​Journal of Current Ophthalmology
Year:2004 | Volume:17 | Issue:2|Papers Count:14

Purpose: Assessing the corneal thickness in the central, thinnest and peripheral regions of the cornea in an Iranian population and analyzing possible correlations between them and also with independent variables of age, gender, refraction, and iris color.Method: This is part of the population based, cross-sectional "Tehran Eye Study" (TES).Among the TES study population, selected through a stratified random cluster sampling method, 800 (399 right and 401 left) eyes of 410 residents of the first four municipality areas of Tehran, aged 14 years and over, were enrolled to be examined with Orbscan II.Analysis was done through calculating the mean, standard deviation, standard error, and 95% confidence interval of the mean for the thinnest, central, and peripheral corneal thicknesses in each eye separately and grouped according to age, gender, subjective refraction, and iris color while considering the design effect. All estimated values have also been directly standardized for age and gender. Only the results of the right eyes are reported.Results: The participants' mean age (±SD) was 40.9±t16.9 (range; 14-81) years and 60.9% were female. Mean thickness values (±SD) at the central and thinnest points were 555.6:t39.9 and 550.7±t40.6 microns, respectively. The highest corneal thickness related to the superior region, and the most common location of the thinnest point was the inferotemporal quadrant. The mean distance and thickness differences (±SD) between the thinnest and central points were 0.52±0.31 mm and 4.85±6.2 microns, respectively, and proved to be significantly correlated (r=0.708, P<0.001). Sex and refraction showed no significant correlation with corneal thickness.Subjects in the <20 years age group had thicker corneas in different regions compared to the >20 years age group (P=0.001 for the central and thinnest points, and P<0.001 for the peripheral region). Those with darker irises had thicker corneas (P value; 0.048 to 0.005 for different corneal regions).Conclusion: This study has provided valuable information concerning corneal thickness measurements as one of the most important eye indices collected from the population of Tehran. We found that sex and refraction had no significant effect on the corneal thickness while age and iris color did. Results of this study can be an important reference for experts in related fields and can also be used for comparison at an international level.

Purpose: Many studies showed that glutamate has an important role in retinal ischemic injury. Dextromethorphan is an antagonist of glutamate receptors and may prevent ischemic injury in retina. Six studies on rabbits showed the effectiveness of this drug in decreasing retinal injury in central retinal artery occlusion. This study evaluates effect of dextromethorphan on improving LogMAR of patients with central retinal artery occlusion.Methods: All patients with central retinal artery occlusion (except those with cilioretinal sparing) were treated with routine treatments. One group of them was given oral dextromethorphan (30 mg qid for 3 weeks with tapering over 1 week). Difference of LogMARs between first and last visits (3 months after the first visit) was calculated for each patient. Mean of these differences was compared in 2 groups.Results: We followed 30 patients with central retinal artery occlusion. 15 patients were given dextromethorphan. The mean age of all patients was 56.33 years. Only 2 patients in no-dextromethorphan group had NVI. Mean difference of LogMARs in no-dextro group was 0.6 (SD=0.6) and in dextro group was 1.21 (SD=0.8). Difference of means was significant (P=0.01). This difference was significant among patients without systemic disease (P=0.005) and patients coming after 12 hours (P=0.005, 0.03) but was not significant among patients with systemic disease (P=0.2) and patients coming before 12 hours (P=0.9).Conclusion: Dextromethorphan can be effective in improving visual prognosis in central retinal artery occlusion. Loss of effectiveness of this drug in patients with systemic disease may be due to associated retinal lesions or severe ischemia. Loss of effectiveness in patients coming before 12 hours may be due to less neuronal injury and better visual prognosis.

Purpose: Macular corneal dystrophy (MCD) is an autosomal recessive disorder characterized by progressive central haze, confluent punctate opacities and abnormal deposits in the cornea. It is caused by mutations in the CHST6 gene, encoding corneal GLC N Ac-6.0-ST. We screened the GHST6 gene for mutations in Iranian Families with MCD, in order to determine the range of pathologic mutations.Methods: DNA was extracted from venous blood of 17 patients and healthy control subjects. The coding region of the CHST6 gene was amplified using three pairs of primers and ampified products were directly sequenced.Results: Analysis of the CHST6 coding region in 17 patients with MCD identified 4 homozygous missense mutations (H249 R, P31L, R127C, S136?), 4 compound heterozygous missense mutations (C165S and P132L, C149Y and C149 ?), one heterozygous missense mutation (D203 V), One frameshift homozygous mutation (1580 Ins C) and One homozygous nonsense mutation (stop codon in serine 48). None of these mutations were detected in the control group.Conclusion: Seven novel mutations and four previously reported mutations were identified in our patients. These molecular results in Iranian patients with MCD combined with those reported in previous studies indicated CHST6 mutational heterogeneity.

The present data indicate that the prevalence of myopia has been increasing in many countries and in some areas like eastern Asia myopia will be an important public health problem by the next two decades and its clinical economical and social impacts will be prominent. On the other hand, while there are many evidences for the role of genetic in myopia, the observed association between myopia and other factors like near work, intelligence, education, height, occupation, nutrition, sex, age, etc indicates the role of environmental factors in myopia. Considering easy correction of the problem with glasses and contact lens it has received low priority from public health point of view. There are no effective modalities for prevention and progression of the disease. However, evolution of the surgical techniques for correction of myopia like corneal surgery and intraocular lenses has provided effective treatment for the error. Regarding the mentioned points, the epidemiology of myopia has retracted considerable attention recently. This review discusses on the studies about myopia, its distribution in the world, the evidences about its etiology, control and prevention.

Objective: To determine the association between the axial length of the eye and retinal vein occlusion [Branch Retinal Vein Occlusion (BRVO) and Central Retinal Vein Occlusion (CRVO)].Method: 18 patients with CRVO and Hemi-Retinal Vein Occlusion (hemiRVO) and 18 patient with BRVO were selected and 18 patient who referred for cataract extraction were matched with cases as control group. Axial length was measured in both eyes in cases and controls with A-scan biometry. The data were analysed according to student t test.Results: The affected and fellow eyes in CRVO group differ significantly in axial length (P=0.007). In BRVO group this difference was less but still significant (P=0.048). The axial length of non affected eye of CRVO and BRVO groups is lower than control group with P=0.047 & P=0.017 respectively. In BRVO group mean axial length of the affected eyes was 22.52 mm (80=0.72) and mean axial length of the fellow eyes was 22.77 mm (80=0.64). In CRVO group mean axial length of the affected eyes was 22.71 mm (80= 0.85) and mean axial length of the fellow eyes was 23.23 mm (80=0.71).In control group mean axial length was 23.77 mm (80=1.02).Conclusion: In our study the affected eyes in both groups were smaller than the fellow eyes, this difference in CRVO group is more pronounced. However this study could not clarify that this difference is either the cause or the effect of the vein occlusion, on the other hand even the fellow eye in BRVO & CRVO group is smaller in axial length than control eyes.

Purpose: Evaluation of corneal topographic changes after LASIK with quantitative and qualitative methods.Materials and Methods: A semiexperimental clinical trial was done in 80 eyes of 41 patients from 1380-1382 (2001-2003) in Tabriz. In this study eyes with myopia and myopic astigmatism undergo LASIK with Nidek EC-5000.Computerized video keratography was made before, 5days after and in the last visit following LASIK with Eye sys corneal analysis system and Holladay diagnostic summary programs. Findings are comparised and differences was analysed with T-test and Wilcoxon statistical methods. Results: Mean age of Patients was 30±10 (SD) Year. Mean duration of follow up was 12 months. Mean level of best corrected visual acuity before operation was 0.1 LogMar (20/25) and mean uncorrected visual acuity after operation in the last visit was 0.2 LogMar (20/30). Mean Level of best corrected visual acuity in the last visit was 0.35 LogMar (20/22).Mean amount of refractive error before operation in the spectacle plan was -5.75±3 (SD) that reached to -0.35±0.62 (SD) after operation.Mean amount of corneal asphericity (Q) before operation was -0.105 (min -1.04 and max +0.35) that raised to +1.07 (min +0.01 and max +1.99) in the last visit after LASIK. Mean corneal uniformity index (CUI) before operation was 97.25%, that reached to 85.37% in the last visit after LASIK.Mean predicted corneal acuity (P.C.A) before operation was 20/14 that reduced to 20/25 in the last visit after LASIK.Mean decentration of corneal center before and after LASIK in the horizontal axis was 0.03 mm and 0.045 mm (respectively) and in the vertical axis was 0.037mm and 0.024mm (respectively).Mean amount of effective refractive power before operation was 43.83±1.63 (SD) that reduced to 38.98±2.05 (SD) in the last visit after LASIK.Topographic profiles after LASIK were: Circular (C) in 53 eyes (66.25%), circular with central bowtie (CCB) in 25 eyes (31.25%) and assymetric bowtie (ASB) in 2 eyes (2.5%).Conclusion: This study shows that LASIK with Nidek-EC 5000 causes corneal topographic change from prolate to oblate with resultant correction of myopia and myopic astigmatism but, CU index and PCA are reduced after LASIK that causes unwanted effects on visual quality.

Epinephrine is frequently used in cataract surgery to dilate the pupil. To determine the effects of different concentrations of pure epinephrine on the corneal endothelial cells, forty-two eyes of twenty-one rabbits were randomly allocated into five groups. Solutions containing balanced salt solution, 1/500,000 epinephrine, 1/100,000 epinephrine,1/50,000 epinephrine, and 1/10,000 epinephrine were injected into the anterior chamber of the eyes of the five groups. Changes in the corneal cell density and polymegathism were assessed using specular biomicroscope, before, 2 hours and one week after the injection. The results showed that there was no significant difference in cell density and polymegathism among the five groups. Intracameral injection of pure epinephrine does not produce toxic effects on corneal endothelial cells in the rabbit.

Purpose: To report a patient with unilateral proptosis and Burkitt's-lymphoma. Patients and Findings: 4 year old child referred to our clinic with chief complain of sudden unilateral proptosis.The patient also had history of common cold 2 weeks later. Vision of right eye 4/10 and left eye 10/10 and 2+ Marcus gun in R eye.Right eye also deviated down and out in presentation.C.T-Scan also reported soft- tissue density in ethmoid sinuses, which biopsy showed Burkitt's lymphoma.Conclusion: In orbital tumors especially in pediatric age group also considered rare tumors too, and biopsy document the diagnosis.

Purpose: To evaluate the efficacy of intracameral recombinant tissue plasminogen activator in prevention of fibrinous effusion after lensectomy, anterior vitrectomy and PC IOL implantation in patients with congenital cataract. Methods: The study was done as a double-masked randomized clinical trial. Between April 2002 and Nov 2003, 34 eyes from 26 patients with congenital cataract were included in the study and randomized into two groups (18 cases & 16 controls). Each eye underwent lensectomy and anterior vitrectomy with PC IOL implantation. At the end of surgery 20 μg r-TPA was injected intracamerally in case group. No injection was done in control group. All patients received periocular, systemic and topical steroids after surgery. Follow up examinations were done in the following 3 months.Results: The incidence of intraocular fibrin membrane formation was significantly lower in case group on days 1 (P=0.024), 3 (p=0.01), 7 (P=0.01), 14 (P=0.01); but there was no significant difference on days 30 and 90. The frequency of pigmented IOL precipitates were significantly lower in case group at the end of third month (P<0.001). No gross ocular side effects were noted after r-TPA injection.Conclusion: It seems that prophylactic intracameral r-TPA is effective in prevention of fibrinous effusion at least in the first two weeks after cataract extraction in pediatric age group and decreases incidence of pigmented IOL precipitates.

Purpose: The purpose of this study is to investigate the efficacy of recombinant tissue plasminogen activator (r-tPA) in treatment of postsurgical fibrinous membrane and to experience the special and relatively difficult process of preparing and preserving this drug.Patients and Methods: In a prospectivestudy, 5 eyes of 5 patients with thick fibrin membrane following anterior segment surgery received 20 μg r-tPA intracamerally through a paracentesis.Results: Complete fibrinolysis occurred 2-20 h after injection in 3 eyes without any complication or recurrence over the three months follow up. In one case with a thick fibrin membrane for 3 months, r-tPA injection failed. In one patient, the membrane disappeared completely during the first 24 h after injection, but recurred 1 week later due to underlying mild endophthalmitis.Conclusion: The authors believe that intraocular r-tPA is effective and relatively safe in the treatment of severe therapy-resistant cases of intracameral fibrin reaction, if given at appropriate time.

Purpose: To report a case of central retinal artery occlusion after neurosurgical repair of intracranial aneurysm.Patients and Findings: A 23-year-old woman presented with loss of vision in the right eye following repair of intracranial aneurysm. Visual acuity was NLP in the right eye and funduscopic examination showed cherry-red-spot appearance, Systemic evaluations were all negative for causes of CRVO.Conclusion: This case confirms the risk of postoperative blindness after repair of intracranial aneurysm. So it was advised that all of the patients with paraclinoid aneurysm should receive precise postoperative neuro ophthalmologic examinations.

We describe a case of orbital apex syndrome due to Perineural Spread (PNS) of forehead Squamous Cell Carcinoma (SCC). This type of tumor spread occurs rarely and has a highly aggressive nature. Therefore, the high level of suspicion for perineural invasion is required and early diagnosis increases the likelihood of success in treatment.

Ocular Toxoplasmosis may result from either congenital or acquired Toxoplasmosis. The infection is commonly diagnosed by ophthalmologic examination and the empiric therapy instituted against the organism may confirm the clinical findings. But in some patients the clinical presentation is not diagnostic and in some others the response to the treatment is inadequate. Amplipification of parasite DNA can be used to support or confirm the diagnosis of Toxoplasma Gondii as the causative agent of ocular toxoplasmosis. In this study the utility of polymerase chain reaction (PCR) for diagnosis of ocular toxoplasmosis in a patient with sever inflammation and retinal detachment is demonstrated.