Medical Compass: Strategies to save your vision

Diabetes complications can include permanent vision loss

By David Dunaief, M.D.

Diabetic retinopathy (DR) is the leading cause of blindness among U.S. adults, ages 20 to 74 years old (1). As the name implies, it’s a follow-on to diabetes, and it occurs when the blood vessels that feed the light-sensitive tissue at the back of your eye become damaged. It can progress to blurred vision and blindness, typically affecting both eyes.

As of 2023, only about 66 percent of adults with diabetes had a recommended annual eye screening (2). Why is this important? Because the earlier you catch it, the more likely you will be able to prevent or limit permanent vision loss with treatments that target its early stages.

A consequence of DR can be diabetic macular edema (DME) (3). With DME, swelling of the macula, which is an oval spot in the central portion of the retina, can cause significant vision loss. Those with the longest duration of diabetes have the greatest risk for DME.

Unfortunately, the symptoms of vision loss often don’t occur until the later stages of the disorder, after it’s too late to reverse the damage.

How do you treat diabetic macular edema?

DME treatments often include eye injections of anti-VEGF medications, either alone or alongside laser treatments. They work by inhibiting overproduction of a protein called vascular endothelial growth factor (VEGF) (4). These can slow the progression of DME or reverse it (4).

The results from a randomized controlled trial showed that eye injections with ranibizumab (Lucentis) in conjunction with laser treatments, whether laser treatments were given promptly or delayed for at least 24 weeks, were effective in treating DME (5).

Other treatments can include NSAID and/or steroid drops that attempt to reduce swelling of the macula.

Can you reduce DME risk by treating diabetes?

Unfortunately, medications that treat type 2 diabetes do not lower your risk of DME. The THIN trial, a retrospective study, found that a class of diabetes drugs, thiazolidinediones, which includes Avandia and Actos, actually increased the occurrence of DME compared to those who did not use these oral medications (6). Those receiving these drugs had a 1.3 percent incidence of DME at year one, whereas those who did not had a 0.2 percent incidence. This persisted through the 10 years of follow-up. In addition to DME occurrence, the FDA warns of other significant side effects from these drugs.

To make matters worse, of the 103,000 diabetes patients reviewed, those who received both thiazolidinediones and insulin had an even greater incidence of DME. It was unclear whether the findings were caused by the drugs or by the severity of the diabetes, itself.

This contradicts a previous ACCORD eye sub-study, a cross-sectional analysis, which did not show an association between thiazolidinediones and DME (7). This study involved review of 3,473 participants who had photographs taken of the fundus (the back of the eye).

What does this ultimately mean? Both studies had weaknesses. It was not clear how long the patients had been using the thiazolidinediones in either study or whether their sugars were controlled and to what degree. The researchers were also unable to control for all other possible confounding factors (8). There are additional studies underway to clarify these results.

Can glucose control and diet                   change the equation?

The risk of progression of DR was significantly lower with intensive blood sugar controls using medications, one of the few positive highlights of the ACCORD trial (9). Unfortunately, medication-induced intensive blood sugar control also resulted in increased mortality and no significant change in cardiovascular events. However, an inference can be made: a nutrient-dense, plant-based diet that intensively controls blood sugar is likely to decrease the risk of diabetic retinopathy and further vision complications (10, 11).

If you have diabetes, the best way to avoid DR and DME is to maintain effective control of your sugars. It is also crucial that you have a yearly eye exam by an ophthalmologist. This will help detect issues early, before permanent vision loss occurs. If you are taking the oral diabetes class thiazolidinediones, this is especially important.

References:

(1) cdc.gov. (2) odphp.health.gov. (3) mayoclinic.org. (4) Community Eye Health. 2014; 27(87): 44–46. (5) ASRS. Presented 2014 Aug. 11. (6) Arch Intern Med. 2012;172:1005-1011. (7) Arch Ophthalmol. 2010 March;128:312-318. (8) Arch Intern Med. 2012;172:1011-1013. (9) www.nei.nih.gov. (10) OJPM. 2012;2:364-371. (11) Am J Clin Nutr. 2009;89:1588S-1596S.

Dr. David Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, visit www.medicalcompassmd.com or consult your personal physician.