NEW YORK (Reuters Health) – Patients with type 2 diabetes without retinopathy can be safely screened for sight-threatening vision problems every 3 years instead of every 1 or 2 years, researchers from Sweden conclude based on a study they conducted.

Screening for diabetic retinopathy is “highly recommended, but opinions regarding optimal screening intervals differ,” Dr. Elisabet Agardh and Dr. Poya Tababat-Khani from the ophthalmology department, Skane University Hospital in Malmo, Lund University, note in the May 11 online issue of Diabetes Care.

In the United States, annual screening for diabetic retinopathy is recommended. In Sweden, screening every 2 years has long been the standard for patients with no retinopathy. Since 2006, however, Skane University Hospital has used 3-year screening intervals for this patient population and this interval appears to be safe.

As part of this 3-year screening program, 1,691 patients in their mid-50s with type 2 diabetes for about 6 years and no detectable retinopathy in 2 fundus photographs were scheduled for follow-up screening 3 years later.

Of the 1,322 patients available for follow-up, 960, or 73%, were still retinopathy-free 3 years later; 362 (28%) had developed mild or moderate retinopathy and none showed severe nonproliferative or proliferative retinopathy.

Three subjects had signs of macular edema, 2 in both eyes and 1 in 1 eye. Only 1 of those 5 eyes required laser treatment.

“Thus, sight-threatening retinopathy occurred in 5 of 2,644 eyes, or 0.19%, but affected visual acuity in only 1 eye (0.04%),” Dr. Agardh and Dr. Tababat-Khani report.

These findings indicate that it is safe to extend the screening interval to 3 years in patients with type 2 diabetes and no retinopathy at the initial screen.

They note, however, that the patients in the cohort had mild diabetes of short duration and their metabolic control was good. To reduce the risk of dropout, patients were given screening reminders well in advance of their scheduled follow-up visit, which led to good compliance. With a 3-year screening interval instead of shorter interval, patients might be more prone to disregard their follow-up screening appointment, they investigators note.

In 2010, Swedish National Board of Health and Welfare changed its general recommendation for screening intervals from 2 to 3 years in patients with type 2 diabetes and a low risk of progression from no retinopathy to sight-threatening retinopathy.

“The results of the current study support that advice, but it may be necessary to individualise the intervals for patients with severe diabetes.”

Diabetes Care 2011.