In this article I hope to acquaint readers with the prevailing status of diabetes and diabetic eye disease in India, still the world’s largest democracy. To do so, I will consider the current incidence of diabetes, its impact upon eye health, and where we are at present regarding screening, treatment and disease prevention.
Prevalence
Diabetes in India is a growing health concern, with over half the population at risk of developing the condition at some point of their lives. There are 77 million adults living with diabetes and, as per predictions, this figure is likely to increase to 140 million by 2045 (see figure 1).1 According to a survey conducted from 2015-19 at the All India Institute for Medical Sciences (AIIMS) based in New Delhi, undertaken as part of the National Programme for Control of Blindness & Visual Impairment, the prevalence of diabetic retinopathy amongst diabetics in India is 16.9%.2 Of these, 3.6% have sight-threatening diabetic retinopathy. So, the magnitude of the problem is huge. Added to this is a gross lack of awareness about getting the eyes examined for diabetic changes. As many as 89.9% of people with diabetes in India have never had their eyes examined for diabetic changes.3
People who live in cities and metropolitan areas are more likely now to develop diabetes than ever before. This is because of the promotion of a certain lifestyle that typically leads to an increase in a person’s body mass index (BMI). Rural areas, however, are also experiencing a surge in type 2 diabetes cases. As people develop a higher fat-to-muscle ratio, insulin is retained in the body for longer periods and the risk of diabetes grows. One likely contributor to this is the increasing popularity of the so-called Western diet, associated with greater consumption of fast foods, processed foods and higher levels of saturated fat. Sugary drinks and sweetened foods are also responsible for increasing people’s risk of developing obesity and type 2 diabetes.
People in middle-income groups are suffering from economic stress; lower income; fewer savings for dowry; price inflation and so on. This has a negative impact on both diet and lifestyle and represents a further risk factor for diabetes.
Eye health
The major causes of blindness in India include uncorrected refractive errors, cataract, glaucoma, age-related macular degeneration, diabetic retinopathy and childhood blindness among others.
In recent years, several initiatives have led to better control of some eye disease, such as cataract. However, other conditions, like diabetic retinopathy, glaucoma and macular degeneration, have shown an increased incidence. And the major problem associated with these non-communicable eye diseases (NCEDs) is that, unlike cataract, they are not so easy to treat, with no single surgical procedure likely to be able to restore near normal vision. An improvement in the standard of living has led to an increase in the life expectancy of people, with the likelihood of increase in NCED.4
One sad factor is that tall claims by the manufacturers of ayurvedic (herbal) medicines about a ‘permanent cure’ of diabetes (as well as other diseases like hypertension, stress, insomnia, cholesterol, cough, cold, asthma and arthritis) appear to be constantly luring a large number of innocent followers away from proper treatment and, thus, putting their eyes and vision at the risk of complications. There are many cases where this has led to blindness (figure 2).
Figure 2b: Claim in an advertisement from an established ayurvedic medicine manufacturer published in a leading newspaper
Figure 2a: Advertisement for Ayurvedic Medicines for Diseases from Times of India dated March 2, 2022.
Eye disease impact
Diabetes is a chronic disease that results due to a defect in insulin secretion by the pancreas. While Type 1 diabetes occurs due to decreased quantity of insulin, Type 2 diabetes happens when the body’s response to insulin is compromised.
Sight loss can result from a number of causes, including diabetic retinopathy (leading to haemorrhaging, ischaemic damage and tractional detachment), maculopathy, cataract, open and closed angle glaucoma, muscle palsies and reduced resistance to traumatic or infectious insult.
Diabetic retinopathy (DR), a complication of diabetes, affects or damages retinal blood vessels, and can lead to blindness if left untreated (figure 3). The sad part is that, even those patients who suffer from long-standing diabetes with blood sugar levels well controlled show some form of diabetic retinopathy inevitably occurring over time. The high levels of sight loss also relate to the high number of undiagnosed diabetics. While diabetes affects 69.2 million people, more that 36 million people remain undiagnosed, and the number of diabetes cases is estimated to rise to 109 million by 2035, which increases the risk of the eye disease and blindness. Available estimates show that six to 12 million diabetic patients in India have some form of sight-threatening retinopathy.
Figure 3: A (left) Diabetic retinopathy and B (right) maculopathy are a major cause of sight loss in India
Lack of awareness about DR, delays in follow-up in treatments, self-monitoring of diabetes, shortage of human resources, and gaps in collaboration between physicians and ophthalmologists, result in complicating the situation.
People with diabetes may be twice as likely to develop cataracts as those without diabetes (figure 4), and the insidious onset of cataract might hinder any awareness of the underlying metabolic disease. Cataract surgery in people with diabetes can have poorer outcomes.
Figure 4: Cataract is more likely with diabetes and might be less easy to treat because of the underlying disease
Glaucoma in people with diabetes is more common and its likelihood increases with increasing age, just as in the general population. In most instances, the condition is bilateral, and open-angle glaucoma is more common than angle-closure glaucoma (figure 5). A relatively high proportion of people age 40 years and above in India have one or both conditions and this must be borne in mind while screening for diabetic retinopathy or examining people with diabetes and/or glaucoma.5
Screening
In 1976, the National Programme for Control of Blindness (NPCB) was launched by the Government of India, its aim to reduce the incidence of blindness. Furthermore, with the announcement of the National Health Policy of India in 1983, emerging diseases such as diabetic retinopathy, glaucoma, retinopathy of prematurity and others causing blindness were recognised.
In recent years, the Ministry of Health and Family Welfare (MOHFW) has set up a National Task Force on diabetic retinopathy for the first time. Their aim is to implement a diabetic retinopathy programme at the grass roots level. In 2014, the Queen Elizabeth Diamond Jubilee Trust provided funds for prevention, screening and treatment for diabetic retinopathy in India, along with other countries such as Bangladesh, Pakistan and at-risk countries in the Pacific and the Caribbean.
Figure 5: Diabetics have a risk of developing either (a, left) open-angle or (b, right) closed-angle glaucoma, or both5
Stated aims of the DR screening programme include the following:2,6
- Screening for detecting DR should be undertaken for all people known to be diabetic.
- Screening should readily be integrated into the health system at different levels and in locations where people with diabetes are able to access services. This might be at a government-run hospital or a local physician’s clinic.
- Screening for DR should be undertaken at least annually for people with diabetes. More frequent examinations might be considered on a case-by-case basis depending on the presence and severity of DR. It is also emphasised that a person may have sight-threatening diabetic retinopathy (STDR) without any visual symptoms. This knowledge underlies the importance of regular examination.
- The gold standard for diagnosing and grading the severity of DR is stereoscopic fundus photography through dilated pupils, using guidelines established by the Early Treatment Diabetic Retinopathy Study (ETDRS) group.7
Retinal imaging, including non-mydriatic imaging system, has high validity in DR screening, However, in a country like India, the population distribution is too disparate, there is an unequitable distribution of health services, lack of awareness about diabetes among the general public is widespread, and there is a lack of adequate infrastructure and health resources.
In such a situation, telemedicine and use of a networked non-mydriatic fundus camera, has been successfully used to screen for DR.8 Smartphone usage (figure 6) has also been quite effective and has been validated for DR screening.9
The All India Ophthalmological Society diabetic retinopathy task force and the Vitreoretinal Society of India Consensus Statement have provided the guidelines for screening, referral, follow-up care and management of DR.
It is well recognised that reliable systems need to be used to communicate the results of screening to patients and expertise for the diagnosis and management of DR must be in place before screening is initiated. Likewise, screening for glaucoma needs to be included, by way of tonometry and fundoscopy (usually by direct ophthalmoscopy, preferably on dilated pupils) of every adult over 40 years of age.
Treatment
Management includes a range of options, including laser photocoagulation, anti-VEGF injection and intravitreal steroids.2 Likewise, the Queen Elizabeth Diamond Jubilee Trust has published guidelines on management of DR.10
There is high level evidence that laser pan-retinal photocoagulation (figure 7) for proliferative diabetic retinopathy (PDR) and severe non-proliferative diabetic retinopathy (NPDR) preserves vision. Repeated injections of Anti-VEGF agents can also be effective for PDR. Which treatment is recommended for any individual patient is influenced by several factors, but principal among these is a patient’s ability to comply with the frequent and long-term follow-up appointments required for Anti-VEGF agents. There is good evidence that vitrectomy is of benefit for vitreous haemorrhage, but less so for the other forms of advanced DR.
Alongside any direct treatment of the eyes, a set protocol should be in place incorporating the physician’s opinion regarding systemic control of such risks as hyperglycaemia, hypertension, hyperlipidaemia and nephropathy.
The problem faced in the treatment of glaucoma is daunting and any association with diabetes complicates the matter further. The rate of undiagnosed glaucoma cases in India is 90%, in contrast to 40% to 60% in the developed world. Most of these patients eventually present already either sight impaired or severely sight impaired from the disease.
Glaucoma awareness in both rural and urban communities is poor. Unfortunately, many low-cost generic drugs have flooded the market and their quality control is debatable. Generic drugs are often not as potent as the original formulations,4,10 but they are often the only hope for many poor patients.
Figure 6: Smartphone imaging has been validated for retinopathy screening (image courtesy Bill Harvey)
In India, there does seem to be a great need for underlining the importance of compliance, early treatment, and regular follow-up at glaucoma screening sessions. Even though trabeculectomy is still the gold standard for glaucoma management in India, there is a need to perform surgery in patients with advanced glaucomatous damage as soon as possible because of the poor compliance with other treatment options and the difficulty of long-term follow-up.11
Prevention
Vision impairment and blindness from DR and maculopathy will only increase unless systems and services are put in place to reduce the incidence of the diseases and to improve access to diagnosis and effective treatment.
The main risk factors for sight loss are:
- Duration of disease
- Poor control of glucose levels
- Hypertension12
It is imperative that people consider a healthier diet, undertake regular exercise, and take medication as advised. Up to 98% of blindness can be prevented by timely laser treatment and/or vitreous surgery.12
Final thought
To conclude, I can confirm that the increasing threat of diabetes-related blindness has prompted the development of India-specific evidence-based guidelines for the detection, treatment and prevention of diabetic retinopathy and maculopathy, and improved access for cataract surgery in patients with diabetes. It is essential that we apply these guidelines for a better tomorrow.
Figure 7: Pan-retinal photocoagulation for proliferative and severe non-proliferative diabetic retinopathy preserves vision
Acknowledgement
I would like to thank ophthalmologist Dr Maneesh Kumar of Ophthacare Eye Centre for his assistance with references.
- Dr Narendra Kumar, BAMS, DROpt, PGCR is Editor of Optometry Today and a clinician at Ophthacare Eye Centre, Janakpuri, New Delhi.
References
- International Diabetes Federation. IDF diabetes atlas; factsheet for South East Asia 2021. [accessed January 2022]. Downloadable factsheet PDF available from: https://diabetesatlas.org/regional-factsheets/
- Raman R, Ramasamy K, Rajalakshmi R, Sivaprasad S, Natarajan S. Diabetic retinopathy screening guidelines in India: All India Ophthalmological Society diabetic retinopathy task force and Vitreoretinal Society of India Consensus Statement. Indian Journal of Ophthalmology, 2021;69:678-88
- National diabetes and diabetic retinopathy survey 2015-2019. National Programme for Control of Blindness & Visual Impairment, Directorate General of Health Services, Ministry of Health & Family Welfare, Government of India, New Delhi
- Chatterjee D. Diabetic Retinopathy: an emerging eye disease in India. Geography and You, May 17, 2017
- Umesh C Behera, Harsha Bhattacharjee, Taraprasad Das, Clare Gilbert, G V S Murthy, R Rajalakshmi and Hira B Pant: Spectrum of Eye Disease in Diabetes (SPEED) in India: A prospective facility-based study. Report # 4. Glaucoma in people with type 2 diabetes mellitus. Indian Journal of Ophthalmology, 2020 Feb; 68 (Suppl 1): S32-S36
- Guidelines for the Prevention and Management of Diabetic Retinopathy and Diabetic Eye Diseases in India, version 1, June 2019. The Queen Elizabeth Diamond Jubilee Trust, London School of Hygiene & Tropical Medicine and Indian Institute of Public Health Hyderabad
- American Diabetes Association. Diabetic retinopathy. Diabetes Care 2000;23 (Suppl 1):S73‑6
- Gadkari SS. Diabetic retinopathy screening: Telemedicine, the way to go! Indian Journal of Ophthalmology, 2018;66:187‑8
- Rajalakshmi R, Arulmalar S, Usha M, Prathiba V, Kareemuddin KS, Anjana RM. Validation of smartphone based retinal photography for diabetic retinopathy screening. PLoS One 2015; 10:e0138285
- Guidelines for the Prevention and Management of Diabetic Retinopathy and Diabetic Eye Disease in India, 2019. The Queen Elizabeth Diamond Jubilee Trust, Indian Institute of Public Health, London School of Hygiene & Tropical Health
- Rengaraj Venkatesh and Krishnamurthy Palaniswami: Glaucoma care in India, GT Glaucoma Today, January/February 2013
- Clare Gilbert, Iris Gordon, Chandashi Rea Mukherjee and Vishal Govindhari: Guidelines for the prevention and management of diabetic retinopathy and diabetic eye disease in India, Indian Journal of Ophthalmology, February 2020, Volume 68-Issue suppl 1-p563-566