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Diabetes and cataract: All eyes on sugar control

Diabetes and cataract: All eyes on sugar control

People with diabetes are at greater risk of developing cataracts. However, they can safely undergo cataract surgery, provided their sugar levels are in check, say experts

People with diabetes are at greater risk of developing cataract early

Uncontrolled diabetes can lead to early onset of cataract, say experts. Several articles report that people with diabetes are five times more likely to develop cataracts earlier than usual

“The lens in the eye is usually a clear structure,” explains Dr Tejal SJ, consultant, cataract and refractive services work, Narayana Nethralaya, Bangalore. “As one becomes older, it gets opaque. The light does not pass through the lens to the retina. So, the vision gets blurred. The lens turning opaque is called cataract.” Uncontrolled diabetes can lead to the early onset of cataract.

A 2019 article in the World Journal of Diabetes (added the link) reports that people with diabetes are five times more likely to develop cataracts earlier than usual. Experts say people with uncontrolled diabetes can have complications after the cataract surgery as well.

Why does diabetes cause cataract?

Cataract is an age-related condition. Dr Tejal informs that while it usually occurs at the age of 50 to 55 years, a person with diabetes can develop it even a decade earlier. It depends on their sugar control. Dr Pramod V Satya, diabetologist and consultant – internal medicine, Manipal Hospital, Millers Road, Bangalore, says it usually starts with vascular complications. “Diabetes increases the sugar levels inside the blood vessels. So, we first find changes in retinal blood vessels, which we call diabetic retinopathy. The risk of cataract also increases with it,” he says.

Diabetes can cause cataracts through different mechanisms. He explains, “If one has diabetes, the glucose gets converted into sorbitol, which accumulates in the lens. It draws water and swells up the lens. While the lens is normally transparent and clear, its swelling results in loss of transparency, causing cataract.” Dr Tejal adds oxidative stress can also cause swelling of the lens fiber, increasing the chances of cataracts.

Symptoms of cataract

The initial symptoms include a decrease in vision, noticing multiple halos around lights and difficulty in driving due to glare in the night. If it is a long-standing condition where the vision is drastically reduced, one can also develop cataract-related complications, causing pain and redness in the eye.

There are different types of cataracts. “But with diabetes, usually the cataract is sticky in nature. It is usually nuclear sclerosis (where the lens becomes cloudy) associated with a posterior subcapsular cataract (when the area near the back of the lens is opacified) or calcified anterior capsule (opacity beneath the part which acts as a barrier, separating the lens from infectious viruses and bacteria),” she says.

Diabetes and cataract surgery: Is it safe?

The only treatment for a cataract is surgery, where the opaque lens is replaced with an artificial lens to improve the vision.

Experts say it is safe for people with diabetes to undergo cataract surgery, provided their sugar levels are in check. “Long-term and short-term complications of diabetes are monitored to consider if a person is fit to undergo the surgery. Short-term complications include the blood sugar levels in the HbA1c test, and both fasting and postprandial (after a meal). The three-month average should be less than seven percent and the fasting and postprandial sugars should be within normal limits. Long-term complications like issues with blood vessels of the kidney, nerves and eyes and macrovascular complications in blood vessels of heart and brain are also checked,” says Dr Satya.

Diabetic cataract surgery complications

Like any other surgery, cataract surgery can have complications for people with diabetes. Dr Satya highlights that if the sugar is not well controlled, it can very rarely lead to endophthalmitis (eye infection). Other common complications include delayed wound healing, corneal edema (increase in thickness of the cornea) and retinal issues.

Dr Tejal adds, “One can also develop macular edema (swelling in a part of the retina), leading to a decrease in vision post-surgery. They can also develop posterior capsular opacification (secondary cataract). So, they will require another laser treatment to improve their vision.”

Diabetes and cataract surgery recovery

In people with uncontrolled sugar levels, recovery from cataract surgery is usually delayed. Dr Satya says most people with diabetic cataracts will also have some type of diabetic retinopathy. “Both are different conditions, but if the vision is severely affected due to diabetic retinopathy, merely changing the lens may not improve the vision,” he says.

Dr Tejal adds once the retina gets affected, the vision starts to deteriorate faster. “Thus, it is crucial to have annual eye checkups and get the retina evaluated regularly,” she says.

Dos and don’ts after surgery

  • Use eyedrops as per a doctor’s advice.
  • Take diabetes medications as per a doctor’s advice.
  • Keep sugar levels under control.
  • Make sure water doesn’t enter the eye for a few days.
  • Shower carefully, ensure soap or chemicals do not enter the eyes.
  • Ensure regular eye checkups.
  • Get any retina issues treated as they can reduce vision further.

For six weeks after the cataract surgery, people are prescribed eyedrops as a precaution. However, Dr Tejal adds, “But all drops are not given for six weeks. We taper the medicines after few days and prescribe them for better healing of the eye.”

She adds if proper care is taken, a person with diabetes can recover in a week. But a two-week gap is maintained before operating on the other eye.

Ways to delay cataract when one has diabetes

  • Keep sugar levels under control
  • Follow a healthy diet
  • Ensure no diabetes complications are setting in
  • Ensure regular eye checkups
  • Get retina issues treated, if any, as it can reduce vision further


  • People with diabetes are five times more likely to develop cataracts at an earlier age if the sugar level is not under control.
  • Diabetes can lead to swelling of the lens, causing loss of its transparency and cataract.
  • It is safe for people with diabetes to undergo cataract surgery if their blood sugar levels are under control.
  • The surgery can sometimes lead to complications like eye infection, delayed wound healing and retinal issues.
  • Maintaining sugar levels under control and ensuring no diabetes complications are setting in are the best ways to postpone cataracts.

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