Search

Background: Several rheological disorders of the erythrocytes, such as increased aggregation and decreased deformability, have been observed in diabetes mellitus and have been implicated in the development of diabetic microangiopathy. Structural alterations of the erythrocyte membrane proteins caused by the diabetic process may be at the origin of those observations. In the present study, we searched for erythrocyte membrane protein alterations in diabetic retinopathy., Methods: We examined peripheral blood samples from 40 type-2 diabetic patients with diabetic retinopathy of variable severity (19 males and 21 females, mean age 66.8 years, Group A) and we compared them with samples from 19 type-2 diabetic patients without diabetic retinopathy (13 males and six females, mean age 66.5 years, Group B) and 16 healthy volunteers (eight males and eight females, mean age 65.6 years, Group C). Erythrocyte membrane ghosts from all samples were subjected to SDS-PAGE, and the electrophoretic pattern of transmembrane and cytoskeletal proteins was analysed for each sample. The protein quantification of each electrophoretic band was accomplished through scanning densitometry., Results: No significant deviations from normal electrophoresis were observed in Groups B and C, apart from an increase in band 8 in two samples from Group B (11%). In contrast, in 14 samples from Group A (35%) we detected increases in protein band 8 and/or membrane-bound haemoglobin along with a decrease in spectrin. Moreover, increased mobility of band 3, an aberrant high molecular weight (MW) (> 255 kDa) band and a low MW (42 kDa) band were evident in ten samples from Group A (25%). Glycophorins were altered in 46% of Group-A patients versus 38% of Group-B patients. Females and patients with long duration of diabetes presented more electrophoretic abnormalities., Conclusions: Structural alterations of the erythrocyte membrane proteins are shown for the first time in association with diabetic retinopathy. Their detection may serve as a blood marker for the development of diabetic microangiopathy. Further studies are needed to assess whether pharmaceutical intervention to the rheology of erythrocytes can prevent or alleviate microvascular diabetic complications.

Purpose: To determine the clinical microbiological characteristics of corneal ulcers in contact lens wearers., Methods: A retrospective study of 23 patients admitted to our department with contact lens-related corneal ulcers during a 43-month period. Detailed demographic data, the type of contact lens, duration of lens wear, and wearing schedule were derived from a self-administered questionnaire. The severity of the ulcer; cultures of corneal scrapings, storage solutions, and contact lenses; treatment; and final outcome were evaluated., Results: Of the 86 cases of ulcerative keratitis admitted during the study period, 23 (26.74%) were attributed to contact lens use. Most patients were young women from urban areas. All of them were using soft contact lenses for 3 days to 20 years. Five patients used daily-wear lenses as extended-wear lenses. Most ulcers (47.82%) were mild; 30.43% were moderate; and 21.47% were severe. Corneal scrapings for cultures were obtained in 15 of the cases and were positive in 10 (43.47%) of them, whereas in 33.33% of the culture-positive storage solutions and in 66.67% of the culture-positive contact lenses, corneal scrapings were negative. Pseudomonas aeruginosa was the most frequent isolated pathogen (60%). The final visual acuity was 20/40 or better in 60.87% of the cases., Conclusions: Contact lens use is an important risk factor for the development of ulcerative keratitis, with P. aeruginosa remaining the predominant pathogen. It seems important to culture contact lenses and contact lens storage solutions, in addition to the corneal scrapings, and the role of initial therapy for the corneal ulcers remains important.

Objective: To determine the epidemiological characteristics of severe eye injuries in childhood, in a mixed urban and rural Greek setting., Methods: Retrospective analysis of 95 cases (103 eyes) of eye injuries in children younger than 17 years of age admitted to the Department of Ophthalmology, University Hospital of Patras, Greece, during a five-year period. The data were analyzed with respect to age, sex, type, cause and mode of injury, method of management, duration of hospitalization and final visual deficit., Results: The average age was 9.8 years and males were involved in 80% of the cases. The most common type of eye injury was mechanical closed-globe injury (71.8%). Mechanical open-globe injuries were found in 21.3% of the eyes, while burns comprised 6.7% of the injuries. Most injuries were agent-related, with blows and falls being responsible most often. Multiple operations were part of the treatment in 11.6% of the eyes; 14.5% of the eyes were blinded and 15.5% had significant final visual acuity loss., Conclusions: These hospital-based data suggest that there is a need for health education of both parents and children, since some injuries in children could easily have been prevented.

Purpose: To investigate whether identification of the causal organism in corneal ulcers influences their outcome., Methods: We retrospectively studied 114 patients, 72 males and 42 females aged 6-89 years, admitted to this eye clinic during the years 1994-2000 on account of an infectious corneal ulcer. Their examination included a detailed history, visual acuity measurement, and biomicroscopy in everyday follow-up. The ulcers were classified according to their severity and outcome. We assessed the cases where cultures had been done, reviewed the results, and searched for a possible correlation between the outcome and the fact of culturing the ulcer and identifying the causal organism., Results: Of the 114 corneal ulcers studied, 23 were mild, 49 moderate, and 42 severe. Fifty (44%) had not been cultured, but 64 ulcers (56%) had been cultured, with a positive result in 37 cases (58%), Staphylococcus and Pseudomonas species being the most common organisms found. In moderate and severe ulcers, there was a tendency to a higher proportion of successful outcome for cultured ulcers, but with no significant correlation., Conclusions: Despite a tendency towards favorable results in culture-positive corneal ulcers, the influence of the detection of the organism on their outcome has not been proved. The role of the initial broad-spectrum antibiotic therapy remains important.

Purpose: To evaluate the efficacy of the management of diabetic retinopathy (DR) in the teaching center of the University Eye Clinic of Patras in Greece., Methods: From 1989 to 1999, 302 patients with type I (5.3%) and type II (94.7%) diabetes mellitus (DM) were examined. Standard examination and treatment protocols were employed. Examinations and laser treatment were done by trainee specialists, under the supervision of the head physician (N.Ph), during their rotation in the retina and vitreous disorders outpatient department., Results: At baseline examination, 17.9% of the eyes had no DR, 71.7% had nonproliferative DR, and 10.4% had proliferative DR. In 34.4%, no laser treatment followed. The other 65.6% underwent focal and/or grid laser and/or panretinal photocoagulation and/or vitrectomy. At the final examination, DR was still the same in 63.1% of the eyes, progression had occurred in 34.1%, and regression in 2.8%. Type I DM patients' eyes had a higher prevalence of proliferative DR at the final examination than type II DM eyes. There was also a significant correlation between progression of DR and duration of DM, insulin treatment for DM, and elevated glycosylated hemoglobin (HbA1c)., Conclusions: Having applied standard examination and treatment protocols, the efficacy of the management of our diabetic patients was consistent with international standards, even though patients were treated mostly by doctors in training.

Purpose: To describe corneal complications in three patients following abuse of topical anesthetics., Materials and Methods: We describe one case with bilateral corneal perforation, another with unilateral corneal perforation and a third case of chronic keratitis following excessive use of topical anesthetics., Results: Two patients continued to instill topical anesthetic drops despite all recommendations to stop. The result was a bilateral corneal perforation in the first case and a large unilateral descemetocele in the second. The third patient who had chronic toxic keratitis discontinued the anesthetic drops and after the appropriate treatment the cornea returned to normal. Corneal grafting and conjunctival flaps were used to seal the corneal perforation but the long-term anatomical and functional results were very poor., Conclusions: The initial presentation of this rare clinical entity creates difficulties in reaching a correct diagnosis. A presumed acanthamoeba keratitis is the first choice among many similar conditions. Thus abuse of topical ocular anesthetic drops should be included in the differential diagnosis of cases of chronic keratitis as it may masquerade as acanthamoeba keratitis. A current or past history of psychiatric and mental disorders or psychoactive substance abuse is important in the diagnosis. Functional and anatomical results after appropriate treatment are usually poor. Psychiatric counselling is extremely helpful and is in fact mandatory in the management of these patients.

Staphylococcus epidermidis is an important cause of bacterial keratitis. Certain S. epidermidis strains produce an extracellular slime layer rich in an acidic polysaccharide with a molecular size of 20 kDa (20-kDa PS). We have demonstrated that the level of 20-kDa PS-specific antibodies significantly rises after establishment of slime-producing S. epidermidis bacteraemia and, furthermore, that rabbit polyclonal antibodies to 20-kDa PS opsonize cells of slime-producing S. epidermidis to a great degree and promote their clearance by polymorphonuclear cells (Arch. Biochem. Biophys. 342 (1997) 389; J. Pharm. Biomed. Anal. 22 (2000) 1029). The purpose of this study was to examine the protective and therapeutic effects both of active immunization, using 20-kDa PS as antigen, and of passive administration of specific antibodies towards the 20-kDa PS in a rabbit keratitis model. For active immunization, 20 rabbits were subcutaneously immunized with 20-kDa PS, whereas for passive immunization specific polyclonal IgG antibodies against 20-kDa PS were administered to 20 rabbits 1 day before induction of infection. Clinical observations were made weekly for 1 month and levels of 20-kDa PS antibodies in serum and aqueous humor in both immunization groups were determined by an enzyme immunoassay. The levels of specific anti-20-kDa PS IgG in serum and aqueous humor following either active or passive immunization were significantly higher as compared with control groups (P<0.001). Although, actively immunized rabbits showed significantly less corneal damage than control animals, passively immunized ones were significantly better protected as compared with both control and those actively immunized. Obtained results suggest that 20-kDa PS plays crucial role in the pathogenesis of S. epidermidis keratitis and that both types of immunization significantly protect against corneal S. epidermidis pathology and damage.

Endophthalmitis is a well-recognized, frequently devastating ophthalmic disease. The colonization of the eye and the subsequent development of endophthalmitis may be exogenous (including postsurgical and post-traumatic infections) or it may be of endogenous origin, representing a metastasis from a focus of infection elsewhere in the body associated with bacteremia (such as meningitis or cellulitis).

Purpose: To evaluate contrast sensitivity function in patients with impaired oral glucose tolerance test (OGTT) compared with normal subjects., Methods: Sixteen patients with impaired OGTT and 11 normal control subjects were tested for contrast sensitivity function at four spatial frequencies. Glucose intolerance was established by the 1985 World Health Organization criteria., Results: The two groups were similar in terms of age, visual acuity, refractive correction, and lens opacities. A statistically significant loss of contrast sensitivity was associated with impaired OGTT (p < 0.001) in every spatial frequency tested., Conclusions: Functional visual loss in patients with impaired glucose tolerance using the 1985 World Health Organization criteria indicates that at least part of those patients should be classified as diabetic according to the 1997 American Diabetic Association criteria. It seems that the 1997 American Diabetic Association criteria are more efficient at detecting patients with abnormal visual function.

Purpose: To investigate contrast sensitivity function in patients with beta-thalassemia major, after regular transfusion and chelation therapy., Methods: We measured contrast sensitivity at four spatial frequencies in 30 patients with beta-thalassemia major and in 30 matched normal control subjects. All subjects underwent an ophthalmic examination that included fluorescein angiography. The contrast sensitivity results from the two groups were compared between them. Patients' contrast sensitivity values were correlated to the variables age, duration of transfusion, duration of chelation therapy and serum ferritin levels, to select the important predictors., Results: Contrast sensitivity function in all beta-thalassemic patients was significantly lower (p<0.0001) compared to the normal control subjects, for all spatial frequencies tested. The most important predictor of contrast sensitivity loss was patients' age., Conclusion: Contrast sensitivity testing can detect early changes in the visual function of beta-thalassemic patients and should be considered as a monitor for patients under chronic transfusion-chelation therapy.

Background and Objective: To evaluate the efficacy of topical brimonidine tartrate 0.2% (Allergan, Irvine, CA) in the prophylactic treatment of acute intraocular pressure (IOP) rises following Nd:YAG laser posterior capsulotomy., Patients and Methods: This was a double-masked, randomized, placebo-controlled clinical study in 60 patients who underwent Nd:YAG laser posterior capsulotomy after extracapsular cataract extraction. Two doses of brimonidine or vehicle were administered before and after capsulotomy. Intraocular pressure was measured prior to commencing instillation and for 48 hours postoperatively., Results: Following posterior capsulotomy, the brimonidine group showed a significant mean percent reduction in IOP, while the vehicle group showed a significant mean percent increase in IOP. At 48 hours, mean IOP of both groups had returned to pre-laser level. There were no differences between the 2 groups in the incidence of clinical adverse experiences., Conclusion: Two-dose brimonidine tartrate 0.2% effectively prevents acute IOP rises after Nd:YAG laser posterior capsulotomy.

Contrast sensitivity function after cataract extraction and intraocular lens implantation has been mainly correlated to the type or the material of the intraocular lens. Our purpose was to identify other possible factors, like posterior capsule, to contrast sensitivity alterations after cataract surgery, comparing patients operated for cataract by techniques that mainly differed on the posterior capsule's integrity. The intraocular lens implanted was either a posterior or an anterior chamber one, always monofocal and made of PMMA. We measured contrast sensitivity function at four spatial frequencies in two groups of operated individuals (group A and B) and in one group of healthy control individuals. Each group consisted of 42 eyes. Group A comprised eyes with intact, clear posterior capsule and posterior chamber monofocal intraocular lens. Group B comprised eyes with ruptured or removed posterior capsule and anterior chamber monofocal intraocular lens. Control group comprised healthy control eyes. A pair matched design was used to compare contrast sensitivity values among the individuals of the three groups. No statistically significant differences in contrast sensitivity values were found when group B patients were compared to healthy controls (p >0.05). Patients of group A exhibited contrast sensitivity function impairment at intermediate and high spatial frequencies when compared to patients of group B (p <0.05) and to controls (p <0.01). It seems that intact posterior capsule provides inferior visual function, in spite of relatively good visual acuity and apparently satisfactory results.

Divergent contrast sensitivity findings have been reported in patients with intraocular lens implants. The purpose of this study was to determine contrast thresholds of patients with good visual acuity after uncomplicated cataract extraction and posterior chamber conventional IOL implantation. Fifty-two eyes of fifty two patients, who had undergone uncomplicated extracapsular cataract extraction and posterior chamber intraocular lens implantation together with 48 eyes of 48 control subjects were tested for contrast sensitivity function. All of the patients had best corrected visual acuity 0.8 (20/25) or better, on the Snellen scale. Patients with concomitant eye disease were excluded. Contrast sensitivity was measured using stationary sine-wave gratings of four spatial frequencies (3.0 to 18.0 cycles/degree), at the testing distance of 8 feet. A loss of contrast sensitivity was found in patients with intraocular lens implants, compared with control subjects of similar age, sex and visual acuity. The loss was statistically significant at intermediate (6 cyc/deg) and high spatial frequencies (12.0 and 18.0 cycles/degree), while it was not statistically significant at low spatial frequencies (3 cyc/deg). This may be the reason of nonspecific visual complaints ('washed-out images'), despite normal Snellen acuity, after cataract surgery and monofocal IOL implantation.

This study presents results obtained after implantation of 25 diffractive multifocal intraocular lenses. The follow-up ranged from six to 12 months. Visual acuity for distance without correction was 0.5 or better in 72% of cases; for near, it was J1 to J3 in 84% of cases. Slight decentration of the lens and pupil size did not affect visual acuity.

Quantitative changes were measured and ultrastructural alterations were detected in rabbit corneas after exposure to a far ultraviolet irradiation (UV). Low dose exposure (105 - 8 x 105 erg/cm2) resulted one day later in a thicker epithelium and loss of the intercellular permeability barrier. In corneas exposed to higher doses (5 x 106 erg/cm2), the epithelium was considerably thinner one day later, whereas 4 days later it was of normal thickness and the endothelial cells became degenerated. The highest UV dose exposure used (a total of 20 x 106 erg/cm2 given in 4 equal daily doses) resulted in (1) swelling of the stroma and disorganization of the collagen fibers; (2) disappearance of the basement membrane; (3) degeneration of the endothelial cells; and (4) considerable reduction of epithelium thickness.

The effects of far ultraviolet light irradiation upon an amphibian cornea were studied to compare the effects observed both quantitatively and ultrastructurally with data obtained after UV irradiation of mammalian corneas. The ultimate goal of this series of investigations is the elucidation of the alterations and the regeneration mechanisms, which might reflect existing morphological diversities among the species, observed in vertebrate corneas following exposure to UV light. It was found that while the epithelial cells undergo oedema after low dose exposures and are gradually damaged after high doses of UV light, 2-4 days leter a new epithelium has been formed. Intercellular permeability is increased by low dose exposure as was detected by the penetration of Ruthenium Red into the intercellular clefts. Under these conditions desmosomal structure revealed a 21-laminar configuration. The basement membrane of the amphibian, unlike that of the mammal, does not dissolve away upon exposure but shows localized disruptions which are thought to accommodate the passage of leucocytes from stroma to epithelium. That a new basement membrane is subsequently formed is evident by the existence of extracellular and intracellular secretion granules. In comparison to irradiated rabbit corneas, this stroma remains remarkably at the same thickness following a high dose exposure although a noticeable disorganization of collagen arrangement is apparent. Finally, as in the case of the rabbit corneas, a secondary degeneration of endothelium was observed 4 days after a moderate dose exposure.

The cornea of the urodele amphibian Triturus c. cristatus was studied ultrastructurally in order to provide the basis for a comparison among corneas throughout the vertebrate phylum. The cornea of this salamander consists of relatively thick epithelium and basement membrane and thin Descemet's membrane, unlike the mammalian corneas. The outermost epithelial cells contain Ruthenium Red stainable extracellular filaments and intracellular vesicles which are thought to play a role in the process of lubricating the corneal surface. Occluding junctions have been observed in the apical region of the superficial epithelial cells and are considered as barriers to the intercellular passage of material. A thin substantia propria (stroma) consists of about 40 collagenous highly organized lamellae. The thicknesses of the basement membrane, Descemet's membrane and the epithelium are believed to represent the primitive situation in the process of corneal evolution.

Chemical burns were produced using a 4 N NaOH solution in 21 rabbit corneas. The ultrastructural findings were examined under an electron microscope five minutes and 1, 2, 4, 8, 15, and 30 days after the burn. A morphologic disturbance of the basement membrane and its complexes was detected from the first day of the experiment. These findings suggest that the basement membrane plays an important role in the pathogenesis of corneal recurrent erosions and ulcer formation after chemical burns.