Usha (name changed), 62, was experiencing sudden and painless loss of vision in the right eye for one day when she turned up at the out-patient department. On examination, vitreous haemorrhage, bleeding inside the vitreous - the space in the eye filled with a gel-like fluid, was noted in the right eye, leading to the sudden loss of vision. “Upon examination, we came to know that she is a known case of type-2 diabetes for the past 15 years. The patient has been on medication, but her blood sugar levels were not well-controlled. After completing the examination, it was concluded that the vitreous haemorrhage in the right eye was a complication of her long-standing, uncontrolled blood sugar levels,” said Dr Rahul P Vijayakumar, specialist in ophthalmology at Aster Medcity, Kochi.
The patient was also presented with severe diabetic retinal changes, including proliferative diabetic retinopathy in the left eye. However, the patient denied ever having been screened for eye changes. “She was aware that diabetes could affect the eyes but had never sought to check for it. Further examination revealed a significant reduction in vision in the left eye as well,” he added.
The right eye was managed surgically, and the retina of both eyes was treated with a laser. The left eye also showed significant diabetic macular oedema, for which intravitreal injections were administered. As a result, a significant amount of her vision was salvaged. According to Dr Rahul, the number of people who are affected by eye diseases following uncontrolled diabetes is high.
“In people with diabetes, who often go blind from diabetic retinopathy, there is a higher chance of developing glaucoma and vascular blocks. Also, diabetic people may experience cataracts 10 years earlier than usual. So controlling diabetes and conducting eye screening can help the patients in multiple ways,” said Dr Gopal S Pillai, clinical professor and head of department of ophthalmology at Amrita Hospital, Kochi. He added that it can also cause a sudden loss of vision due to reduced blood flow to the optic nerves of the eyes.
According to a study published in 2021, ‘Prevalence of diabetic retinopathy in India: Results from the National Survey 2015-19,’ diabetic retinopathy (DR) is an important cause of visual impairment among persons with diabetes. “The prevalence of diabetes is higher in urban areas (11.2%) than in rural areas (5.2%), but diabetic retinopathy does not show this variation. DR accounted for 1.07% of blindness and 1.25% of moderate to severe visual impairment (MSVI) in 2015,” stated the study.
Controlling diabetes
Diabetes mellitus can lead to several ocular complications such as diabetic retinopathy, diabetic papillopathy, glaucoma, cataracts, and ocular surface diseases. “Vision loss diabetes mellitus can be caused by capillary non-perfusion, diabetic macular oedema (DME), vitreous haemorrhage, tractional retinal detachment and neovascular glaucoma,” said Dr Rahul.
Diabetic retinopathy, Dr Gopal added, is a slow progressive disease. “The patients may not notice the disease many times even in the late stages of the condition, and almost always, the first 10-15 years in any patient with diabetic retinopathy is completely asymptomatic. By the time we diagnose the condition, it might have moved through mild, moderate, and severe stages to reach proliferative stage causing vision loss. In this late stage, proliferative diabetic retinopathy, new blood vessels grow in the retina and can bleed into the eye or detach the retina causing sudden severe vision loss,” he emphasized.
“According to research, people with diabetes have a higher risk of developing primary open-angle glaucoma (POAG), a condition usually seen in people in the 60s and 70s. Cataract is a condition that usually affects elderly people. A person with uncontrolled diabetes may be affected by the disease in his or her 40s and 50s; the incidence rate is four times more in diabetes patients,” said Dr Susheela B Nair, senior consultant in ophthalmology at KIMS Health, Thiruvananthapuram. Diabetic papillopathy too is seen in type 1 and 2 diabetes mellitus in rare cases.
Regular screening
Diabetes patients should undergo eye screening at least once a year, according to Dr Nice Rose, chief ophthalmologist at Allen and Habour, Kottayam. “The changes in the eye may occur over a period of time - in 5-10 years. If the changes are identified as soon as possible, the progression of the condition can be prevented, and permanent vision loss can be prevented,” she said.
“Regular screening in diabetic patients can help in identifying the stage of the disease. When treatment is started at the right time, we can retain good vision in 80-85% of people. Also, early detection of complications by regular screening can prevent loss of vision in patients,” added Dr Gopal.
Every patient should undergo an eye check-up at the time of detecting diabetes. “If found normal, they can continue with diabetes treatment. If any changes are noticed in the eye, treatment should be started,” said Dr Susheela, adding that several people tend to drop treatment and checkups.
Impact on eye health
People with diabetes can experience frequent fluctuations in their refractive status (eye-focusing ability) depending on fluctuations in their blood glucose levels. “In addition to diabetic retinopathy, they may experience both myopic and hyperopic (long sight) shifts - blurry vision. That is why doctors prescribe lenses to patients only after the glucose levels are normal,” said Dr Nice, adding that diabetes is recognised for delayed wound healing, which means injuries to the eye, especially cornea, may take longer to heal. “After several years, treatment will also be difficult in the advanced stages of diabetes,” she said.