Pre-Clinical Evaluation of Six Novel Dyes for Chromovitrectomy

Abstract

Purpose: : To investigate the retina biocompatibility of novel dyes.

Methods: : A total of 72 rabbits were used to perform the experiments. The amount of 0.05 ml of 0.5 % and 0.05 % light green (LG), fast green (FG), evans blue (EB), brilliant blue (BriB), bromophenol blue (BroB) or indigo carmine (IC) were injected intravitreally into the right eye, while in the left eye 0.05ml of balanced salt solution (BSS) was applied for control. Fundus photograph, fluorescein angiography (FA), histology with light microscopy (LM), and transmission electron microscopy (TEM) were performed after one day and seven days. The retinal cellular layers were evaluated according to morphologic alterations and number of cells. The electroretinographic (ERG) changes were assessed at baseline, 24 hours and 7 days. Both latency and amplitude of maximum response, rod response, and oscillatory potentials as well as ratio of dye-injected / control group were used for detection of retinal toxicity.

Results: : LM and TEM disclosed slight focal morphologic changes without loss of cellular elements in eyes exposed to 0.05% LG, IC, FG, BriB, and BroB, similar to the control group. At the higher dose of 0.5%, BroB, LG and EB promoted cellular edema and vacuolization within the ganglion and bipolar cells, whereas 0.5% FG and IC caused slight retinal alterations similar to BSS injection. BriB at 0.5% induced just focal changes in the photoreceptors. Intravitreal injection of 0.5% EB caused significant loss of neuroretinal cell counts in comparison to BSS-injected eyes (p<0.05). ERG revealed intermittent prolonged latency and increased amplitude in eyes submitted to injection of 0.5% EB, LG, BriB and BroB, and at the lower dose only LG and EB induced functional changes in the ERG. FA disclosed RPE window defects in the 0.5% EB group.

Keywords: retinal pigment epithelium • retinal degenerations: cell biology • retina