Abstract
Purpose:
To determine if hard exudates (HE) secondary to diabetic macular edema (DME) promote persistence of edema and if resolving of HE proceeds differently depending on type of treatment (Ranibizumab (RBZ) vs. macular laser photocoagulation vs. combination therapy).
Methods:
Multimodal retinal images of eyes with DME were analyzed in a subanalysis of a prospective randomized phase III clinical trial (RESTORE CORE study). Patients were randomized into 3 arms to receive 0.5mg RBZ, 0.5mg RBZ+laser or laser alone. After an initial loading phase of 3 injections (RBZ or sham in laser alone arm) or 1x laser treatment (laser alone arm) at baseline (BL), patients were treated as needed according to their group assignment (RBZ and/or laser). Retinal thickness was assessed on optical coherence tomography (OCT) and amount and presence of HE on mydriatic 7-field ETDRS photos by the Vienna Reading Center. Results were correlated with best corrected visual acuity (BCVA) at BL and change in BCVA from BL to month 12.
Results:
A total of 312 eyes were included at BL of which 84.6% were available for analysis at month 12. Across groups 80.6%±0.1% of patients showed any HE present in the retina, 67.4%±0.1 showed HE within 1 disc diameter of the foveal center (DD) and 32.7%±0.03 showed HE affecting the foveal center at BL. HE minimally increased from BL to month 6 (RBZ: +5.5%; RBZ+laser: +7.4%) before decreasing from month 6 to 12 in both of the RBZ arms (RBZ: -14.2%; RBZ+laser: -11.7%) whereas HE decreased linearly in the laser treatment arm (BL to month 6: -6.42%, month 6 to 12: -4.7%). However, differences between arms were not statistically significant. Using statistical general linear models presence of any HE, HE within 1 DD or HE affecting the center of the fovea at BL were consistently not associated with BCVA at BL, change in retinal thickness or change in BCVA over 12 months in any of the 3 arms, respectively.
Conclusions:
There are no significant differences in the resolving of HE comparing anti-VEGF and laser therapy. Further, there is no association between the presence of HE and treatment response to laser coagulation or anti-VEGF therapy. Unlike earlier assumptions large amounts of HE in the macula seem not to be a risk factor for RBZ therapy and on the long term faster resolution of DME secondary to RBZ therapy does not aggravate HE formation in the retina.