Tarkan Mumcuoglu

Corneal biomechanical changes in diabetes mellitus and their influence on intraocular pressure measurements.

PURPOSE To investigate possible corneal biomechanical changes in patients with diabetes mellitus and understand the influence of such changes on intraocular pressure measurements. METHODS The study group was composed of 120 eyes from 61 healthy control subjects and 81 eyes from 43 diabetic subjects. IOP was measured first with an ocular response analyzer (ORA) and subsequently with a Goldmann applanation tonometer (GAT). Central corneal thickness (CCT) was measured with an ultrasonic pachymeter attached to the ORA. Axial length (AL), anterior chamber depth (ACD), and keratometry readings were acquired with partial coherence laser interferometry during the same visit before all IOP and CCT determinations were made. RESULTS Corneal hysteresis (CH) was found to be significantly lower in diabetic patients when compared with healthy control subjects (9.51 +/- 1.82 mm Hg vs. 10.41 +/- 1.66 mm Hg, P < 0.0001). There was no significant difference in terms of corneal resistance factor (CRF; P = 0.8). Mean CCT, GAT IOP, Goldmann-correlated IOP (IOPg), and corneal-compensated IOP (IOPcc) were significantly higher in diabetic patients than in healthy control subjects (P = 0.01 for CCT, P < 0.0001 for GAT IOP, IOPg, and IOPcc). CONCLUSIONS Diabetes affects corneal biomechanics and results in lower CH values than those in healthy control subjects, which may cause clinically relevant high IOP measurements independent of CCT.

Effect of subconjunctival bevacizumab (Avastin) on experimental corneal neovascularization in guinea pigs.

Purpose: To evaluate the effect of subconjunctival bevacizumab (Avastin) on experimental corneal neovascularization in guinea pigs. Methods: Forty eyes of 40 guinea pigs were chemically cauterized with 75% silver nitrate and 25% potassium nitrate sticks. Fifteen eyes (group 1) received 2 subconjunctival injections of bevacizumab (0.1 mL, 1.25 mg) simultaneously with cauterization and 3 days later. Fifteen eyes (group 2) received 2 subconjunctival injections of bevacizumab (0.1 mL, 1.25 mg) 3 and 5 days after cauterization. Ten eyes (group 3, control group) received 2 subconjunctival injections of 0.1 mL of balanced salt solution 3 and 5 days after cauterization. After we determined the burn and neovascularization scores for all groups, the animals were killed on the 10th day. The percentages of neovascularization on the surface of the cornea were measured in terms of pixels on digital photographs. The average number of vessels at maximally vascularized areas was determined for each specimen. Results: Neovascularization score was 1.1 ± 0.3 in group 1, 2.46 ± 1.3 in group 2, and 3.5 ± 0.5 in the control group. The difference was statistically significant (P < 0.001). The area of neovascularization at the cornea surface was 15.6% ± 10.1% in group 1, 19.74% ± 11.2% in group 2, and 23.5% ± 7.4% in the control group (P = 0.194). The average number of neovascular vessels at group 1 was significantly reduced in comparison with group 2 and the control group (P < 0.001). Conclusions: Subconjunctival injection of bevacizumab decreases the extent of chemically induced corneal neovascularization in guinea pigs. The antineovascular effect of bevacizumab is higher if the injection is performed simultaneously with the chemical cauterization.

Ingestion of IH636 grape seed proanthocyanidin extract to prevent selenite-induced oxidative stress in experimental cataract

PURPOSE: To investigate whether dietary supplementation with IH636 grape seed proanthocyanidin extract (GSPE) prevents selenite‐induced cataract. SETTING: Department of Ophthalmology, Gulhane Military Medical Academy, Ankara, Turkey. METHODS: Thirty Spraque‐Dawley rat litters were put randomly into 3 groups. In group 1 (n = 10), sodium selenite (30 nmol/g body weight) was injected subcutaneously on postpartum day 10. In group 2 (n = 10), sodium selenite (30 nmol/g body weight) was injected on postpartum day 10 and oral GSPE (100 mg/kg body weight) was given for 1 week after sodium selenite injection. Only subcutaneous saline was injected in group 3 (control, n = 10). The development of cataract was assessed for 3 weeks, and its density was graded and photographed with a slitlamp. Removed rat lenses were analyzed for glutathione (GSH) and malondialdehyde (MDA). RESULTS: All of the rats in group 1 had cataract between stage 6 and stage 3. In group 2, only 5 of 10 eyes had cataract between stage 3 and stage 2 and no cataract occurred in the remaining 5 rats. The difference between mean cataract stages in group 1 and group 2 was significant (P<.05). The mean GSH level in group 1 was significantly lower than in group 2 and controls (P<.05). The mean MDA level in group 1 was significantly higher than in group 2 and controls (P<.05). CONCLUSIONS: IH636 grape seed proanthocyanidin extract effectively suppressed cataract formation in rats. Routine consumption of grape seed proanthocyanidin extract in the form of food or dietary supplement may offer a prophylactic measure against onset and progression of cataract.

Screening for retinopathy of prematurity in a tertiary care newborn unit in Turkey: frequency, outcomes, and risk factor analysis.

PURPOSE To report the frequency, risk factors, and outcomes of screening for retinopathy of prematurity (ROP). METHODS Data of neonates with a gestational age of 34 weeks or less were analyzed and the predictors on the development of ROP were determined by using logistic regression analysis. RESULTS Of the 318 neonates, the frequency of ROP was 37.1% for any stage and 7.2% for stage 3 or greater. Treatment was needed in 16.1% of neonates with ROP. No treatment was required in neonates with a gestational age of greater than 32 weeks. Oxygen therapy, sepsis, gestational age of 32 weeks or less, and birth weight of less than 1,250 g were determined as the independent risk factors. CONCLUSIONS Although frequency of ROP in Turkey is similar to that in the United States, the rate of severe ROP necessitating treatment seems to be higher in Turkey. Neonates with a gestational age of 32 weeks or less, a birth weight of less than 1,250 g, sepsis, and oxygen therapy may have a greater risk of developing ROP and screening should be intensified in the presence of these risk factors.

The effect of bevacizumab on wound healing modulation in an experimental trabeculectomy model.

Abstract Purpose: Glaucoma filtration surgery remains the most effective surgical procedure for lowering intraocular pressure (IOP) in uncontrolled glaucoma. Modulation of wound healing is critical to ensure long-term surgical success. This study aimed to determine if bevacizumab is an alternative agent for wound modulation in glaucoma surgery. Materials and methods: Forty-eight eyes of New Zealand rabbits were divided into four groups undergoing standard trabeculectomy surgery in the right eye. In group 1, balanced salt solution injections (0.1 ml) were performed into the bleb. Bevacizumab (0.1 ml, 1.25 mg) was injected into the bleb in group two and into the vitreous body in group three. Subconjunctival injections of 5-fluorouracil (5-FU) were performed into the non-bleb area in group four. Postoperatively; IOP, bleb size, bleb height, bleb vascularity were evaluated. Right eyes of two animals from each group were enucleated in 10th, 20th and 30th d postoperatively and evaluated histopathologically for inflammation, neovascularization and fibrosis. Results: The length, the width and the height of the bleb in the group two were greater than other groups. Mean IOP values were lower in group two. IOP measurements in the operated eyes of group two were statistically significantly lower than the other groups until the 28th d. Inflammation (p = 0.030), neovascularization (p = 0.004) and fibrosis (p < 0.000) in group two were lower in histopathological evaluation. Conclusions: Post-operative subconjunctival injection of bevacizumab is more effective than intravitreal bevacizumab or subconjunctival 5-FU injections for bleb survival. Furthermore, IOP is lower for a long period with lower level of fibrosis, which increases the success of trabeculectomy.

Evaluation of essential and toxic trace elements in pseudoexfoliation syndrome and pseudoexfoliation glaucoma.

Pseudoexfoliation syndrome (PEX), an age-related disorder of the eye, is associated with significant ophthalmic morbidity and can lead to pseudoexfoliation glaucoma (PEG). The etiology of this disorder has not been clearly understood. Trace elements have been suggested to have roles in the pathogenesis of several disorders. This study aimed to determine whether trace element levels have a role in the development of PEX and/or PEG. Levels of zinc (Zn), copper (Cu), selenium (Se), manganese (Mn), chromium (Cr), cobalt (Co), molybdenum (Mo), nickel (Ni), vanadium (V), arsenic (As), aluminum (Al), mercury (Hg), cadmium (Cd), and strontium (Sr) were determined in serum samples of 32 cases of PEX, 30 cases of PEG, and 32 control subjects using inductively coupled plasma–mass spectrometry. Mn, Mo, and Hg concentrations were found to be significantly increased in patients with PEX. Logistic regression revealed Mn and Hg as the strongest determinants of PEX and Mo as the strongest determinant of PEG in the studied Turkish subjects. Levels of Mn, Cr, Co, Mo, Al, Hg, Sr, Ni, V, and As were determined for the first time in these ophthalmological disorders. Increased levels of serum Mn, Mo, and Hg suggest a possible role of these elements in the pathobiology of PEX.

Comparison of Oculus Pentacam and Stratus optical coherence tomography for measurement of central corneal thickness.

Purpose: Measurement of central corneal thickness (CCT) plays an essential role in the diagnosis and treatment of many ocular diseases. In this study, we aimed to compare the CCT measurements obtained using the Scheimpflug system (Pentacam; Oculus, Inc) with a retinal optical coherence tomography device (Stratus OCT; Carl Zeiss Meditec, Inc) to examine healthy corneas. Methods: CCT measurements of 80 eyes belonging to 40 male patients (mean age: 24.48 ± 6.01 years) were evaluated with the Pentacam and the Stratus OCT. The relationship between the CCT values obtained with these 2 devices was examined with a Pearson correlation analysis, a paired t test, and a Bland-Altman analysis. Results: The average CCT value obtained with Pentacam was 546.11 ± 34.15 μm and that obtained with Stratus OCT was 567.76 ± 35.02 μm. Although the average difference between the devices was 21.65 ± 8.59 μm (P < 0.0001), the measurements obtained with both devices were significantly correlated (r = 0.969, P < 0.0001). In Bland-Altman analysis, there was a high consistency between measurements obtained with either Pentacam or Stratus OCT devices. Conclusions: Corneal thickness measurements differ depending on the device used. Corneal thicknesses that have been calculated with Pentacam were lower than the values obtained with Stratus OCT. Both devices used for CCT measurement are easily applied, noninvasive, and effective. However, the devices are not interchangeable. Stratus OCT is not optimal for CCT measurement because of the important limitations of using manual measurements, but it can be used if other measurement devices designed for the purpose are not available.

Intravitreal bevacizumab treatment of macular edema due to optic disc vasculitis.

Purpose: To report the efficacy of intravitreal bevacizumab injection in treatment of macular edema in a case of optic disc vasculitis. Design: Retrospective case review. Methods: A patient diagnosed with macular edema due to optic disc vasculitis was treated with intravitreal bevacizumab injection. Results: One week after injection, fundus appearance dramatically improved and macular edema regressed. The patient was followed up for 1 year after injection and there was no recurrence of macular edema. Conclusions: This case suggests that intravitreal bevacizumab treatment might be effective in the management of macular edema in patients with optic disc vasculitis.

Retina nerve fiber layer and choroidal thickness changes in obstructive sleep apnea syndrome

ABSTRACT Objectives: The purpose of this study was to determine the effects of obstructive sleep apnea syndrome (OSAS) on the submacular and peripapillary retinal nerve fiber layer (RNFL) and choroidal thickness (ChT). Methods: Eighty-four eyes of 42 male patients with OSAS and 112 eyes of 56 aged-matched and body mass index-matched healthy male subjects were enrolled in this case-control study. The ChT and peripapillary RNFL thickness was measured using enhanced depth imaging optical coherence tomography. The ChT and RNFL thickness measurements of the groups were compared, and correlations among the Apnea Hypopnea Index (AHI) values and these measurements were calculated. Right and left eyes were separately evaluated. Results: There were no significant differences in the subfoveal and temporal ChT between the groups (p > 0.05). The OSAS group had significantly thicker ChT at 0.5 and 1.5 mm nasal to the fovea in both eyes than the control group (p < 0.05). The peripapillary ChT were significantly thicker in the OSAS group at all segments except for the temporal and superotemporal segments when compared with the control group (p < 0.05 for all quadrants except temporal and superotemporal). When compared with controls, the OSAS group had significantly thinner nasal RNFL thickness in the right eye (p = 0.01) and thinner mean RNFL thickness in both eyes (p < 0.001). Other RNFL thickness measurements were similar between groups (p > 0.05). Between AHI and mean RNFL thickness showed a median negative correlation (r = − 0.411, p = 0.001). Conclusion: The choroidal thickening in patients with OSAS may be associated with the pathophysiology of the neurodegeneration process of the disease.

An unusual complication of blunt ocular trauma: A horseshoe-shaped macular tear with spontaneous closure

A case of horseshoe-shaped macular tear after blunt trauma with the course of the tear and the relevant findings obtained by spectral-domain optical coherence tomography (SD-OCT) is described. A 21-year-old man who had suffered blunt trauma 5 days previously visited our clinic complaining of vision loss in his left eye. Ophthalmic examination and SD-OCT images revealed a horseshoe-shaped macular tear. A month later at the second visit, the macular tear was found to have spontaneously closed. There have been many cases reported previously of the spontaneous closure of traumatic macular holes. A horseshoe-shaped macular tear is an atypical clinical presentation. However, the mechanism of spontaneous closure is hypothetically as same as that for a macular hole. High-resolution images and three-dimensional maps taken with SD-OCT can provide more details on macular diseases and are more useful than time-domain OCT images.