Diabetes and diabetes-related complications are on the rise. India and China are global leaders having the highest number of people with Diabetes Mellitus (DM). Diabetes, a multisystem disease, can affect small blood vessels (eye, kidney and nerves) and larger blood vessels in the body (heart and brain).
Diabetes can cause vision loss and blindness affecting various parts of the eye. Studies say Diabetic Retinopathy (DR) could potentially be an epidemic in India in future, given the increasing number of diabetics, especially in urban areas. The Diabetes Atlas, 2015, published by the International Diabetes Federation said that 8.7% Indians — around seven crore — are diabetic. The number is expected to go up to 12 crore by 2040.
As per data from various epidemiological and screening programmes, the proportion of diabetic eye diseases in people with DM include refractive errors in 60% (needing power glasses), cataract in 40%, glaucoma 5% and Diabetic Retinopathy (DR) affecting small vessels of retina in 20%. LVPEI being a tertiary referral centre, about 70% of OPD patients are those suffering from DR. And out of all DR patients, 30-40% have irreversible vision loss.
The leading cause of blindness in India is cataract. But it is reversible. However, in DR, after a certain stage, vision loss cannot be reversed. DR also does not show symptoms in the early stages, which means many — including those diagnosed with diabetes — are unaware that they even have it. About 18-20% of diabetics get DR.
Diabetic Retinopathy affects retina through various stages of severity. It can also affect macula, the central part of the retina with highest visual sensitivity responsible for reading and writing vision. Most common cause of visual loss due to DR occurs when there is fluid accumulation at the macula called Diabetic Macular Edema (DME).
Other diabetic eye diseases include extra ocular muscle palsies causing diplopia, ischemic optic neuropathies and retinal vascular occlusions. Diabetic Retinopathy is one of the leading causes of vision loss in people with diabetes, especially the working age group.
Hypertension, smoking or chewing tobacco, cholesterol abnormalities, kidney problems and anaemia worsen DR. Thus, the morbidity and treatment costs of DR results in significant economic burden to the society. Blindness and visual impairment related to DR also has significant impact on the quality of life of people with diabetes.
The three important numbers to remember in the management of DR are:
• Hba1c (Glycosylated Haemoglobin) level should be ≤ 7 gm%. Hba1c levels help us to know the three months control of diabetes. It also has an advantage as its estimation is not influenced by food intake
• Blood pressure levels should be at ≤ 130/80 mm of Hg
• Serum lipid levels should be normal
Regular eye examination is mandatory. In the initial stage, patients don’t experience any symptoms. By the time they realise there is a problem, irreversible damage is already caused. This can lead to significant psychological and economic burden on the individual and family. Hence, it is very important that all diabetic patients undergo annual eye check-up comprising detailed retinal screening with fundus examination once a year.
Screening for DR is essential at the time of diagnosis in people with type 2 diabetes and at five years after diagnosis of type 1 diabetes. Type 1 diabetes, or juvenile diabetes, affects people less than 30 years of age. DR screening is also important in gestational diabetes (during pregnancy) in the first trimester.
Regular physical activity in the form of brisk walking, yoga and cessation of smoking do have a positive influence in preventing progression of DR. However, one with severe form of DR should be cautious in performing vigorous exercises, such as heavy breathing exercises, lifting heavy weights etc, which can increase pressure on the tiny fragile new blood vessels causing significant vitreous bleeding, thus impairing vision.
The physician should be the first point of contact for people with diabetes. About 90% of DR (early stage) needs management by physician in the form of good diabetes-hypertension control and lipid level regulation. Only 10% of DR (sight threatening) requires referral to an ophthalmologist. Hence, visual acuity examination and fundus imaging (portable fundus camera) should be part of the examination protocol.
(The writer is Consultant, Smt Kanuri Santhamma Centre for Vitreoretinal Diseases, L V Prasad Eye Institute, Hyderabad)