Hüseyin Ortak

Mapping corneal thickness using dual-scheimpflug imaging at different stages of keratoconus.

Purpose: To map the thickness of the entire cornea using dual-Scheimpflug imaging and to evaluate the changes in the corneal thickness over the entire cornea at different stages of keratoconus. Methods: Corneal pachymetry was performed using the Galilei dual-Scheimpflug analyzer. The thinnest (TCT), central (CCT), paracentral (PaCT), and peripheral corneal thicknesses (PeCT) were also analyzed. The study examined 150 eyes of 150 patients who had myopia or myopic astigmatism and 107 eyes of 75 patients with keratoconus. Of these 107 eyes, 48 were evaluated at stage I keratoconus, 32 at stage II, 12 at stage III, and 15 at stage IV keratoconus. The level of severity of the keratoconus was based on the Amsler–Krumeich classification. Results: There were significant decreases in the thickness values of the entire corneas at all the different stages of progression defined in the Amsler–Krumeich classification. Analysis of the receiver operating characteristic curve showed that the TCT provided a better parameter than did the CCT, PaCT, and PeCT for distinguishing between keratoconus at its different stages and myopic eyes. Although the TCT and CCT parameters provided an effective distinction of eyes with stage II, III, and IV keratoconus from normal eyes, they were not effective for discriminating eyes with stage I keratoconus from eyes with myopia. But, PaCT and PeCT parameters enabled the effective discrimination between eyes with stage IV keratoconus and those with myopia only. Conclusions: The data obtained by dual-Scheimpflug imaging for the corneal thicknesses of the entire cornea provide useful information for grading the severity of keratoconus.

Association of MMP2-1306C/T and TIMP2G-418C polymorphisms in retinal vein occlusion.

Matrix metalloproteinases (MMPs) are large groups of zinc-dependent proteases that play an important role in many diseases and pathological processes such as cancer, angiogenesis, atherosclerosis, and vascular disease. Also, it was found that the expression of MMPs was high during the initial period of thrombosis in a rat model of traumatic deep vein thrombosis. Moreover, the presence of metalloproteinase activity and endogenous inhibitor activity in vitrectomy samples are associated with neovascularization of several retinal diseases such as exudative age related maculopathy, proliferative diabetic retinopathy, and central retinal vein occlusion. In this study, we aimed to investigate the possible association of the matrix metalloproteinase 2-1306C/T (rs 243865) and tissue inhibitors of matrix metalloproteinase 2 G-418C (rs 8179090) polymorphisms with the risk of retinal vein occlusion (RVO). Genomic DNA was extracted from peripheral leukocytes from ethylenediaminetetraacetic acid anticoagulated blood. Genotyping of the MMP2-1306C/T and TIMP2G-418C polymorphisms were performed using real-time polymerase chain reaction. The MMP2-1306 T allele carriers (CT + TT) had a significantly increased risk of RVO compared with the CC homozygotes (p < 0.001, odds ratio = 4.78; 95% CI = 2.85-8.09). After adjusting for hypertension, diabetes, hypertriglyceridemia, and hypercholesterolemia, MMP2-1306 T allele carriers (CT + TT) also had a significantly increased risk of RVO (B = 1.453; p < 0.001; odds ratio = 4.275; 95% CI:2.529-7.224). MMP2-1306C/T, but not TIMP2G-418C, gene variants are a risk factor for the development of retinal vein occlusion.

Age-related changes of aquaporin expression patterns in the postnatal rat retina

Previous studies revealed that the rat retina contains numerous membrane-located water channels, the aquaporins (AQPs). Protein expression patterns of AQP1-4, 6 and 9 were examined by immunohistochemistry. In the present study, we investigated the immunolocalization of AQP1-4, 6 and 9 during postnatal development in the rat retina and examined the effect of age on the tissue distribution of these channels. AQP1, 3, 4, 6 and 9 showed gradually increased expression in rat retinas from postnatal week 1 to week 12, and decreased in the 40-week-old rat retinas. AQP2 expression was barely seen in the first week in rat retinas and displayed a significant increase from week 1 to week 4, however no significant alteration of AQP2 was observed after 4weeks of development. AQP1 and 4 immunoreactivities were present in the inner limiting membrane (ILM), the ganglion cell layer (GCL), inner nuclear layer (INL) and retinal pigment epithelium (RPE) in the 4-, 12- and 40-week-old rat retinas. The RPE, OLM and ILM showed a remarkable expression of AQP1-4, 6 and 9 in the 4, 12 and 40-week-old rat retinas. The reduced expression of AQPs in aged rat retinas may indicate the involvement of AQPs in the pathogenesis of age-related retinal diseases.

Duration of the depressive episode is correlated with ganglion cell inner plexifrom layer and nasal retinal fiber layer thicknesses: Optical coherence tomography findings in major depression

Optical coherence tomography (OCT) is a relatively new, noninvasive imaging technique that has been used increasingly to diagnose and manage a variety of retinal diseases. Since the axons in retinal nerve fiber layer (RNFL) are nonmyelinated within the retina, OCT has been used in various neurodegenerative diseases to visualize the process of neurodegeneration. Decreases in RNFL and ganglion cell inner plexiform layer (GCIPL) thicknesses were observed in patients with schizophrenia. To date, there is no clinical research investigating OCT parameters in patients with MD. We compared the RNFL thickness, GCIPL thickness in 58 MD patients and 57 healthy controls, and investigated their correlation with clinical variables of depression. Depressed patients were not different from the healthy controls with regard to OCT parameters. GCIPL and nasal RNFL were correlated with the duration of the latest depressive episode. Some measures of OCT were negatively associated with clinical variables like a family history of psychiatric diagnosis and the duration of the latest episode. Larger studies including depressed patients of different severity, including structured interviews and controlling for the effect of antidepressant treatment will provide better results.

Central corneal thickness and its relationship to Parkinson's disease severity

OBJECTIVE To investigate the effect of Parkinsons disease (PD) on blink rate (BR), tear breakup time test (TBUT), Schirmers test, and corneal thickness, and the relationship of these effects with disease severity. DESIGN Prospective controlled study. PARTICIPANTS Fifty-five eyes from 55 patients with PD and 40 eyes from 40 healthy subjects were analyzed in the study. METHODS The patients were divided into 2 groups according to their Hoehn-Yahr (H-Y) scores; patients classified as H-Y 1-2 were designated as the mild group, and those classified as H-Y 3-5 were designated as the moderate group. Subjects were screened for BR, TBUT, and Schirmers test, and the central corneal thickness (CCT) was measured. RESULTS The BR, Schirmers test, TBUT, and CCT values of the patient group were significantly lower than those of the control group. The BR and TBUT of the mild group were significantly lower than those of the control group, but the decreases in the Schirmers test values and CCT were not statistically significant. In addition, significant decreases in the BR, TBUT, Schirmers test scores, and CCT were observed in the patient group as the H-Y score increased. CONCLUSIONS A reduced BR and poor tear quality in the early stages of PD, as well as decreased tear production as the disease progresses, can result in reduced CCT. The possibility of a thin cornea should be taken into consideration while measuring the intraocular pressure in patients with severe PD.

Peripapillary Retinal Nerve Fiber Layer and Ganglion Cell–Inner Plexiform Layer Thickness in Children with Familial Mediterranean Fever

ABSTRACT Purpose: To evaluate the thickness of the peripapillary retinal nerve fiber layer (RNFL) and retinal ganglion cell-inner plexiform layer (GCIPL) in children with familial Mediterranean fever (FMF). Methods: The study included 39 FMF patients and 36 healthy controls. After detailed ocular examination, the thickness of the peripapillary RNFL and GCIPL were measured by spectral domain optic coherence tomography (SD-OCT). All measurements were taken from the right eye of the patients and controls. According to their disease severity score (DSS), the patients were divided into two groups: patients with DSS ≤5 and those with DSS >5. Results: There were no statistically significant differences in peripapillary RNFL and retinal GCIPL thickness between patients with FMF and controls. Conclusion: It appears that FMF does not affect the RNFL and GCIPL thickness.

The Role of MMP2 (-1306C>T) and TIMP2 (-418 G>C) Promoter Variants in Age-related Macular Degeneration

Abstract Purpose: To investigate the possible association between the matrix metalloproteinase 2 (-1306C>T) (rs 243865) and tissue inhibitors of matrix metalloproteinase 2 (-418 G>C) (rs 8179090) polymorphisms and the risk of age-related macular degeneration. Methods: This case-controlled prospective study included 144 age-related macular degeneration patients and 172 control subjects. All subjects were screened for age, gender, hypertension (HT), diabetes (DM), and body mass index (BMI). Serum levels of high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides (TG), total cholesterol (TC), and smoking were also determined. Genomic DNA was extracted from peripheral leukocytes from ethylenediaminetetraacetic acid anticoagulated blood. Genotyping of the MMP2 (-1306C>T) and TIMP2 (-418 G>C) polymorphisms was performed using real-time polymerase chain reaction. Results: Genotype distributions or allelic frequencies of MMP2 (-1306C>T) and TIMP2 (-418 G>C) did not significantly differ between patients with AMD and control subjects. Similarly, no significant differences in either genotype distributions or allelic frequencies of MMP2 (-1306C>T) and TIMP2 (-418 G>C) were found between dry and wet AMD. Conclusion: MMP2 (-1306C>T) and TIMP2 (-418 G>C) promoter variants are unlikely to have a major role in age-related macular degeneration risk susceptibility.

The relation between keratoconus and plasma levels of MMP-2, zinc, and SOD.

Purpose: To evaluate the levels of matrix metalloproteinase-2 (MMP-2), superoxide dismutase (SOD), and zinc in plasma taken from patients with keratoconus and to investigate the likely association between these factors and keratoconus. Methods: A total of 36 patients with keratoconus and 40 control subjects at the Department of Ophthalmology, Faculty of Medicine, Gaziosmanpaşa University, were included in the study. Plasma levels of zinc were determined with atomic absorption spectrometry for all the subjects. Measurements of plasma MMP-2 levels were performed by the enzyme-linked immunosorbent assay method. Total plasma (Cu/Zn and Mn) SOD activity was also determined photometrically. Results: The plasma concentrations of zinc and MMP-2 were significantly lower in patients with keratoconus than in the healthy controls (P < 0.001). Total plasma SOD levels were significantly higher in patients with keratoconus than in the healthy controls (P < 0.001). Conclusions: We detected reduced plasma levels of zinc and MMP-2, and enhanced plasma levels of SOD in patients with keratoconus compared with the healthy subjects. The data presented provide insight into the potential role these molecules may play in the etiopathogenesis of this disease.

Increased Expression of Aquaporin-1 and Aquaporin-3 in Pterygium.

Purpose: Recent studies have shown that aquaporins (AQPs) play an important role in proliferating tumor microvessels and angiogenesis. In this study, the authors investigated the expression of aquaporin-1 (AQP1) and aquaporin-3 (AQP3) in pterygial and normal conjunctival tissues. Methods: Fifteen patients with pterygium were enrolled in the study. Pterygium was excised, and a conjunctival rotational flap or autograft was inserted. Normal conjunctival tissue was obtained from the flap or graft. Western blot analysis was performed to assess the expression of AQP1 and AQP3 in pterygial and normal conjunctival tissues. Tissue localization of AQP1 and AQP3 was determined by immunohistochemical analysis. Results: AQP1 and AQP3 are localized in the epithelial and subepithelial regions in pterygial and normal conjunctival tissues. Protein expression of both AQP1 and AQP3 was elevated in pterygia when compared with conjunctival tissues. The significant increase in protein expression of AQP1 was 3-fold in pterygium over normal conjunctiva (P = 0.004) and 2-fold increase in AQP3 expression of pterygium was detected (P = 0.02) according to densitometric analysis. Conclusions: Elevated protein expression of AQP1 and AQP3 was observed in pterygial tissues when compared with normal conjunctiva. The data suggest that the increased expression of AQP1 and AQP3 in pterygial tissues may be involved in the pathogenesis of pterygia, and therefore, AQP1 and AQP3 are potential therapeutic targets for preventing or delaying the progression of the disease.

Predictive value of the vitamin K epoxide reductase complex subunit 1 G-1639A and C1173T single nucleotide polymorphisms in retinal vein occlusion

Background:  To determine if vitamin K epoxide reductase complex subunit 1 gene polymorphisms have an effect on the risk of having a retinal vein occlusion.