Abstract
Purpose: :
To assess the incidence or progression of macular edema (ME) after cataract surgery in diabetics using optical coherence tomography (OCT) and correlating this with degree of diabetic retinopathy or other known risk factors prior to surgery.
Methods: :
Study participants consisted of a consecutive cohort of diabetic patients scheduled for routine cataract surgery. Each study eye underwent 7–field fundus photography no more than 3 months prior to surgery and OCT testing no more than 4 weeks prior to surgery. OCT testing was repeated at the month 1 and month 3 post–operative visits. Best–corrected visual acuity was recorded at the time of those visits. ME was defined as an increase of center point thickness greater than 30% from pre–operative baseline.
Results: :
A total of 50 study eyes of 41 study subjects completed 1 month follow–up (98% completion) and 49 study eyes completed 3 month follow–up (96% completion). The incidence of ME was 22% (95% CI 13% to 35%). The average increase in foveal thickness at 1 month for eyes with ME was 202 µm, which resulted in nearly 1 line loss of vision (0.07 logMAR units). Eyes without ME gained more than 2 lines of vision (0.24 logMAR units). This difference of 3 lines (P < 0.001) remained so at the month 3 exam. Eyes with no diabetic retinopathy at baseline developed minimal thickening of 18 µm and 14 µm at 1 and 3 months, respectively, which resulted in improvement of 2 and almost 3 lines of vision, respectively (0.22 and 0.26 logMAR units). Eyes with moderate, severe nonproliferative, or proliferative diabetic retinopathy developed severe thickening of 145 µm and 131 µm at 1 and 3 months, respectively, which resulted in less than 1 and 2 lines of improved vision, respectively (0.08 and 0.17 logMAR units). This difference in thickening (P = 0.05) at 1 and 3 months (127 µm and 117 µm) was inversely correlated with visual improvement (r = –0.662). Both duration of diabetes of 10 years or greater (P = 0.04) and insulin–dependence (P = 0.007) were associated with reduced visual improvement. Eyes with a history of focal laser for ME (resolved on pre–operative OCT) treated with intra–operative corticosteroid injections enjoyed decreased thickening and improved vision when compared to non–treated eyes.
Conclusions: :
Diabetics have a high incidence of increasing center point thickness as detected on OCT after cataract surgery, which was associated with a loss of vision at 1 month and limited visual recovery at 3 months. There was a strong correlation between development of center point thickening and some baseline characteristics. Treatment to prevent this might improve outcomes after surgery.
Keywords: macula/fovea • diabetic retinopathy • imaging/image analysis: clinical