Yusuf Akar

Assessment of optic nerve head topographic parameters with a confocal scanning laser ophthalmoscope

Aim: To assess the disc area, age, sex, laterality (side of the eyes) and refractive error dependent differences in optic nerve head topographic parameters in a normal population.

Outbreak of toxic anterior segment syndrome associated with glutaraldehyde after cataract surgery.

PURPOSE: To present clinical findings of a cluster of cases of toxic anterior segment syndrome (TASS) after uneventful phacoemulsification cataract surgery. SETTING: Department of Ophthalmology, Akdeniz University, Antalya, Turkey. METHODS: Six eyes of 6 patients developed TASS after uneventful phacoemulsification cataract surgery with implantation of a 3‐piece acrylic IOL performed by 2 ophthalmologists on the same day. Clinical findings included corneal edema, Descemets membrane folds, anterior chamber reaction, fibrin formation, and irregular, dilated, and unreactive pupils. RESULTS: Glutaraldehyde 2% solution was used inadvertently by the operating room staff who cleaned and sterilized reusable ocular instruments before autoclaving. None of the affected corneas improved. Additional surgical procedures were required and included penetrating keratoplasty, trabeculectomy, and glaucoma tube implantation. CONCLUSIONS: Glutaraldehyde in concentrations generally used for cold sterilization is highly toxic to the corneal endothelium. The operating room staff involved in sterilizing instruments should be well educated about and careful to follow the protocols to properly clean and sterilize reusable ocular instruments.

Effect of hypercholesterolemia on inducible nitric oxide synthase expression in a rat model of elevated intraocular pressure

PURPOSE This study was performed to examine the effect of hypercholesterolemia on inducible nitric oxide synthase (NOS-2) expression and oxidative tissue injury in an experimental rat model of elevated IOP. METHODS Wistar rats were maintained on either regular chow or a high-cholesterol diet for 24 weeks. Intraocular pressure (IOP) was elevated in hypercholesterolemic rats by unilaterally cauterizing three episcleral vessels. Rats were divided into four experimental groups as follows; hypercholesterolemia, hypercholesterolemia+elevated IOP, elevated IOP and control. NOS-2 distribution, lipid peroxidation and retinal nerve fiber layer (RNFL) thickness was evaluated in all experimental groups at the end of 24 weeks. RESULTS Light microscopic evaluation of retinas in hypercholesterolemic rats revealed breaks and discontinuation in focal areas in the outer nuclear layer (ONL). NOS-2 positive staining was observed throughout the outer plexiform layer (OPL), inner plexiform layer (IPL) and ganglion cell layer (GCL) in rats with elevated IOP and/or hypercholesterolemia. Calculated values of RNFL thickness in hypercholesterolemic rats were significantly higher than those in the control and elevated IOP group. Vitreous malondialdehyde (MDA) levels detected in elevated IOP (3.51+/-0.31 nmol/mg protein) and hypercholesterolemia+elevated IOP (5.14+/-1.28 nmol/mg protein) groups were significantly higher than those detected in hypercholesterolemic (1.92+/-1.43 nmol/mg protein) and control (1.89+/-0.24 nmol/mg protein) groups. CONCLUSION The presented data confirms hypercholesterolemia as a risk factor in the development of glaucomatous optic neuropathy (GON) and suggests that increased circulating cholesterol may exacerbate disease progression by inducing NOS-2 expression and elevating oxidant tissue injury.

Effect of Pregnancy on Intraobserver and Intertechnique Agreement in Intraocular Pressure Measurements

Aim: To evaluate the effect of pregnancy on intraobserver and intertechnique agreement for intraocular pressure (IOP) measurements. Material and Methods: Right eyes of 88 healthy women who were likely to become pregnant and of 94 healthy age-matched females were included in the study. Complete ocular examinations were performed on each eye. IOP measurements were obtained by Goldmann, Schiötz and non-contact tonometers (NCT) during 3-week exam periods before (within 6 weeks of conception) and during pregnancy (first, second and third trimesters) for pregnant cases, and in similar time intervals for control subjects. In each exam period, three readings with each of three separate tonometers were obtained, at least 1 day apart. Intraobserver and intertechnique agreements for IOP measurements were assessed. Results: The mean visual acuity, keratometry and refractive error of both control and pregnant subjects did not change significantly during the study (all p values >0.01). In late pregnancy, pregnant cases demonstrated significant decreases in IOP measurements obtained with each of the three tonometers, and in intraobserver agreement with Goldmann and Schiötz tonometers (all p values <0.01). Intertechnique agreement of both Goldmann and Schiötz tonometers with NCT decreased significantly in the third trimester. Both intraobserver and intertechnique agreement in IOP measurements of control subjects were not found to change significantly during the study (all p values >0.01). Conclusion: IOP significantly decreased in the third trimester of pregnancy. Perfect intraobserver agreement in IOP readings of pregnant subjects was obtained with NCT. This may suggest that NCT is a viable option for IOP measurements during the follow-up of pregnant patients at risk for glaucoma.

Conversion to deep anterior lamellar keratoplasty (DALK): learning curve with big-bubble technique.

BACKGROUND AND OBJECTIVE To report the perioperative complications and clinical outcomes of 50 deep anterior lamellar keratoplasty (DALK) cases. PATIENTS AND METHODS Fifty eyes of 50 patients with pathologies involving the corneal stroma and sparing the Descemets membrane and endothelium were included consecutively in this prospective, noncomparative interventional case series study. DALK was performed using the big-bubble technique. RESULTS The most frequent indication for DALK surgery was keratoconus (26 eyes), followed by corneal dystrophy (10 eyes) and superficial corneal scar (14 eyes). The average follow-up period was 12.0 ± 3.9 months. DALK was completed in 41 cases (82%). A big bubble was achieved successfully in 37 cases (74%). Descemets membrane perforations occurred in 14 (28%) eyes, 8 of which were macroperforation and necessitated conversion to penetrating keratoplasty. Complications tended to decrease throughout the study. Postoperative best-corrected visual acuity of 0.5 or better was present in 30 of 41 (73.2%) eyes that underwent DALK. There was no episode of graft rejection. CONCLUSION DALK big-bubble technique may be a valuable procedure during transition from penetrating keratoplasty to anterior lamellar keratoplasty. It provided acceptable visual and refractive outcome even during the learning period in a variety of corneal lesions.

Nitrotyrosine formation and apoptosis in rat models of ocular injury.

This study was performed to examine inducible nitric oxide synthase (NOS-2) expression, nitrotyrosine formation and apoptosis in rats with elevated intraocular pressure (IOP) and/or ocular inflammation. Ocular inflammation was induced via injection of intra-vitreal lipopolysaccharide (LPS) while IOP was elevated by episcleral vessel cauterization. Animals were randomized to one of the following conditions: elevated IOP, LPS, elevated IOP+LPS, and control. Immunohistochemical staining and western blot analysis of retinal lysates revealed NOS-2 and nitrotyrosine immunoreactivity in all disease groups. NOS-2 expression and protein nitration was significantly greater in rats with elevated IOP+LPS compared to elevated IOP, LPS, and control groups. Nitrite levels in the retina affirmed significantly increased levels of nitric oxide generation in LPS-treated rats with elevated IOP (346 ± 23.8 μM) vs LPS-treated, elevated IOP and control groups (195.6 ± 12.6, 130 ± 2.5 and 76.6 ± 15.6 μM, respectively). Retinal TUNEL staining showed apoptosis in all diseased groups. Percent of apoptotic cells was significantly greater in the elevated IOP+LPS group compared to LPS-treated or elevated IOP groups. Presented data illustrates that both elevated IOP and ocular inflammation augment NOS-2 expression, retinal protein nitration and apoptosis in rats.

Transmission electron microscopy and autofluorescence findings in the cornea of diabetic rats treated with aminoguanidine

BACKGROUND The accumulation of advanced glycation end products (AGEs) has been implicated in the pathogenesis of diabetic keratopathy. The present study was aimed to understand if aminoguanidine (AG), an AGE inhibitor, was protective against the development of corneal complications in a diabetic rat model. METHODS Wistar rats were divided into three experimental groups: control, diabetic, and AG-treated diabetic. Diabetes was induced in rats via a single intraperitoneal injection (60 mg/kg) of streptozocin (STZ) and AG was administered in drinking water at a dose of 1 g/L. All animals were sacrificed at the end of 10 weeks and corneas from diabetic and nondiabetic rats were analyzed via transmission electron microscopy (TEM). Corneal autofluorescence measurements were also performed in all experimental groups. RESULTS Electron microscopic evaluation revealed that aminoguanidine treatment in diabetic rats prevented the formation of intracellular spaces between neighbouring cells in the superficial corneal epithelium. Hyperglycemia-induced degeneration of intracellular organelles and formation of cytoplasmic vacuoles in the corneal stroma was also prevented with the treatment of AG. Corneal autofluorescence detected in the diabetic group (5.98 +/- 2.17 Fi/mg protein) was found to be significantly greater than the control (3.92 +/- 0.56 Fi/mg protein) and the AG-treated diabetic group (4.18 +/- 0.59 Fi/mg protein) (p < 0.05). INTERPRETATION The presented data provide evidence that AG is preventive against corneal alterations in experimental diabetes.

Endoscopic Transnasal Dacryocystorhinostomy and Bicanalicular Silicone Tube Intubation

Purpose: To evaluate the results of endoscopic transnasal dacryocystorhinostomy (ETDCR) combined with bicanalicular silicone tube intubation (BSTI) performed in 49 patients with nasolacrimal canal obstructions secondary to chronic dacryocystitis. Material and Methods: ETDCR combined with BSTI was applied as a primary procedure in 47 cases, and as a secondary procedure in 2 cases. All patients underwent dacryocystography, and 41 patients underwent radionuclide dacryoscintigraphy before the surgery. Silicone tubes were left in place for about 6.2 months. The patency of the lacrimal passages was controlled with a clinical examination, nasolacrimal canal lavage, and dacryoscintigraphy. Results: Patients were followed up for a mean period of 25.1 months after the removal of the tubes. The epiphora symptom disappeared and a successful drainage could be maintained in 43 out of 49 cases (87.7%). The obstruction rate found in the dacryoscintigraphy performed 15 days after extubation was 22.9%, while it was found to be 14.2% in the nasolacrimal canal lavage. Conclusion: ETDCR combined with BSTI proved to be an effective surgical method in chronic dacryocystitis. The sensitivity and specificity of the postoperative dacryoscintigraphy in determining the surgical success were lower than those of the nasolacrimal canal lavage.

Menstrual Cycle-Dependent Changes in Visual Field Analysis of Healthy Women

Purpose: To determine the effect of menstrual cycle phases on the visual field analysis of healthy females. Material and Methods: One randomly selected eye each of 59 healthy normally menstruating women, and of 54 men with no systemic and ocular problems, other than refractive error, were included in the study. Subjects underwent complete ocular examination, and standard achromatic perimetric (SAP) and short-wavelength automated perimetric (SWAP) analysis in both follicular (7th to 10th day of the cycle) and luteal phases (days 3–7 before the menstrual bleeding) of the menstrual cycle. Visual field analysis was performed using a Model 750 Humphrey Field Analyzer II (Humphrey Instruments Inc., San Leandro, Calif., USA) with full-threshold, central 30-2 program. Visual fields were divided into four regions as superior temporal, inferior temporal, superior nasal and inferior nasal, respectively. Results: The mean age of female (n = 59) and the male subjects (n = 54) were 34.6 ± 2.9 and 35.0 ± 2.7 years, respectively (p = 0.49). SWAP tests demonstrated a significantly decreased mean MS value in the luteal phase (p < 0.05). However, it did not change significantly with SAP tests. Regional MS values of both SAP and SWAP tests were not different in both phases of the menstrual cycle (all p values >0.05). Mean perimetric test durations obtained with both SAP and SWAP were not different throughout the menstrual cycle (both p values >0.05). Conclusion: Clinicians should verify menstrual status when evaluating a suspected loss of visual field sensitivity in menstruating women. The findings of the present study suggest that the SWAP test may be more sensitive to determine subtle sex hormone-dependent changes in visual field analysis of healthy women.

Effect of the menstrual cycle on standard achromatic and blue-on-yellow visual field analysis of women with migraine

BACKGROUND It has been postulated that migraine and glaucoma may have common vascular causative factors. Significant sex-based differences in the incidence of many important ocular conditions raise the possibility that estrogens may have direct effects on the eye. We performed a study to determine the effect of the menstrual cycle on standard achromatic automated perimetry (SAP) and short-wavelength automated perimetry (SWAP) (blue-on-yellow perimetry) of women with migraine. METHODS Both eyes of 73 normally menstruating women (31 subjects with migraine and 42 healthy control subjects) were included in the study. Subjects underwent a complete ocular examination including SAP and SWAP in both the follicular phase (12th to 13th day of the cycle) and the luteal phase (1 to 2 days before the onset of bleeding) of two consecutive menstrual cycles.We performed visual field analysis using the Humphrey Field Analyzer II with the full-threshold central 30-2 program. Mean sensitivity was calculated for the superior temporal, inferior temporal, superior nasal and inferior nasal regions separately. RESULTS Thirteen subjects were lost to follow-up (5 in the migraine group and 8 in the control group), leaving 26 subjects and 34 subjects respectively. There was no significant difference in mean age between the two groups (33.9 years [standard deviation (SD) 3.4 years] vs. 35.1 years [SD 3.3 years]). The mean duration of migraine was 7.6 (SD 3.1) years (range 3-14 years). In both groups, serum estradiol levels were significantly lower (p = 0.001) and serum progesterone levels were significantly higher (p < 0.001) in the luteal phase than in the follicular phase. In the control group, the mean sensitivity values with SWAP were significantly lower in the luteal phase than in the follicular phase (p = 0.04). A similar decrease was observed for the subjects with migraine with both SAP and SWAP (p = 0.01). There was no difference in regional mean sensitivity between the two phases with either perimetric test in the control group. For the subjects with migraine, there was no difference in regional mean sensitivity between the two phases with SAP. However, with SWAP, the mean sensitivity for the nasal visual field locations was significantly lower in the luteal phase than in the follicular phase (p = 0.01). INTERPRETATION Our study provides further evidence of an effect of sex hormones on the visual field of women with migraine. In addition to assessment of intraocular pressure, menstrual cycle phases should be considered in women with migraine at risk for glaucomatous optic neuropathy.