Macular hypotrophy after internal limiting membrane removal for diabetic macular edema

To compare the anatomic and functional effects of three different approaches to nontractional diabetic macular edema.

Retrospective comparative study. Sixty eyes of 60 patients diagnosed with cystoid diabetic macular edema and treated with 1.25 mg/mL intravitreal bevacizumab (Group A), laser photocoagulation (Group B), or vitrectomy with inner limiting membrane peeling (Group C) were included in the study. Changes in number of Early Treatment Diabetic Retinopathy Study letters, central macular thickness, largest diameter of the intraretinal cysts (IC), and choroidal thickness were investigated. Analyses were performed during follow-up visits at Months 1, 3, 6, 9, and 12.

Visual acuity only significantly improved in Group A at the last follow-up (P = 0.004). Central macular thickness significantly decreased in every group throughout the follow-up period. Differences in central macular thickness between Groups A and B (P < 0.01), A and C (P < 0.01), and B and C (P < 0.01) were significant. Intraretinal cysts also significantly decreased in each group throughout the follow-up period. Differences in IC size between Groups A and B (P = 0.8), A and C (P = 0.1), and B and C (P = 0.1) were not significant. Choroidal thickness did not undergo any significant change in any group throughout the follow-up period. A significant correlation was also found in Group A between best-corrected visual acuity at month 12 and baseline central macular thickness (R = 0.3; P = 0.006), and in Group B between postoperative best-corrected visual acuity at month 12 and baseline IC size (R = 0.8; P < 0.01, negatively correlated at 92.4%).

According to our retrospective data, diabetic macular edema with intraretinal cysts larger than 390 μm should not be treated with vitrectomy with ILM peeling, because this may induce subfoveal atrophy, defined as the "Floor Effect," and subsequent visual deterioration.