Abstract
Purpose:
To compare the effects of intravitreal Ranibizumab (IVR) associated or not with panphotocoagulation (PRP) using single (EDTRS) or multiple (pattern scan laser - PASCAL) spot targeting laser on retinal function in proliferative diabetic retinopathy.
Methods:
A total of 44 patients have been so far enrolled in this randomized, prospective clinical trial, and assigned to treatment with only IVR, IVRPASCAL or IVREDTRS. Comprehensive ophthalmological evaluations were performed at baseline and every 4 weeks after treatment including full-field electroretinography (ERG) (Espion E2 - Diagnosys LLC) using a recording protocol in accordance with the ISCEV standard, to measure a- and b-wave amplitude and implicit time for dark-adapted 0.01 (Rod) and 3.0 cd.s/m2 (CR); and light-adapted 3.0 cd.s/m2 (Cone) single flash and 30 Hz flicker, at baseline and at 12, 24 and 48 weeks after treatment. PRP was performed exclusively at baseline in 2 sessions. In eyes with macular edema, macular short-pulse grid laser was associated to IVR at baseline. IVR was repeated monthly if central subfield macular thickness measured with SDOCT was higher than 300 µm, or quarterly if neovascularization was detected by angiography.
Results:
Currently, IVR=8, PASCAL=8, and ETDRS=9 eyes were evaluated with ERG at 24 weeks follow-up. There was no significant difference between groups for any ERG parameters at baseline, but a significant reduction for dark-adapted Rod b-wave amplitude was observed at 12 and 24 weeks after treatment for groups PASCAL: -62.7 ± 21.3 µV (60%; P=0.013) and EDTRS: -62.9 ± 17 µV (67%; P=0.004), but not for IVR: -28.6 ± 20.7 (90%; P=0.108). Results are similar for dark-adapted CR, and light-adapted stimuli.
Conclusions:
These preliminary data indicate that IVR associated to single spot or PASCAL laser PRP cause similar ERG amplitude reductions, which is not observed with IVR alone. Forthcoming reports from this study will focus on correlations between ERG and visual field findings, and treatment efficacy as measured by the number of injections needed to control neovascularization up to one-year follow-up.
Keywords: 509 electroretinography: clinical •
499 diabetic retinopathy •
688 retina