Vitrectomy for diabetic macular edema may be limited

The visual benefit of vitrectomy for patients with diabetic macular edema may be limited to those who exhibit signs of macular traction either clinically or on optical coherence tomography, according to a study.

S.P. Shah and colleagues in London prospectively studied 33 patients who underwent vitrectomy and inner limiting membrane peel for diabetic macular edema. The mean age of the patients was 65.4 years; 14 patients were women. Eighteen patients had a clinically normal attached posterior hyaloid (four had OCT signs suggestive of traction), six had a taut thickened posterior hyaloid, one had an epiretinal membrane with OCT signs of epiretinal traction, seven had posterior vitreous detachment but no OCT or clinical signs suggestive of traction, and one patient had a posterior vitreous detachment and clinically normal macular surface but undetermined OCT appearance.

Patients were followed for 1 year after surgery. OCT macular thickness was taken preop and at 1 year postop. Outcome measures included visual acuity and macular thickness.

On average, visual acuity deteriorated by 0.035 logMAR, but macular thickness significantly improved by a mean of 139 µm. Patients with evidence of clinical or OCT macular traction significantly improved logMAR acuity compared with patients without traction. Patients who exhibited a presence of subretinal fluid had worse postop results that could be predicted preop.

“The results in this study show 15% improving and 24% deteriorating by two or more ETDRS logMAR lines,” the authors said.

“Our findings suggest that the benefits of vitrectomy for chronic diabetic macular edema are limited to patients with clinical and/or OCT signs suggestive of traction. Macular detachment on OCT may additionally be an adverse predictive indicator,” they said.

The study is published in the January issue of British Journal of Ophthalmology.