Cataract surgery has a significantly higher incidence rate and is typically done at an earlier age in patients with diabetes compared with the general population; however, the procedure doesn’t come without potential complications. Recent research has shown that cataract surgery increases the risk of postoperative diabetic macular edema (DME) and proliferative diabetic retinopathy (PDR) in patients with diabetes. The study also discovered that there are different hazards for developing each condition.

The team set out to identify parameters that can predict the risk for progression of retinopathy to a vision-threatening stage following cataract surgery. Of the 2,797 diabetic patients included in the analysis, 2,540 (98%) had undergone cataract surgery for at least one eye by age 90. They found that the risk of DME was highest for patients in the first five years after surgery, but that it steadily reduced in subsequent years until the risk became stable after the 20-year mark. 

During those first five years, risk correlated with variability in HBa1c and systolic blood pressure; from five to 20 years, with cumulative exposure to HBa1c; above 20 years, with cumulative exposure to the diastolic blood pressure.

As for PDR, the risk of postoperative development increases in patients after five years by increasing variability of HBa1c, body mass index, later calendar year for the onset of diabetes and for females. 

“The risk for developing both types of vision-threatening diabetic retinopathy was higher during the first years, after which it decreased,” the researchers explained. “This change in the risk over time was confirmed by the finding that the studied covariate contributed differently to the risk for developing vision-threatening diabetic retinopathy at different follow-up times.” They also compared the finding that increased preoperative variability of HBa1c increased the risk for developing DME within the first five postoperative years to one from another study that shows the risk for developing postoperative macular edema is increased in patients with poor metabolic control. 

Patients with diabetes may benefit from tighter blood sugar control to minimize their risk of developing DME or PDR following cataract surgery. You should also consider monitoring patients even more closely in the first five postoperative years when their risk of developing a sight-threatening condition runs the highest. The authors conclude by noting that other than similarities in the impact of HBa1c, “the other parameters contributed differently to the development of DME and PDR and support that the two complications should be regarded as separate late complications.”

Bek T, Tilma K, laCour M. The risk for developing vision-threatening retinopathy after cataract surgery in diabetic patients depends on the postoperative follow-up time. Acta Ophthalmol. August 2, 2021. [Epub ahead of print].