Six-year incidence of visually significant age-related cataract: the Chennai eye disease incidence study.

BACKGROUND: The aim of this study is to report the 6-year incidence of age-related cataract in a population-based study. DESIGN: The design used is a population-based cohort study. PARTICIPANTS: A cohort of 2484 phakic subjects, aged 40 years and above at baseline, from a south Indian population was included in the study. METHODS: Bilateral phakics with visual acuity of 6/12 or better and cataract less than N2, C2 and P2 on the Lens Opacities Classification System II at baseline were included. Subjects with glaucoma and corneal or retinal diseases were excluded. Incident visually significant cataract was defined as visual acuity of less than 6/18 with a corresponding one grade or greater change in Lens Opacities Classification System II or history of having undergone cataract surgery with evidence of pseudophakia or aphakia at the 6-year follow-up. MAIN OUTCOME MEASURES: Six-year incidence of visually significant cataract and associated risk factors data were collected. RESULTS: Incident visually significant cataract at 6 years was seen in 158 subjects (6.36%, 95% CI: 5.40-7.32, phakics:pseudophakics/aphakics 70:88). Incidence was higher in the rural cohort as compared with the urban cohort (P < 0.001). Incidence increased with age and was highest in the ≥70 years age group (odds ratio (OR):31.23, 95% CI: 15.20-64.16, P < 0.001). Other associated risk factors included illiteracy (OR 1.75, 95% CI: 1.17-2.61, P = 0.007) and smoking (OR 1.77, 95% CI: 1.08-2.88, P = 0.02). CONCLUSIONS: A significant proportion of the population developed visually significant age-related cataract at 6 years. Incident visually significant cataract was significantly greater for the rural cohort between 50 and 69 years old.

Six-year incidence of ocular hypertension in a South Indian population: the Chennai eye disease incidence study.

AIMS: To report the 6-year incidence and risk factors for ocular hypertension (OHT) in a population-based study in southern India. METHODS: 6 years after baseline evaluation, 56.9% subjects (participants:non-participants, 4421:3353) were re-examined at the base hospital. Incident OHT was defined as an intraocular pressure above the 97.5th centile for the population with no evidence of glaucoma in the 2852 phakic subjects, 40 years or older. Subjects with trauma, laser or incisional surgery at baseline or follow-up were excluded (total exclusions: 1569). RESULTS: Incidence of OHT at 6 years was 62/2852 subjects (2.17% (95% CI 1.64% to 2.71%, men:women, 36:26)). Incidence was higher in the rural cohort as compared with the urban cohort (80.6% vs 19.4%, p<0.001). A higher baseline intraocular pressure (with increasing OR: 16-18 mm Hg (OR 4.0, 95% CI 2.1 to 7.9), 19-21 mm Hg (OR 11.4, 95% CI 5.7 to 22.9), 22-24 mm Hg (OR 42.6, 95% CI 11.0 to 164.8, in the urban cohort)) and increasing age (50-59 years (OR 1.9, 95% CI 1.1 to 3.3), 70 years and above (OR 3.6, 95% CI 1.2 to 10.6)) were significantly associated risk factors for incident OHT. CONCLUSIONS: A significant proportion of this normal population converted to OHT. A higher incidence of conversion was seen in the rural population.

Baseline risk factors for incidence of blindness in a South Indian population: the chennai eye disease incidence study.

PURPOSE: To report the baseline risk factors and causes for incident blindness. METHODS: Six years after the baseline study, 4419 subjects from the cohort underwent a detailed examination at the base hospital. Incident blindness was defined by World Health Organization criteria as visual acuity of less than 6/120 (3/60) and/or a visual field of less than 10° in the better-seeing eye at the 6-year follow-up, provided that the eye had a visual acuity of better than or equal to 6/120 (3/60) and visual field greater than 10° at baseline. For incident monocular blindness, both eyes should have visual acuity of more than 6/120 (3/60) at baseline and developed visual acuity of less than 6/120 (3/60) in one eye at 6-year follow-up. RESULTS: For incident blindness, 21 participants (0.48%, 95% confidence interval [CI], 0.3-0.7) became blind; significant baseline risk factors were increasing age (P = 0.001), smokeless tobacco use (P < 0.001), and no history of cataract surgery (P = 0.02). Incident monocular blindness was found in 132 participants (3.8%, 95% CI, 3.7-3.8); it was significantly more (P < 0.001) in the rural population (5.4%, 95% CI, 5.4-5.5) than in the urban population (1.9%, 95% CI, 1.8-1.9). Baseline risk factors (P < 0.001) were increasing age and rural residence, and no history of cataract surgery was a protective factor (P = 0.03). CONCLUSIONS: Increasing age was a significant risk factor for blindness and monocular blindness. No history of cataract surgery was a risk factor for blindness and a protective factor for monocular blindness.

Predictors for incidence of primary open-angle glaucoma in a South Indian population: the Chennai eye disease incidence study.

OBJECTIVE: To determine the 6-year incidence of primary open-angle glaucoma (POAG) and its associated predictors. DESIGN: Population-based cohort study. PARTICIPANTS: A total of 4316 subjects without POAG at baseline who were 40 years of age and older from a south Indian population. METHODS: Participants were examined at baseline and after a 6-year interval. Detailed ophthalmic examination included applanation tonometry, gonioscopy, pachymetry, optic disc evaluation, and automated perimetry. Glaucoma was defined using the International Society of Geographical and Epidemiological Ophthalmology Classification. Multivariable logistic regression was performed to identify the baseline risk factors that could predict the incident POAG. MAIN OUTCOME MEASURES: Six-year incidence of POAG and its associated risk factors. RESULTS: In 6 years, incident POAG developed in 129 subjects (2.9%; 95% confidence interval [CI], 2.4-3.4; male-to-female ratio, 65:64). Baseline age was a risk factor. In reference to the group 40 to 49 years of age, the incidence increased from 2.3 (95% CI, 1.4-3.7) for the group 50 to 59 years of age to 3.5 (95% CI, 2.2-5.7) for the group 60 to 69 years of age (P<0.001). Other baseline risk predictors were urban residence (odds ratio [OR], 1.6; 95% CI, 1.1-2.2; P = 0.01), higher intraocular pressure (IOP; OR, 2.0; 95% CI, 1.5-2.6 per 10 mmHg; P<0.001), myopia (OR, 1.7; 95%, CI, 1.1-2.5; P<0.001), and axial length (OR, 1.5; 95% CI, 1.0-2.2 per millimeter; P = 0.03). Thinner corneas with higher IOP at baseline had the highest incidence of POAG. In 80% of the urban population and 100% of the rural population, incident glaucoma was previously undetected. CONCLUSIONS: A significant proportion of this population demonstrated incident POAG. The baseline risk factors could help in identifying those at highest risk of disease.

Six-year incidence of angle-closure disease in a South Indian population: the Chennai Eye Disease Incidence Study.

PURPOSE: To estimate the 6-year incidence of primary angle-closure (PAC) disease among adult population aged 40 years and older from rural and urban south India. DESIGN: Population-based longitudinal study. METHODS: A complete ophthalmologic examination, including applanation tonometry, gonioscopy, biometry, stereoscopic fundus examination, and automated perimetry was performed at both baseline and at the 6-year follow up at base hospital. Incident PAC disease was defined as the development of PAC disease during the 6-year follow-up in phakic subjects without PAC disease at baseline. Diagnosis was made using the International Society Geographical and Epidemiological Ophthalmology classification. RESULTS: The data were analyzed for 3350 subjects (mean age, 56.4 ± 8.9 years; 1547 males, 1803 females) for a diagnosis of PAC disease at baseline and at follow-up examinations. The incidence of PAC disease was identified in 134 subjects (6-year incidence rate, 4.0%; 95% confidence interval (CI), 3.3-4.7). Among the 134 subjects, 88 subjects (2.6%, 95% CI, 2.1-3.2) were primary angle-closure suspects; 37 subjects (1.1%, 95% CI, 0.7-1.5) had primary angle closure, and 9 subjects (0.3%, 95% CI, 0.1-0.4) had primary angle-closure glaucoma. There was an inverse relationship between the incidence of PAC disease and the cataract surgery rates. Significant risk factors for PAC disease on logistic regressions were higher intraocular pressure, increased lens thickness, shorter axial length, shallow anterior chamber depth, anteriorly positioned lens, and hyperopia. CONCLUSIONS: The average incidence of PAC disease per year was 0.7%. All biometric parameters were found to be strong predictors for the incidence of PAC disease.

Perimetric severity in hospital-based and population-based glaucoma patients.

BACKGROUND: The aim was to compare the severity of glaucoma among newly diagnosed patients presenting to a hospital-based glaucoma care centre (HBGS: Sankara Nethralaya, Medical Research Foundation) with that of age matched subjects from the population-based Chennai Glaucoma Follow-up Study (CGFS). METHODS: Newly diagnosed subjects with primary glaucoma from HBGS and age- and gender-matched subjects from the urban arm of CGFS examined during the same time period were included. All subjects underwent comprehensive ocular examinations including Humphrey visual field (HVF: 24-2 SITA Standard). Glaucoma was defined as: an intraocular pressure (IOP) of 22 or greater mmHg in either eye; vertical cup-to-disc ratio (VCDR) of 0.7 or greater or asymmetry 0.2 or more or the presence of focal thinning, notching or a splinter haemorrhage. All subjects had a minimum of three follow-up visits and reliable visual fields. The IOP, vertical cup-to-disc ratio, mean deviation (MD) and pattern standard deviation (PSD) of the Humphrey field measurements at the third follow-up visit of CGFS were compared for assessing the severity of glaucoma with the HBGS group. RESULTS: Forty-seven age-matched subjects from both the study populations were selected. Significantly higher (p = 0.04) IOP was noted in the HBGS population than the CGFS, with a difference in mean IOP of 2.80 mmHg (95% CI of diff: 0.14 to 5.46). The mean ± SD of the mean deviation and pattern standard deviation were -6.92 ± 6.53 dB and 6.05 ± 4.20 dB among the HBGS and -4.47 ± 4.19 dB and 3.26 ± 2.69 dB among the CGFS population, respectively, the difference in the mean deviation (p = 0.036) and pattern standard deviation (p = 0.0001) were statistically significant. The mean vertical cup-to-disc ratio did not vary between populations (p = 0.14). CONCLUSION: Patients from the HBGS group had higher IOP and more severe visual field defects than the CGFS group. Hence, results from hospital-based studies on severity and the rates of progression should be interpreted with caution.