Macular thickness fluctuations and visual acuity outcomes after intravitreal dexamethasone implant for diabetic macular edema.

Abstract

Purpose: To assess macular thickness fluctuations and their association with visual acuity (VA) outcomes in eyes with diabetic macular edema (DME) treated with intravitreal dexamethasone (DEX) implant.

Methods: The standard deviation (SD) of all post-baseline central subfield thicknesses (CST) recorded over a 12-month period after the first injection of DEX implant was used to quantify CST fluctuations. Linear regression models were used to identify factors associated with the VA at 12 months (measured with the Early Treatment of Diabetic Retinopathy Study (ETDRS) score), and predictors of CST SD.

Results: A retrospective review of 80 eyes of 80 patients treated with DEX implant for DME revealed a CST SD of 75.3 ± 50.3 μm. The CST SD was negatively associated with the VA at 12 months (-7.7 EDTRS letters for each 100-µm increase in CST SD, p=0.01), while changes in CST from baseline did not show any significant association. Eyes were stratified into quartiles based on the CST SD and a difference by -14.2 letters in VA at 12 months was observed between the first and fourth quartiles (p <0.001). Significant predictors of CST SD included the baseline VA (-12.0 μm for each 10-letter increase, p=0.02), and the number of DEX injections received (n=17.1, p=0.03).

Conclusion: Greater fluctuations in retinal thickness were found to be associated with poorer visual outcomes in eyes with DME treated with DEX implant. Analyzing the CST SD could be a more predictive indicator of visual prognosis than individual measurements of the CST.