The unseen comorbidity of diabetes

Diabetes is the most prevalent cause of blindness in working-age individuals. However, 64 percent of Malaysians are not aware that diabetes can lead to eye problems. On the other hand, heart disease, kidney disease, and amputations are some of the health issues that come to mind when diabetes is mentioned.

“One-in-five Malaysians are diabetic, which equals an estimated 4.6 million Malaysians, and diabetic eye disease affects one-in-three diabetics. From this figure, a third will experience vision-threatening eye disease, suggesting that 500,000 Malaysians have vision-threatening diabetic eye disease,” said Dr Peh Khaik Kee, a consultant ophthalmologist and vitreoretinal surgeon.

Peh noted that diabetic retinopathy has reached epidemic levels because Malaysia spends 16 percent of its national healthcare budget on diabetes, ranking it among the top 10 countries in the world for this expenditure. “A large part of this issue is due to poor awareness. Many people with diabetes do not undergo regular eye exams to check for signs of the condition. Diabetic retinopathy does not present with any particular symptoms and does not cause loss of vision until very late. Therefore, there are a large number of patients presenting at a severe stage. That is where the importance of screening comes in."

Diabetes has several effects on the eye, including changes to the lens that cause blurry vision, increased eye pressure that causes glaucoma, damage to the nerves that control the eye muscles that causes double vision, and damage to the blood vessels in the retina that causes diabetic retinopathy, the most prevalent eye condition connected to diabetes.

Until recently, a slit-lamp microscope was used as part of a routine eye examination to detect diabetic retinopathy. First, dilating drops are used to widen the pupils, and it takes some time for the drops to work so that the retina can be seen clearly. This allowed the retina to be illuminated and the macula and each segment of the retina to be inspected. This entails looking at a bright light for up to 5 minutes per eye, which can be extremely painful, especially if the patient is already sensitive to light. After the exam, patients may experience blurred vision for up to 4 hours.

Peh said: “There have been many new developments in our ability to examine the eye more effectively and accurately, and at the same time, make the experience much more comfortable for patients. These days, we have ultra-widefield fundus cameras that can capture a single, 150-degree field view of the retina—three times more field view than a standard camera.” Ophthalmologists may now review the photos digitally and manipulate them to acquire a clearer and brighter image, enabling them to make better and more accurate diagnoses. In addition, patients can view the photographs and gain a better grasp of their situation, facilitating consultation on their progress and treatment options.

Screening and treatment are key
With routine screening and early management, vision loss is virtually entirely avoidable, said Peh. Citing the UK as an example, he noted diabetes is no longer the leading cause of blindness among working adults there as of 2014, thanks to the formal implementation of diabetic eye screening in 2009.

Depending on its severity, diabetic retinopathy is treated with laser therapy, injections, and surgery. There are effective injections for diabetic retinopathy in its early stages, but patients must endure this procedure intensively. Patients would receive these injections once every 4 or 8 weeks for at least three years, depending on the type of drug. "I would argue that injections work better than laser therapy. Although laser therapy reduces the risk of vision loss by 50 percent, injections provide a 50 percent chance of gaining more than three lines of vision. However, lately we have been doing a combination of laser therapy and injections, which have seen good response,” said Peh.

There are also new, less invasive surgical techniques and instruments with improved outcomes. Today, surgery can be a preemptive step that offers a huge leap forward in overtaking the disease. Diabetes-related retinopathy is a debilitating condition, but it is preventable through less invasive procedures that result in improved outcomes.

“About 20 percent of patients will progress despite adequate treatment. This is because their diabetes is not under control; hence, I need to work closely with our diabetes physicians to manage our patients effectively,” Peh said. The eyes are nonregenerative organs, unlike the liver, and once vision is lost, it cannot be restored. Consequently, early detection of potentially vision-threatening eye diseases can prevent irreversible vision loss.