Mete Güler

Plasma and vitreous homocysteine concentrations in patients with proliferative diabetic retinopathy.

Purpose: An increase in plasma concentrations of homocysteine (Hcy) in proliferative diabetic retinopathy (PDR) has been described. The aim of this study was to investigate vitreous Hcy levels in patients with PDR. Methods: Plasma and vitreous samples were obtained simultaneously at the time of vitreoretinal surgery from 20 patients with PDR and 12 nondiabetic patients with nonproliferative ocular diseases. Hcy levels were determined by high-performance liquid chromatography. Results: The mean vitreous and plasma Hcy concentrations for the diabetic group were 3.64 ± 0.65 &mgr;mol/L and 16.04 ± 2.75 &mgr;mol/L, respectively. The mean intravitreal and plasma Hcy concentrations for the control group were 1.08 ± 0.45 &mgr;mol/L and 9.18 ± 3.91 &mgr;mol/L, respectively. Both plasma and vitreous Hcy concentrations for the diabetic group were significantly higher than those for the control group (P < 0.001). A statistically significant correlation between vitreous and plasma Hcy concentrations was present only for the diabetic group (r = 0.525; P = 0.017). Conclusion: Vitreous Hcy concentrations were elevated in patients with PDR probably due to breakdown of the blood–retina barrier.

Levels of circulating homocysteine, vitamin B6, vitamin B12, and folate in different types of open-angle glaucoma

Objective: To compare the levels of plasma homocysteine (Hcy), vitamin B6 (vit-B6), serum vitamin B12 (vit-B12), and folate in healthy individuals and in patients with normal tension glaucoma (NTG), pseudoexfoliative glaucoma (PXG), or primary open-angle glaucoma (POAG). Study design: A prospective controlled trial. Participants and methods: Forty healthy subjects, 48 patients with NTG, 38 patients with PXG, and 34 patients with POAG were included in the study. Those who used vitamin supplements or medications affecting Hcy and vitamin levels were excluded from the study. The levels of Hcy and vit-B6 were measured by High Performance Liquid Chromatography (HPLC). The levels of serum vit-B12 and folic acid were measured by competitive chemiluminescent enzyme immunoassay (CEI). One-way analysis if variance (ANOVA), analysis of covariance (ANCOVA), and the Tukey honestly significant difference test were used for statistical analysis. Results: The mean Hcy level of the PXG group was 15.46 ± 9.27 μmol/L which was significantly higher (P = 0.03) than that of the control group. There were no statistical differences in serum vit-B12 and folate levels among control subjects and NTG, PXG and POAG groups (P > 0.05). It was found that the mean plasma vit-B6 level was significantly higher in subjects with NTG (P = 0.03) and POAG (P = 0.025) versus controls. Mean vit-B6 levels in NTG and POAG were 30.50 ± 11.29 μg/L and 30 ± 12.15 μg/L, respectively. Conclusions: The plasma level of Hcy was found to be increased only in PXG patients and the plasma levels of vit-B6 were found to increase in the NTG and POAG sample groups. Using homocysteine and vit-B6 levels as the determinants of hyperhomocysteinemia still needs further research.

The Inhibitory Effects of Trastuzumab on Corneal Neovascularization

PURPOSE To investigate the effect of systemic administration of trastuzumab in the prevention of experimentally induced corneal neovascularization in a rat model. DESIGN An experimental animal study. METHODS Sixteen male Wistar-Albino rats weighing 250 g to 300 g were used in the study. Silver nitrate sticks (75% silver nitrate, 25% potassium nitrate) were used to induce chemical cauterization on the corneas of 16 eyes. The rats were randomized to 1 of 2 groups: Group 1 (n = 8) received intraperitoneally 1 ml (4 mg/kg) trastuzumab and Group 2 (n = 8) received 1 ml saline. The corneal surface covered with neovascular vessels was measured on the photographs as the percentage of the total area of the cornea by using computer imaging analysis on the eighth day. The corneas obtained from rats were evaluated for vascular endothelial growth factor (VEGF) immunostaining semicantitatively. The number of the corneal neovascularizations were also determined on slides. The results were evaluated with the Mann-Whitney U test. RESULTS The burn stimulus was similar between groups. The average neovascularization area in treatment group was statistically smaller than control (P = .008). The mean VEGF staining intensity of epithelial and endothelial layers of cornea in treatment group was less than control (P = .038 and P = .041, respectively). The stroma of the treatment group showed less staining, but the difference was not significant (P = .056). The number of corneal neovascularizations on slides in trastuzumab treated eyes were less than the control group (P = .02). CONCLUSION Systemic administration of trastuzumab is effective in prevention of the corneal neovascularization.

The Impact of Tacrolimus on Vascular Endothelial Growth Factor in Experimental Corneal Neovascularization

Purpose: To investigate the impact of tacrolimus on vascular endothelial growth factor (VEGF) in experimental corneal neovascularization (NV) immunohistochemically. Material and Methods: Five groups of seven Wistar albino rats were formed. A silver nitrate cauterization technique was used to induce corneal NV in the study groups, excluding Group 1 (Control Group). Rats in group 1 did not receive any treatment. Rats in group 2 (sham 1) were administered 1 ml of saline intraperitoneally once a day and those in group 3 (sham 2) received one drop of saline four times a day. Rats in group 4 were administered 0.3 mg/kg tacrolimus intraperitoneally once a day. For group 5, 0.3 mg/ml tacrolimus was installed four times a day. Digital photography for each cornea was performed and the percentage area of the NV on the total corneal surface was calculated. The intensity of VEGF immunostaining in the epithelial, the stromal, and endothelial layers was performed in a semi quantitative fashion. Results: The mean percentages of the neovascularized areas of intraperitoneally and topically tacrolimus-treated groups were lesser than those of the sham groups (p = 0.002, p = 0.038, respectively). The mean intensity of the epithelial VEGF immunostaining of the intraperitoneally tacrolimus-treated group was less than that of its sham group (p = 0.002), while the mean intensity of the stromal VEGF staining of the topically tacrolimus-treated group was lesser than that of its sham group (p = 0.042). The intensities of the endothelial VEGF immunostaining of the intraperitoneally and topically tacrolimus-treated groups were less than those of the sham groups (p = 0.038, p = 0.032). Conclusion: Systemic and topical administration of tacrolimus may be beneficial in the prevention of corneal NV because of its effect on VEGF.

Biometric and intraocular pressure change after cataract surgery.

Purpose To evaluate changes in ocular biometric parameters with optical biometry and intraocular pressure (IOP) by Goldmann tonometry after uneventful phacoemulsification in normotensive eyes. Methods This prospective study was composed of 117 eyes of 117 patients who had undergone uncomplicated phacoemulsification and foldable intraocular lens implantation. The measurements were obtained preoperatively and 1 month postoperatively. Axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter (PD), and lens thickness were measured by the LenStar optical biometer, and IOP was measured by Goldmann applanation tonometry. The relationships between IOP change and ocular biometric parameters were evaluated. Results Mean age was 64.73 ± 10.83 years; 45 patients were women (38.46%) and 72 patients were men (61.54%). Comparing preoperative and postoperative 1-month measurements, the mean AL, PD, and IOP decreased (p < 0.01), whereas ACD (p < 0.01) and CCT (p > 0.05) increased. Intraocular pressure change correlated positively with AL change (p < 0.05) and PD change (p < 0.05) and preoperative IOP (p < 0.01) and preoperative CCT (p < 0.05). Anterior chamber depth change correlated positively with preoperative ACD (p < 0.01) and negatively with preoperative PD (p < 0.05). Pupil diameter change positively correlated with preoperative PD (p < 0.01). Regression analyses showed that preoperative IOP significantly associated with postoperative IOP reduction according to the standardized coefficient beta (−0.649). Conclusions Anterior segment morphometry changed and IOP decreased after phacoemulsification. The preoperative IOP may be the best parameter for estimating postoperative IOP reduction.

Modulation of Postoperative Scarring with Tacrolimus and Octreotide in Experimental Glaucoma Filtration Surgery

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

A case of ectopic cilia

Ectopic cilia are the most rare of cilial anomalies. We report a 27-year-old man who presents with tarsal conjunctival symptomatic ectopic cilia. On slit-lamp examination eversion of the lower eyelid demonstrated that several black–white cilia were protruding from the conjunctiva.

A Case with Bilateral Chorioretinal Coloboma Appearing as Double Optic Disc

Choroidal coloboma is a congenital anomaly caused by incomplete and defective closure of the embryonal fissure. Choroidal colobomas are frequently associated with some ocular and systemic anomalies involving the cardiovascular, central nervous, musculoskeletal, gastrointestinal, genitourinary and nasopharyngeal systems. In this article, we report a case of bilateral chorioretinal coloboma mimicking accessory optic disc. Thirty four year-old woman visited us with a complaint of low visual acuity in both eyes and strabismus. At ophthalmological examination, her best-corrected visual acuity was 2/10 with (+10.75–5.00x90 ̊) on right eye and 2/10 with (+11.00-3.75x 55 ̊) on left eye. 35-40 PD of exotropia was detected with prism alternating cover test. Fundus examination revealed bilateral chorioretinal coloboma. Fluorescein angiography revealed no notable findings other than chorioretinal coloboma. Extraocular muscles, optic nerve (single optic nerve in each orbit) and retrobulber structures were normal in both eyes under magnetic resonance imaging evaluation.