Sengul Ozdek

Assessment of nerve fiber layer in diabetic patients with scanning laser polarimetry

Objective To evaluate the effects of diabetes mellitus, diabetic retinopathy and degree of blood glucose (BG) regulation on retinal nerve fiber layer (RNFL) thickness by using a scanning laser polarimeter (NFA-GDx).Methods We prospectively assessed RNFL thickness in four groups of patients, who were all age matched. Diabetic patients without diabetic retinopathy were grouped according to their BG regulation level into two, as: BG-regulated group (BG <140 mg/dl, HbA1c <8%, fructosamine <285 μmol/l, TG <200 mg/dl, n = 50), and BG-non-regulated group (BG = 140–250 mg/dl, HbA1c >8%, fructosamine >285 μmol/l, TG >200 mg/dl, n = 44). A group of patients with nonproliferative diabetic retinopathy (NPDR) formed the 3rd group (n = 41). The 4th group consisted of healthy subjects and acted as a control group (n = 50). Symmetry, superior maximum, ellipse modulation and the average thickness variables of NFA-GDx were used for the assessment. ANOVA test was used for the statistical analysis of variables between groups.Results The mean superior maximum and ellipse modulation values were statistically significantly lower than the control group in BG-non-regulated and NPDR groups (P < 0.05). The average thickness value was also statistically significantly lower than the control group in NPDR group. These values in the BG-regulated group were not statistically significantly different from the control group (P > 0.05).Conclusions This is the first clinical study demonstrating the effects of diabetic glucose regulation level on RNFL by using NFA-GDx. RNFL thickness was seen to decrease with development of diabetic retinopathy and with impairment of metabolic regulation. This issue should be taken into account while assessing RNFL in diabetic glaucomatous patients.

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 (Students 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.

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 (ttest, 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.

Ocular Fungal Infections

Purpose: Microbiology, clinical perspective of ocular fungal infections, and the experimental models were overviewed. Methods: Review of published studies were evaluated and personal experience was mentioned. In this review, clinical features of keratitis and endogenous and exogenous endophthalmitis are also mentioned, but this article mainly focused on laboratory diagnosis and the experimental models of ophthalmic mycoses. Results: Fungal infections were discussed according to the anatomical part of the eye involved in the disease. Trauma is the most important predisposing cause; the species of Fusarium, Aspergillus, and Candida are the most frequently isolated organisms. Laboratory methods, such as culture, remains the cornerstone of diagnosis; direct microscopic detection of fungal structures in ocular samples permits a rapid presumptive diagnosis. New approaches, such as serological and molecular methods, have been widely used in recent years. A variety of antifungals have been evaluated in the therapy of this condition. Experimental models would facilitate investigations exploring the pathophysiology, cell biology, genetics, immunology, and therapy of this disease. Conclusions: Fungal infections of the eye continue to be an important cause of ocular morbidity, particularly in the developing world. Understanding ocular infections will improve the outcome of this condition.

The effect of blood glucose regulation on retinal nerve fiber layer thickness in diabetic patients.

Purpose: To evaluate the effect of blood glucose (BG) regulation on the retinal nerve fiber layer (RNFL) in diabetic patients by using a scanning laser polarimeter (NFA-GDx). Methods: We prospectively assessed RNFL thickness in diabetic patients and an age-matched control group. Patients without diabetic retinopathy, with BG >250 mg/dl, HbA1c >8%, fructosamine >285 µmol/l and triglyceride >200 mg/dl were included in the study. RNFL assessment was performed before and after metabolic regulation of diabetes. Symmetry, superior maximum, ellipse modulation and the average thickness variables of NFA-GDx were used for the assessment. Mann-Whitney U and Wilcoxon tests were used for the statistical analysis. Results: A total of 40 diabetic patients were included in the study and a repeat RNFL examination could be performed in 22 of them following regulation of BG levels. None of the GDx variables were significantly different between pre- and postregulation measurements (p > 0.05, Wilcoxon test). The mean superior maximum, ellipse modulation and average thickness values of the diabetic group were significantly lower than the control group (p < 0.05, Mann-Whitney U-test). Conclusions: Poor metabolic control of diabetes mellitus adversely affects the thickness of RNFL and this effect does not seem to be acute since it was not reversed by short-term BG regulation. This issue needs to be kept in mind when assessing glaucomatous progress in diabetic patients.

Topical vitamin E and hydrocortisone acetate treatment after photorefractive keratectomy.

Purpose To investigate the effects of topical vitamin E and hydrocortisone acetate treatments on corneal healing response after -10.0 D photorefractive keratectomy (PRK) in rabbits.Methods Thirty-three New Zealand white rabbits were divided into four groups and -10 D PRK was performed under in vivo conditions. Following PRK, group 1 (n = 9) received no topical treatment and served as control. Group 2 (n = 8) received 0.1% hydrocortisone acetate ointment twice a day, group 3 (n = 8) received 1% vitamin E ointment and group 4 (n = 8) received both 0.1% hydrocortisone acetate and 1% vitamin E twice a day for a month. At the end of the third month, corneal haze was graded and the corneal hydroxyproline levels were measured, as a crude indicator of new collagen synthesis. Finally corneal samples were examined by transmission electron microscopy.Results Non-homogeneously distributed strong haze was identified in group 1 which was greater than in the other groups; haze was least in groups 2 and 4. Corneal hydroxyproline levels were found to be significantly lower in groups 2, 3 and 4 compared with the control (Students t-test, p < 0.05). Histopathologically, the most aggressive wound healing response was detected in group 1. The corneal wound healing response of group 2 was less than that of group 1 and equal to or more than that of group 4.Conclusions Deep corneal photoablation induces an aggressive healing response, and topical hydrocortisone acetate reduces this corneal wound healing effectively. The inhibitory effect of topical vitamin E on corneal wound healing seems to be less than that of hydrocortisone acetate, but combined treatment with these two drugs may have an additive effect in controlling corneal wound healing after PRK.

Reproducibility of choroidal thickness measurements in healthy Turkish subjects.

Purpose: To assess intraobserver and interobserver reproducibility of the measurement of choroidal thickness by using enhanced depth imaging optical coherence tomography (EDI-OCT). Methods: A prospective, cross-sectional study was performed at Gazi University Ophthalmology Department. The macular areas of the right eyes of 110 healthy volunteers with no ophthalmic or systemic disease were recruited. Choroidal thickness was measured at the fovea and at 1000-μm intervals from the foveal center in both temporal and nasal directions. Each examiner measured choroidal thickness 30 days after the first measurement to assess intraobserver variability. Interobserver and intraobserver reproducibility were described by intraclass correlation coefficient (ICC) and coefficient of variation (CV). Results: The mean age was 44.0 ± 14.7 years (range 18-70 years). The mean choroidal thickness at the fovea was 315.5 ± 78.6. All the parameters evaluated were highly reproducible. Intraobserver CV of choroidal thickness measurements ranged from 24.76% to 35.74%, and the CV of subfoveal choroidal thickness was 24.92. The intraobserver and interobserver intraclass correlation coefficient was greater than 0.90 for all the parameters. Repeatability was slightly better at locations not exceeding 400 μm. Conclusions: Choroidal thickness measurements obtained by EDI-OCT showed good repeatability for healthy Turkish subjects; EDI-OCT examinations of choroid are reliable in healthy eyes.

Changes in intraocular pressure and corneal and retinal nerve fiber layer thicknesses in hypothyroidism

Purpose To evaluate the changes in intraocular pressure (IOP), corneal thickness (CT), and retinal nerve fiber layer thickness (RNFLT) in patients with hypothyroidism before and after treatment. Methods A complete ophthalmic examination including visual acuity, IOP, anterior segment, and fundus examination together with CT and RNFLT measurements were performed for each patient with newly diagnosed hypothyroidism, at the initial diagnosis and the third and ninth months of the L-thyroxine treatment. Wilcoxon signed rank test and Spearmans correlation test were used for statistical evaluation of the results. Results A total of 56 eyes of 28 patients were included in the study. The mean IOP and CT values were found to decrease with medical treatment (p=0.000). There was no significant change in any of the RNFLT parameters measured with scanning laser Polarimeter after L-thyroxine treatment (Wilcoxon, p>0.05). The change in IOP levels was not correlated with the change in thyroid hormone levels (Spearmans correlation test, p>0.05). The mean increase in serum free T3 and serum free T4 levels and the mean decrease in serum TSH levels at the ninth month of the therapy were found to be correlated with the decrease in CT in the left eyes (Spearmans correlation test, R>0.4 and p<0.05). Conclusions Hypothyroidism seems to cause a reversible increase in CT and IOP. IOP changes may be secondary to CT changes. RNFLT parameters measured with scanning laser Polarimeter do not seem to be affected by hypothyroidism. When the CT is taken into account and the IOPs corrected for CT, the prevalence of glaucoma in hypothyroidism may not be as high as previously reported. This issue should be taken into account while assessing glaucoma in patients with hypothyroidism.

Effect of mitomycin C on ciliary body and intraocular pressure with various application depths: an experimental study

Background: To evaluate the effects of mitomycin C (MMC) on intraocular pressure (IOP) and ciliary body via transmission electron microscopy when applied under conjunctiva or different depths of sclera, without performing any filtering surgery.

Posterior Subtenon Triamcinolone, Intravitreal Triamcinolone and Grid Laser Photocoagulation for the Treatment of Macular Edema in Branch Retinal Vein Occlusion

Purpose: To evaluate the efficacy of posterior subtenon triamcinolone (PSTT), intravitreal triamcinolone (IVT) injections and grid laser photocoagulation (GLP) in eyes with macular edema secondary to branch retinal vein occlusion (BRVO). Material and Methods: Patients with macular edema due to BRVO treated with PSTT, IVT injections or GLP were evaluated retrospectively. Complete ophthalmic examination with fluorescein angiography and optic coherence tomography were noted before and in the 1st, 3rd, and 6th months of the treatment. The visual and anatomical responses were evaluated and compared between the groups using paired t test and one-way ANOVA test. Results: There were 20, 35 and 24 eyes in the PSTT, IVT and GLP groups. In the PSTT group, the mean visual acuity (VA) and central foveal thickness (CFT) were 0.23 ± 0.23 and 413.2 ± 143.5 µm before treatment and 0.23 ± 0.18 and 358.7 ± 109.2 µm at the 3rd month, respectively (p = 0.504 and p = 0.031). The mean VA increased from 0.14 ± 0.15 to 0.33 ± 0.26 and the mean CFT decreased from 518.2 ± 145 to 292.9 ± 121 µm in IVT group at the 3rd month (p = 0.001). The mean VA increased from 0.29 ± 0.25 to 0.47 ± 0.32 (p = 0.001); CFT decreased from 397.3 ± 105.9 to 307.1 ± 88.4 µm (p = 0.005) in the GLP group. VA and CFT changes were significantly different between the groups at the 3rd month (p = 0.031). VA increase was significantly greater in the IVT group than in the PSTT group. Decrease in CFT was the highest in the IVT group (Tukey, p = 0.001). Conclusions: IVT and GLP seemed to be more effective than PSTT for the treatment of BRVO-associated macular edema. Possible complications of IVT and GLP must be weighted with the advantages of each treatment modality for each patient.