A pilot study of the use of objective structural clinical examinations for the assessment of ophthalmology education.

PURPOSE: A pilot study was carried out to evaluate the practicality, reliability, and validity of an objective structured clinical examination (OSCE) for assessing the clinical skills and abilities of specialists in ophthalmology. METHODS: Ten unfolded OSCE style, criterion referenced questions were asked to nine candidates to assess their clinical skills and abilities, as opposed to subject knowledge. Candidate and assessor reactions to the examination process were monitored and analyzed using participant observation and questionnaires administered immediately after the event. Relevant statistical techniques were applied to the results. RESULTS: A total of 89% of candidates passed the examination, with the pass boundary set at 70%. Candidates revealed themselves more successful in meeting clinical skill criteria (mean 77%) than clinical ability criteria (mean 72%). Candidates, assessors, and observers all expressed the view that the OSCE pilot had been a successful way of assessing clinical skills and abilities. CONCLUSIONS: OSCE style assessment is an effective and efficient means of assessing skills and abilities in clinical ophthalmology education.

Antioxidative role of ocular melanin pigment in the model of lens induced uveitis.

Ocular melanin pigment has antioxidant effect against excess of dispersed light. To investigate whether it has a similar effect in ocular inflammations, we used albino and pigmented guinea pigs and measured retinal glutathione peroxidase activities and lipid peroxide levels (expressed as thiobarbituric acid reactive substances) in a model of lens induced uveitis. Although the increase in the levels of the retinal lipid peroxides were higher in the albino group (204%, p < 0.05), the decrease in the activities of glutathione peroxidase were higher in pigmented guinea pigs (26%, p < 0.005). The results of the study suggest that pigmentless animals are more sensitive to the ocular inflammations, and ocular melanin pigment may act as an endojen antioxidant in lens induced uveitis.

Results of photorefractive keratectomy in keratoconus suspects at 4 years.

PURPOSE: We studied the long-term results of photorefractive keratectomy (PRK) in keratoconus suspects detected by videokeratography (TMS). METHODS: Bilateral inferior corneal steepening was detected in 6 candidates for PRK presenting with moderate myopia or astigmatism. Mean follow-up was 44.5 +/- 4.4 months (range, 38 to 54 mo). Mean spherical equivalent refraction was -5.18 +/- 1.60 D (mean sphere, -4.73 D; mean cyclinder, -0.92 D) which was stable for at least the preceding year. The quantitative measurement of inferior corneal steepening (I-S value) was greater than +1.60 (mean, 1.83 +/- 0.11) in all eyes. An Aesculap Meditec Mel 60 excimer laser was used for the PRK procedures and mean follow-up was 44.5 months. Postoperative pachymetric measurements were also performed in 6 eyes. RESULTS: Postoperative uncorrected visual acuity was 20/20 in 8 eyes (66.6%) and 20/32 or better in all eyes with a mean postoperative spherical equivalent refraction of -0.70 +/- 0.74 D (mean sphere, -0.63 D; mean cyclinder, -0.39 D). Five eyes (41.6%) were within +/- 0.50 D spherical equivalent refraction. Inferior steepening was associated with thinning of the inferior cornea which was statistically significantly thinner than the superior thickness (Student's t-test, P < .05). There were no wound healing problems or any sign that the excimer laser adversely affected the cornea during follow-up. CONCLUSIONS: Photorefractive keratectomy seems to be a safe procedure for reducing or eliminating myopia or astigmatism in keratoconus suspect eyes-most probably forme fruste keratoconus-with a stable refraction, but this may be different in eyes with early keratoconus, known to be a progressive disease.

Photorefractive keratectomy for visual rehabilitation of anisometropia induced by retinal detachment surgery.

PURPOSE: To evaluate the efficacy of unilateral photorefractive keratectomy to correct anisometropia induced by retinal detachment surgery. METHODS: Photorefractive keratectomy was performed in 10 eyes of 10 patients with anisometropia induced by previous retinal detachment surgery. The Aesculap Meditec MEL 60 excimer laser was used. RESULTS: Preoperative mean spherical equivalent refraction was -5.20 D. Mean postoperative spherical equivalent refraction was -0.25 D after a mean follow-up of 12.9 months. Mean preoperative spherical equivalent refraction difference between two eyes of 4.87 D was decreased to a mean 0.60 D postoperatively (t-test, P < .0001). All patients were free of anisometropic symptoms after laser surgery. CONCLUSION: Unilateral photorefractive keratectomy seems to be an effective method to correct anisometropia induced by conventional retinal detachment surgery, especially for patients with spectacle and contact lens intolerance.

Neurofibromatosis associated with retinoblastoma: case report.

A case of neurofibromatosis is presented in a 3-year-old male with leucokoria in his left eye. Enucleation was performed, and on pathological examination the mass filling the globe proved to be retinoblastoma. We believe ours to be the first reported case of this rare association.

Corneal aldehyde dehydrogenase and glutathione S-transferase activity after excimer laser keratectomy in guinea pigs.

BACKGROUND: The free radical balance of the eye may be changed by excimer laser keratectomy. Previous studies have demonstrated that excimer laser keratectomy increases the corneal temperature, decreases the superoxide dismutase activity of the aqueous, and induces lipid peroxidation in the superficial corneal stroma. Aldehyde dehydrogenase (ALDH) and glutathione S-transferase (GST) are known to play an important role in corneal metabolism, particularly in detoxification of aldehydes, which are generated from free radical reactions. METHODS: In three groups of guinea pigs mechanical corneal de-epithelialisation was performed in group I, superficial corneal photoablation in group II, and deep corneal photoablation in group III, and the corneal ALDH and GST activities measured after 48 hours. RESULTS: The mean ALDH and GST activities of group I and II showed no differences compared with the controls (p > 0.05). The corneal ALDH activities were found to be significantly decreased (p < 0.05) and GST activities increased (p < 0.05) in group III. CONCLUSION: These results suggest that excimer laser treatment of high myopia may change the ALDH and GST activities, metabolism, and free radical balance of the cornea.

Scanning laser polarimetry in normal subjects and patients with myopia.

AIMS: To examine the changes in the retinal nerve fibre layer (NFL) thickness with age and myopia in normal population. METHODS: Retinal nerve fibre layer thickness was measured with a scanning laser polarimeter (NFA-I) in 180 normal subjects of varying age (range 7-83 years) and in 110 eyes of 85 patients with myopia of varying degrees (range -1.00 to -15.00D). They were all voluntary Anatolian people. Superior to nasal (S/N), inferior to nasal (I/N), and the superior to inferior (S/I) ratios were used for the assessment of retinal NFL thickness. RESULTS: The mean superior NFL ratio was 2.96 and the mean inferior NFL ratio was 2.93 in normal subjects. There was a gradual decrease in NFL ratio with increasing age (simple regression analysis, p<0.05). The mean S/I ratio was 1.01 with a large variation. In patients with myopia, the mean superior NFL ratio was 2.60 and the mean inferior NFL ratio was 2.72. Superior and inferior NFL retardations, and S/I ratio in myopic patients were significantly (15.5%, 10.8%, and 4.9% respectively) lower than that of age matched normals (t test, p<0.05). There was also a gradual decrease in NFL thickness with increasing degree of myopia (simple regression analysis, p<0.05). CONCLUSIONS: Nomograms we obtained for retinal NFL thickness may serve as reference points for the assessment of normal Anatolian people and myopic patients in future studies. NFL thicknesses gradually decreased with increasing age. Patients with myopia had significantly lower NFL thicknesses than normal subjects and, although weakened by wide age range of myopic group, there is a linear relation between severity of myopia and NFL thickness in myopic patients.

Laser in situ keratomileusis in an eye with congenital nystagmus.

A 38-year-old man with congenital nystagmus had laser in situ keratomileusis (LASIK) to correct a spherical equivalent of -11.0 diopters (D) in the right eye and -10.0 D in the left eye. Baseline uncorrected visual acuity (UCVA) was 20/400 in both eyes, and best spectacle-corrected visual acuity was 20/60 in the right eye and 8/20 in the left. The procedure was performed using the Aesculap Meditec MEL 60 excimer laser system and a semicircular suction ring device. Six months after LASIK, the patient had a UCVA of 20/60 in the right eye and 8/20 in the left eye, with no improvement with spectacle correction. Laser in situ keratomileusis can be performed with a semicircular suction ring device to correct refractive errors in patients with congenital nystagmus, but more cases have to be performed to confirm that the device is safe and suitable for these patients.

Pars plana lensectomy with double-capsule-supported intraocular lens implantation in children.

An alternative technique to manage pediatric cataracts comprises a pars plana lensectomy and anterior vitrectomy with anterior and posterior capsulotomies and posterior chamber heparin-surface-modified intraocular lens (IOL) implantation in the ciliary sulcus through a scleral tunnel. The surgical results in 7 eyes of 6 consecutive patients between 3.5 and 12.0 years old with developmental or traumatic cataract who had surgery using this technique were evaluated prospectively. Follow-up ranged from 12 to 19 months. All 7 eyes maintained a clear pupillary axis and a well-centered IOL from immediately after surgery to the last follow-up. Final best corrected visual acuity was 20/40 or better in 71% of cases.

Photorefractive keratectomy for post-penetrating keratoplasty myopia and astigmatism.

PURPOSE: To determine the safety, effectiveness, and predictability of photorefractive keratectomy (PRK) for the correction of myopia and astigmatism after penetrating keratoplasty. SETTING: Gazi University, Medical School, Department of Ophthalmology, Ankara, Turkey. METHODS: Photorefractive keratectomy was performed in 16 eyes of 16 patients with postkeratoplasty myopia and astigmatism who were unable to wear glasses due to anisometropia and were contact lens intolerant. They were examined for uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), and corneal transplant integrity before and after surgery. RESULTS: The mean follow-up after PRK was 26.0 months +/- 15.7 (SD) (range 12 to 63 months). The mean preoperative spherical equivalent refraction of -4.47 +/- 1.39 diopters (D) was -3.39 +/- 1.84 D (P >.05) at the last postoperative visit and the mean preoperative cylinder of -5.62 +/- 2.88 D was -3.23 +/- 1.70 D (P <.05); refractive regression correlated with the amount of ablation performed. The BSCVA decreased in 3 eyes (18.8%), and the UCVA decreased in 2 (12.5%). Six eyes (37.5%) had grade 2 to 3 haze, which resolved spontaneously in 4 eyes within a relatively long time but caused a decrease in BSCVA in 2 (12.5%). Two of the eyes (12.5%) had a rejection episode after PRK and were successfully treated with topical steroids. CONCLUSIONS: Photorefractive keratectomy to correct postkeratoplasty myopia and astigmatism appears to be less effective and less predictable than PRK for naturally occurring myopia and astigmatism. Corneal haze and refractive regression are more prevalent, and patient satisfaction is not good.

Corneal iron ring after hyperopic photorefractive keratectomy.

PURPOSE: To report the incidence and course of corneal iron deposition after hyperopic photorefractive keratectomy (PRK). SETTING: Gazi University, Medical School, Department of Ophthalmology, Ankara, Turkey. METHODS: Between January 1995 and December 1997, 62 eyes had PRK to correct hyperopia. RESULTS: Nine eyes developed corneal iron ring 5 to 8 months (mean 6.25 months +/- 1.3 [SD]) after PRK for hyperopia. The rings persisted during the mean follow-up of 19 +/- 11.09 months. CONCLUSION: The ring-shaped iron deposition after PRK for hyperopia must be differentiated from the Fleischer ring. Our results suggest that the slitlamp findings of peripheral corneal iron deposition in hyperopic PRK patients correlate with achieved correction.

Ascorbic acid levels in human tears after photorefractive keratectomy, transepithelial photorefractive keratectomy, and laser in situ keratomileusis.

PURPOSE: To investigate the level of ascorbic acid in human tear fluid after photorefractive keratectomy (PRK), transepithelial PRK, and laser in situ keratomileusis (LASIK). SETTING: Departments of Ophthalmology and Biochemistry, School of Medicine, Gazi University, Ankara, Turkey. METHODS: Twenty patients (7 women and 13 men) were included in this study. Traditional PRK with epithelial scraping by a blunt spatula followed by surface ablation (7 eyes), transepithelial PRK (7 eyes), or LASIK (6 eyes) was performed. Tears were collected preoperatively and 1 and 5 days postoperatively. Ascorbic acid levels were measured using 2-4 dinitrophenylhydrazine. RESULTS: Ascorbic acid levels in the tear fluid were decreased significantly 1 day after PRK, transepithelial PRK, and LASIK (P <.05). On the fifth day, the ascorbic acid levels were significantly lower than preoperatively in all groups. CONCLUSION: After PRK, transepithelial PRK, and LASIK, the ascorbic acid levels of the tear fluid decreased significantly. Because ascorbic acid is the major scavenger of superoxide radicals in tears, topical ascorbic acid therapy may help eliminate the harmful effect of free radicals from excimer laser surgery.

Comparison of uveitis induced by interleukin-8 (IL-8) and endotoxin in rabbits.

IL-8 is a potent chemoattractant which has been postulated to play a role in the cytokine cascade associated with uveitis. The authors studied the effect of intravitreal IL-8 on the induction of uveitis in the rabbit. IL-8 at varying concentrations (1 ng, 10 ng or 100 ng) or endotoxin (100 ng) was injected intravitreally within the rabbit eye. At 6, 24 and 48 hours following injection the induction of uveitis was evaluated by clinical scoring, anterior chamber (AC) leukocyte count, AC protein concentration and histopathology in 15 rabbits. Only the 100 ng concentration of IL-8 induced uveitis at 6 and 24 hours by clinical scoring and AC leukocyte count; the AC protein concentration remained normal. In contrast, endotoxin caused a severe uveitis with a significant increase in all the parameters evaluated. The authors conclude that intravitreal IL-8, in the concentrations studied, induces a limited uveitis which is detectable at six hours and resolves within 48 hours. It is characterized by leukocyte infiltration without an increased AC protein concentration. Thus, IL-8 may play a role in the cytokine cascade involved in the induction of uveitis.

Nerve fiber layer assessment with scanning laser polarimetry in glaucoma patients and glaucoma suspects.

PURPOSE: To investigate whether scanning laser polarimeter can differentiate glaucoma and suspected glaucoma patients from normals. METHODS: Polarimetric measurements were obtained using the nerve fiber analyzer (NFA)-I from 80 eyes of patients with glaucoma with mostly moderate glaucomatous optic nerve damage (37 eyes with primary open angle glaucoma, 21 with normal tension glaucoma, 17 with pseudoexfoliative glaucoma, 3 with angle closure glaucoma, and 2 with juvenile glaucoma), 53 eyes of patients suspected of glaucoma based on disc appearance, and from age-matched healthy volunteers as control groups. Ratios (superior/nasal, inferior/nasal, superior/inferior) were used for assessing nerve fiber layer (NFL) thickness. Student's t-test and linear regression analysis were used for statistical analysis. RESULTS: Both the glaucoma patients and glaucoma suspects had significantly lower NFL ratios (mean S/N 2.34 +/- 0.47, I/N 2.46 +/- 0.52, S/I 0.94 +/- 0.18) than the control groups (respectively 2.88 +/- 0.48, 2.88 +/- 0.48, 1.00 +/- 0.13) (p<0.05). There was an ample overlap between the patient groups and the normals. The superior and inferior NFL ratios in glaucoma patients gradually decreased as the mean defect in visual field increased (linear regression analysis, p<0.05). CONCLUSIONS: The NFL of glaucomatous eyes and eyes suspected of glaucoma based on disc appearance was significantly less thick than normals. NFA-I detects pathological abnormalities in some patients with glaucomatous optic nerve damage and normal visual fields as measured by conventional achromatic computerized perimetry. NFA-I, however, is unable to distinguish these patients from normals, at least using these parameters, because of the considerable overlap.

Assessment of retinal nerve fiber layer thickness with NFA-GDx following successful scleral buckling surgery.

PURPOSE: To assess the effect of retinal detachment (RD) on retinal nerve fiber layer (RNFL) thickness by using a scanning laser polarimeter (NFA-GDx) after successful scleral buckling surgery for the treatment of rhegmatogenous RD. METHODS: Consecutive patients who had successful scleral buckling surgery in one eye were assessed for RNFL thickness by using NFA-GDx prospectively. Fellow healthy eyes of the patients formed the control group. Eyes with RD surgery were compared with the control group with respect to three variables (superior average, inferior average, and average thickness) of NFA-GDx by using two-sampled t-test. Additionally, a possible effect of duration of RD on RNFL thickness was assessed with a correlation test. RESULTS: The study group consisted of 16 patients with a mean age of 49.8 years. The mean duration of RD was 28 days. Although the retardation values in operated eyes were less than that of the control eyes, the difference was not statistically significant (p > 0.05). However, these three values were seen to increase with increased duration of detachment and this correlation was statistically significant (R > 0.5, p < 0.03). CONCLUSIONS: RD seemed to cause minimal or no change in RNFL thickness as determined by GDx variables. The positive correlation between RNFL thickness and duration of RD, however, may be because of the proliferated Muller cells in eyes with RD, which may be responsible for some of the retardation measurements, which may be even more prominent in longstanding RD cases. This needs to be supported by further studies in larger patient groups with longer duration of RD and with histopathologic studies.

Nitric oxide levels of aqueous humor after photorefractive keratectomy.

PURPOSE: To measure the nitric oxide (NO) levels of aqueous humor in rabbits after photorefractive keratectomy (PRK) and to evaluate the alterations of NO levels according to the PRK surgery steps, ablation depth, and time. METHODS: Fifty eyes of 25 New Zealand white rabbits were included in the study. One eye was later randomly excluded from the study in order to equalize the number of eyes in groups. Eyes were divided into seven groups, each comprising seven eyes: unwounded control (Group 1), epithelial scrape (Group 2; aqueous humor samples taken at the 4th hour), superficial PRK (Group 3; samples taken at the 4th hour), deep PRK (Group 4; samples taken at the 4th hour), epithelial scrape (Group 5; samples taken at the 24th hour), superficial PRK (Group 6; samples taken at the 24th hour), and deep PRK (Group 7; samples taken at the 24th hour). The corneal epithelium was mechanically removed in surgical groups. The authors performed superficial corneal ablation (59 microm) in Groups 3 and 6 and deep corneal ablation (99 microm) in Groups 4 and 7. Aqueous humor samples were taken at the 4th hour (Groups 2-4) or 24th hour (Groups 5-7) after corneal surgeries. NO measurements were performed indirectly by using the Griess reaction with a spectrophotometer. RESULTS: Aqueous humor NO levels 4 hours after corneal surgery were statistically significantly lower than the control group (p<0.05). However, there was no difference among the surgical groups at the 4th hour (p>0.05). At the 24th hour, the deep PRK group had significantly lower NO levels than both the control group and Groups 5 and 6 (p<0.05). NO levels were normalized at the 24th hour in epithelial scrape and superficial PRK groups (p>0.05) but remained stable at lower levels in deep PRK groups (p<0.05). CONCLUSIONS: Corneal surgery caused low NO levels in aqueous humor 4 hours after surgery. However, 24 hours after surgery, NO levels normalized following epithelial scrape and superficial PRK and were stable at lower levels in the deep PRK group. Complications of deep PRK application are possibly induced by low NO existence in the aqueous humor.

Excimer laser corneal surgery and free oxygen radicals.

Corneal photoablation with 193 nm argon fluoride excimer laser is a new technique for the treatment of refractive errors and for removing corneal opacities and irregularities. Ultraviolet radiation and thermal injury induce free radical formation in the tissues. The aim of this study was to confirm the production of free radicals by excimer laser photoablation in rabbits. The thermal changes of the posterior corneal surface were recorded during excimer laser photoablation. The lipid peroxide (LPO) levels and superoxide dismutase (SOD) activities of aqueous humour were measured after excimer laser keratectomy. The aqueous LPO levels were not changed after excimer laser ablation, but both the thermal increase in the cornea during the photoablation and the decreased aqueous SOD activities suggest that free radicals are formed in the cornea during excimer laser keratectomy, and that they may be responsible for some of the complications of excimer laser corneal surgery.

Pars plana vitrectomy in chronic myelogenous leukemia with vitreous hemorrhage.

Pars plana vitrectomy operations were performed on two cases of vitreous hemorrhage due to chronic myelogenous leukemia. Fundus examination and fluorescein angiography revealed optic disc neovascularization in both, which is a rare fundus finding in chronic leukemias. The first case seen with vitreous hemorrhage in both eyes also had diabetes mellitus with a negative family history, and had received laser therapy on his right eye. His chronic myelogenous leukemia was diagnosed 4 months after vitrectomy was performed on this eye, when he presented with widespread subcutaneous hemorrhages. The second case showed a nonproliferative retinopathy with old laser scars in his right eye and vitreous hemorrhage in his left eye, and had no diabetes mellitus. The diagnosis of chronic myelogenous leukemia was made before the vitrectomy operation when the physical examination revealed splenomegaly. The pathogenesis of retinal and optic disc neovascularization in myeloproliferative diseases, its possible relation with chemotherapy, and the results of the vitrectomy operations were discussed with special emphasis on the importance of ruling out chronic leukemias and other blood dyscrasias in vitreal hemorrhages, retinopathies of unknown origin, and even in diabetic retinopathies with a negative family history.

Hemodynamic alterations in diabetic retinopathy.

PURPOSE: This study was designed to examine the characteristics of retrobulbar circulation and the role of glycemic control in patients with diabetes and varying stages of retinopathy. METHODS: Seventy-three eyes in 37 patients with diabetes were assigned to one of the following four study groups: nonproliferative diabetic retinopathy (non-PDR), proliferative diabetic retinopathy (PDR), post-panretinal photocoagulation (PRP), or preretinopathy (the control group). Color Doppler imaging was used to quantitate peak systolic blood flow velocities of the central retinal artery (CRA), the central retinal vein (CRV), the posterior ciliary artery (PCA) and the ophthalmic artery. Glycated hemoglobin (HbA1c) levels were used as an indicator of glycemic control. RESULTS: The authors found that the CRA maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (9.8 +/- 2.1 cm/second) than in the non-PDR group (8.1 +/- 2.2 cm/second). In addition, the CRV maximum blood flow velocity levels were significantly higher in the pre-retinopathy group (5.7 +/- 0.9 cm/second) than in both the PDR group (4.8 +/- 1.5 cm/second) and the PRP group (4.9 +/- 1.7 cm/second). No significant differences were seen in blood flow velocity levels of the ophthalmic artery and the PCA among the retinopathy groups. No correlation was found between HbA1c levels and the stage of retinopathy. The presence of systemic hypertension showed no significant effect on blood flow velocities in the various retinopathy groups. CONCLUSION: This study demonstrates the presence of some circulatory changes in the CRA and the CRV in patients' eyes with diabetic retinopathy when compared with patients' eyes in the pre-retinopathy stage of the disease. These data support the contention that changes in retrobulbar circulation and microcirculation occur during the pathogenesis of diabetic retinopathy. The clinical significance of these findings needs to be determined.

Effects of perfluorophenanthrene on the human corneal endothelium.

PURPOSE: To evaluate long term effects of perfluorophenanthrene (C12F24), a perfluorocarbon fluid, in the anterior chamber of the human eye, where residual perfluorophenanthrene was retained in the eye postoperatively. METHODS: Slit-lamp microscopic and specular microscopic examinations of 4 eyes of 4 patients were performed. All the eyes were operated for complicated retinal detachment and they were aphakic at the end of the operations. Mean follow-up period was 10 months (6-16 months). RESULTS: Perfluorophenanthrene was seen in the anterior chamber in the first or second day postoperatively as a single drop. In the third week, postoperatively, the first signs of splitting the perfluorophenanthrene (fish egging phenomena) was observed. There was no sign of corneal or anterior segment toxicity with the slit lamp microscopic examinations and the intraocular pressure was within normal limits during the follow-up period in all eyes. However, some structural changes of the corneal endothelium were shown by specular microscopy. Decreased endothelial cell density, a reversed illumination pattern in which the normally dark cellular boundaries appear bright and intracytoplasmic light reflecting bodies were signs of cellular damage at the contact sites whereas no significant changes were seen at non contact sites. CONCLUSION: Residual perfluorophenanthrene in the anterior chamber does not induce gross corneal damage or ocular inflammation, although structural changes indicating the damage of the corneal endothelium, can be shown by specular microscopy at the contact sites. Corneal endothelial changes seem to arise from a contact-dependent effect of the perfluorophenanthrene.