Year : 2010 | Volume
: 58 | Issue : 3 | Page : 243--245
The Chennai glaucoma study: Prevalence and risk factors for glaucoma in cataract operated eyes in urban Chennai
Ronnie George, Hemamalini Arvind, M Baskaran, S Ve Ramesh, Prema Raju, Lingam Vijaya
Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India
Medical Research Foundation, Sankara Nethralaya, 18, College Road, Chennai - 600 006
We report the prevalence and risk factors for glaucoma among aphakes and pseudophakes in 3850 subjects who participated in a population-based study in urban south India. The subjects underwent an ophthalmic examination including applanation tonometry, gonioscopy, optic disc evaluation and frequency doubling perimetry. Glaucoma was diagnosed using the International Society of Geographical and Epidemiological Ophthalmology (ISGEO) criteria. Thirty eight, 15 aphakes and 23 pseudophakes (0.99% of 3850 subjects) of the 406 persons who had undergone cataract surgery were diagnosed with glaucoma. Aphakes/pseudophakes were at higher risk of glaucoma as compared to the phakic population (Odds Ratio: 2.71, 95% CI: 1. 94, 3.38, p=0.001). On multivariate analysis, older age and higher intra ocular pressure were risk factors for glaucoma. Blindness attributable to glaucoma was detected in 20% of aphakic and 4.3% of pseudophakic eyes. Glaucoma was a significant cause of morbidity in those who had undergone cataract surgery in this urban population.
|How to cite this article:|
George R, Arvind H, Baskaran M, Ramesh S V, Raju P, Vijaya L. The Chennai glaucoma study: Prevalence and risk factors for glaucoma in cataract operated eyes in urban Chennai.Indian J Ophthalmol 2010;58:243-245
|How to cite this URL:|
George R, Arvind H, Baskaran M, Ramesh S V, Raju P, Vijaya L. The Chennai glaucoma study: Prevalence and risk factors for glaucoma in cataract operated eyes in urban Chennai. Indian J Ophthalmol [serial online] 2010 [cited 2023 Feb 3 ];58:243-245
Available from: https://www.ijo.in/text.asp?2010/58/3/243/62655
Glaucoma is responsible for significant ocular morbidity in India. Primary glaucoma accounts for 2/3 rds of the morbidity.  A significant proportion of those who had undergone cataract surgery from the rural cohort of the Chennai glaucoma study had glaucoma. 
Since rural India is comparatively underserved in terms of both availability and the quality of ophthalmic care it is possible that the reported rate of aphakic and pseudophakic glaucoma is an exaggeration.  We report the prevalence and risk factors for glaucoma in aphakia and pseudophakia, among the urban population of the Chennai glaucoma study.
Materials and Methods
The Chennai glaucoma study is a population-based study designed to report the prevalence of glaucoma in South India. The methodology has been described in detail elsewhere.  This study was approved by the Institutional Ethics Review Board and performed in accordance with the tenets of the Declaration of Helsinki for research; written informed consent was obtained from all participants.
All subjects underwent a comprehensive eye examination including slit lamp examination, Goldman applanation tonometry, gonioscopy, dilated fundus examination, optic disc examination using a 78 diopter (D) lens. Automated visual fields were performed for all the subjects with best corrected visual acuity of 4/16 or better, using frequency doubling perimetry (FDP; Carl Zeiss Meditec, Inc. Dublin, CA). All eligible subjects underwent C-20-1 screening, and the N-30 threshold test. 
A provisional diagnosis of suspected glaucoma was made if: intra ocular pressure (IOP) ≥ 21 mm Hg in either eye; vertical cup disc ratio (VCDR) ≥ 0.7 or a cup disc ratio (CDR) asymmetry ≥ 0.2; and focal thinning, notching, or a splinter hemorrhage. All these subjects were advised threshold visual field testing using the Swedish interactive threshold algorithm (SITA) standard 30-2 program (Humphrey Field Analyser model 750; Carl Zeiss Meditec).
Glaucoma was defined based on the International Society of Geographical and Epidemiologic Ophthalmology (ISGEO) classification.  Blindness was defined as a best corrected visual acuity of 0 from fixation, in the better eye.
Age, gender, IOP, peripheral anterior synechiae (PAS) ≥ 180°;, pseudoexfoliation (PXF), diabetes,  hypertension  and duration from surgery were included to assess risk for glaucoma using both univariate and multivariate analysis (adjusted for age and gender). Significance was assessed at the p 
Aphakia/pseudophakia was seen in 406 persons (10.54% of the entire population; age and gender adjusted prevalence 10.16%; 95% CI: 9.57-11.50%). Rural adjusted prevalence was 9.77% (95% CI: 8.84-10.69%). In the urban population, 49 (12.09%, 95% CI: 8.9, 15.24%) were diagnosed to have glaucoma, 11 were excluded from the analysis because they were considered to have primary glaucoma. Thirty eight of the 3850 persons examined (0.99%, 95%CI: 0.68, 1.30%) were diagnosed with glaucoma post cataract surgery. Those who had undergone surgery were significantly older (pp  This is higher than that reported in most other studies. , except the Zulu population among whom the rates of aphakic glaucoma were higher (33%) 
From an etiologic perspective, glaucoma in aphakes/pseudophakes could be either - pre-existing, developed de novo or secondary to surgical trauma. We have tried to exclude primary glaucoma by excluding those with glaucoma in the phakic fellow eye. Preexisting glaucoma could remain undiagnosed if an inadequate preoperative evaluation was performed. Thirty nine per cent of the phakic subjects with glaucoma in this urban population had significant cataract. If the healthcare system could detect these cases when they present for cataract surgery it would dramatically improve the detection rates for glaucoma in the population (current detection rates are 7.8% for primary glaucoma in this urban cohort  and 1% for the rural sample).
From our results it appears that the availability of better eye care facilities in an urban population does not necessarily translate into lower rates of post cataract surgery glaucoma, even though the visual outcomes of surgery in the urban cohort were better than in the rural cohort.  For many people in the country the only point of contact with the eye care system is when they seek or are "screened" for cataract surgery. Inadequate or inappropriate examination at this time is a lost opportunity to detect and treat other non cataract ocular pathology.
Our findings that nearly 10% of the population aged 40 years and older, who had undergone cataract surgery, had glaucoma, highlight the need for a comprehensive evaluation pre cataract surgery and improved quality of cataract surgery. In addition, with increasing life expectancy those undergoing cataract surgery would be at risk of developing glaucoma with time and should be encouraged to continue to undergo periodic eye examinations.
|1||Vijaya L, George R, Baskaran M, Arvind H, Raju P, Ramesh SV, et al. Prevalence of primary open-angle glaucoma in an urban south Indian population and comparison with a rural population. The Chennai Glaucoma Study. Ophthalmology 2008;115:648-54.|
|2||Arvind H, George R, Raju P, Ramesh SV, Baskaran M, Paul PG, et al. Glaucoma in aphakia and pseudophakia in the Chennai Glaucoma Study. Br J Ophthalmol 2005;89:699-703.|
|3||Murthy G, Gupta SK, John N, Vashist P. Current status of cataract blindness and Vision 2020: the right to sight initiative in India. Indian J Ophthalmol 2008;56:489-94.|
|4||Arvind H, Paul PG, Raju P, Baskaran M, George R, Balu S, et al. Methods and design of the Chennai Glaucoma Study. Ophthalmic Epidemiol 2003;10:337-48.|
|5||Foster PJ, Buhrmann R, Quigley HA, Johnson GJ. The definition and classification of glaucoma in prevalence surveys. Br J Ophthalmol 2002;86:238-42.|
|6||Lamb EJ, Day AP. New diagnostic criteria for diabetes mellitus: are we any further forward? Ann Clin Biochem 2000;37:588 - 92.|
|7||Bharucha NE, Kuruvilla T. Hypertension in the Parsi community of Bombay: A study on prevalence, awareness and compliance to treatment. BMC Public Health 2003;3:1.|
|8||Rotchford AP, Johnson GJ. Glaucoma in Zulus: a population-based cross-sectional survey in a rural district in South Africa. Arch Ophthalmol 2002;120:471-8.|
|9||Weih LM, Nanjan M, McCarty CA, Taylor HR. Prevalence and predictors of open-angle glaucoma: results from the visual impairment project. Ophthalmology 2001;108:1966-72. |
|10||Vijaya L, George R, Rashima A, Raju P, Arvind H, Baskaran M, et al. Outcomes of cataract surgery in a rural and urban south Indian population. Indian J Ophthalmol 2010;58:223-8.|