Retinal nerve fiber layer thickness in amblyopia

Purpose: To report retinal nerve fiber layer thickness (RNFLT) in eyes with amblyopia compared with contralateral healthy eyes. Methods: In this cross-sectional study, we included patients with anisometropic amblyopia, strabismic amblyopia, and mixed amblyopia. All subjects underwent complete ophthalmic examination, including RNFLT measurement with time-domain OCT (Stratus OCT) and scanning laser polarimeter (GDX VCC). A paired “t” test was used to compare average and quadrant-wise RNFL thickness between the amblyopic and contralateral normal eyes. In addition, an analysis of variance test was used to compare various RNFL thickness parameters between the three groups. Results: A total of 33 eyes of 33 subjects with anisometropic amblyopia, 20 eyes of 20 subjects with strabismic amblyopia, and 38 eyes of 38 subjects with mixed amblyopia were included. In the anisometropic amblyopia group, the average RNFLT in the amblyopic eye was 98.2 ?m and 99.8 ?m in the fellow normal eye (P = 0.5), the total foveal thickness was 152.82 ?m (26.78) in the anisometropic eye and 150.42 ?m (23.84) in the fellow eye (P = 0.38). The difference between amblyopic and contralateral normal eye for RNFL and macular parameters was statistically insignificant in all three groups. The RNFL thickness in four quadrants was similar in the amblyopic and non-amblyopic eye between all three groups and statistically non-significant. Conclusion: Our study showed that RNFL thickness was similar in amblyopic and non-amblyopic eyes between all three amblyopia groups

Evaluation of blotchy pigments in the anterior chamber angle as a sign of angle closure.

Background: Blotchy pigments in the anterior chamber (AC) angle are considered diagnostic of primary angle closure (PAC). But there are no reports either on the prevalence of blotchy pigments in AC angles or the validity of this sign. Aims: To determine the prevalence of blotchy pigments in AC angles and to evaluate their relationship with glaucomatous optic neuropathy (GON) in eyes with occludable angles. Setting and Design: Cross-sectional, comparative study. Materials and Methods: Gonioscopy was performed in 1001 eyes of 526 subjects (245 eyes of 148 consecutive, occludable angle subjects and 756 eyes of 378 non-consecutive, open angle subjects), above 35 years of age. Quadrant-wise location of blotchy pigments was documented. Statistical Analysis: Odds of blotchy pigments in occludable angles against that in open angles were evaluated. Relationship of GON with blotchy pigments in occludable angle eyes was evaluated using a multivariate model. Results: Prevalence of blotchy pigments in occludable angles was 28.6% (95% CI, 22.9-34.3) and in open angles was 4.7% (95% CI, 3.2-6.3). Blotchy pigments were more frequently seen in inferior (16%) and superior quadrants (15%) of occludable angles, and inferior quadrant of open angles (4%). Odds of superior quadrant blotchy pigments in occludable angles were 33 times that in open angles. GON was seen in 107 occludable angle eyes. Blotchy pigments were not significantly associated with GON (odds ratio = 0.5; P = 0.1). Conclusions: Blotchy pigments were seen in 28.6% of occludable angle eyes and 4.7% of open angles eyes. Presence of blotchy pigments in the superior quadrant is more common in occludable angles. Presence of GON in occludable angle eyes was not associated with blotchy pigments.

Unusual presentation in Axenfeld-Rieger syndrome.

We report an unusual presentation of a case of Axenfeld-Rieger (A-R) syndrome. A 14-year-old male presented with gradual dimness of vision for 1 year and redness of left eye for 3 days. The patient had megalocornea with Haab's striae in the right eye and posterior embryotoxon in both the eyes. In the left eye, there was a white cord-like structure traversing the anterior chamber with adhesions to iris tissue along its course. On two antiglaucoma medications, his intraocular pressure (IOP) was 22 mm Hg in the right eye and 18 mm Hg in the left eye. Gonioscopy revealed a cord-like structure originating at the level of Schwalbe's line. He underwent right eye trabeculectomy with mitomycin-C. This case highlights a rare presentation of a strange cord-like structure, a rare presentation of A-R syndrome.

Role of anterior segment optical coherence tomogram in Descemet's membrane detachment.

Descemet's membrane detachment (DD) is a rare but serious complication of intraocular surgery. In rare cases where corneal edema is severe and we may not be able to visualize DD on slit-lamp examination, anterior segment optical coherence tomogram (AS-OCT) would be helpful. We describe two patients with DD, highlighting the role of AS-OCT in early diagnosis and management of patients with DD. One of the patients had DD with rolled in edge, which could only be visualized with AS-OCT. In such a situation, AS-OCT can identify the edge of detachment and show the exact position of the rolled edge, which can allow us to plan the surgical strategy to unroll the DD.

Dilated episcleral veins with secondary open angle glaucoma.

We report a case of dilated episcleral vein with secondary open angle glaucoma. A 65-year-old female presented with redness of both the eyes without any prior systemic history. Her ocular examination revealed dilated episcleral veins and a high intraocular pressure (IOP) of 38 mm Hg in the right eye. Systemic examination was negative for carotid cavernous fistula, low-grade dural arteriovenous fistula, dysthyroid ophthalmopathy, and primary pulmonary hypertension. During follow-up, her IOP remained in high thirties despite maximum medications. She underwent right eye trabeculectomy with partial thickness sclerectomy with sclerotomy. In the beginning, the sclerotomy incision was not deepened into the suprachoroidal space. She developed choroidal effusion during surgery and the sclerotomy was deepened into suprachoroidal space and straw color fluid was drained. Postoperatively, she developed choroidal effusion, which resolved with conservative management. This case highlights the importance of sclerotomy in such cases of high episcleral venous pressure.

Alternative therapy in glaucoma management: Is there any role.

Glaucoma is one of the leading causes of blindness worldwide. Various randomized controlled clinical trials have shown that lowering intraocular pressure (IOP) does reduce progression of primary open-angle glaucoma. However, there is lots of interest in nonpharmacological options that includes lifestyle adjustment and alternative and complementary therapy (ACT). At least 5% glaucoma population uses ACT. Various lifestyle activities like exercise and alcohol can reduce IOP by 1 to 2 mm Hg but would have small effect on glaucoma. The psychological stress can increase IOP. Hypothetically and few studies do show neuroprotective effect (or effect on ocular blood flow) of alcohol, Gingko biloba, bilberry, but the current evidence is weak for its routine use. We must also remember the side effects of ‘medications’ (e.g., marijuana, alcohol) before promoting as remedy for glaucoma. In current armamentarium of glaucoma management, ACT cannot substitute the conventional treatment available to lower IOP.

Evaluation of a glaucoma patient.

The diagnosis of glaucoma is usually made clinically and requires a comprehensive eye examination, including slit lamp, applanation tonometry, gonioscopy and dilated stereoscopic evaluation of the optic disc and retina. Automated perimetry is obtained if glaucoma is suspected. This establishes the presence of functional damage and provides a baseline for follow-up. Imaging techniques are not essential for the diagnosis but may have a role to play in the follow-up. We recommend a comprehensive eye examination for every clinic patient with the objective of detecting all potentially sight-threatening diseases, including glaucoma.

Clinical measurement and categorization of optic disc in glaucoma patients.

Background: Assessment of optic disc size is an important component of optic nerve head examination. Agreement between different methods of disc size measurements is not very good. Purpose: To assess the agreement between the disc size assessed by Heidelberg retina tomograph (HRT) and stereobiomicroscopy with a 90 diopter (D) lens. To report the clinical (measured by biomicroscopy) disc diameters of small, average and large optic discs categorized by HRT disc areas. Setting and Design: Observational study of subjects examined in the glaucoma clinic of a tertiary eye institute. Materials and Methods: Seventy-five eyes of 75 glaucoma subjects were studied. Disc diameter was measured using stereobiomicroscopy and HRT. The agreement between the two sets of measurements was assessed by intraclass correlation coefficient (ICC). Discs were classified into small (<1.6 mm2), average (1.6-2.6 mm2) and large (>2.6 mm2) depending on cutoffs provided by the manufacturers of HRT. The means (95% CI) of the corresponding vertical disc diameter in these groups were assessed. Statistical Analysis: ICC, Bland and Altman plots. Results: ICC for measurements of clinical and HRT horizontal disc diameter was 0.518 and for vertical disc diameter measurement was 0.487. The mean difference between the clinical and HRT measurements as analyzed by the Bland and Altman plot was 0.17 (95% CI, 0.13- 0.47) for horizontal and 0.22 (95% CI, 0.11- 0.54) for vertical disc diameter. Of the 75 eyes, 3 eyes had small discs, 54 average and 18 large discs. The mean clinical vertical disc diameter for small discs was 1.55 mm (95% CI, 1.2-1.7), for average discs was 1.91 mm (95% CI, 1.87-1.96) and for large discs was 2.15 mm (95% CI, 2.03–2.27). Conclusion: The agreement between clinical and HRT disc diameter measurements is moderate. Disc diameter measurement on stereobiomicroscopy can be used to categorize discs into small, average and large discs.

Aniridia associated with congenital aphakia and secondary glaucoma.

We report a case of aniridia associated with congenital aphakia and secondary glaucoma. A 35-year-old male presented with aniridia, congenital aphakia and secondary glaucoma in both eyes. After an unsuccessful medical management, he underwent trabeculectomy with mitomycin C and anterior vitrectomy under local anesthesia in his left eye. Postoperatively, at the end of six months, intraocular pressure (IOP) in his left eye was controlled without medications. This case highlights the rare association of aniridia with congenital aphakia and secondary glaucoma.

Likelihood ratios: Clinical application in day-to-day practice.

In this article we provide an introduction to the use of likelihood ratios in clinical ophthalmology. Likelihood ratios permit the best use of clinical test results to establish diagnoses for the individual patient. Examples and step-by-step calculations demonstrate the estimation of pretest probability, pretest odds, and calculation of posttest odds and posttest probability using likelihood ratios. The benefits and limitations of this approach are discussed.

Practical approach to medical management of glaucoma.

Primary open angle glaucoma (POAG) is usually a chronic, slowly progressive disease. At present, all resources are directed towards reduction of intraocular pressure (IOP), the only known causal and treatable risk factor for glaucoma, and medical management is frequently the first choice in most cases. With the introduction of innovative tools for early diagnosis and newer medications for treatment, decision-making in diagnosis and treatment of glaucoma has become more complex. The philosophy of glaucoma management is to preserve the visual function and quality of life (QOL) of the individual with minimum effects on QOL in terms of cost, side effects, treatment regime, follow-up schedules as well as socioeconomic burden. Our aim should be not to treat just the IOP, optic disc or visual field, but to treat the patient as a whole so as to provide maximum benefit with minimal side effects. In this article, we describe the scientific approach to medical management, mainly of POAG.

Learning micro incision surgery without the learning curve.

We describe a method of learning micro incision cataract surgery painlessly with the minimum of learning curves. A large-bore or standard anterior chamber maintainer (ACM) facilitates learning without change of machine or preferred surgical technique. Experience with the use of an ACM during phacoemulsification is desirable.

Understanding and using sensitivity, specificity and predictive values.

In this article, we have discussed the basic knowledge to calculate sensitivity, specificity, positive predictive value and negative predictive value. We have discussed the advantage and limitations of these measures and have provided how we should use these measures in our day-to-day clinical practice. We also have illustrated how to calculate sensitivity and specificity while combining two tests and how to use these results for our patients in day-to-day practice.

Role of frequency doubling technology perimetry in screening of diabetic retinopathy.

PURPOSE: To study the ability of frequency-doubling technology perimetry (FDT) to detect sight-threatening diabetic retinopathy. METHOD: Fifty-eight eyes of fifty-eight patients with established diagnosis of diabetes mellitus with diabetic retinopathy, fifty-five eyes of fifty-five diabetic patients without retinopathy and forty-one eyes of forty-one normals underwent FDT and dilated stereo-biomicroscopic fundus examination. The sensitivity and specificity of FDT in identification of "sight-threatening retinopathy" (severe and very severe nonproliferative diabetic retinopathy and proliferative diabetic retinopathy) and clinically significant macular edema (CSME) were determined. RESULTS: For the detection of sight-threatening retinopathy, two abnormal adjacent points depressed to any level on the 20-1 screening program had a sensitivity of 90.5% and specificity of 97.6%. At (assuming a) 10% prevalence of sight-threatening retinopathy in a diabetic clinic, two abnormal adjacent points anywhere in the field depressed to any level has a positive predictive value (PPV) of 48% with a negative predictive value of 98.8%. Sensitivity and specificity for the detection of CSME was poor. CONCLUSIONS: The 20-1 screening program of the FDT is useful in the detection of sight-threatening diabetic retinopathy (PPV 48%). A normal 20-1 test rules out sight-threatening retinopathy. FDT was not useful in the detection of CSME.

Efficacy and safety of latanoprost for glaucoma treatment: a three-month multicentric study in India.

PURPOSE: To evaluate the short-term efficacy and safety of 0.005% topical latanoprost in Indian eyes. DESIGN: Prospective non-randomised open-label multicentric trial. METHODS: One hundred and fifty patients with ocular hypertension (OHT), primary open-angle, pseudoexfoliation or pigmentary glaucoma were enrolled at four centers. Each center contributed at least 20 patients. Following baseline measurements, 0.005% latanoprost was applied topically once daily in the evening for three months. Patients were examined at 2, 6 and 12 weeks. The primary outcome measure was mean intraocular pressure (IOP) reduction. The mean diurnal variation of IOP (difference between highest and lowest IOP) at baseline and at 12-weeks was compared. RESULTS: One hundred and thirty of 150 enrolled patients completed the study. One randomly selected eye of each patient was included for analysis. At three months, latanoprost reduced the mean IOP from 24.9 (+/- 3.16) mmHg at baseline to 16.10 (+/- 2.7) mmHg, a reduction of 35.25%. 83% had a reduction in IOP of > 25%. The IOP reduction was maintained throughout the study period, and was not affected by gender or age of the patient. One eye did not show any response to the drug. Daytime diurnal variation of IOP was reduced from 4.5 to 2.9 mmHg. 20 patients had conjunctival hyperemia. Six patients had side effects requiring withdrawal from the study. CONCLUSIONS: In this short-term multicentric study, latanoprost effectively reduced IOP and stabilised the diurnal curve in Indian eyes. There were no clinically significant ocular or systemic adverse effects.

Five-year risk of progression of ocular hypertension to primary open angle glaucoma. A population-based study.

PURPOSE: To report the progression of ocular hypertension (OHT) to primary open angle glaucoma (POAG) during a 5-year follow up of a population-based sample. METHODS: Twenty-nine patients diagnosed to have OHT and 110 randomly selected normals from a population-based study in 1995 were invited for ocular examination in 2000. All patients underwent a complete ophthalmic examination; including the daytime diurnal variation of intraocular pressure (IOP) and measurement of central corneal thickness (CCT). The "corrected" IOP was used for analysis. Progression to POAG was based on typical optic disc changes with corresponding field defects on automated perimetry. RESULTS: Twenty-five of the 29 persons with OHT who could be contacted were examined. After correcting for CCT, two persons were reclassified as normal. Four of 23 (17.4%; 95% CI: 1.95-32.75) had progressed to POAG. One person amongst the 110 normals progressed to normal tension glaucoma (NTG). The relative risk of progression amongst OHT was 19.1 (95% CI: 2.2-163.4). All those who progressed had bilateral OHT. The mean and peak IOP in those who progressed was 25.4 mm Hg and 29.3 mm Hg compared to 23.9 mm Hg and 25.7 mm Hg in those who did not. Those who progressed had more than 8 mm Hg diurnal variation. The diurnal variation was less than 6 mm Hg in those who did not progress. No patient developed blindness due to glaucoma. CONCLUSION: The 5-year incidence of POAG amongst OHT in this population was 17.4% (3.5% per year). Bilateral OHT, higher peak IOP and large diurnal variation may be the risk factors for progression.

Comparison between latanoprost and brimonidine efficacy and safety in Indian eyes.

PURPOSE: To compare the short-term efficacy and safety of topical latanoprost and brimonidine in Indian eyes. MATERIALS AND METHODS: Twenty-eight patients with ocular hypertension, primary open-angle, pseudoexfoliation or pigmentary glaucoma were enrolled. Following baseline measurements, latanoprost was applied topically once daily in the evening for 12-weeks. After a washout period, brimonidine was applied twice daily in all patients for 6 weeks; 16 patients continued for 12 weeks. Patients were examined at 2, 6 and 12 weeks. The primary outcome measure was the difference in mean intra ocular pressure (IOP) reduction at 6 and 12 weeks. The mean diurnal variation of IOP at baseline and at 12 weeks was also compared. RESULTS: Twenty-six of 28 enrolled patients completed the study. One randomly selected eye of each patient was used for analysis. At 6 weeks, the mean IOP reduction was 11.2 mm Hg (+/- 2.9 mmHg) with latanoprost and 6 mmHg (+/- 3.3 mmHg) with brimonidine. At 12 weeks this was 10.8 mmHg (+/- 2.8 mmHg) and 6.9 mmHg (+/- 3.1 mmHg) respectively. At 6 weeks 85.7% (24) eyes obtained more than 25% reduction in IOP with latanoprost compared to 13 (46.4%) with brimonidine. IOP reduction was maintained with both drugs throughout the study period. Two eyes did not show any response to brimonidine. Latanoprost reduced the diurnal variation of IOP from 5.10 to 2.90 mmHg; brimonidine reduced it from 4.70 to 3.90 mmHg. Conjunctival hyperaemia was present in one patient on latanoprost and three patients on brimonidine. Two patients experienced drowsiness with brimonidine. Neither drug produced side effects necessitating withdrawal from the study. CONCLUSION: In this short-term study, both latanoprost and brimonidine effectively reduced IOP and stabilised the diurnal curve in Indian eyes. Latanoprost was more effective than brimonidine.

The incidence of vitreous loss and visual outcome in patients undergoing cataract surgery in a teaching hospital.

PURPOSE: To determine the incidence of vitreous loss in patients undergoing cataract surgery and the visual outcome in a tertiary teaching hospital. METHODS: Hospital records of 2095 consecutive patients undergoing cataract surgery between July 1999 and June 2000 were reviewed in this non-concurrent cohort study. Incidence and visual outcome of vitreous loss managed using standard vitrectomy techniques were assessed for different cataract surgical techniques (extracapsular, Blumenthal technique and phacoemulsification) as well as at different levels of surgical training. The outcome was compared with matched cases without vitreous loss (controls). RESULTS: Vitreous loss occurred in 160 of 2095 eyes (7.63%; CI -7 to 9.3): 8.3% for ECCE, 8.1% for the Blumenthal technique and 5% with phacoemulsification. Vision > or = 6/18 was achieved in 85% of cases and 95% of controls. For experienced surgeons, 95% of the cases and controls had vision > or = 6/18. 5.8% of cases and 0.7% of controls had vision < 6/60. One patient in each group was blind following cataract surgery; both had operable cataracts in the fellow eye. CONCLUSIONS: The vitreous loss rate in this tertiary teaching hospital is relatively high. This complication, managed with standard surgical techniques, is compatible with good visual outcome. In eyes with vitreous loss, the final visual acuity achieved by experienced surgeons was similar to that in uncomplicated cases.