intravitreally with a combination of TA and BA, TA without BA, BA alone or a balanced saline solution (BSS). The electroretinograms were assessed 1 week and 7 weeks post-injection. The rabbits were euthanized and the sectioned retinas were studied. Immunohistochemical analysis was performed on rods, cones, rod bipolar cells, horizontal cells, amacrine cells and Müller cells. Results: Rabbits injected with BA showed a significantly lower rod-mediated b-wave amplitude than the controls 1 week after injection. TA-injected rabbits demonstrated significantly higher a- and b-wave amplitudes in the total retinal response than the controls 1 week post-injection. The rabbits injected with TA + BA demonstrated a significantly higher b-wave amplitude in the total retinal response than the controls 1 week after injection. The significantly higher a-wave amplitude in the total retinal response remained in the TA-injected rabbits 7 weeks after injection. Immunohistochemistry revealed that protein kinase C alpha (PKC α) was down-regulated in both the perikarya and the axons of bipolar cells in histological sections from rabbit retina injected with TA + BA, BA and TA. Conclusions: Intravitreal injection of the preservative BA reduces the isolated rod-mediated retinal response in the rabbit, transiently and selectively. Intravitreal injection of TA increases the total retinal response in the rabbit up to seven weeks after injection. The effects observed are not only limited to retinal function, but also include changes in the expression of PKC α in rod bipolar cells, indicating drug-related interference with normal retinal physiology in the healthy rabbit eye. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the potential toxicity of multiple intravitreal injections of bevacizumab on the uveal capillaries of rabbit eyes. Materials and methods: Nine eyes of nine rabbits that received single intravitreal injections of bevacizumab (IVB) constituted the single IVB group, while nine eyes of nine rabbits that received three injections of IVB, with an interval of 28 days between injections, constituted the repeat IVB group. Seven eyes of seven rabbits constituted the control group. The rabbits in the single and repeat IVB groups were sacrificed 7 and 28 d after the single and third IVB injection, respectively. Uveal specimens were compared between groups after immunohistochemical staining. Ultrastructural findings were evaluated by electron microscopy. Control group rabbits were sacrificed 7 d after saline injection. Clinical examination and fundus fluorescein angiography were performed at baseline, 7 d after the first injection, and after the last injection. Results: Differences in the CD31-positive areas of the iris, ciliary body and choroid 7 d after IVB were not statistically significant among the single IVB, repeat IVB and control groups ( p = 0.0749, p = 0.7237 and p = 0.7346, respectively; analysis of variance). Endothelial cell fenestrations (ECFs) in the choriocapillaris and ciliary body observed by electron microscopy on day 7 in the single and repeat IVB groups were decreased by 50% ( p < 0.0001) and 33% ( p < 0.0001), respectively, in both IVB groups compared with those in the control group. However, ECFs observed on day 28 in both groups were comparable to those observed in the control group. Conclusions: Single IVB and repeated IVB did not have any effect on normal vessel endothelium density as per immunohistochemical findings. Ultrastructural findings revealed that IVB transiently decreased the ECFs in the choriocapillaris and ciliary body. [ABSTRACT FROM AUTHOR]

Purpose: New treatments against long-lasting uveitis need to be tested. Our aim was to develop a six-week model of uveitis in rabbits. Methods: Rabbits were presensitized with an s.c. injection of Mycobacterium tuberculosis H37RA emulsified with TiterMax® Gold adjuvant. Uveitis was induced at day 28 and 50, by intravitreal challenges of antigen suspension. Ocular inflammation was assessed till euthanasia at day 71 after s.c. injection of M. tuberculosis H37RA by: (a) the number of inflammatory cells in aqueous humor (AH); (b) the protein concentration in AH; (c) the clinical score (mean of conjunctival hyperaemia, conjunctival chemosis, oedema and secretion); (d) the microscopical score (mean presence of fibrin and synechiae, aqueous cell density and aqueous flare grade, as scored by slit lamp). Results: At the sites of presensitization injection, rabbits presented flat nodules which progressively vanished. The first challenge induced a significant increase in the four parameters ( p < 0.05 the Wilcoxon/Kruskal-Wallis test). The AH contained 764 ± 82 cells/µl and 32 ± 0.77 mg protein/ml. During the following days, inflammatory parameters decreased slightly. The second intravitreal challenge increased inflammation (3564 ± 228 cells/µl AH and 31 ± 1 mg protein/ml), which remained at a high level for a longer period of time. Conclusion: We developed a model of long-term uveitis, which could be maintained in rabbits for at least six weeks. Such a model could be used to test the efficacy of either new drugs or various drug delivery systems intended to deliver active agents during a few months. [ABSTRACT FROM AUTHOR]

Purpose: To assess density and spatial distribution of the goblet cell orifices at the surface of the rabbit bulbar conjunctiva as an indicator of functional activity. Methods: Specimens of the superior or inferior bulbar conjunctiva from six healthy young adult (2 kg) pigmented rabbits were obtained using a special preparation technique by which the conjunctiva was carefully stretched out during fixation with buffered glutaraldehyde. The apical surface of the specimens was examined by scanning electron microscopy. From high magnification prints, the areas and dimensions of 32-49 orifices/image were measured. In addition, the centre-to-centre spacing and spatial distribution of the orifices were assessed using a nearest neighbors principle. Results: The bulbar conjunctival surface is composed of polygonal cells decorated with surface microplicae and in between which are individual goblet cell orifices. The goblet cell orifices are characterized by tending to be oval in shape (long:short dimensions ratio of 1.57 +/− 0.23) and usually having a distinct line of microvilli around the perimeter. The orifices had a wide range of areas (from 13 to 188 μm2; group mean +/− SD of 54 +/− 36 μm2), and distribution of orifice areas was skewed or even bimodal. The overall orifice density was 387 +/− 68/mm2, with the group-averaged nearest neighbors distance being 34 +/− 3 μm. Comparisons of the measured nearest neighbors distances to that for an optimum spacing based on numerical density reveals the goblet cell orifices to be slightly further apart and that they were not obviously in groups or clustered. Conclusions: Goblet cell orifices at the bulbar conjunctival surface, a presumed indicator of functional secretory activity, appear to have reproducible density and a discrete and reasonably predictable spatial distribution. [ABSTRACT FROM AUTHOR]

Purpose: We investigated the role that the cystic fibrosis transmembrane conductance regulator (CFTR) may play in Cl− transport in the acinar and ductal epithelial cells of rabbit lacrimal gland (LG). Methods: Primary cultured LG acinar cells were processed for whole-cell patch-clamp electrophysiological recording of Cl− currents by using perfusion media with high and low [Cl−], 10 µM forskolin and 100 µM 3-isobutyl-1-methylxanthine (IBMX), the non-specific Cl− channel blocker 4,4′-disothiocyanostilbene-2, 2′ sulphonic acid (DIDS; 100 µM) and CFTRinh-172 (10 µM), a specific blocker for CFTR. Ex vivo live cell imaging of [Cl−] changes in duct cells was performed on freshly dissected LG duct with a multiphoton confocal laser scanning microscope using a Cl− sensitive fluorescence dye, N-[ethoxycarbonylmethyl]-6-methoxy-quinolinium bromide. Results: Whole-cell patch-clamp studies demonstrated the presence of Cl− current in isolated acinar cells and revealed that this Cl− current was mediated by CFTR channel. Live cell imaging also showed the presence of CFTR-mediated Cl− transport across the plasma membrane of duct cells. Conclusions: Our previous data showed the presence of CFTR in all acinar and duct cells within the rabbit LG, with expression most prominent in the apical membranes of duct cells. The present study demonstrates that CFTR is actively involved in Cl− transport in both acinar cells and epithelial cells from duct segments, suggesting that CFTR may play a significant role in LG secretion. [ABSTRACT FROM AUTHOR]

Purpose/Aim: To explore changes in morphology and function in the rabbit retina after intravitreal high-dose injection of three commonly used VEGF inhibitors. Materials and methods: Forty-eight rabbits of mixed strain (6 months of age, body weight ≈≈ 3 kg) were randomized into four groups ( n == 12). They were examined with full-field electroretinography (ERG) and with multifocal electroretinography (mf ERG) prior to drug exposure. The rabbits were then injected intravitreally with bevacizumab, ranibizumab, pegaptanib, or with a balanced saline solution. The dose of VEGF inhibitor was chosen to achieve a vitreous concentration approximately three times higher than the one clinically used in the adult human eye. ERG was then performed 8 weeks postinjection, and mf ERG 9 weeks postinjection. After 9 weeks, the rabbits were sacrificed and the sectioned retina was studied. Immunohistochemical analysis was performed of rods, cones, rod bipolar cells, horizontal cells, and amacrine cells. Results: Rabbits injected with VEGF inhibitors all showed significantly lower amplitude of the dark-adapted b-wave rod-mediated response to dim light, compared to the rabbits injected with BSS. The a wave (reflecting photoreceptor function) in the response to single flash white light was however not affected. Immunohistochemistry revealed a significant reduction in PKC labeling of rod bipolar cells in pegaptanib and ranibizumab injected eyes whereas bevacizumab injected eyes displayed normal PKC labeling. No apparent morphological change was seen with markers for remaining retinal cells. Conclusions: Our results indicate that the use of high-dose intravitreal VEGF inhibitors in the rabbit eye affects rod-mediated retinal function and PKC expression in rod bipolars cells for at least 9 weeks after drug administration. The three VEGF inhibitors influence the retina slightly differently. These results are important for the understanding of drug action and when devising therapeutical strategies in new areas such as retinopathy of prematurity where vitreous volume is significantly lower compared to the adult eye. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of osmolarity on the transepithelial permeability of riboflavin solutions in a cross-linking procedure. Methods: Several riboflavin 0.1% solutions that contained different NaCl and benzalkonium chloride (BAC) concentrations were applied to 36 rabbit eyes for 30 min. To serve as a control, the epithelium was removed in group A (standard protocol). The groups then received the following solutions: (A) riboflavin 0.1% in NaCl 0.9% solution; (B) riboflavin 0.1% in NaCl 0.44% solution with BAC 0.02%; (C) riboflavin 0.1% in NaCl 0.44% solution with BAC 0.01%; (D) riboflavin 0.1% in NaCl 0.44% solution without BAC; (E) riboflavin 0.1% in NaCl 0.9% solution with BAC 0.02%; and (F) riboflavin 0.1% in NaCl 0.9% solution without BAC. Six eyes in each group were treated. The absorption coefficients of the corneas were measured to characterize the riboflavin penetration into the cornea. Results: There is a large difference in the transepithelial riboflavin penetration of riboflavin 0.1% ++ BAC 0.02% solutions that contain different NaCl concentrations (NaCl 0.9% versus NaCl 0.44%). The absorption coefficients differed by more than a factor of two ( P == 0.004). No statistically significant difference was found between riboflavin 0.1% in NaCl 0.44% solution containing BAC 0.02% and BAC 0.01%. Compared to the standard protocol, these solutions resulted in an absorption coefficient of 37% (BAC 0.02%) and 33% (BAC 0.01%) of the standard epithelium-off procedure. Conclusion: The transepithelial riboflavin solution should contain no dextran, but it should include 0.01% BAC and 0.44% NaCl to promote the permeability of riboflavin through the epithelium, resulting in a sufficient concentration of riboflavin in the corneal stroma. [ABSTRACT FROM AUTHOR]

Purpose: The purposes of this study were to investigate the effects of topically administrated Tacrolimus and Octreotide on modulation of postoperative scarring in experimental glaucoma filtration surgery and to compare the antifibrotic properties of these agents with mitomycin-C (MMC). Material and methods: A total of 28 New Zealand rabbits weighing 2.5-3 kg were randomly divided into a surgical control (SC) group and three experimental groups. Standard filtration surgeries were performed on the right eyes of all the rabbits. The rabbits in the SC group received only vehicle after the surgeries, whereas the rabbits in the three experimental groups were treated either with 0.4 mg/mL MMC during the surgery (MMC group) or with 0.3 mg/mL Tacrolimus drop four times a day (TT group) or with 10 µg/mL Octreotide drop three times a day (OT group) for 14 days. The animals were killed on day 14, eyes were enucleated and histologically and immunohistochemically analyzed. Results: In SC group mean fibroblast, mononuclear cell number and fibroblast growth factor-β (FGF-β), transforming growth factor-β (TGF-β) immunostaining intensity was higher than all treatment groups. In OT group mean fibroblast number was lesser than MMC ( p < 0.01) and TT ( p < 0.05) group. In TT group mean fibroblast number was lesser than MMC group ( p < 0.05). Mean mononuclear cell number was similar between MMC, OT and TT groups ( p > 0.05). In MMC, OT and TT groups mean TGF-β and FGF-β immunostaining intensity was similar ( p > 0.05). Conclusions: Topically administration of Tacrolimus and Octreotide effectively reduced the subconjuntival scarring response 2 weeks after experimental glaucoma filtration surgery. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the cytotoxicity of benzalkonium chloride (BAC)-containing ophthalmic solutions of prostaglandin analogs (latanoprost, travoprost, bimatoprost, and preservative-free (PF) tafluprost), BAC mixture (BACmix) and BAC homologs with different alkyl chain lengths using human corneal epithelial (HCE) and conjunctival epithelial (IOBA-NHC) cell cultures. The distribution of BAC homologs in rabbit ocular surface tissues in vivo was examined. Methods: The cells were exposed for one hour to prostaglandin analogs, BACmix and three homologs. Cytotoxicity was assessed with the WST-1 and lactate dehydrogenase (LDH) assays for cellular viability and cell membrane integrity. BAC 0.02% solution was instilled on the rabbit eye daily for 14 days and the concentrations of BAC homologs in external ocular tissues were determined. Results: The order of decreasing cytotoxicity in the WST-1 test was latanoprost ≥ travoprost > bimatoprost ≥ PF tafluprost. IOBA-NHC cells were more sensitive than HCE cells. In HCE, only latanoprost diluted to 10% increased LDH leakage. In IOBA-NHC, LDH leakage was statistically significant with 3-10% travoprost and 10% latanoprost. The order of decreasing cytotoxicity of preservatives was C14 > C12 > BACmix > C16 in HCE and C12 > C14 > BACmix > C16 in IOBA-NHC. Following treatment with BAC 0.02% solution, the amounts of BAC-C12, -C14 and -C16 in rabbit cornea and conjunctiva, respectively were: 0.37 ± 0.08 and 2.64 ± 0.27 ng/mg; 0.42 ± 0.07 and 4.77 ± 0.43 ng/mg; 0.04 ± 0.01 and 0.54 ± 0.05 ng/mg. Conclusions: The cytotoxic effects of latanoprost, travoprost, and bimatoprost were dependent on the BAC concentration in their formulations. BACmix was cytotoxic at the concentrations above those corresponding to 0.001% BAC in ophthalmic medications. PF tafluprost was the least toxic of the drugs tested. Within studied BAC homologs, those with longer alkyl chain and higher lipophility penetrated effectively into rabbit external ocular tissues. [ABSTRACT FROM AUTHOR]

Purpose: Staphylococcus aureus, a leading cause of bacterial keratitis, secretes α-toxin, a cytotoxin active on the corneal epithelium. This study describes the production and testing of chemical inhibitors of α-toxin action. Methods: Purified α-toxin was titered by its ability to lyse rabbit erythrocytes in buffered saline (PBS). To prepare potential toxin inhibitors, each of 18 lipids was incorporated into a complex with methyl-β-cyclodextrin (MβCD) or hydroxypropyl-β-cyclodextrin (HPβCD). Serial dilutions of each lipid-cyclodextrin (CD-lipid) complex were mixed with α-toxin prior to the addition of rabbit erythrocytes. Select CD-lipid complexes were mixed with 12 hemolytic units (HU) α-toxin and injected into the rabbit corneal stroma so the resulting corneal erosions could be measured at 4 and 8 hours post-injection (PI). Eyes injected with toxin alone, MβCD, or HPβCD alone served as controls. Results: Neither form of CD alone inhibited α-toxin. Of the 36 complexes prepared, 6 lipid-CD complexes were found to inhibit >100 HU of α-toxin. Four lipid complexes able to inhibit >200 HU of α-toxin were tested in toxin-injected corneas; at 4 and 8 hours PI, the complexes of cholesterol or lanosterol with MβCD and squalene or desmosterol with HPβCD caused a significant reduction in the corneal erosion size as compared to eyes injected with α-toxin alone ( P ≤ 0.05). Conclusions: Specific lipid inclusion complexes with either MβCD or HPβCD demonstrated a significant inhibition of α-toxin in both in vitro and in vivo assays. Changes in either the cyclodextrin or lipid of a complex affected the inhibitory activity. [ABSTRACT FROM AUTHOR]

Purpose: To compare the intravitreal pharmacokinetic profile of a triamcinolone acetonide formulation containing the preservative benzyl alcohol (TA-BA) versus a preservative-free triamcinolone acetonide formulation (TA-PF), and evaluate potential signs of toxicity to the retina. Methods: A total of 60 New Zealand male white rabbits, divided into two groups, were studied. In the TA-BA group, 30 rabbits received an intravitreal injection of TA-BA (4 mg/0.1ml) into the right eye. In the TA-PF group, 30 rabbits received an intravitreal injection of TA-PF (4 mg/0.1ml) into the right eye. The intravitreal drug levels were determined in 25 animals from each group by high-performance liquid chromatography (HPLC). The potential for toxicity associated with the intravitreal triamcinolone injections was evaluated in five randomly selected animals from each group by electroretinography (ERG) and by light microscopy. Results: Median intravitreal concentrations of TA-BA (µg/ml) were 1903.1, 1213.0, 857.8, 442.0, 248.6 at 3, 7, 14, 21 and 28 days after injection. Intravitreal concentrations of TA-PF (µg/ml) were 1032.9, 570.1, 516.6, 347.9, 102.8 at 3, 7, 14, 21 and 28 days after injection. The median intravitreal triamcinolone concentration was significantly higher in the TA-BA compared to the TA-PF group at 7 days post-injection ( p < 0.05). There was no significant difference between the two groups in median triamcinolone concentration at the other time points evaluated. There was no evidence of toxic effects on the retina in either group based on ERG or histological analyses. Conclusions: Following a single intravitreal injection, the median concentration of triamcinolone acetonide is significantly higher in the TA-BA compared to the TA-PF group at 7 days post-injection. No toxic reactions in the retina were observed in either group. [ABSTRACT FROM AUTHOR]

Aims: To test the hypotheses that some epithelial cells in the rabbit lacrimal gland (LG) are mucin-secreting cells that are also particularly rich in aquaporin 5 (AQP5) and sodium potassium ATPase β1 subunit (NKAβ1), LG-secreted mucins contribute to the total mucin pool in tear film, and that the rabbit LG is a heterogenic gland where proteins secreted in response to different agonists are varied. Materials and methods: LGs were obtained from adult female rabbits and processed for paraffin sections for hematoxylin and eosin (HE) staining, periodic acid-Schiff (PAS), mucicarmine, and Alcian blue (pH 0.4, 1.0, and 2.5) for the detection of mucins. Serial sections were used for immunohistochemistry (IHC) and PAS. LG lysates and fluids were assayed by dot blot for detection of mucins, and by SDS-PAGE to detect differences in protein profiles of LG fluids stimulated by different agonists. Results: HE staining demonstrated that the LG is a heterogeneous gland where most epithelial cells are serous, while all duct cells are mucous cells. Some acini and individual acinar cells within serous acini are also mucous or seromucous cells and these cells are particularly rich in AQP5 and NKAβ1. Dot blot assay showed the presence of mucins in the LG fluids. The protein profiles of LG fluids from pilocarpine, phenylephrine, and isoproterenol varied significantly, particularly in the mid range. Conclusions: Our data indicated that the rabbit LG is a heterogeneous gland that is composed of both serous and mucin-secreting cells, and mucins produced by the LG contribute to the mucin pool in the tear film. The heterogeneity of the rabbit LG supports the notion of differential secretion, i.e. the volume and composition of the LG fluids vary depending on various circumstances in the ocular surface and the body's needs. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate ' in vivo' the effect of topical travoprost on the central corneal thickness (CCT) of rabbit eyes, and the changes in the CCT after acute increases of intraocular pressure (IOP) in these eyes. Materials and Methods: This is an interventional, prospective, case-control, masked study. Topical travoprost was applied once daily for one month to the right eye of six New Zealand male rabbits, the left eye of each animal served as control. The baseline CCT and IOP were measured under general anesthesia. After the IOP was stabilized at 15 and 30 mmHg, as registered by direct cannulation of the anterior chamber, CCT measurements were measured again at both pressure levels. Results: The baseline CCT was thicker in eyes previously treated with travoprost (study group) than in control eyes ( p < 0.01). The CCT decreased in both groups when IOP was raised to 15 and 30 mmHg, and there were no statistically significant difference in absolute CCT values between study and control eyes at any of the IOP levels ( p == 0.5). However, the amount of CCT decrease from baseline values was greater in eyes previously treated with travoprost (study group) than in control ones, at both 15 and 30 mmHg IOP levels ( p == 0.01 and 0.02, respectively). Conclusions: Rabbit corneas treated with topical travoprost show a different strain response to acute increases in IOP than control eyes. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of acupuncture on rabbit tear secretion and compare the difference in tear protein expression caused by acupuncture. Materials and Methods: Ten male New Zealand White rabbits were enrolled in this study. The following acupoints around the left eye, Extra 1 (Taiyang), BL 2 (Zanzhu) and SJ 23 (Sizhukong), were selected for acupuncture therapy. Each rabbit received 10 acupuncture sessions of 30 min, three times per week. A quantity of 50 μl rabbit tear was collected at the pre- and post-acupuncture stage in every subject, respectively. Total protein content analysis, one-dimensional gel electrophoresis and quantitative proteomics analysis (iTRAQ) were performed and the results were compared. Results: Generally, the tear protein expression after acupuncture was different from that before acupuncture though to some extent they were similar. The time spent collecting rabbit tear after acupuncture was shorter than that before acupuncture. The total protein content in rabbit tear pre- and post-acupuncture was 7.12 μg/μl versus 11.28 μg/μl, respectively. One-dimensional gel electrophoresis showed that tear proteins collected before acupuncture were substantially different than post-acupuncture proteins. In total, twenty-eight tear proteins were identified by iTRAQ. Associated with acupuncture were six up-regulated proteins (tear lipocalin, α-1-antiproteinase, histidine-rich glycoprotein, hemopexin, Vitamin D-binding protein, α-2-HS-glycoprotein) and five down-regulated proteins (Annexin A1, serum amyloid A-3 protein, Helicase-like transcription factor, 15 kDa protein A, protein S100-A9). Conclusions: The rabbit tear protein expression difference caused by acupuncture indicates that acupuncture not only stimulates lacrimal gland secretion function but also induces the quantitative change of some proteins in rabbit tear, which may support a positive effect of acupuncture in the treatment of dry eye. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of Y-39983, a selective Rho-associated coiled coil-forming protein kinase inhibitor, on blood flow in the optic nerve head (ONH) in rabbits and axonal regeneration of retinal ganglion cells (RGCs) in rats. Methods: Blood flow in ONH was measured by the laser speckle method after topical administration of 0.05% Y-39983 solution or its vehicle in rabbit eyes. To investigate the effects of Y-39983 on axonal regeneration of RGCs, RGCs purified from rat eyes were cultured with or without 10 μM Y-39983 and morphologically observed by phase-contrast microscopy. Moreover, the effects of intravitreal administration of Y-39983 were evaluated using an in vivo model of axotomized RGCs in peripheral nerve-grafted rats. Results: Topical administration of 0.05% Y-39983 solution significantly increased blood flow in ONH compared with the vehicle group in rabbits. Maximum increase in blood flow in the 0.05% Y-39983 group was 122.84 ± 5.98 % (Mean ± S.E.) at 90 minutes after administration compared with before administration. Neurites in rat RGCs treated with 10 μM Y-39983 were extended compared with those without Y-39983 treatment of RGCs in vitro. Y-39983 dose-dependently increased the number of RGCs with regenerating axons in vivo. The numbers of RGCs with regenerating axons in 10 and 100 μM Y-39983-treated rats were 99.3 ± 10.5 and 169.5 ± 43.3 cells/mm2 (Mean ± S.D.), respectively, and significantly increased compared with those in saline-treated rats (43.3 ± 6.0 cells/mm2). Conclusion: Y-39983 may be a candidate drug not only for lowering of IOP but also for increasing of blood flow in ONH in the treatment of glaucoma. Moreover, Y-39983 may have therapeutic potential for axonal regeneration of RGCs in the treatment of diseases with degenerating axons of RGCs including glaucoma, although improvements of formulation or route of administration are needed in order to reach an effective concentration in retina. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to use 7.1T magnetic resonance imaging (MRI) to determine the correct anatomical position of a non-metallic glaucoma microstent following implantation in rabbit eyes. Materials and Methods: In an in vitro experiment three microstents (made from silicone, polyurethane, and nickel titanium) were embedded in a standard vial filled with agar. In a second series of experiments a prefabricated polyurethane microstent connecting the anterior chamber with the suprachoroidal space (SCS) was implanted in rabbit eyes ( n == 12). High-resolution images were acquired ex vivo ( n == 6) and in vivo ( n == 6) on an ultra high-field MRI unit using a 2-channel coil with four coil elements and T2-weighted turbo spin-echo sequences. Finally, the eyes were dissected and processed for histology. Results: Artifact-free MR imaging of silicone and polyurethane microstents was achieved in vitro, with slightly higher contrast for silicone stents. Image quality for the nickel titanium stent was greatly reduced due to artifacts. MRI examination of rabbit eyes ex vivo and in vivo following polyurethane microstent implantation presented no problems in terms of the size and placement of the coil. The sequences showed good image quality; the full length of the microstent was visualized in cross-section and longitudinal section, and correct anatomical placement was demonstrated from the anterior chamber into the SCS. These findings were verified by histology. Conclusions: The excellent image quality obtained with both of the non-metallic materials generates detailed information about microstent placement, including the surrounding tissues. High-resolution MRI can be used to monitor the anatomical position of a microstent after glaucoma surgery in animal experiments and is therefore a valuable tool for documenting experimental research findings ex vivo and in vivo. [ABSTRACT FROM AUTHOR]

Purpose: To observe the inhibitory effect of tetrandrine on haze formation after Epi-LASIK surgery in rabbits. Materials and Methods: Twenty-seven healthy New Zealand rabbits were selected and underwent Epi-LASIK surgery. According to a self comparison principle, these rabbits were randomly divided into three groups. The first group was treated with tetrandrine eye drops (Tet), the second (negative control, NC) group was treated with pure solvent, and the third group was treated with fluorometholone (FML) solvent. Haze grades of each group were respectively observed by slit lamp exam at half-month, one month, and two months after surgery. After corneal tissues were extracted, optical microscopy, Sirius Red staining, immunohistochemistry, and semi-quantitative RT-PCR tests were conducted, in order to test collagen formation of operated eyes after surgery and expression of transformation growth factor beta 2 (TGF-ββ2) in corneal stroma. Results: At a half month and one month after surgery, haze grades and type III collagen expression in Tet and FML groups were significantly lower than that in NC groups ( P < 0.01). No statistical difference was observed between Tet and FML groups. Immunohistochemistry showed that, at each time point after surgery, expressions of TGF-ββ2 protein in Tet and FML groups were significantly lower than that in the NC group ( P < 0.01), whereas there was no statistical difference between Tet and FML groups. The expression level of TGF-ββ2 protein increased, reaching its peak one month after surgery. RT-PCR also showed that, at each point after surgery, the TGF-ββ2 mRNA expression in Tet and FML groups was lower than that in the NC group ( P < 0.01), nevertheless no statistical difference was observed between Tet and FML groups. Conclusions: Like FML, Tet could inhibit haze formation in rabbits after Epi-LASIK surgery, possible through TGF-ββ2-collagen-III pathway. [ABSTRACT FROM AUTHOR]

Purpose: Exposure of the cornea to UV radiation from sunlight evokes intraocular inflammation, photokeratitis. Photokeratitis is caused by UVB radiation. It is accompanied by changes of corneal hydration and light absorption. The aim of this study was to examine the effect of two UVB doses on corneal optics in rabbits and to compare these UVB doses with the equivalent exposure of UVB radiation reaching the human cornea from sunlight. Materials and Methods: Rabbit corneas were irradiated with a daily UVB dose of 0.25 J/cm2 or 0.5 J/cm2 for 4 days. One day after finishing the irradiations the rabbits were sacrificed and corneal light absorption measured using our spectrophotometrical method. Corneal hydration was examined using an ultrasonic Pachymeter every experimental day before the irradiation procedure and the last day before sacrificing the animals. Results: Changes in corneal optics appeared after the repeated exposure of the cornea to a UVB dose of 0.25 J/ cm2 and massively increased after the repeated exposure of the cornea to a UVB dose of 0.5 J/cm2. The first significant changes in corneal hydration appeared after a single exposure of the cornea to a UVB dose of 0.25 J/cm2. Conclusions: Changes in corneal hydration appeared after the exposure of the rabbit cornea to a single UVB dose equivalent to 2.6 hours of solar UVB radiation reaching the human cornea, as measured by UVB sensors embedded in the eyes of mannequin heads facing the sun on a beach at noon in July. Repeated exposure of the rabbit cornea to the same UVB dose evoked profound changes in corneal optics. Although comparison of experimental and outdoor conditions are only approximate, the results in rabbits point to the danger for the human eye from UVB radiation when short stays in sunlight are repeated for several consecutive days without UV protection. [ABSTRACT FROM AUTHOR]

Aims: To test the hypothesis that the expression of aquaporins (AQPs) 4 and 5 is altered in the lacrimal glands (LG) of rabbits with induced autoimmune dacryoadenitis (IAD). Materials and Methods: LGs were obtained from adult female rabbits with IAD, and age-matched female control rabbits. LGs were processed for laser capture microdissection (LCM), real time RT-PCR, Western blot, and immunofluorescence for the detection and quantification of protein and mRNAs of AQP4 and AQP5 in whole LGs, and purified acinar cells and duct cells from specific duct segments. Results: In rabbits with IAD, abundances of mRNAs for AQP4 and AQP5 from whole LGs were significantly lower than controls. Levels of mRNA for AQP4 were lower in most duct segments from rabbits with IAD. However, the mRNA abundance for AQP5 was significantly lower in acini from rabbits with IAD, while its abundance was higher in each duct segment. Western blot showed that the expression of AQP4 in LGs from rabbits with IAD was 36% more abundant than normal controls, whereas AQP5 was 72% less abundant. Immunofluorescence indicated that AQP4 immunoreactivity (AQP4-IR) was present on the basolateral membranes of acinar and ductal cells in control and diseased LGs, with ductal cells showing stronger AQP4-IR than acinar cells. AQP5-IR was found on apical and basolateral membranes of acinar cells, and showed a ''mosaic'' pattern, i.e., with some acini and/or acinar cells showing stronger AQP5-IR than others. Minimal AQP5-IR was detected in ductal cells from control animals, while its intensity was significantly increased in rabbits with IAD. Conclusions: These data strongly support our hypothesis that expressions of AQPs are altered in rabbits with IAD, and that specific ductal segment play important roles in lacrimal secretion. [ABSTRACT FROM AUTHOR]

Purpose:The overall objective of this study was to investigate and characterize the expression of folate transport proteins in Staten''s Seruminstitut rabbit corneal (SIRC) epithelial cell line. Methods: [3H]Folic acid uptake was studied with respect to time, pH, temperature, sodium, and chloride ion dependency. Inhibition studies were conducted with structural analogs, vitamins, and metabolic inhibitors. [3H]Folic acid uptake was also determined with varying concentrations of cold folic acid. Uptake kinetics was studied in the presence of various modulators of intracellular regulatory pathways, protein kinases A and C (PKA and PKC), protein tyrosine kinase (PTK), and calcium-calmodulin modulators. Ex vivo corneal permeability studies were carried out with [3H]folic acid in the presence and absence of 1 mM cold folic acid. Results: Linear increase in [3H]folic acid uptake was observed over 30 min. The process followed saturation kinetics with apparent Km of 14.2 ±± 0.2 nM, Vmax of (1.5 ±± 0.1)**10−−5 micro.moles/min/mg protein, and Kd of (2.1 ±± 0.2)**10−−6 min−−1. The uptake process was found to be dependent on pH, sodium ions, chloride ions, temperature, and energy. Uptake was inhibited in the presence of structural analogs (cold folic acid, methyltetrahydro folate, and methotrexate), but structurally unrelated vitamins did not show any effect. Membrane transport inhibitors SITS, DIDS, probenecid and endocytic inhibitor, colchicine significantly inhibited the [3H]folic acid uptake indicating the involvement of receptor/transporter mediated process. PKA, PTK, and Ca2++/calmodulin pathways significantly regulate the process. RT-PCR and Western blot analysis confirmed the presence of folate receptor-αα (FR-alpha) and proton-coupled folate transporter (PCFT). Permeability of [3H]folic acid across the rabbit cornea was (1.48 ±± 0.13)**10−−05 cm/sec, and in the presence of cold folic acid it was (1.08 ±± 0.10)**10−−05 cm/sec. Conclusions: This work demonstrated the functional and molecular presence of FR-alpha and PCFT in SIRC epithelial cell line. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the influence of positional deviations on the rebound tonometer measurement. Materials and Methods: Ten white rabbits were used. A bottle of balanced salt solution was connected to the anterior chamber, and the IOP was altered by changing the height of the bottle. A pressure transducer was also connected to the anterior chamber. The IOP was measured by the rebound tonometer (RBT), the Tonopen XL, and the Perkins handheld applanation tonometer at optimal conditions and compared each tonometer. Then, the effect of placing the RBT probe at different distances, different lateral positions, and different angles to the cornea on the IOP was determined. Results: The RBT had the lowest variance in all three tonometers. The IOP measured with the RBT was not significantly altered when the distance from the cornea was 4 to 8 mm, or when the probe was displaced 2 mm to the central cornea, or when the probe was placed at an angle of 20°° from the central axis. Conclusions: The low variance of the RBT measurements and the non-significant changes in the IOP when the probe of the RBT was not on the central axis indicate that the RBT is useful for animal models of glaucoma. Further studies examining its use (repeatability and reliability) in human infants whose eyes and head are usually moving are required. [ABSTRACT FROM AUTHOR]

Purpose: Topically administered indomethacin is used in the management and prevention of ocular inflammation and cystoid macular edema related to cataract surgery and in the maintenance of mydriasis during cataract surgery. Pharmaceutically, the main obstacle in formulating indomethacin as eye drops is its low solubility and aqueous instability. Inclusion complexation of indomethacin with cyclodextrins (CDs) was our interest in this research to obtain stable and effective aqueous indomethacin eye drops. Materials and Methods: The influence of ββ-CD, hydroxypropyl-ββ-CD (HP-ββ-CD), and sulfobutyl ether-ββ-CD (SBE-ββ-CD) on indomethacin solubility was investigated. Indomethacin-HP-ββ-CD complex was prepared and characterized by infrared spectroscopy, differential scanning calorimetry, and X-ray diffractometry and was subjected to in vitro release and stability studies. The anti-inflammatory effect of formulated indomethacin-HP-ββ-CD eye drops on chemically burned albino rabbit eyes was compared to those of Indocollyre®® and Voltaren®® eye drops. Results: HP-ββ-CD was found to have a high solubilizing effect towards indomethacin and was thus selected for its formulation. Formulated indomethacin-HP-ββ-CD eye drops exhibited delayed release and high drug stability compared to the drug solution. Draize rabbit eye irritation test and histological examination on albino rabbit eyes treated with indomethacin-HP-ββ-CD eye drops revealed that these eye drops were non-irritant. The anti-inflammatory studies indicated that formulating indomethacin eye drops via complexation with HP-ββ-CD significantly improves the therapeutic efficacy of the indomethacin compared to the investigated eye drops. Conclusion: An aqueous ocular delivery system for the poor water soluble anti-inflammatory indomethacin was prepared using HP-ββ-CD as a complexing agent. Besides a sufficient solubility for the drug, many factors were studied in the development of this system, such as stability and safety. In addition, indomethacin-HP-ββ-CD eye drops showed promising management to corneal inflammation. [ABSTRACT FROM AUTHOR]

Purpose: To determine the virulence of Staphylococcus aureus strains in the rabbit conjunctiva. Methods: Three strains of methicillin-sensitive S. aureus (8325-4, Newman, and UMCR1) and two strains of methicillin-resistant S. aureus (70490 and MW2) were analyzed. Rabbit bulbar conjunctivas ( n ≥ 6 per group) were injected with 105 colony forming units (CFU) in 10 µl. Eyes were photographed and analyzed for pathology at 20 hr postinfection (PI) using slit lamp examination (SLE) to measure five parameters on a scale from 0 (normal) to 4 (severe): injection, chemosis, iritis, corneal edema, and pinpoint conjunctival hemorrhages. The parameter grades were added to produce a SLE score. Bacteria were enumerated and histopathological analysis was done at 20 hr PI. Myeloperoxidase assays were performed on conjunctival swabs ( n ≥ 3 per strain) at 0 and 20 hr PI. Results: Conjunctivas injected with 8325-4 or Newman had SLE scores of 1.67 ± 0.12 and 0.81 ± 0.16, respectively. Strain 70490 produced an average SLE score of 2.94 ± 0.47, whereas MW2 produced a score of 5.04 ± 0.73. UMCR1 produced severe conjunctivitis having a SLE score of 13.25 ± 0.80. Only strain UMCR1 grew in the conjunctiva showing a 2.7 log increase in CFU; all other strains remained near the inoculated numbers or decreased as much as 1.85 logs. Myeloperoxidase activity was greatest in the tear film of UMCR1 infected eyes with over one million PMN present at 20 hr PI. Conclusions: Only one S. aureus strain, UMCR1, was able to cause a reproducible severe conjunctivitis. This conjunctival infection could be used to test new antimicrobials and to help understand the pathogenesis of conjunctivitis, especially in terms of overcoming the host defenses. [ABSTRACT FROM AUTHOR]

Purpose: Aims of the present investigation were to prove that natural polysaccharide arabinogalactan (AG) is well tolerated after ocular administration and exerts a high restoring effect on corneal epithelium abrasions. Materials and Methods: AG interactions with corneal cells, as well as its effect on their proliferation, were evaluated employing rabbit corneal epithelial cell cultures. The effects due to the presence of benzalkonium chloride (BAK) were also studied on cell cultures, ex vivo on rabbit isolated corneas, evaluating the hydration level, and on the healing rate of experimental corneal wounds in rabbits. Furthermore, the healing process of corneal lesions treated with an experimental 5.0% AG solution was studied and compared with those obtained applying solutions of hyaluronic acid and tamarind seed polysaccharide, both chosen as a reference by virtue of their well-known adjuvant properties on corneal trophism; the study was carried out by light and transmission electron microscopy. Results: BAK showed toxic effects on corneal epithelium in all experiments. AG proved to stimulate the growth of the corneal epithelial cells by interacting at the level of the cell plasma membrane. The microscopy observations of the epithelial surface of AG-treated damaged corneas revealed a well-restored and histologically organized ultrastructure characterized by fully formed microvilli and glycocalyx; the healing process resulted faster with respect to spontaneously recovered untreated corneas. Conclusion: Our results suggest that AG can interact with corneal epithelial cells without any toxic side effect; moreover, it proved to stimulate cell proliferation, thus promoting tissue re-epithelialization and reorganization just 48 hr post-wounding. [ABSTRACT FROM AUTHOR]

Purpose: Primary intraocular lymphoma (PIOL) provides a therapeutic challenge because of its diverse clinical picture and variable clinical course. The main objective of this study was to evaluate the retinal permeability of methotrexate for rabbit and human eyes and then investigate its kinetics in a human eye following the standard induction-consolidation-maintenance (I-C-M) injection protocols for the treatment of PIOL. Additionally, the therapeutic release rate of a 90-day sustained-release methotrexate implant was also determined for the effective treatment of PIOL. Methodology: The 3-dimensional model of a rabbit eye was adapted from our previous studies and a human eye model was constructed based on its physiological dimensions. The retinal permeability of methotrexate was the only unknown parameter in the numerical calculations and was determined by comparing the model simulated vitreous concentrations for rabbit and human eyes with the available in vivo and clinical data, respectively. Results: The retinal permeability values of methotrexate calculated for an albino rabbit and human eye were 1.1 × 10−5 cm/s and 9.25 × 10−6 cm/s, respectively. Given that the dosage above 0.1 µM is considered tumoricidal, the cytotoxic levels of methotrexate were consistently achieved only in the induction phase and the concentration levels dropped below the cytotoxic levels for part of the consolidation and maintenance phases of the treatment following the I-C-M protocols. A sustained-release implant with a mean release rate of 0.2 μg/day-2 μg/day should be designed in order to maintain tumoricidal levels of methotrexate inside the vitreous of the human eye for a period of 3 months. Conclusions: By making use of the results of this study, one could select a dosing interval for serial injections of methotrexate or establish a treatment schedule using a controlled release methotrexate implant for the treatment of PIOL. [ABSTRACT FROM AUTHOR]

Purpose: The aim of the present study was to analyze and compare in vivo morphology of healthy cornea of six different laboratory animals. Matherials and Methods: One Pomeranian Coarsewool sheep, 5 Beagle dogs, 1 Norwegian and 2 Domestic Short-haired cats, 20 New Zealand White rabbits, 6 Wistar rats, and 10 Balb/c mice were included. The examination was performed bilaterally, using Heidelberg Retina Tomograph equipped with Rostock Cornea Module. The morphology of living corneal layers was visualized and compared between species. The central corneal thickness, density of keratocytes, and endothelial cells were quantified. Results: The epithelial multilayer showed a similarity in morphology between animal types, displaying three clearly distinguishable layers: superficial, intermediate, and basal. Subbasal nerve fibers were displayed as hyperreflective structures underneath basal cells. The subbasal fibers were confirmed in all species, however, the density varied between species. A pronounced Bowman's membrane was visualized in sheep. In all other species, however, a thin acellular layer with overlying nerve fibers could be seen between basal epithelial cells and anterior stroma. The keratocytes nuclei could be demonstrated in all species except for mice, where no nuclei but only reflective structures resembling keratocytes cell bodies were detected. Overall, the density of keratocytes nuclei was significantly higher in the anterior than in the posterior stroma. Besides endothelial cells density, the endothelial cells morphology was very similar among all species, except for sheep. The endothelial cells were displayed as polygonal structures with bright cytoplasm and dark borders. In sheep, the appearance of the endothelium was very poor because of a thick hyperreflective Descemet's membrane. Conclusions: The present study will help researchers consider appropriate models for animal experiments, depending on focus of investigation. In vivo CLSM can be used for the characterization of the living cornea over time, thus, reducing the number of animal experiments. [ABSTRACT FROM AUTHOR]

Purpose: The pneumococcal capsule is required for pathogenesis in systemic infections, yet reports show most conjunctivitis outbreaks are caused by nonencapsulated pneumococci, while keratitis infections are caused by encapsulated strains. This study aims to determine the effect of capsule in pneumococcal keratitis and conjunctivitis in rabbit models of infection. Methods: A capsule-deficient isogenic mutant was created using homologous transformation. Parent and mutant strains were injected within the upper bulbar conjunctiva (conjunctivitis) or into the corneal stroma (keratitis) of New Zealand white rabbits. Clinical examinations were performed 24 and 48 hr post-infection at which time corneas or conjunctivae were removed, homogenized, and plated to determine the recovered bacterial load. Whole eyes were removed for histological examination. The neuraminidase activity was determined following in vitro and in vivo growth. Results: There were no significant differences in clinical scores between the eyes infected with the parent or mutant for either infection, nor was there a difference in the amount of bacteria recovered from the cornea. In the conjunctivae, however, the mutant strain was cleared by the host faster than the parent strain. Histological examination showed slightly more infiltrating polymorphonuclear leukocytes (PMN) and macrophages in the conjunctivae infected with the parent strain. The neuraminidase activity of both strains was not significantly different when the strains were grown in vitro. However, the neuraminidase activity of the parent was significantly less than that of the mutant at 3 and 12 hr post conjunctival infection. Conclusions: Although more outbreaks of pneumococcal conjunctivitis are tied to nonencapsulated S. pneumoniae strains, this study showed that an encapsulated strain was capable of establishing conjunctivitis in a rabbit injection model and survive attack by the host immune system longer than its nonencapsulated isogenic mutant. Nonetheless, the nonencapsulated pneumococci had an increased neuraminidase activity level in vivo when compared to the parent strain. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the penetration of topical 1% voriconazole through the cornea into the aqueous humor in New Zealand white rabbits and to determine the effect of mechanical scraping of the corneal epithelium. Materials and Methods: The right eyes of 29 New Zealand white rabbits were maintained with the epithelium intact, and the left eyes underwent mechanical epithelium debridement of the central 7.5 mm of the cornea. A loading dose consisted of a drop of 1% voriconazole applied every 5 min for the initial half hour and followed by a maintenance dose consisting of a drop every 20 min, which was applied for about 2 hr. Then, the first sample was obtained 5 min after the first seven doses (loading dose) were given, and then four more samples were taken 5 min after four more subsequent drops (maintenance dose). The samples were analyzed by high performance liquid chromatography. Results: The mean aqueous concentration of voriconazole was 33.44 ± 5.77 μg/mL 5 min after the loading dose in the non-scraped group and 57.67 ± 6.77 μg/mL in the scraped group, respectively. The mean aqueous concentration of voriconazole was maintained in a range from 19.97 to 23.70 μg/mL 5 min after the maintenance doses in the non-scraped group and from 44.44 to 49.02 μg/ mL in the scraped group. The mean vitreous concentration of voriconazole ranged from 0.38 to 0.49 μg/mL in the non-scraped group and ranged from 0.72 to 0.94 μg/mL in the scraped group. These levels were statistically significant ( P < 0.05) between the scraped and non-scraped groups. Conclusions: Topically administered voriconazole achieved minimum inhibitory concentrations in the aqueous for all the organisms most commonly involved in fungal endophthalmitis and achieved minimum inhibitory concentrations in the vitreous for some pathogenic fungi. The concentrations of voriconazole were higher in the scraped group than in the non-scraped group. [ABSTRACT FROM AUTHOR]

Purpose: Secretion from the lacrimal gland is an important part of the well-being of the eye, and a central part in the search for treatment of dry eye syndrome. Adenosine has stimulatory effects on the lacrimal gland, and can potentiate the effect of the cholinergic agonist carbachol (Cch). The aim of the present study is to investigate the presence of the adenosine A2 receptor subtypes A2A and A2B in the rabbit lacrimal gland, and to characterize their role in regulated acinar cell secretion. Methods: Expression of the receptors was investigated using reverse transcriptase-PCR (RT-PCR) and immunofluorescence, and secretion effects were studied using a secretion assay in isolated lacrimal gland acinar cells. Results: Presence of both receptors was detected by RT-PCR and immunofluorescence. The secretion assay revealed a minor effect of stimulation of the A2 receptors, and a strong synergistic effect with the cholinergic agonist Cch. The synergistic effect was significantly reduced by the A2B antagonist PSB 1115, but not by the A2A antagonist SCH 58261, indicating that A2B is the receptor responsible for this potentiation. Conclusions: The study reveals the presence of the adenosine A2 receptor subtypes as well as a role for them in lacrimal gland secretion, and especially in the synergy with purinergic and cholinergic stimulation. [ABSTRACT FROM AUTHOR]

Purpose: Staphylococcus aureus is an important cause of ocular infections including endophthalmitis. The purpose of this study was to determine the ability of a relatively large molecule, such as lysostaphin, to remain in the rabbit aqueous humor for extended periods while retaining its bactericidal activity. Methods: Lysostaphin, gatifloxacin, or Tris-buffered saline (TBS) was injected into the rabbit anterior chamber. Aqueous humor was sampled at 0.5, 1, 2, 3, and 4 days after injection, and then assayed for bactericidal activity against S. aureus. The anterior chamber of treated eyes was also challenged 2 days after treatment by an infection of S. aureus. The surviving bacteria were quantified to determine bactericidal effectiveness in the anterior chamber. The aqueous humor of lysostaphin injected eyes was assayed by western blot for the presence of the molecule 2 days post-injection. Results: The bactericidal activity of lysostaphin was confirmed by lysis of S. aureus and sensitivity to zinc. Eyes injected with lysostaphin showed no adverse reactions. Aqueous humor of gatifloxacin injected eyes demonstrated no greater effectiveness than that of TBS injected eyes in vitro at any time point assayed, whereas lysostaphin injected eyes retained potent bactericidal activity for at least 3 days. In an in vivo challenge, the anterior chamber of lysostaphin injected eyes retained significant bactericidal activity for at least 2 days after treatment, whereas gatifloxacin injected eyes demonstrated no significant difference from those injected with TBS. Western blot analysis demonstrated the presence of lysostaphin in the aqueous humor 2 days post-injection. Conclusions: Lysostaphin demonstrated the ability to remain in the aqueous humor for days while maintaining its bactericidal activity, an indication that a high molecular weight antimicrobial can provide prolonged prophylactic protection of the anterior chamber. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of DA-6034, 7-carboxymethyloxy-3′,4′,5-trimethoxy flavone, in experimentally-induced inflammatory dry eye in rabbit. In addition, to elucidate the mechanism of DA-6034, we evaluated the mitogen-activated protein kinase (MAPK) signaling pathway and transcriptional factor-kappa B (NF-kB) in corneal epithelial cells. Methods: Rabbit lacrimal glands were injected with the T-cell mitogen concanavalin A (Con A). DA-6034 was then administered topically four times a day for six days starting 24 hr after Con A injection. Tear volume, tear function, MMP-9 and inflammatory cytokine levels in the lacrimal glands, and histological evaluation were subsequently assessed. In in vitro study, phosphorylated MAPKs (c-Jun NH2-terminal kinase (JNK) and p38 MAPK) and NF-kB were detected by enzyme-linked immunosorbent assay (ELISA) using human corneal epithelial cells. Results: A single injection of Con A into the lacrimal glands induced a pronounced inflammatory response, caused elevated levels of MMP-9 and cytokines IL-8 and TGF-β1, and induced a decrease in tear volume and shortening of tear breakup time (TBUT). In this inflammation model of dry eye, DA-6034 clearly showed therapeutic efficacy by restoring tear function and inhibiting inflammatory responses after topical ocular application. Furthermore, DA-6034 attenuated the phosphorylation of JNK and p38 MAPK and inhibited NF-kB activation in a concentration-dependent manner in corneal epithelial cells. Conclusions: These results suggest that DA-6034 has the therapeutic effect in rabbit lacrimal gland inflammation model of dry eye and might be a potential treatment option for acute dry eye syndrome. [ABSTRACT FROM AUTHOR]

Purpose: This study was undertaken to determine the effect of the topical application of diadenosine tetraphosphate on lactoferrin levels in rabbit tears. Methods: Diadenosine tetraphosphate was topically instilled in a single-dose, tear samples were collected by micropipette and lactoferrin was measured by Enzyme-Linked ImmunoSorbent Assay (ELISA). Results: The concentration of lactoferrin in rabbit tears was significantly increased 1 h after diadenosine tetraphosphate application, remaining elevated for 3 h more. This effect was blocked by P2 receptors antagonists. Conclusions: Topical application of diadenosine tetraphosphate stimulates the secretion of lactoferrin in rabbit tears through P2 receptor activation. [ABSTRACT FROM AUTHOR]

Purpose: To determine the in vivo efficacy of cyclosporine A-loaded solid lipid nanoparticles (SLNs) in rabbit eyes. Methods: SLNs were prepared and administered to the cul-de-sac of rabbits, and the drug amount in aqueous humor was detected by high performance liquid chromatography (HPLC). The irritation was evaluated by modified Draize testing. Results: The particle size of SLNs was detected as 225.9 ± 5.5 nm with a negative surface charge. Aqueous humor drug levels reached 50.53 ng/mL, and there was no serious irritation in rabbit eyes. Conclusions: Topical ophthalmic efficacy of cyclosporine A was enhanced via administration of SLNs. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the potential toxicity of the vehicle used for triamcinolone acetonide (TA) to the cornea, lens, ciliary body, and retina of pigmented rabbits. Methods: Forty chinchilla rabbits (40 eyes) were divided into four groups: group A (control group) eyes received an intravitreal injection of 0.1 ml sterile saline solution; group B eyes received 0.1 ml (1.3 mg) TA plus vehicle; group C eyes received 0.1 ml (1.3 mg) TA alone (vehicle eliminated); group D eyes received 0.1 ml vehicle only. Intraocular pressure (IOP) was measured pre-injection and at 1, 7, 14, 30, and 90 days post-injection. Scotopic and photopic electroretinograms (ERG) were examined pre-injection and 7, 30, and 90 days post-injection. Animals were sacrificed 7, 30, and 90 days post-injection. Eyes were enucleated and examined by light microscopy (LM) and electron microscopy (EM). Results: The IOP of groups B and C was higher than that of other groups on days 1, 7, and 14 post-injection (p < 0.05). ERG amplitudes of groups B and D were lower than those of other groups on days 7 and 30 post-injection (p < 0.05). Histopathological sections indicated morphologic changes in the ciliary body, lens, and retina of eyes in groups B and D. Conclusions: Vehicle used for TA is toxic to the lens, ciliary body, and retina of pigmented rabbit eyes after injection of intravitreal TA. [ABSTRACT FROM AUTHOR]

Purpose: Long-term intraocular pressure control by glaucoma drainage implants is compromised by the formation of an avascular fibrous capsule that surrounds the glaucoma implant and increases aqueous outflow resistance. It is possible to alter this fibrotic tissue reaction and produce a more vascularized and potentially more permeable capsule around implanted devices by enclosing them in a porous membrane. Methods: Ahmed glaucoma implants modified with an outer 5-μ m pore size membrane (termed porous retrofitted implant with modified enclosure or PRIME-Ahmed) and unmodified glaucoma implants were implanted into paired rabbit eyes. After 6 weeks, the devices were explanted and subject to histological analysis. Results: A tissue response containing minimal vascularization, negligible immune response, and a thick fibrous capsule surrounded the unmodified Ahmed glaucoma implant. In comparison, the tissue response around the PRIME-Ahmed demonstrated a thinner fibrous capsule (46.4 ± 10.8 μ m for PRIME-Ahmed versus 94.9 ± 21.2 μ m for control, p < 0.001) and was highly vascularized near the tissue-material interface. A prominent chronic inflammatory response was noted as well. Conclusions: Encapsulating the aqueous outflow pathway with a porous membrane produces a more vascular tissue response and thinner fibrous capsule compared with a standard glaucoma implant plate. Enhanced vascularity and a thinner fibrous capsule may reduce aqueous outflow resistance and improve long-term glaucoma implant performance. [ABSTRACT FROM AUTHOR]

Purpose: To compare the antiviral effect of a peptide derived from human apolipoprotein E (1% apoEdp) with 1% trifluorothymidine against HSV-1 thymidine kinase (TK)-positive (HSV-1 McKrae) and with 3% foscarnet against HSV-1 TK-negative (KOS background) in the rabbit eye model of acute HSV-1 epithelial keratitis. Materials and Methods: Topical treatment began three days post-infection and continued for five days. Rabbits were treated 5 times per day with 1% apoEdp, 1% trifluorothymidine, 3% foscarnet, or PBS. Slit lamp examination was performed on a masked basis from post-infection days 3-10 to determine the severity of epithelial keratitis. Results: Topical treatment with 1% apoEdp was as effective as 1% trifluorothymidine against TK-positive and 3% foscarnet against TK-negative HSV-1 epithelial keratitis. Conclusions: ApoEdp 1% has efficacy for the topical treatment of TK-positive and TK-negative ocular herpes in the rabbit eye model. Thus, apoEdp has the potential to be used for treatment of keratitis caused by TK mutants. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effect of intravitreal injection of triamcinolone acetonide (TA) in the treatment of experimental Staphylococcus epidermidis endophthalmitis. Materials and Methods: Experimental endophthalmitis induced in one eye of 38 rabbits by intravitreal injection of Staphylococcus epidermidis. The infected rabbits were randomly divided into three groups. The rabbits in group 1 (n = 15) received intravitreal injection of 1 mg vancomycin hydrochloride. Group 2 eyes (n = 15) received intravitreal TA (4 mg) plus vancomycin hydrochloride (1 mg). Group 3 eyes (8 eyes) received normal saline. Clinical examination in each group was performed two, seven, and 15 days after inoculation of the bacteria. The eyes were enucleated for histopathologic evaluation on the 15th day. Clinical and histological scoring systems were used to evaluate clinical and histological severity of the intraocular infection. Results: The mean clinical scores of three study groups at the 7th day were 5.8 ± 2.3, 3.3 ± 1.5, and 9.5 ± 2.1, respectively. The mean of this value at 15th day were 6.2 ± 2.6, 3.9 ± 2.1, and 10 ± 2.2, respectively. At the 7th and 15th day, the mean clinical score of group 2 was significantly lower when compared with the other two groups. Mean histopathologic scores of group 1, group 2, and group 3 were 11 ± 2.7, 7.9 ± 2.9, and 14.0 ± 3.1, respectively. Histopathologic studies revealed less tissue destruction for eyes treated with TA. There was a significant positive correlation between the severity of clinical signs and pathologic damage in all three experiment groups; however, it was weakest in the IVTA treated group. Conclusion: A standard clinical dose of intravitreal TA attenuates the clinical signs and tissue destruction in a rabbit model of Staphylococcus epidermidis endophthalmitis. [ABSTRACT FROM AUTHOR]

Purpose: To compare hydrophilic acrylic intraocular lenses (IOLs) as an antibiotic drug-delivery system with intracameral antibiotic administration in terms of the ability to prevent endophthalmitis. Methods: Antibiotic solutions of 0.3% (3 mg/ml) and 0.5% (5 mg/ml) gatifloxacin (GFLX) and 0.5% (5 mg/ml) and 1.5% (15 mg/ml) levofloxacin (LVFX) were prepared. IOLs made of hydrophilic acrylic and silicone were used. Hydrophilic acrylic IOLs were allowed to adsorb the antibiotic solutions. A clinically isolated strain, KOS1, of Enterococcus faecalis was used to induce experimental endophthalmitis in vivo. Antibiotic concentrations were determined with high-performance liquid chromatography (HPLC). Twelve hydrophilic acrylic IOLs with antibiotics were used for the in vitro antibiotic concentration assay. In vivo experiments were conducted with 51 rabbits in total. Antibiotic concentrations in the aqueous humor and effects against bacterial proliferation were evaluated. Results: Concentrations of released antibiotics in vitro were highest on the first day and had decreased by the second day. When a comparison was made between similar initial concentrations, GFLX was released to a significantly higher concentration than LVFX (p < 0.001). In the antibiotic-treated IOL group, GFLX concentrations in the aqueous humor reached a peak at four hours postoperatively and then decreased. The intracameral antibiotic group showed similar tendencies, with a remarkably higher peak concentration. Effects against bacterial proliferation were comparable between the antibiotic-treated IOLs and intracameral antibiotic administration. Conclusions: Preventive effects against endophthalmitis were similar between antibiotic-treated IOL implantation and intracameral antibiotic administration. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the ability of a novel polysaccharide-based tissue adhesive to seal corneal incisions, and to determine the effect of the tissue adhesive on corneal endothelial cells. Methods: A polysaccharide-based tissue adhesive composed of dextran aldehyde and star PEG amines was applied to a 5-mm corneal incision on an enucleated rabbit eye, and the leak pressure of the eye was measured. The tissue adhesive was additionally incubated in direct contact with bovine corneal endothelial cells to evaluate cytotoxicity. Results: The polysaccharide-based tissue adhesive was successful in sealing corneal incisions to pressures of > 10 psi (500 mmHg). The tissue adhesive was non-cytotoxic to bovine corneal endothelial cells. Conclusions: Polysaccharide-based tissue adhesives are efficacious in sealing corneal wounds and are non-cytotoxic to corneal endothelial cells. Such adhesives represent a promising new technology for ophthalmic surgery. [ABSTRACT FROM AUTHOR]

Purpose: To develop a method for the quantitative analyses of the ring-shaped features usually observed on the surface of mammalian corneal epithelial cells. Methods: The corneas of 10 young adult female albino rabbits were prepared for scanning electron microscopy (SEM) by fixation in 2% glutaraldehyde in 80 mM cacodylate buffer (pH 7.2 to 7.4, 320 to 340 mOsm/kg) and single images taken at 1000× of the central region of the corneal epithelial surface. On enlarged prints at 5000× final magnification, cell-cell borders were marked as were the outlines of the ring-shaped features. Cell areas and the dimensions of the ring-shaped features were measured and the cell characteristics in terms of electron reflex (light, medium, and dark) as well as the number of apices (sides) also noted. Results: The ring-shaped features had an overall density of 2.5/100 μm2, or an average of 6.5/cell. With the corneal epithelial cells being small and light in appearance (median area 36 μm2), medium in size and appearance (median area 151 μ m2), or larger and darker (median area 476 μ m2), the number of features/cell was very strongly associated with both the cell type (p < 0.001) and the cell area (p < 0.001). The ring-shaped features could be between 0.65 and 5.5 μm in diameter, but sizes more than 3 μm were most unusual. Ring-shaped features of light cells were smallest (median diameter 1.35 μ m), slightly larger on medium cells (1.55 μm), and largest on the dark cells (1.90 μm). Conclusions: The ring-like features seen on SEM photomicrographs of rabbits (also known as craters or holes) are reproducible in terms of their overall density per unit surface area as well as their diameter. Such methods should be useful for objective analysis of these features after various treatments of the ocular surface. [ABSTRACT FROM AUTHOR]