To evaluate the integrity of outer retina layers after resolution of central involved diabetic macular edema (DME) and to demonstrate the effect of various baseline factors for the final vision and final external limiting membrane (ELM) integrity.
Fifty-nine eyes of 48 patients with resolved DME were included. Several optical coherence tomography parameters including central subfield thickness, maximum foveal thickness, foveal center point thickness, and the extent of the ellipsoidal (ISe) layer and ELM damage were assessed at the time of DME and after resolution of DME. Eyes having laser scars near the fovea were excluded. Final visual acuity was classified as good (Snellen≥20/40, logarithm of the minimum angle of resolution ≤0.3) or impaired (Snellen <20/40, logarithm of the minimum angle of resolution >0.3) for the logistic regression analysis. Zero Inflated Poison Regression model was used to find the best predictors for post-treatment ELM damage.
External limiting membrane and inner segment ellipsoidal band layers were disrupted in 16 eyes (27.2%) and 21 eyes (35.5%) at the final visit, respectively. Baseline ELM damage (p=0.001), baseline impaired vision (p= 0.013), and the most recent glycosylated hemoglobin level (p=0.018) were the best set of parameters for having impaired final visual acuity. Baseline vision, severity of diabetic retinopathy, absence of intravitreal injection, central subfield thickness, and history of extrafoveal macular laser (not within 1 mm of fovea) (p<0.001, for all parameters) were independent predictors for the final ELM damage.
Outer retinal layers may be damaged even after complete resolution of DME, where inner segment ellipsoidal band layer damage appeared to be more common than ELM damage. Poorly controlled diabetic patients with damaged ELM and worse vision at the time of DME were more likely to have ELM damage and subsequent impaired vision after complete resolution of DME.