Purpose
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.
Methods
Fifty-nine eyes of 48 patients with resolved DME were included. Several optical coherence tomography parameters including central subfield thickness (CST), 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, logMAR ≤0.3) or impaired (Snellen <20/40, logMAR>0.3) for the logistic regression analysis. Zero Inflated Poison Regression model was used to find the best predictors for post treatment ELM damage.
Results
External limiting membrane and ISe layers were disrupted in 16 (27.2%) eyes and 21 (35.5%) eyes at the final visit, respectively. Baseline ELM damage (p=0.001), baseline impaired vision (p= 0.013) and the most recent HbA1c 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, CST and history of extra-foveal macular laser (not within 1 mm of fovea) (p<0.001, for all parameters) were independent predictors for the final ELM damage.
Conclusion
Outer retinal layers may be damaged even after complete resolution of DME, where ISe 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.