The prognostic role of optical coherence tomography in diabetic macular edema patients undergoing early dexamethasone implant shift

Abstract

Purpose: To determine the prognostic characteristics of optical coherence tomography (OCT) parameters by evaluating diabetic macular edema (DME) patients with early dexamethasone (DEX) shift after three doses of intravitreal ranibizumab (RNB) injection. Methods: Fifty-four eyes of 34 patients who had DEX implant after three doses of RNB were included in this retrospective study. Early DEX shift includes patients who received direct DEX implant replacement after three doses of RNB load. Baseline OCT values and factors affecting best corrected visual acuity (BCVA) and central macular thickness (CMT) response were analyzed with logistic regression analyses. Results: The presence of subretinal fluid and hyperreflective spot (HRS) >20 were found to be a negative predictive factor for anatomical response. (p=0.009, p=0.001, respectively) Low initial BCVA creates a positive effect on visual gain.( p=0.041) Giant outer nuclear layer cysts, completely disrupted inner segment-outer segment and HRS>20 have a negative effect on visual gain. (p=0.025, p=0.043, p=0.023, respectively) According to the receiver operating characteristic analysis, the subretinal fluid volume threshold at which >20% reduction in CMT occurs was determined to be 0.85mm3 . (sensitivity 70%, specificity 84% area under the curve 0.817, p=0.021). Conclusion: The presence of high number of HRS and high subretinal fluid volume at the baseline negatively affect prognosis even in patient groups with early DEX shift.