Search

Purpose: To compare the visual and refractive outcomes and the corneal structural changes in myopic patients after surface refractive treatments (ie, photorefractive keratectomy [PRK] with adjuvant mitomycin-C [MMC] and epithelial laser in situ keratomileusis [epi-LASIK])., Setting: University of Crete, Heraklion, Crete, Greece., Design: Prospective comparative case series., Methods: One eye of consecutive myopic patients was randomly assigned to PRK-MMC, and the fellow eye was treated with epi-LASIK. Visual and refractive outcomes and corneal confocal microscopy findings were evaluated. All patients were examined preoperatively and 1, 3, 6, 12, and 24 months postoperatively., Results: Twenty-six eyes (13 patients) were included. The mean follow-up was 2.47 years ± 0.35 (SD) (range 1.64 to 2.93 years). In the PRK-MMC group, the mean preoperative spherical equivalent refraction was -3.84 ± 1.59 diopters (D) (range -1.5 to -8.7 D) and -0.21 ± 0.44 D (range -0.5 to 1.0 D) at the last follow-up and in the epi-LASIK group, -3.91 ± 1.48 D (range -1.5 to -8.5 D) and -0.18 ± 0.36 (range +0.5 to -0.5 D), respectively. Qualitative analysis of the subepithelial nerve plexus, haze development, and keratocyte distribution were similar in the 2 groups. There was no statistically significant difference in endothelial cell density between the groups throughout the follow-up (P>.05)., Conclusion: Epithelial LASIK and PRK-MMC gave similar visual, refractive, and corneal structural outcomes in patients with myopia for up to 2 years postoperatively., Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned., (Copyright © 2013 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Purpose: To report 3 cases of keratoconic patients who had progressive corneal topographic flattening during a 2-year follow-up period., Methods: Case series., Results: Three patients with bilateral keratoconus, each operated for advanced keratoconus in one of their eyes, were observed for possible progression of the disorder for a period of 2 years. During the 2-year follow-up period, topographic examination showed progressive corneal flattening in the nonoperated eye. Mean keratometry decreased in all patients, whereas topography showed significant flattening at the apex of the cone. Best-spectacle-corrected visual acuity increased in one of the patients, whereas the others had stable uncorrected and best-spectacle-corrected visual acuity during the follow-up period. All patients had positive family medical history for diabetes mellitus, but none of them was diabetic., Conclusions: This is the first report of topography-based keratoconus regression during a 2-year follow-up period.

Purpose: To evaluate the outcomes of refractive surgery in patients with topographic superior corneal steepening., Methods: This retrospective, noncomparative, interventional, clinical study included 16 patients (29 eyes) with persistent superior corneal steepening as a variation of corneal curvature (inferior to superior topographic corneal difference of at least 1.00 diopter [D] at a 3-mm zone) not related to any underlying disease or condition who underwent corneal refractive surgery. Refractive, keratometric, and visual outcomes were evaluated preoperatively and at 1, 3, 6, 12, and 24 months postoperatively., Results: Twenty-two eyes underwent photorefractive keratectomy and 7 eyes underwent LASIK. Mean follow-up was 27.38±2.37 months (range: 25 to 32 months). Mean preoperative inferior to superior keratometric difference was 1.61±0.36 D (range: 1.20 to 2.63 D). Mean preoperative spherical equivalent refraction was -4.45±1.66 D (range: -2.25 to -8.00 D), which decreased to -0.09±0.61 D (range: +0.75 to -1.38 D) (P<.05) at last follow-up. Mean preoperative topographic corneal astigmatism was 1.44±0.79 D (range: 0.52 to 3.83 D), which decreased to 0.66±0.39 D (P<.05) 3 months postoperatively and remained stable during follow-up (P<.54). Mean preoperative uncorrected distance visual acuity and corrected distance visual acuity in logMAR units were 1.57±0.62 and 0.02±0.06, respectively, which improved at last follow-up to 0.00±0.05 and -0.02±0.04, respectively. No intra- or postoperative complications were noted; specifically, no patients developed postoperative ectasia., Conclusions: Corneal refractive surgery in patients with isolated topographic superior corneal steepening provided acceptable refractive and visual outcomes without any intra- or postoperative complications. Diligence is required to screen for the potential of ectatic corneal disorders in this population. Photorefractive keratectomy may be a safer option for these patients than LASIK., (Copyright 2012, SLACK Incorporated.)

Purpose: To determine the possible effect of corneal collagen crosslinking (CXL) with riboflavin and ultraviolet A (UVA) on intraocular pressure (IOP) measurements by Goldmann applanation tonometry (GAT)., Setting: Institute of Vision and Optics, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece., Design: Prospective case series., Methods: This noncomparative study measured IOP by GAT before CXL and 6 months and 12 months after CXL., Results: The study evaluated 55 eyes (55 patients). There was a statistically significant increase in the measured IOP 6 months and 12 months after CXL (both P<.001). The mean measured IOP was 9.95 mm Hg ± 3.01 (SD) before CXL, 11.40 ± 2.89 mm Hg at 6 months, and 11.35 ± 3.38 mm Hg at 12 months. The change in IOP measurements at both postoperative examinations was not correlated with patient age, preoperative pachymetry, or preoperative keratometry readings., Conclusion: After riboflavin-UVA CXL in eyes with keratoconus, there was a significant increase in IOP measured by GAT that was probably caused by an increase in corneal rigidity., (Copyright © 2010 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

Objective: To study central corneal pachymetric variations during corneal collagen cross-linking (CXL) treatment with the use of riboflavin and ultraviolet A irradiation (UVA)., Design: Prospective, noncomparative, interventional clinical study., Participants: Fifteen keratoconic patients (19 eyes) were enrolled., Methods: All patients underwent riboflavin-UVA-induced corneal CXL. Intraoperative central corneal thickness (CCT) measurements using ultrasound pachymetry were performed during the procedure. Measurements were obtained after epithelial removal, after riboflavin drop instillation, and every 5 minutes (6 interval times) during UVA irradiation (30 minutes)., Main Outcome Measures: Central corneal thickness measurements., Results: Mean patient age was 26.9+/-6.5 years (range, 17-40 years). Ten were male and 5 were female. Mean preoperative CCT was 458.5+/-21.5 microm (range, 427-494 microm; 95% confidence interval [CI], 448-467 microm) and 415.7+/-20.6 microm (range, 400-468 microm; 95% CI, 406-426 microm) before and after epithelial removal, respectively. There was a statistically significant decrease (mean, 75 microm) of CCT between the epithelial removal interval (415.7+/-20.6 microm; range, 400-468 microm) and at the end of riboflavin solution instillation (340.7+/-22.9 microm; range, 292-386 microm; P<0.001). There was no statistically significant change in CCT during irradiation (P>0.05). There was no statistically significant difference between preoperative and 1-month postoperative endothelial cell count (preoperative, 2780+/-197 to 1-month postoperative, 2713+/-116; P = 0.14). No intraoperative, early postoperative, or late postoperative complications were observed in this patient series., Conclusions: During corneal CXL with the use of riboflavin and UVA irradiation, a statistically significant decrease of CCT was demonstrated.

A 34-year-old woman had simultaneous photorefractive keratectomy and corneal collagen crosslinking with riboflavin-ultraviolet-A irradiation for the treatment of progressive pellucid marginal corneal degeneration in both eyes. No intraoperative or early postoperative complications occurred. Twelve months postoperatively, the uncorrected visual acuity was assessed at 20/40 in both eyes compared with counting fingers preoperatively. The corrected visual acuity also improved from 20/50 and 20/63 to 20/25 and 20/32 in the right eye and left eye, respectively. Corneal topography revealed a significant improvement in both eyes. Despite the encouraging results, longer follow-up is necessary to confirm the stability of the results.

Purpose: To compare the refractive outcomes after photorefractive keratectomy (PRK) for low to moderate myopic corrections using 2 excimer lasers with different repetition rates (200 Hz and 400 Hz)., Setting: University refractive surgery center., Methods: This retrospective study included all consecutive patients who underwent PRK using the 200 Hz or the 400 Hz Allegretto laser platform (WaveLight Laser Technologie AG). Thirty-five patients (70 eyes) and 29 patients (58 eyes) had PRK with the 200 Hz platform and the 400 Hz platform, respectively, using the same surgical technique., Results: The mean follow-up was 13.22 months +/- 1.16 (SD) (range 11 to 15 months). No intraoperative or early postoperative (eg, late reepithelialization) complications were found in either group. At 1 year, 66 eyes (94.2%) in the 200 Hz group and 56 eyes (96.6%) in the 400 Hz group were within +/-1.00 diopter of the attempted correction. At 3 months, 20 eyes (29%) in the 200 Hz group and 27 eyes (46%) in the 400 Hz group had mild or moderate corneal haze (P = .03). These corneas showed progressive clearing over subsequent months without statistically significant differences in haze formation between the 2 groups. Twelve months after PRK, all corneas in both groups were clear., Conclusion: Photorefractive keratectomy for the treatment of low to moderate refractive errors using a 200 Hz or 400 Hz excimer laser gave comparable results.

Purpose: To compare histopathologic changes after photorefractive keratectomy (PRK) for myopia using either a solid state laser (SSL) at 213 nm or an excimer laser (EL) at 193 nm in an experimental model., Methods: Forty pigmented rabbits (80 eyes) underwent myopic PRK for the correction of 6 D. Photoablation was randomly assigned, with a solid state laser used in one eye and an EL in the fellow eye. Rabbits were killed immediately after ablation (n = 10) or at 7 days (n = 10), 1 month (n = 8), 3 months (n = 6), or 12 months (n = 6) after surgery. Corneal tissue was preserved for light microscopy and transmission electron microscopy at all postoperative intervals., Results: All eyes reepithelialized in 1 week with no early or late postoperative complication. Immediately after ablation, light, scanning, and transmission electron microscopy revealed relatively smooth ablation surfaces in both groups. Seven days after surgery, epithelium in the SSL specimens appeared thinner than in the EL specimens. Activated keratocytes were observed adjacent to the epithelium in both groups, whereas endothelial cells demonstrated normal morphology. At 1, 3, and 12 months after surgery, tissue appearance of all corneal layers was similar in both groups., Conclusions: PRK in rabbits using ultraviolet SSL and EL revealed similar histopathologic findings up to 1 year after surgery.

Purpose: To evaluate possible changes of the ocular rigidity coefficient in vivo after photorefractive keratectomy (PRK) in a series of rabbit eyes, using an invasive ocular rigidity measurement device., Methods: Sixteen eyes of 8 rabbits were used in this study. One eye from each rabbit underwent PRK for -10.00 diopters (D) in a 5-mm optical zone (92 microm) while the fellow eye served as the control. Five weeks later, the rabbits were examined under general anesthesia. The pressure-volume relationship and the ocular rigidity coefficient were determined in all 16 eyes, by injecting 200 microL of saline solution (in increments of 4.5 microL) through the limbus into the anterior chamber, while the intraocular pressure (IOP) was continually monitored with a transducer, up to a maximum limit of 40 mmHg. Data within an IOP range of 10 to 40 mmHg were used to calculate the ocular rigidity coefficient., Results: The preoperative central corneal thickness was comparable (P = .73, paired t test) in the pre-PRK eyes (mean: 347.5 +/- 17.11 microm) and control eyes (mean: 349.1 +/- 17.46 microm). No statistically significant difference was noted in measured ocular rigidity coefficient between eyes treated with PRK and control eyes (mean rigidity coefficient: 0.42 +/- 0.12 mmHg/microL [range: 0.23 to 0.56] and 0.47 +/- 0.12 mmHg/microL [range: 0.28 to 0.62], respectively, with 95% confidence interval of the difference, lower: -0.10 to upper: 0.015, P = .121)., Conclusions: Photorefractive keratectomy did not significantly alter ocular rigidity measurements in this experimental model.

Purpose: To study the long-term results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in low to moderate myopic corrections using the Pulzar Z1 system (CustomVis), a 213 nm wavelength solid-state laser., Setting: University refractive surgery center., Methods: This prospective noncomparative case series comprised 20 patients (40 eyes) who had refractive surgery using the Pulzar Z1 laser system. Manifest refraction, uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), safety, predictability, stability, and confocal microscopy images were evaluated., Results: Ten patients (20 eyes) had PRK and 10 patients (20 eyes) had LASIK. The mean follow-up was 13.9 months +/- 1.1 (SD) (range 12 to 17 months) and 14.6 +/- 1.2 months (range 12 to 18 months) in the PRK group and LASIK group, respectively. No eye lost a line of Snellen BSCVA during the follow-up period; 2 eyes (10%) gained 2 Snellen lines. There was a statistically significant decrease in spherical equivalent manifest refraction postoperatively in both groups (P<.05). Refractive stability was obtained during the first postoperative month and remained stable during the follow-up period, with no significant changes between any interval in both groups (P>.05). At the last follow-up, 95% of all eyes were within +/-1.00 diopter of emmetropia. No late postoperative complications were observed., Conclusion: Refractive surgery using the Pulzar Z1 213 nm wavelength solid-state laser was a safe, effective procedure in the treatment of low to moderate myopia.

Purpose: To evaluate long-term follow-up of Intacs microthin prescription inserts (Addition Technology, Inc, Fremont, California, USA) for the management of keratoconus., Design: A long-term (five years) retrospective, follow-up study., Methods: Seventeen eyes of 15 patients with keratoconus ages 24 to 52 years (mean age +/- standard deviation [SD], 34.0 +/- 10.5 years) who had completed five years of follow-up (mean follow-up +/- SD, 67.2 +/- 7.5 months; range, 58 to 78 months) were included. Two Intacs segments of 0.45-mm thickness were inserted in the cornea of each eye, aiming at embracing the keratoconus area to try to achieve maximal flattening., Results: No late postoperative complications occurred in this series of patients. At five years, the spherical equivalent error was statistically significantly reduced (pre-Intacs, mean +/- SD -5.54 +/- 5.02 diopters [D]; range, -12.50 to 3.63 D; -3.02 +/- 2.65 D; range, -8.25 to 1.88 D) (P = .01). Pre-Intacs uncorrected visual acuity (UCVA) was 20/50 or worse in all eyes (range, counting fingers to 20/50), whereas, at the last follow-up examination, 10 (59%) of 17 eyes had UCVA of 20/50 or better (range, counting fingers to 20/32). Six eyes (35%) maintained the pre-Intacs best spectacle-corrected visual acuity (BSCVA) and one eye lost 3 lines of BSCVA, whereas the rest of the 10 eyes (59%) experienced a gain of one up to 8 lines., Conclusions: After five years, intracorneal ring segments implantation improved UCVA, BSCVA, and refraction in the majority of the keratoconus patients. There was no evidence of progressive sight-threatening complications in this study.

Purpose: To report the long-term (11-year) outcomes (stability and complications) of laser in situ keratomileusis (LASIK) in patients with high myopia., Setting: University refractive surgery center., Methods: Seven patients (4 with bilateral treatment and 3 with unilateral treatment) who had myopic LASIK and completed 11 years of follow-up were included in the study., Results: The mean age of the 2 men and 5 women was 41.7 years +/- 6.5 (SD) (range 34 to 50 years). The mean follow-up was 140.18 +/- 6.70 months (range 132 to 150 months). At 11 years, the spherical equivalent error was statistically significantly reduced, from a mean of -12.96 +/- 3.17 diopters (D) (range -19.00 to -10.00 D) before LASIK to a mean of -1.14 +/- 1.67 D (range -4.25 to 1.00 D) after (P<.001). Predictability of postoperative refraction 6 months and 11 years after LASIK showed that 6 eyes (55%) were within +/-1.00 D of intended correction. No late postoperative complications occurred. Five patients (8 eyes, 73%) were satisfied with the final outcome., Conclusions: Laser in situ keratomileusis was moderately predictable in the correction of high degrees of myopia. After the sixth postoperative month, refractive and topographic stability were obtained. No long-term sight-threatening complications occurred during the follow-up period.

Purpose: To compare the central corneal thickness (CCT) measurements of patients with neovascular age-related macular degeneration (AMD) and control subjects., Methods: The CCT value (measured with ultrasound corneal pachymetry) of 130 eyes (130 patients, 1 eye from each patient) with neovascular AMD (AMD group) and 98 eyes (98 patients, 1 eye from each patient) of similar age, sex, and eye's axial length healthy control subjects (normal group) was compared., Results: The mean age (AMD group: 69.1 years vs. control group: 69.5 years, P = 0.81), sex (AMD group: 77 women, 59% vs. control group: 59 women, 60%, P = 0.77), and eye's axial length (AMD group: 25.05-mm vs. control group: 24.61-mm, P = 0.38) of patients with neovascular AMD and healthy control subjects were comparable. There were no statistically significant differences in the mean CCT measurements in the neovascular AMD group in comparison with the control group (549.44 vs. 544.35 microm, P = 0.11)., Conclusions: CCT measurements do not differ in patients with neovascular AMD compared with healthy control subjects.

Purpose: To compare the effect of Epi-LASIK or Laser In Situ Keratomileusis (LASIK) on corneal sensitivity and tear function., Design: Prospective, non-randomized comparative clinical trial., Methods: Seventy-nine eyes (Group A) underwent Epi-LASIK and 61 eyes underwent LASIK (Group B) for the treatment of myopia. Matching parameters between the groups were age and attempted correction. Corneal sensitivity, tear break-up time (BUT), and Schirmer test II were evaluated before and at one, three, and six months after the procedure., Results: Corneal sensitivity and BUT were decreased at one month in Group A (P < .001) to be restored by the third month (P = .71 and P = .58, respectively). In Group B, corneal sensitivity and BUT were reduced postoperatively (P < .001). There was a significant difference in corneal sensitivity between the two groups at all postoperative intervals. Schirmer test II was not significantly decreased postoperatively in Group A. In Group B, it was decreased at one and three months and restored by the sixth month., Conclusion: Epi-LASIK-treated eyes had faster rehabilitation of corneal sensitivity and tear function than LASIK-treated eyes.

Purpose: To evaluate the safety, efficacy, predictability, and stability of conductive keratoplasty (CK) for the treatment of hyperopic astigmatism., Setting: University of Crete Medical School, Vardinoyannion Eye Institute of Crete, Heraklion, Greece., Methods: In this prospective nonrandomized noncontrolled single-center study, 47 eyes of 34 patients (15 women and 19 men) were treated for hyperopic astigmatism (up to + 3.50 diopters [D]) with a Refractec ViewPoint CK system and followed for 24 months +/- 0.6 (SD). The treatment consisted of 4 to 36 spots applied to the periphery of the cornea. Mean age was 48.5 years +/- 9.7 years, range 25 to 68 years. All the treated eyes were analyzed for safety, efficacy, predictability, and stability., Results: The mean patient age was 48.5 +/- 9.7 years (range 25 to 68 years). Preoperatively, the mean manifest refraction spherical equivalent (MRSE) was +2.11 +/- 0.88 D (range -0.50 to + 4.13 D); at 12 months, it was -0.52 +/- 0.73 D and at 24 months, -0.50 +/- 0.77 D. At 24 months, the mean MRSE was within +/-0.50 D in 61% of eyes, within +/-1.00 D in 83%, and within +/-2.00 D in all eyes. At 24 months, the uncorrected visual acuity was 20/20 or better in 37% of eyes and 20/40 or better in 97%. By the end of the follow-up period, no eye had lost > or =2 Snellen lines or had an induced cylinder > or =1.50 D., Conclusions: Conductive keratoplasty for low hyperopic astigmatism was a safe, effective, and stable procedure. Nomogram adjustments and careful patient selection should contribute to higher levels of predictability when treating hyperopic astigmatism.

Purpose: To describe lipid-induced specific videokeratographic (VKG) corneal changes and subsequent resolution after eyelid washing., Methods: VKG was performed with C-Scan corneal topography. In all patients an excessive meibomian gland lipid secretion was found with or without coexistent chronic posterior blepharitis. After the initial VKG, a meticulous cleaning of the lids with a mild alkali shampoo (10% Johnson's baby shampoo in sterile water) was done, first by gently scrubbing the closed eyelid fissure with the solution to mobilize and emulsify any Meibomian gland secretions followed by cleaning of the upper and lower margins individually, using Q-tip applicators soaked in the detergent., Results: Three patients with tear film lipid layer excess (TFLE), which correlated with the presence of a superior or central corneal steepening in VKG, were studied. In two of the subjects, careful lid washing reversed either completely or partially this VKG effect, whereas in the last patient the VKG changes after artificially increasing the tear film lipid content is described., Conclusions: Meibomian gland lipid secretions may induce mainly superior and occasionally central VKG corneal steepening that is not correlated with any slit-lamp pathologic findings. Computerized corneal topography can help detect such corneal abnormalities, and their reversibility may distinguish them from other pathologic conditions (such as contact lens-induced warpage, eccentric ablations, irregular astigmatism, superior keratoconus).

Purpose: To evaluate the efficacy, predictability, and safety of topographically supported customized ablations (TOSCAs) for decentered ablations following laser in situ keratomileusis (LASIK)., Design: Prospective nonrandomized clinical trial., Methods: Nine patients (11 eyes) with LASIK-induced decentered ablations underwent TOSCA following flap lifting. Topographically supported customized ablation was performed using a corneal topographer to obtain a customized ablation profile, combined with a flying spot laser., Results: Mean follow-up was 9.22 +/- 2.82 months (range 6-12 months). No intra- or postoperative complications were observed. Manifest refraction (spherical equivalent) did not change significantly (pre-TOSCA: -0.14 +/- 1.58 diopters [range, -1.75 to +3.00 diopters] to +0.46 +/- 1.02 diopters [range, -1.00 to +1.75 diopters]; P =.76), whereas there was a statistically significant reduction in the refractive astigmatism (pre-TOSCA: -1.55 +/- 0.60 diopters [range, -3.00 to -0.75 diopters] to -0.70 +/- 0.56 diopters [range, -2.00 to -0.25 diopters]; P =.003). Mean uncorrected visual acuity improved significantly (P <.001) from 0.45 +/- 0.16 (range, 0.2-0.7) to 0.76 +/- 0.29 (range, 0.2-1.2) at last follow-up. Mean best-corrected visual acuity improved from 0.74 +/- 0.22 (range, 0.4-1.0) to 0.95 +/- 0.20 (range, 0.6-1.2; P =.002). Eccentricity showed a statistically significant reduction after TOSCA treatment (pre-TOSCA: 1.59 +/- 0.46 mm [range, 0.88-2.23 mm]; post-TOSCA: 0.29 +/- 0.09 mm [range, 0.18-0.44 mm]; P <.001)., Conclusion: In our small sample, enhancement LASIK procedures with TOSCA appear to improve uncorrected and best-corrected visual acuity as well as eccentricity in patients with LASIK-induced decentered ablation.

To compare the effect of mechanical and alcohol-assisted excision on the histological ultrastructure of epithelial disks from human corneas. Vardinoyiannion Eye Institute of Crete, University of Crete, Medical School, Crete, Greece. Ten eyes of 10 patients were deepithelialized by 1 of 2 two techniques. In 6 eyes, a customized instrument was used to mechanically separate the epithelial layer. In 4 eyes, the epithelial disks were obtained using the conventional laser-assisted subepithelial keratectomy (LASEK) technique; that is, with alcohol concentrations of 15% and 20%. All specimens were assessed by light and electron microscopy, and the histological findings of the 2 methods were compared. Transmission electron microscopy showed that when the epithelial disks were excised by mechanical separation, the lamina densa and lamina lucida were preserved and the hemidesmosomes had normal morphology along almost the entire length of the basement membrane. The basal epithelial cells of the separated epithelial disks showed minimal trauma and edema. Specimens obtained using 15% and 20% alcohol concentrations showed formation of cytoplasmic fragments of the basal epithelial cells, enlargement of the intercellular spaces, and extensive discontinuities in the basement membrane, which was excised at the level of the lamina lucida. Mechanical separation did not affect the normal cell morphology of the excised epithelial disks. Transmission electron microscopy of the specimens proved the manual technique is less invasive to epithelial integrity than LASEK using either alcohol concentration.

Purpose: The aim of the current study was to control the hypothetical effects of decreased laser energy delivered to the peripheral cornea during phototherapeutic keratectomy (PTK) and provide quantitative calculation of induced low and high order aberrations., Methods: We employed a model eye to simulate the refractive effect of homogeneous laser corneal irradiation, as in PTK, for different laser fluences (range 125 to 225 mJ/cm2) and treatment depths up to 200 microm., Results: The hyperopic shift induced by the relatively lower energy delivered at the peripheral ablation zone during PTK was proportional to the treatment depth and inversely proportional to the energy fluence. The hyperopic shift calculated using the above ablation parameters was lower compared to previously reported clinical results. Higher order wavefront aberration (total root mean square) changes were of minimal significance for treatment depths up to 200 microm., Conclusions: After PTK, a hyperopic shift cannot be attributed to the energy delivery method alone. Modification of laser energy delivery algorithms may only minimize PTK-induced hyperopia.

Purpose: To evaluate the efficacy of conductive keratoplasty in the treatment of pre-existing and surgically induced hyperopic astigmatism., Methods: In this prospective, noncomparative case series, four eyes of four subjects, two female and two male (age 25 to 47 yr) were treated for hyperopia (up to +5.50 D) and hyperopic astigmatism (up to +5.75 D) with the Refractec ViewPoint conductive keratoplasty system. The follow-up period was 6 months. Uncorrected and spectacle-corrected visual acuity, manifest and cycloplegic refraction, and videokeratographs were obtained before and after surgery. We treated two patients who had already had LASIK, one of them with a decentered ablation and the other with flap striae, one patient after PRK, and one patient with keratoconus., Results: No complications were observed. No eye lost lines of spectacle-corrected visual acuity. All eyes showed improvement of uncorrected visual acuity of 3 or more lines. Videokeratographs demonstrated improved centration and reduction in keratometric power readings. Each eye was analyzed separately, including a comparative analysis of the proposed nomograms and quality of vision after surgery., Conclusions: Conductive keratoplasty may be a minimally invasive solution for patients with irregular hyperopic astigmatism, offering improved quality of vision in instances of flap striae by tightening the central cornea.

Objective: To prospectively study the effects of the use of Intacs microthin prescription inserts (Addition Technology Inc, Fremont, Calif) for the postoperative management of corneal ectasia resulting from laser in situ keratomileusis (LASIK)., Methods: In this prospective nonrandomized clinical trial, 10 eyes of 7 patients with post-LASIK corneal ectasia (2 men and 5 women) aged 33 to 46 years (mean +/- SD, 40.67 +/- 5.99 years) were included. The follow-up ranged from 6 to 24 months (mean +/- SD, 15.0 +/- 6.5 months). Two Intacs segments of thickness depending on the residual refraction of the patients were inserted in each eye., Main Outcome Measures: Uncorrected visual acuity, best spectacle-corrected visual acuity, refractive outcome, and topographic findings after Intacs implantation., Results: Intacs were successfully implanted in all eyes. Spherical equivalent error was statistically significantly reduced after Intacs implantation (pre-Intacs, mean +/- SD: -4.81 +/- 3.24 Diopters (D) (range, -13.75 to -2.50 D) to -0.96 +/- 2.93 D (range, -8.75 to 2.50 D) (P<.001). Pre-Intacs uncorrected visual acuity was 20/100 or worse in all eyes (range, counting fingers to 20/100) while at the last follow-up examination, 9 (90%) of 10 eyes had uncorrected visual acuity of 20/40 or better (range, counting fingers to 20/20). Three eyes maintained the pre-Intacs best spectacle-corrected visual acuity while the rest of the eyes (7) experienced a gain of 1 to 2 lines. The mean difference between pre-Intacs and last follow-up best spectacle-corrected visual acuity was a gain of 1.00 +/- 0.82 lines., Conclusions: Intracorneal ring segments implantation improved uncorrected visual acuity and best spectacle-corrected visual acuity in patients with post-LASIK ectasia. Even though the results are encouraging, concern still exists regarding the long-term effect of such an approach for the management of post-LASIK ectasia.

Purpose: To test the accuracy and reliability of the first-generation prototype of Tracey-1, a ray-tracing refractometer., Setting: Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, USA., Methods: The refractive spherical equivalent (SE) and astigmatism measured by Tracey-1, subjective manifest refraction (MR), and autorefraction (AR) (Nidek AR-3300) were compared in 58 pseudophakic eyes of 44 patients with a mean age of 69.95 years +/- 8.6 (SD). The astigmatic values obtained from Tracey-1 and computerized videokeratography were also compared. Astigmatism values were compared using power vector analysis., Results: The mean SEs measured by MR, Tracey, and AR were -0.76 diopter (D) +/- 0.96 (SD) (range 1.00 to -3.00 D), 0.37 +/- 0.64 D (range 1.68 to -1.49 D), and -0.44 +/- 1.13 D (range 1.63 to -3.50 D), respectively. The Pearson correlation coefficients between MR and Tracey values and between MR and AR values were high (r = 0.895 and r = 0.875, respectively; both P < .0001). However, the mean difference between the Tracey and MR values was 1.13 +/- 0.48 D (range 2.45 to -0.06 D) (P < .001). The mean cylindrical differences between MR and Tracey and between MR and AR were 0.03 +/- 0.51 D (range 1.22 to -1.07 D) (P = .709) and -0.30 +/- 0.62 D (range 0.50 to -2.25 D) (P = .003), respectively. Power vector analysis revealed difference vectors of -0.16 x 60 between Tracey and MR and -0.22 x 87 between AR and MR., Conclusions: Spherical and cylindrical refractive data obtained with the Tracey system correlated well with those derived from MR; however, there was a mean spherical error of approximately 1.10 D. Further work is required to refine the accuracy and range of this device.

Objective: To identify the incidence and refractive outcome of intraoperative laser in situ keratomileusis (LASIK) complications using one type of microkeratome., Design: Retrospective noncomparative case series., Participants: Three hundred thirty-four consecutive myopic LASIK patients (September 1997 to November 1998) operated on by one surgeon., Intervention: Myopic LASIK surgeries were performed with the Mediate Mel 60 Aesculap Meditec Laser system., Main Outcome Measures: Preoperative and 1-year postoperative spherical equivalent, best spectacle-corrected visual acuity (BSVA), and corneal anatomic features (as obtained from videokeratography) were recorded, as was the incidence of intraoperative complications., Results: Forty-eight (14%) eyes had keratome-related complications. Thirty-seven (77%) eyes were immediately treated; the remaining eyes were treated on a later date. One year after treatment, 13% of the immediately treated complicated eyes maintained the preoperative BSVA; 24% had a 1-line loss; 2.7% had a greater loss of BSVA., Conclusions: Microkeratome-related complications may result in loss of BSVA. The complication of an irregular flap had the poorest refractive outcome in this series of eyes. We did not find any statistically significant relationship between corneal anatomic factors and keratome-related complications in this series.

Purpose: To investigate in vitro the accuracy of dynamic contour tonometry, Goldmann applanation tonometry, and Tono-Pen XL in edematous corneas. Methods: Experimental study included 20 freshly enucleated porcine eyes. Epithelium was debrided, and eyes were divided in four groups. Groups were immersed in 35%, 40%, 50%, and 60% glycerin solutions for 3 hours. Subsequently, globes were mounted in a special holder, and their intraocular pressure was hydrostatically adjusted. Intraocular pressure was measured by means of dynamic contour tonometry, Goldmann applanation tonometry, and Tono-Pen XL while adjusting true intraocular pressure to 17, 33, and 50 mm Hg. Ultrasound pachymetry was performed. Results: Mean corneal thickness was 914.5 ± 33.3 μm (730–1015 μm). In true intraocular pressure of 33 mm Hg, Goldmann applanation tonometry and dynamic contour tonometry significantly underestimated true intraocular pressure (mean Goldmann applanation tonometry: 14.7 ± 4.8 mm Hg, p < 0.001, mean dynamic contour tonometry: 21.6 ± 6.8, p < 0.001). Tono-Pen XL also underestimated, but difference was not statistically significant (Tono-Pen XL: 27.9 ± 9.7, p = 0.064). In true intraocular pressure of 50 mm Hg, all three methods significantly underestimated (Goldmann applanation tonometry: 17.6 ± 5.3 mm Hg, p < 0.001, dynamic contour tonometry: 26.8 ± 6.3 mm Hg, p < 0.001, Tono-Pen XL: 35.6 ± 8.4 mm Hg, p < 0.001). The error in measured intraocular pressure for each method (true minus measured intraocular pressure) was significantly correlated to true intraocular pressure (p < 0.001). The intraocular pressure measurements of each eye taken under true intraocular pressure of 17 and 33 mm Hg with the three methods were correlated to each other. Measurements taken under intraocular pressure of 50 mmHg were not correlated to each other. Corneal thickness was not correlated to intraocular pressure measurement. Conclusion: Goldmann applanation tonometry, dynamic contour tonometry, and Tono-Pen XL underestimate intraocular pressure when measured under edematous conditions. Tono-Pen XL showed better accuracy, especially in lower true intraocular pressure. The measurement error increases when true intraocular pressure increases in all three methods. [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the feasibility of anterior segment optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) for the imaging of EX‑PRESS® implant. Materials and Methods: This nonrandomized comparative case series was performed at the Department of Ophthalmology of the University Hospital of Heraklion, Crete, Greece. The Ellex Eye Cubed (40 MHz) UBM and the Zeiss Visante OCT systems were used. The filtering bleb morphology (BL), aqueous outflow (AS), and tube position (TB) were evaluated by two independent observers using a quality scale of 1 (worst) to 4 (best). Data were also collected on corneal and iris clearance from the tip of the tube (CC and IC, respectively). Data from both the devices were statistically analyzed. P < 0.05 was considered as statistically significant. Results: Ten eyes of 10 patients (6 males) with EX‑PRESS® implant were examined. TB, AS, and BL scores using UBM were 2.40 ± 0.39, 3.45 ± 0.72, and 2.45 ± 0.64, respectively. TB, AS, and BL scores for OCT were 3.35 ± 0.41, 1.55 ± 0.43, and 2.55 ± 0.55, respectively. AS was significantly higher with UBM whereas the opposite was true for TB. Differences in BL between OCT and UBM were not statistically significant (P > 0.05). Conclusion: Imaging of the EX‑PRESS® implant is feasible with both UBM and OCT. Both modalities allow visualization of the position of the implant tube in relation to the iris or cornea and delineate the internal structure of the filtering bleb. [ABSTRACT FROM AUTHOR]

Background: To compare the corneal healing response between conventional and phototherapeutic keratectomy through a masking agent, in rabbit corneas. Methods: 24 adult rabbits underwent phototherapeutic keratectomy. Animals were divided in two groups: 12 received photoablation through a masking agent (PALM gel) and the remaining 12 received conventional phototherapeutic keratectomy of equal depth and served as control. Light and transmission electron microscopy was performed in specimens of both groups obtained: immediately after, four hours, one week, one, three and six months after treatment. Results: Reepitheliazation was complete within five days in all eyes. Light and transmission electron microscopy did not reveal any differences of the healing process in the experimental eyes compared to the controls. Conclusion: Photoablation through the PALM technique did not result any evident alterations of the reepithelisation and stromal healing process. [ABSTRACT FROM AUTHOR]

Purpose: To use anterior segment optical coherence tomography (AS-OCT) to compare corneal stroma demarcation line depth after corneal collagen crosslinking (CXL) with 2 treatment protocols. Setting: Vardinoyiannion Eye Institute of Crete, Faculty of Medicine, University of Crete, Heraklion, Crete, Greece. Design: Prospective comparative interventional case series. Methods: Corneal collagen crosslinking was performed in all eyes using the same ultraviolet-A (UVA) irradiation device (CCL-365). Eyes were treated for 30 minutes with 3 mW/cm2 according to the standard Dresden protocol (Group 1) or for 10 minutes with 9 mW/cm2 of UVA irradiation intensity (Group 2). One month postoperatively, 2 independent observers measured the corneal stroma demarcation line using AS-OCT. Results: Sixteen patients (21 eyes) were enrolled. Group 1 comprised 7 patients (9 eyes) and Group 2, 9 patients (12 eyes). The mean corneal stroma demarcation line depth was 350.78 μm ± 49.34 (SD) (range 256.5 to 410 μm) in Group 1 and 288.46 ± 42.37 μm (range 238.5 to 353.5 μm) in Group 2; the corneal stroma demarcation line was statistically significantly deeper in Group 1 than in Group 2 (P=.0058, t test for unpaired data). Conclusion: The corneal stroma demarcation line was significantly deeper after a 30-minute CXL treatment than after a 10-minute CXL procedure with high-intensity UVA irradiation. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. [ABSTRACT FROM AUTHOR]

: PurposeTo report formation of corneal iron ring deposits after conductive keratoplasty.: DesignObservational case report.: MethodsCase report.: ResultsA 54-year-old woman underwent conductive keratoplasty for hyperopia. One year after conductive keratoplasty, iron ring pattern pigmentation was detected at the corneal epithelium of both eyes.: ConclusionsThis is the first report of the appearance of corneal iron ring deposits following conductive keratoplasty treatment in a patient. It is suggested that alterations in tear film stability, resulting from conductive keratoplasty-induced changes in corneal curvature, constitute the contributory factor for these deposits. [Copyright &y& Elsevier]