Shankar Khanal

A Population-based Survey of the Prevalence and Types of Glaucoma in Nepal: The Bhaktapur Glaucoma Study

OBJECTIVE To determine the prevalence and types of glaucoma in a Nepalese population. DESIGN Cross-sectional, population-based survey. PARTICIPANTS A total of 4800 subjects aged 40 years or older from the Bhaktapur district of Kathmandu valley. METHODS Subjects aged 40 years or older were selected using a cluster sampling procedure and door-to-door enumeration for a population-based, cross-sectional study. All subjects underwent a detailed ocular examination at the base hospital, which included logarithm of minimal angle of resolution visual acuity, refraction, applanation tonometry, gonioscopy, Lens Opacities Classification System II cataract grading, retinal examination, and Swedish Interactive Thresholding Algorithm standard perimetry when indicated. MAIN OUTCOME MEASURES Diagnosis of glaucoma was based on criteria described by the International Society for Geographic and Epidemiological Ophthalmology. RESULTS A total of 4003 subjects underwent a comprehensive eye examination (response rate 83.4%), and complete data were available in 3991 subjects. The mean intraocular pressure was 13.3 mmHg (97.5th and 99.5th percentiles, 18 and 20 mmHg, respectively), and the mean vertical cup-to-disc ratio was 0.26 (97.5th and 99.5th percentiles, 0.6 and 0.8 mmHg, respectively). There were 75 subjects with glaucoma, an age- and sex-standardized prevalence of 1.80 (95% confidence interval [CI], 1.68-1.92). Age- and sex-standardized prevalence was 1.24% (95% CI, 1.14-1.34) for primary open-angle glaucoma (POAG), 0.39% (95% CI, 0.34-0.45) for primary angle-closure glaucoma (PACG), and 0.15% (95% CI, 0.07-0.36) for secondary glaucoma. The prevalence of glaucoma increased with an increase in age with no significant difference in gender. Primary angle-closure glaucoma was 3 times more common in women. Nine eyes were blind, and 2 subjects were bilaterally blind from glaucoma. CONCLUSIONS The overall prevalence of glaucoma was 1.9%. Of all glaucoma cases, POAG accounted for 68%, PACG accounted for 22.67%, and secondary glaucoma accounted for 9.33%. Among the subjects with POAG, 96.08% had not been previously diagnosed.

Comparison of axial lengths in occludable angle and angle-closure glaucoma-The Bhaktapur Glaucoma Study

Purpose. To compare the anterior chamber depth (ACD) and axial length of eyes in a population-based sample among normal, occludable angle, and primary angle-closure glaucoma (PACG) groups. Methods. Totally, 3979 subjects from a population-based glaucoma prevalence study underwent complete ocular examination including four mirror gonioscopy. An angle in which >270 degrees of the posterior trabecular meshwork could not be seen was considered occludable. PACG was considered when there were features of primary angle closure (eye with an occludable angle, peripheral anterior synechiae, increased intraocular pressure, iris whorling, lens opacities, or excessive pigment deposition on the trabecular surface) and optic disc with glaucomatous damage. A handheld ultrasonic biometer was used to measure the ACD and the axial length of subjects. The ACD and axial length were measured on all subjects with occludable angles (n = 86), PACG (n = 17) and a random subgroup of normal subjects (n = 685). The measurements were compared among the groups and statistically analyzed using independent t-test, one-way analysis of variance, &khgr;2 test, and logistic regression. Results. The mean age among occludable angle and angle-closure glaucoma groups was 59.64 ± 9.70 and 71.23 ± 8.5 years, respectively, which was significantly higher (p < 0.001) than the mean of 54.03 ± 10.90 years among normal subjects. In the occludable angle group, the ACD (2.55 ± 0.69) was significantly different (p < 0.001) than the normal group (2.85 ± 0.39). The axial length (22.08 ± 0.83) in the occludable angle group was also considerably different (p < 0.001) when compared with the normal group (22.62 ± 0.90). In PACG group, the ACD and axial length were 2.48 ± 0.22 and 22.02 ± 0.59, respectively. The risk of having an occludable angle decreased with per unit millimeter increase in ACD (odds ratio, 0.24; 95% confidence intervals, 0.12–0.50) and axial length (odds ratio, 0.49; 95% confidence intervals, 0.36–0.67) after adjusting the effect of age and sex. Conclusions. The eyes in Nepalese population with occludable angle and angle-closure glaucoma appear to have significantly shallower anterior chambers and shorter axial lengths when compared with the normal group.

Central Corneal Thickness and Intraocular Pressure in a Nepalese Population: The Bhaktapur Glaucoma Study

PurposeThe purpose of the study was to evaluate the characteristics of central corneal thickness and its association with age, sex, and intraocular pressure in a Nepalese population. Patients and MethodsThe study design was a cross-sectional, population-based survey. Two thousand three hundred thirty patients aged 40 years and older were examined at Tilganga Institute of Ophthalmology, a tertiary referral eye centre in Kathmandu, Nepal. All patients underwent a complete ophthalmic examination that included measurements of central corneal thickness with an ultrasonic pachymeter and intraocular pressure with a Goldman type applanation tonometer. ResultsThe main outcome measures were central corneal thickness and intraocular pressure. Mean age of the 2330 patients examined was 51.3 years (SD±9.56). The mean central corneal thickness and mean intraocular pressure was 539.10 &mgr;m (SD±33.73) and 13.33 mm Hg (SD±2.26), respectively. Central corneal thickness showed an average decrease of 2.67 &mgr;m (95% confidence interval, 2.21-4.1) per decade increase in age. A 100 &mgr;m increase in central corneal thickness was associated with a 1.03 mm Hg (95% confidence interval, 0.79-1.26) increase in intraocular pressure after adjusting for age and sex. ConclusionsThe changes in central corneal thickness values cause a significant variation in intraocular pressure in this population, suggesting that measurement of central corneal thickness will have implications in the diagnosis and management of glaucoma.

Outcomes of cataract surgery: a population-based developing world study in the Bhaktapur district, Nepal.

Background:  To evaluate the visual outcome after cataract surgery in a population of Nepal.

Effect of phacoemulsification surgery on various parameters in patients with glaucoma.

BACKGROUND Cataract and glaucoma are both common conditions and are often present in the same patient. The incidence of these diseases increases with age. Besides vision impairment, these diseases are associated with decrement in quality of life (QOL). OBJECTIVE To study the effect of phacoemulsification surgery on various parameters in patients with glaucoma. MATERIALS AND METHODS We enrolled 50 eyes of 36 patients with glaucoma and concomitant cataract scheduled for phacoemulsification cataract surgery . A record was made which included number of anti-glaucoma medications, visual acuity (VA), intra-ocular pressure (IOP), anterior chamber depth (ACD), cataract category/grade, visual field (VF) analysis (mean deviation (MD) and pattern standard deviation (PSD) and responses to Indian visual function questionnaires (IND-VFQ). The patients were re-evaluated at one month after cataract extraction and the above parameters were again obtained to compare them with the firs values. RESULTS The mean age of the patients was 66.34 yrs ± 7.96; 10 eyes (20 %) had angle closure and 40 (80 %) had open angle glaucoma. Following cataract extraction, VA improved, IOP decreased, number of glaucoma medications decreased and AC depth increased. The VF analysis showed that the improvement in MD was significant while changes in PSD were not. The improvements seen in the visual function questionnaires (VFQ) were significant. When these parameters were analyzed based on the types of glaucoma, in the angle closure glaucoma (ACG) group, the decrease of IOP from 15.30 ± 6.18 to 12.70 ± 2.71 was not significant ( p = 0.24). In the open angle glaucoma (OAG) group, the changes in the number of anti-glaucoma medication were not significant. When the parameters were analyzed in subgroups, based on cataract category, nuclear sclerosis and posterior sub-capsular, the VA improved significantly in both and the MD improved in the posterior sub-capsular surgery. Improvement in VFQs was observed in denser nuclear sclerotic and posterior subcapsular cataracts. CONCLUSION Cataract extraction results in significant improvement in vision, IOP reduction, decrease in the number of medications, deepening of AC and in the quality of life in patients with co-existing glaucoma when the cataract is of significant density.

Prevalence of and risk factors for age-related macular degeneration in Nepal: the Bhaktapur Retina Study

Aim This study aimed to explore the prevalence of and risk factors for age-related macular degeneration (AMD) in an elderly population in Nepal. Subjects and methods This is a population-based, cross-sectional study. A sample size of 2,100 was calculated. A total of 1,860 (88.6%) subjects aged >60 years were enrolled for the study from 30 clusters in the district. Detailed history, visual acuity, and anterior segment and posterior segment examinations were performed. AMD was graded according to the International ARM Epidemiological Study Group. Results Among the total study population, 659 subjects had any AMD (35.43%; 95% confidence interval [CI]: 33.25–37.65), 484 had mild dry AMD (26.02%; 95% CI: 24.04–28.08), 143 had intermediate dry AMD (7.69%; 95% CI: 6.52–8.99), 19 had geographic atrophy (1.02%; 95% CI: 0.61–1.59), and 13 had wet AMD (0.70%; 95% CI: 0.37–1.19). The overall prevalence of early and late AMD was 33.71% and 1.72%, respectively. Among subjects with dry and wet AMD, 36.53% and 46.1% had visual impairment, while 2.78% and 23.08% were blind, respectively. In multivariate analysis, AMD was significantly higher in subjects with an increased number of cigarettes smoked per day (odds ratio [OR] 1.02, 95% CI: 1.01–1.04; P=0.007) and in subjects with pseudophakia (OR 1.45, 95% CI: 1.12–1.87; P=0.005). Conclusion One-third of the population aged ≥60 years have some form of AMD. There was a significant association with the number of cigarettes consumed and with previous cataract surgery.

Results of the Bhaktapur Glaucoma Study, Nepal

INTRODUCTION The Bhaktapur Glaucoma Study is a population-based, cross-sectional and longitudinal study undertaken in one of the districts of Nepal. OBJECTIVES To determine the prevalence of glaucoma in Bhaktapur district, Nepal. MATERIALS AND METHODS Thirty clusters were randomly selected and a door-to-door census was conducted to identify citizens 40 years of age and older. Four thousand eight hundred individuals fulfilling the eligibility criteria were referred to the base hospital in Kathmandu for a detailed clinical examination. The diagnosis of glaucoma was based upon criteria described by the International Society for Geographic and Epidemiological Ophthalmology (ISGEO). RESULTS Complete data was available on 3991 subjects (response rate 83.15 %). The mean IOP was 13.3 mm Hg (97.5th and 99.5th percentiles, 18 and 20 mm Hg, respectively) and mean VCDR 0.26 (97.5th and 99.5th percentiles, 0.6 and 0.8 mm Hg, respectively). Seventy-five subjects had glaucoma, an age-sex-standardized prevalence of 1.80 (95 % confidence interval (CI), 1.68 - 1.92). The age-and sex-standardized prevalence of POAG was 1.24 % (CI, 1.14 - 1.34), PACG 0.39 % (CI, 0.34 - 0.45) and secondary glaucoma 0.15 % (CI, 0.07-0.36). The prevalence of glaucoma increased with increase in age and there was no significant difference in gender. Nine eyes were blind and two subjects bilaterally blind from glaucoma. CONCLUSION The overall prevalence of glaucoma was 1.9 %. POAG was the most common form of glaucoma. Visual morbidity from PACG, however, was higher. A large majority of the subjects with POAG had not been previously diagnosed and had intraocular pressure within the normal range.

Prevalence and risk factors of diabetic retinopathy among an elderly population with diabetes in Nepal: the Bhaktapur Retina Study

Aim Diabetic retinopathy (DR) is an emerging cause of blindness in developing countries. This study aimed to explore the prevalence and risk factors of DR in an elderly population in Nepal. Subjects and methods This is a population-based, cross-sectional study. A total of 1860 subjects at the age 60 years and above participated (response rate 88.6%). A detailed history was obtained, presenting and best-corrected visual acuity were measured, and anterior segment and posterior segment examinations were carried out. Blood pressure and random blood sugar were recorded; body mass index was calculated, and abdominal girth was measured. DR was graded by clinical examination using Early Treatment Diabetic Retinopathy Study criteria. Results Diabetes was found in 168 (9%) subjects (mean age 69.6 years), 31 (18.5%) of whom were newly diagnosed. The prevalence of DR was 23.8% (95% confidence interval [CI]: 17.7%–31%) among the persons with diabetes. The prevalence of DR among newly diagnosed subjects with diabetes was 6.5% (95% CI: 0.8%–21.4%). The prevalence of vision-threatening DR was 9.5% (95% CI: 5.5%–15%) and was higher in males. The prevalence of DR was 83.3% (95% CI: 35.9%–99.6%) among those with diabetes for over 20 years. In multivariable logistic regression analysis, duration of diabetes, hypertension, and alcohol consumption were significantly associated with DR. Conclusion DR is a common problem among the elderly population with diabetes in Nepal. The duration of diabetes, hypertension, and alcohol consumption are the risk factors for the development of DR. Strategies have to be developed for timely diagnosis of diabetes and screening for DR.