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 enrolled in this randomized, prospective clinical trial, and assigned to treatment with only IVR, IVR-PASCAL or IVR-EDTRS. Comprehensive ophthalmological evaluations were performed at baseline and every 4 weeks after treatment including full-field electroretinography (ERG) 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 cd.s/m2 (Rod) and 3.0 cd.s/m2 (CR); and light-adapted 3.0 cd.s/m2 (Cone) single flash and 30 Hz flicker, and LED full-field stimulator, first using red (635 to 638 nm), then blue (465 to 470 nm), and then white (6500 K) stimulus, with 5 minutes inter-session interval at baseline and at 12, 24 and 48 weeks after treatment (Espion E2 - Diagnosys LLC, Lowell, MA). 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:
IVR=13, PASCAL=14, and ETDRS=13 eyes finished the 48 weeks follow-up. No significant difference was observed between groups for any ERG parameters at baseline. A significant amplitude reduction was observed dark and light adapted ERG stimuli, for EDTRS and PASCAL groups, but not for IVR, up to 48 weeks. No difference was observed between EDTRS and PASCAL groups regarding ERG amplitude reduction. There was no significant correlation between ERG amplitude or amplitude reduction and OCT macular thickness or visual acuity.
Conclusions:
These data indicate that single spot or PASCAL laser PRP associated to IVR cause similar ERG amplitude reductions, which is not observed with IVR alone, up to one year follow-up.