Journal of Ophthalmic and Vision Research
Year:2009 | Volume:4 | Issue:2|Papers Count:12

Singapore Eye Research Institute, Singapore National Eye Centre, Singapore Glaucoma, an optic neuropathy characterized by progressive visual field loss, is the leading cause of irreversible blindness worldwide. The condition has a substantial heritable basis, as illustrated by the numerous loci and genes identified to date and the large proportion of patients with positive family history. When glaucoma manifests before the age of 40 years, it tends to be more aggressive, more resistant to medical therapy and associated with more visual impairment. 1,2 This category includes congenital/infantile glaucoma which is a genetically heterogeneous group by itself with the involvement of one gene (CYP1B1) and at least two other genetic loci. 3-6 The only known gene for primary congenital glaucoma (PCG), CYP1B1, encodes cytochrome P4501B1 that is involved in the metabolism of many compounds, including the 4-hydroxylation of 17b -estradiol. 7 It has been hypothesized that alterations in the metabolism of estrogens may be the basis for ocular abnormalities associated with defects in this gene.

Purpose: To investigate variations in sex ratio among Iranian primary congenital glaucoma (PCG) patients with and without mutations in the CYP1B1 gene and to evaluate possible clinical variations associated with sex in these two groups.Methods: Phenotypical data on 104 unrelated Iranian PCG patients who had previously been screened for CYP1B1 mutations were analyzed. Emphasis was placed on analysis of sex ratios among patients with and without CYP1B1 mutations. In addition to sex, familial and sporadic incidence and clinical features including age at onset, bilateral/unilateral involvement, corneal diameter, intraocular pressure, and cup-disc ratios were compared between these two groups. Information on phenotypical parameters was available for most but not all patients.Results: Among the 93 PCG patients whose sex was recorded, 57 were male (61.3%) and 36 were female (38.7%) (P=0.03). Patients with CYP1B1 mutations included 37 male (66.1%) and 29 female (43.9%) subjects (P=0.30), while patients without the mutation included 20 (74.1%) male and 7 (25.9%) female individuals (P=0.013). Our data did not provide conclusive evidence on difference in severity of the disease between those with and without CYP1B1 mutations, nor between the two sexes.Conclusion: Consistent with data on PCG patients from other populations, the overall incidence of PCG in Iran seems to be higher among male subjects. The difference in incidence between the two sexes was not significant among patients whose disease was due to mutations in CYP1B1. The overall higher incidence of PCG among male subjects seems to be attributable to a higher incidence in male patients not harboring CYP1B1 mutations, suggesting that other genes or factors may be involved in manifestation of PCG phenotypes in a sex dependent manner.

Purpose: To compare the astigmatic outcomes of phacoemulsification cataract surgery using temporal versus nasal clear corneal incisions.Methods: In a clinical trial, consecutive patients with senile cataracts underwent phacoemulsification and implantation of a hydrophobic acrylic foldable intraocular lens through a horizontal clear corneal incision (temporal in right and nasal in left eyes).Outcome measures included keratometric astigmatism and surgically induced astigmatism (SIA) calculated by the vector analysis method using the Holladay-Cravy-Koch formula.Results: The nasal and temporal groups consisted of 20 eyes each. Mean preoperative keratometric astigmatism was 0.63±0.48 D and 0.38±0.39 D in the temporal and nasal incision groups respectively (P=0.09). Data on 10 eyes in each study group was available for the six-month analysis. Mean keratometric astigmatism was as follows in the temporal and nasal groups respectively: 0.85±0.47 D versus 1.95±0.45 D at 1 week (P<0.001), 0.73±0.46 D versus 1.79±0.55 D at 4 weeks (P<0.001), and 0.63±0.30 D versus 1.05±0.56 D at 6 months (P=0.053) after surgery. SIA at the same follow-up intervals was 0.71±0.20 D versus 1.80±0.22 D (P<0.001), 0.63±0.20 D versus 1.65±0.31 D (P<0.001) and 0.26±0.46 D versus 0.92±0.36 D (P=0.002) in the temporal versus nasal incision groups respectively.Conclusion: Temporal clear corneal phacoemulsification induces significantly less astigmatism as compared to similar surgery using the nasal approach.

Purpose: To determine the effect of trabeculectomy on cataract formation or progression in patients with chronic glaucoma.Methods: This controlled clinical trial was performed on patients over 50 years of age with glaucoma who were referred to Imam Hossein Hospital, Tehran, Iran, from 2006 to 2007. Trabeculectomy was indicated only in one eye while the fellow eye had wellcontrolled intraocular pressure with medication(s). The fellow eyes served as controls.Lens opacity was evaluated using three criteria: visual acuity (VA), and Lens Opacification Classification System III (LOCS III) photographs and scores.Results: Overall 82 eyes of 41 patients including 53.7% male and 46.3% female subjects with mean age of 62.5±9.3 (range 50-75) years were evaluated. Cataract progression in operated eyes was statistically significant according to VA (P=0.02), LOCS III photographs (P=0.05) and LOCS III scores (P=0.01). However, compared to fellow control eyes, cataract progression was significant according to VA (P=0.023) and LOCS III scores (P=0.057) but not based on LOCS III photographs. Mean VA reduction was 2 Snellen lines in operated eyes; there were 3 cases of cataract formation or progression without reduced VA.Conclusion: Cataracts seem to progress following trabeculectomy; therefore it might be advisable to perform a combined procedure in older patients with moderate lens opacities.

Purpose: To compare the anatomical and visual outcomes of three different sclera buckling techniques and to explore the effect of cryotherapy and subretinal fluid drainage (SRFD) on outcomes of surgery.Methods: This retrospective study was performed on 111 eyes of 109 patients undergoing scleral buckling for rhegmatogenous retinal detachments (RRDs) by a single surgeon. Pre-, intra- and postoperative data were retrieved from hospital records.Results: Buckles were radial in 27 (24.3%), circumferential (segmental) in 16 (14.4%) and encircling in 68 (61.3%) eyes. Anatomical and visual results were comparable with all three buckling techniques. Application of cryotherapy, the spot number, and SRFD did not affect anatomical and visual results. The only preoperative factor associated with poorer anatomical results was the presence of multiple retinal breaks (P=0.006). The following preoperative factors affected visual outcomes on univariate analysis: extent of retinal detachment (r=0.417, P=0.011) and relative afferent pupillary defect (r=0.423, P=0.02). Preoperative macular status (attached vs detached) also had a significant effect on visual outcomes (P<0.001). Based on multivariate analysis however, only preoperative macular status was significantly correlated with visual results (P=0.022).Silicone sponges placed for non-encircling surgery were removed due to ocular dysmotility in 4 (3.6%) eyes, cosmetic reasons in 3 (2.7%) cases and extrusion in 2 (1.8%) eyes. One encircling tire was also removed due to extrusion.Conclusion: Surgical technique and performing cryotherapy or SRFD do not seem to influence the anatomical and visual outcomes of scleral buckling. Postoperative complications seem to be more prevalent with non-encircling techniques.

Purpose: To determine normal values of standard full-field electroretinography (ERG) and to evaluate their variations with age in an Iranian population.Methods: Through convenient sampling, 170 normal subjects 1-80 years of age were selected from residents of Tehran. ERG amplitudes and implicit time values were measured according to recommendations by the International Society for Clinical Electrophysiology of Vision. Evaluations consisted of light-adapted ERG including single-white flash and 30-Hz flicker response; and dark-adapted ERG including rod, maximal dark-adapted and cone responses.Results: No significant difference in ERG values was observed between men and women, or between right and left eyes. ERG amplitudes were lower (P=0.04) and implicit time values were greater (P=0.03) in subjects 70-80 years of age as compared to younger individuals.Conclusions: ERG parameters are significantly diminished with age. Our results may serve as a reference against which standard ERG responses can be compared.

Purpose: To report the results of late nasolacrimal duct probing in patients with congenital nasolacrimal duct obstruction (NLDO).Methods: This retrospective study was performed on a consecutive series of patients with congenital NLDO who underwent late (after 15 months of age) nasolacrimal duct probing for the first time.Results: Over a period of five years, 158 patients including 75 (47.4%) male and 83 (52.6%) female subjects with mean age of 3±4.2 years (range, 15 months to 37 years) underwent initial probing for NLDO. Nasolacrimal duct probing was performed unilaterally in 78% and bilaterally in 22% of the patients. Success rate was 75% overall, 72% in unilateral cases and 83% in bilateral instances. Success rate was not correlated with age at intervention.Conclusions: Nasolacrimal duct probing seems to be reasonably successful for treatment of congenital NLDO in patients older than 15 months who are seen for the first time.Silicone intubation or dacryocystorhinostomy should be reserved for refractory cases.

The introduction of pharmacotherapy has been one of the most important advances in the management of retinal disorders. Age-related macular degeneration (AMD) was once considered as an irrepressible disease leading to permanent macular damage, however anti-vascular endothelial growth factor (anti-VEGF) agents are now believed to halt the progression of the condition and improve vision in a considerable proportion of patients. Anti-VEGF agents are among the most commonly used drugs in ophthalmology but questions and uncertainties still surround their indications, efficacy and complications. This paper reviews the role of VEGF under physiologic and pathologic conditions in the eye and available anti-VEGF agents in current ophthalmic practice.

When several and very different treatment modalities exist for one ailment, it usually means that none of them is generally effective or superior to others. Central retinal vein occlusion (CRVO) is a condition for which various types of management have been proposed.However, the only standard care suggested by the Central Vein Occlusion Study Group (CVOSG) is panretinal photocoagulation when the condition is complicated by iris neovascularization.

Purpose: To describe the clinical and pathological features of a case of hydrogel intraocular lens (IOL) calcification.Case Report: A 48-year-old man underwent explantation of a single-piece hydrophilic acrylic intraocular lens in his left eye because of decreased visual acuity and milky white opalescence of the IOL. The opacified lens was exchanged uneventfully with a hydrophobic acrylic IOL. Gross examination of the explanted IOL disclosed opacification of the optic and haptics. Full-thickness sections of the lens optic were stained with hematoxylin and eosin (H&E), von Kossa and Gram Tworts’. Microscopic examination of the sections revealed fine and diffuse basophilic granular deposits of variable size within the lens optic parallel to the lens curvature but separated from the surface by a moderately clear zone. The deposits were of high calcium content as evident by dark brown staining with von Kossa. Gram Tworts’ staining disclosed no microorganisms.Conclusion: This report further contributes to the existing literature on hydrogel IOL calcification.

A 65-year-old woman presented with sudden visual loss of 2 weeks’ duration in her right eye.She had a 20-year long history of systemic hypertension, ischemic heart disease and coronary artery angioplasty. Best-corrected visual acuity was counting fingers at 1m in her right eye and 20/30 in the left with trace positive relative afferent pupillary defect in the right eye. The only remarkable slitlamp finding was mild bilateral nuclear cataracts; intraocular pressure was 12 mmHg in both eyes. Fundus examination revealed 1+ media haziness secondary to mild vitreous hemorrhage in the right eye, normal optic disc, and a dense premacular hemorrhage with a subretinal component superiorly (Figures 1, 2). Funduscopy in the left eye disclosed signs of dry type age-related macular degeneration (AMD) manifesting as moderate-sized hard drusen and mild pigmentary derangement. Retinal vascular tortuosity and arterial narrowing due to hypertensive retinopathy and arteriolar sclerosis were noted in both eyes.

Human corneal endothelial cells (HCECs) do not normally proliferate in vivo. However, they divide in response to wounding ex vivo and proliferate in culture media when stimulated by appropriate growth promoting agents. Elucidating the mechanisms of HCEC proliferation opens a window to novel therapeutic strategies for corneal disease caused by abnormal endothelial cells.