Scope of glaucoma in India

Chandra Garudadri, Harsha Rao

Burden of glaucoma

India is a vast country with over a billion people. Based on the results of the population-based studies conducted in different parts of India till now,^1-5 George et al.⁶ reported the burden of glaucoma in India to be 11.2 million. Of these, primary open-angle glaucoma (POAG) was estimated to be 6.48 million and primary angle-closure glaucoma (PACG) was 2.54 million. If we include primary angle closure (PAC) along with PACG, with the idea of estimating the number of people with primary angle closure disease (PACD) that require treatment, the number is 6.6 million, similar to that of POAG.⁶ There are an additional 21 million primary angle closure suspects (PACS), for whom the need for treatment is controversial. The burden of glaucoma blindness in India is 1.1 million. Bilateral blindness due to PACG on an average was reported to be two times that due to POAG.⁶ It is possible that PACG has a more severe disease course than POAG. However, the progression rates in treated POAG and PACG patients were found to be similar.⁷

The clinical course and severity of primary glaucoma is not uniform across populations. PACD in India is different from that seen in other parts of South-east Asia. It tends to have a more chronic course and acute angle closures are relatively rare.⁸ Studies have reported a higher prevalence of primary glaucoma in urban as compared to rural population.^3-5 With the increased association between urbanization and risk for chronic life style diseases like diabetes mellitus, hypertension and cardiovascular disease,^9-11 it would be interesting to study if glaucoma too is a similar lifestyle disease.

Challenges in glaucoma detection and treatment

The challenges in glaucoma diagnosis include missed diagnosis, overdiagnosis and wrong diagnosis. Population-based studies have reported that close to 90% of glaucoma in the community is undetected. The Aravind Comprehensive Eye Survey has reported that 50% of those diagnosed to have POAG in their study had seen an ophthalmologist in the past and less than 20% of them were detected to have disease.² The Chennai Glaucoma Study has reported that close to 40% (2/5) diagnosed as POAG in their urban cohort were actually PACG.⁴ Lack of comprehensive eye examination and preponderance of cataract centric practices are largely responsible for this scenario. In a survey conducted among the delegates attending the annual conference of the Glaucoma Society of India, it was found that 40% of them continue to depend on Schiotz or non-contact tonometer for IOP evaluation. And only 45% of them performed IOP measurement, gonioscopy and optic disc examination routinely in all their patients. Close to 70% of the country's population reside in villages. There are obvious differences in the availability and access to health care between the urban and rural parts of the country. While the people in the cities have access to the latest technologies, there is no care available in the rural areas. The Eye Health Pyramid of LV Prasad Eye Institute with its village vision complex system is a potential model to address this issue of access to affordable comprehensive eye care in rural India.¹² In the cities where the recent imaging technologies are available, there is a tendency for over-diagnosis. The possible reasons for over-diagnosis are using the results of these technologies in isolation and not in the context of the complete clinical picture¹³ and absence of robust Indian normative data base for these technologies.¹⁴ Cost considerations dictate the choice of glaucoma management in India. There is widespread availability of low-cost anti-glaucoma generic medications. The efficacy of generic equivalents has been reported to be inferior to that of the standard brands in one study, and there is a need for further evaluation of this issue.¹⁵ The safety and efficacy of large-area MMC application in trabeculectomy has been demonstrated.¹⁶ There is an argument for primary surgery as the cost of medications and access to care preclude medical therapy with regular follow up in a large number of patients. The risk benefit ratio of therapy would work in favor of the patient only if the disease diagnosis is on unequivocal signs of disc damage and field loss and not with the use of IOP alone (especially done with Schiotz or non-contact tonometry) and/or imaging technologies in isolation, without comprehensive examination. Overall, the diverse socio-economic conditions and suboptimal comprehensive clinical examination skills and practice patterns pose challenges to detection and management of glaucoma in India.