R. Krishnadas

Glaucoma in a rural population of southern India: The Aravind comprehensive eye survey

PURPOSE To determine the prevalence of glaucoma and risk factors for primary open-angle glaucoma in a rural population of southern India. DESIGN A population-based cross-sectional study. PARTICIPANTS A total of 5150 subjects aged 40 years and older from 50 clusters representative of three southern districts of Tamil Nadu in southern India. METHODS All participants had a comprehensive eye examination at the base hospital, including visual acuity using logarithm of the minimum angle of resolution illiterate E charts and refraction, slit-lamp biomicroscopy, gonioscopy, applanation tonometry, dilated fundus examinations, and automated central 24-2 full-threshold perimetry. MAIN OUTCOME MEASURES Definite primary open-angle glaucoma (POAG) was defined as angles open on gonioscopy and glaucomatous optic disc changes with matching visual field defects, whereas ocular hypertension was defined as intraocular pressure (IOP) greater than 21 mmHg without glaucomatous optic disc damage and visual field defects in the presence of an open angle. Manifest primary angle-closure glaucoma (PACG) was defined as glaucomatous optic disc damage or glaucomatous visual field defects with the anterior chamber angle partly or totally closed, appositional angle closure or synechiae in the angle, and absence of signs of secondary angle closure. Secondary glaucoma was defined as glaucomatous optic nerve damage and/or visual field abnormalities suggestive of glaucoma with ocular disorders that contribute to a secondary elevation in IOP. RESULTS The prevalence (95% confidence interval) of any glaucoma was 2.6% (2.2, 3.0), of POAG it was 1.7% (1.3, 2.1), and if PACG it was 0.5% (0.3, 0.7), and secondary glaucoma excluding pseudoexfoliation was 0.3% (0.2,0.5). On multivariate analysis, increasing age, male gender, myopia greater than 1 diopter, and pseudoexfoliation were significantly associated with POAG. After best correction, 18 persons (20.9%) with POAG were blind in either eye because of glaucoma, including 6 who were bilaterally blind and an additional 12 persons with unilateral blindness because of glaucomatous optic neuropathy in that eye. Of those identified with POAG, 93.0% had not been previously diagnosed with POAG. CONCLUSIONS The prevalence of glaucoma in this population is not lower than that reported for white populations elsewhere. A large proportion of those with POAG had not been previously diagnosed. One fifth of those with POAG had blindness in one or both eyes from glaucoma. Early detection of glaucoma in this population will reduce the burden of blindness in India.

Blindness and vision impairment in a rural south Indian population: the Aravind Comprehensive Eye Survey

OBJECTIVE To determine the prevalence of blindness and vision impairment in a rural population of southern India. DESIGN A population-based cross-sectional study. PARTICIPANTS A total of 17200 subjects aged 6 years or older, including 5150 subjects aged 40 years or older from 50 clusters representative of three southern districts of Tamil Nadu in southern India. METHODS All participants had preliminary screenings consisting of vision using a LogMAR illiterate E chart and anterior segment hand light examinations at the village level. Subjects aged 40 years or older were offered comprehensive eye examinations at the base hospital, including visual acuity using LogMAR illiterate E charts and refraction, slit-lamp biomicroscopy, gonioscopy, applanation tonometry, dilated fundus examinations, and automated Humphrey central 24-2 full threshold perimetry; subjects younger than 40 years of age who had any signs or symptoms of ocular disease were also offered comparable examinations at the base hospital. MAIN OUTCOME MEASURES Visual impairment was defined as best-corrected visual acuity <6/18, and blindness was defined using both Indian (<6/60) and World Health Organization (<3/60) definitions. RESULTS Comprehensive examinations at the base hospital were performed on 5150 (96.5%) of 5337 persons 40 years of age or older. Among those 40 years of age and older, presenting visual acuity at the <3/60 level was present in 4.3% (95% confidence interval [CI]: 3.8, 4.9) and 11.4% (95% CI: 10.6, 12.3) at the <6/60 level. After best correction, the corresponding figures were 1.0% (95% CI: 0.79, 1.2) and 2.1% (95% CI: 1.7, 2.5). Over 70% of subjects improved their vision by at least one line, and nearly a third by three lines after refraction. Age-related cataract was the most common potentially reversible blinding disorder (72.0%) among eyes presenting with blindness. CONCLUSIONS Blindness and vision impairment remain major public health problems in India that need to be addressed. Cataracts and refractive errors remain the major reversible causes for the burden of vision impairment in this rural population.

Utilisation of eye care services in rural south India: the Aravind Comprehensive Eye Survey

Aim: To determine utilisation of eye care services in a rural population of southern India aged 40 years or older. Methods: 5150 subjects aged 40 years and older selected through a random cluster sampling technique from three districts in southern India underwent detailed ocular examinations for vision impairment, blindness, and ocular morbidity. Information regarding previous use of eye care services was collected from this population through a questionnaire administered by trained social workers before ocular examinations. Results: 3476 (72.7%) of 5150 subjects examined required eye care examinations. 1827 (35.5%) people gave a history of previous eye examinations, primarily from a general hospital (n = 1073, 58.7%). Increasing age and education were associated with increased utilisation of eye care services. Among the 3323 people who had never sought eye care, 912 (27.4%) had felt the need to have an eye examination but did not do so. Only one third of individuals with vision impairment, cataracts, refractive errors, and glaucoma had previously utilised services. Conclusions: A large proportion of people in a rural population of southern India who require eye care are currently not utilising existing eye care services. Improved strategies to improve uptake of services is required to reduce the huge burden of vision impairment in India.

Risk factors for age related cataract in a rural population of southern India: the Aravind Comprehensive Eye Study

Aim: To determine risk factors for lens opacities and age related cataract in an older rural population of southern India. Methods: A cross sectional population based study of 5150 people aged 40 years and above from 50 clusters from three districts in southern India. The lens was graded and classified after dilation using LOCS III system at the slit lamp for cataract. Definite cataract was defined as nuclear opalescence ⩾3.0 and/or cortical cataract ⩾3.0 and/or PSC ⩾2.0. Results: Definite cataracts were found in 2449 (47.5%) of 5150 subjects and the prevalence of cataract increased with age. The age adjusted prevalence of cataract was significantly lower in males (p = 0.0002). Demographic risk factors—increasing age and illiteracy—were common for the three subtypes of cataract; females were more likely to have cortical cataracts and nuclear cataracts. Additionally, nuclear cataracts were associated with moderate smoking (OR:1.28, 95% CI:1.01 to 1.64), lean body mass indices (OR: 1.37, 95% CI: 1.17 to 1.59) and higher waist to hip ratios (OR: 0.67, 95% CI: 0.54 to 0.82); cortical cataracts with hypertension (OR: 1.39 95% CI:1.11 to 1.72), pseudoexfoliation (OR:1.53,95% CI:1.17 to 2.01), and moderate to heavy smoking; and posterior subcapsular cataracts with diabetes (OR:1.55, 95% CI:1.12 to 2.15), lean body mass (OR:1.32, 95% CI:1.11 to 1.57), and high waist to hip ratios (OR: 0.77, 95% CI: 0.62 to 0.94). Conclusions: Risk factors for age related cataract in this population do not appear to be different from those reported in other populations. Further studies are required to identify the reason for the high prevalence of age related cataract and to understand better the role of each risk factor for cataractogenesis in this population.

Phacoemulsification in eyes with white cataract.

PURPOSE To study the results of phacoemulsification in eyes with white cataract. SETTING Aravind Eye Hospital, Madurai, India. METHODS This retrospective study comprised 212 consecutive patients with white cataract: 192 mature (90.6%), 11 intumescent (5.2%), and 9 hypermature (4.2%). Patients had phacoemulsification and continuous curvilinear capsulorhexis. After the nucleus was removed by the divide and conquer or the phaco chop technique, a posterior chamber intraocular lens was implanted. Preoperative and intraoperative findings, as well as postoperative outcomes, were analyzed. RESULTS Intraoperative complications included premature entry of the tunnel into the anterior chamber in 4 eyes (1.9%), incomplete capsulorhexis in 60 (28.3%), posterior capsular tear in 4 (1.9%), conversion to a manual nonphacoemulsification technique in 4 (1.9%), intraoperative miosis in 7 (3.3%), and iris chafing in 2 (0.9%). Mean phacoemulsification time was 2.03 minutes (range 0 to 5.8 minutes). A best corrected visual acuity of 6/9 or better was attained in 131 patients (61.8%) on the first postoperative day and in 199 patients (93.9%) at 1 month. Postoperative complications included moderate transient striate keratopathy with corneal edema in 12 eyes (5.7%) and iritis in 2 (0.9%). CONCLUSIONS Phacoemulsification was a safe and effective technique to remove white mature cataract in eyes in a developing country.

Safety and efficacy of mitomycin C trabeculectomy in Southern India : a short-term pilot study

PURPOSE Glaucoma is a major cause of blindness in developing nations. Medical and laser therapy have limitations in this environment. Filtration surgery alone often fails in young, darkly pigmented, individuals. The authors, therefore, evaluated the safety and efficacy of filtration surgery, using topical mitomycin C, in patients undergoing trabeculectomy in India. METHODS A short-term pilot study used mitomycin C at the time of trabeculectomy in a population of southern Indians with various forms of glaucoma. A single 5-minute intraoperative application of 0.4 mg/ml mitomycin C was given to 76 consecutive patients requiring filtration surgery for the control of intraocular pressure (IOP). All patients were admitted for 6 days and were seen at 6-week intervals for a minimum of 18 weeks. RESULTS The mean preoperative IOP was 35.3 +/- 9.6 mmHg. Postoperative IOP control was attained in 93.4% of patients as defined by an IOP of 20 mmHg or less without additional glaucoma medications (or an IOP reduction > 25% if the preoperative IOP was < or = 20 mmHg). No corneal epithelial defects or wound leaks were seen. The major complications were cataract formation and a decreased visual acuity in ten (13%) eyes. CONCLUSION Mitomycin C-aided trabeculectomy was highly successful in controlling IOP in this darkly pigmented population and may become an important adjunct in the treatment of glaucoma in developing countries.

Population-based prevalence of uveitis in Southern India

Purpose To estimate the prevalence of uveitis in rural Tamil Nadu, India. Methods Cluster sampling identified a population-based sample of 5150 persons ages 40 years and older, representative of three districts in Tamil Nadu, India. Each received a comprehensive dilated ocular examination by an ophthalmologist, and results were registered on forms requiring responses about the presence of ocular inflammatory signs and inflammatory diagnoses. Potential uveitis cases were confirmed by consensus of two uveitis specialists, upon review of study and medical records. Crude prevalence rates and prevalence rates age-adjusted to reflect the 2001 Tamil Nadu census population were calculated. Results Crude and age-adjusted prevalence rates for endogenous uveitis were 310/100 000 and 317/100 000. The corresponding rates for all ocular inflammation were 450 and 467/100 000. Males tended to have a greater prevalence than females in this population, and older persons tended to have higher prevalence than younger persons. The majority of cases of posterior uveitis and infectious endophthalmitis were visually compromised, but few among the cases of other forms of ocular inflammation were visually impaired. Conclusions The results suggest that nearly one in 200 persons in rural, South India has been affected by ocular inflammation in at least one eye by mid to late adulthood, about one in 330 if cases related to surgery or trauma are not included. Postsurgical endophthalmitis and posterior uveitis were associated with a high rate of vision loss. These results indicate that uveitis is an important cause of ocular morbidity and of vision loss in this population.

The utility of relative afferent pupillary defect as a screening tool for glaucoma: prospective examination of a large population-based study in a south Indian population

Background Previous authors have suggested that an afferent pupillary defect (APD) may serve as an effective screening tool for some specific eye diseases, especially glaucomatous optic neuropathy, since the disease usually presents asymmetrically. Its success as a screening tool for glaucoma has never been previously prospectively evaluated in a large population. Methods In this study, the authors carry out assessments for the presence of APD as it relates to the diagnosis of glaucoma in an existing population-based eye study in southern India. The authors calculate the sensitivity and specificity for APD, both at the level of a village/household screening and in a more comprehensive/hospital setting, as it pertains to its ability to predict glaucomatous optic neuropathy. Results and discussion The authors find that APD assessed via the swinging flashlight test is a poor screening tool for glaucoma in this setting.

Managing Cataract and Glaucoma in the Developing World – Manual Small Incision Cataract Surgery (MSICS) Combined with Trabeculectomy

There is a strong interrelation between surgical management of glaucoma and cataract. Performing cataract surgery alone can lower the intraocular pressure, by about 4–6 mmHg. Glaucoma and cataract are diseases whose prevalence increases with advancing age. People living in developing countries have the highest risk of developing blindness from glaucoma.1 Angle-closure glaucoma predominates in some parts of East Asia, whereas in most of the Indian subcontinent, Africa, and in Hispanic populations, open angle forms are more common.2 Treatments for glaucoma vary depending on the type of glaucoma and the setting. Glaucoma filtration surgery also has a higher risk of inducing operable cataracts, especially with the addition of antimetabolites such as mitomycin C or if shallow anterior chamber or persistent choroidal detachments occur.3 Patients usually perceive the benefits of cataract surgery, through increased vision, leading to improved quality of life. The advent of small incision cataract surgery and intraocular lens implantation has greatly increased patients’ satisfaction with surgical interventions. In contradistinction, most perceive a worsening of their well-being after glaucoma surgery due to invariable loss of a few lines of visual acuity. In a developed nation, this concept may be difficult to convey to a patient. In a developing nation, the magnitude of this negative social marketing may increase manyfold and even convince an entire village not to come for routine eye care. Individuals may perceive that the doctors are diminishing good vision rather than preserving vision. Thus balancing the benefits of glaucoma surgery against the risk of cataract formation is dependent on the socioeconomic background in which glaucoma occurs.

Enzymatic sclerostomy pilot human study

OBJECTIVE To evaluate the feasibility and safety of enzymatic sclerostomy as a new modality to lower intraocular pressure in patients with open-angle glaucoma. METHODS This single-center, prospective, noncomparative, interventional case series included 15 blind symptomatic eyes of 15 patients with primary open-angle glaucoma. Enzymatic sclerostomy was performed with the patient under topical or peribulbar anesthesia. A specially designed polymethylmethacrylate enzyme applicator filled with a mean +/- SD of 123 +/- 13 microg of collagenase was introduced through a 5-mm peritomy, and affixed to the limbus by means of cyanoacrylate tissue glue. After 22 to 24 hours, the applicators were removed and the patients were followed up for 1 year. Intraocular pressure changes from baseline and complications related to the procedure were the main outcome measures. RESULTS Controlled thinning of the treated sclera associated with aqueous percolation and shallow filtration bleb was seen in all eyes in the immediate postoperative period. The mean +/- SD intraocular pressure decreased from 43.5 +/- 9.8 mm Hg (while the patients were receiving a mean +/- SD of 1.75 +/- 0.75 antiglaucoma medications) preoperatively to 24.8 +/- 10.6 mm Hg (a 43.0% decrease from baseline with no antiglaucoma medication) on the first postoperative day and to 34.8 +/- 10.5 mm Hg (a 20.0% decrease from baseline with no antiglaucoma medication) at the end of 1 year. Ophthalmic adverse effects were limited to the treated area and included immediate postoperative transient conjunctival reaction ranging from mild chemosis to conjunctival maceration. Immediate full-thickness perforation developed in 1 eye; the patient was treated and excluded from data analysis. Two eyes developed symptoms related to increase in intraocular pressure after 9 months; the patients were treated and excluded from further data analysis. No systemic complications were noted. CONCLUSIONS Enzymatic sclerostomy demonstrated immediate and sustained intraocular pressure reduction and provided symptomatic relief in blind eyes with primary open-angle glaucoma. The procedure, however, needs further technical refinement.