Abstract
Purpose: :
Indocyanine green (ICG) is a vital dye used to highlight the internal limiting membrane (ILM) in vitreoretinal surgery. However, there is known toxicity to retinal ganglion cells and pigmented epithelial cells in vitro and in vivo. This study was undertaken to investigate the toxicity of novel dyes using a previously developed lens culture toxicity model.
Methods: :
Bovine lenses exposed to either 0.01% benzalkonium chloride (BAK) (n=5), 10 mg/mL (1%) bromophenol blue (BPB) (n=6), brilliant blue G (BBG) 0.25 mg/mL (n=6), ICG 0.5 mg/mL (n=6) or control conditions (n=3) for 15 minutes, rinsed and incubated in culture medium at 37oC and 4-5% CO2. For 7 days following treatment, lens optics were analyzed once daily back vertex distance (BVD) variability (sharpness of focus) using a laser-scanning device. After 7 days, lens cell viability was quantified through the Alamar Blue assay.
Results: :
Compared to negative controls, ICG treated lenses showed a non-significant loss of sharp focus by 4 hours (1.56 ± 0.59 mm) that recovered to 0.56 ± 0.07 mm within 24 hours. BBG treated lenses induced a non-significant loss of sharp focus by 48 hours (1.22 ± 0.39 mm), with slight recovery by day 7 (0.70 ± 0.08 mm). Lastly, BPB caused a significant persistent increase in BVD variability 5 days after exposure (4.09 ± 1.18 mm, p<0.05). Positive control lenses (BAK) produced a significant increase in BVD variability (4.96 ± 1.93 mm, p<0.01) 3 days following treatment. Alamar Blue assay revealed no significant change in cell viability for control or any vital dye treated group (p>0.05). There was a significant decrease in cell viability seen with BAK treated lenses (p<0.01).
Conclusions: :
ICG, in this study, appears to be a safe vital dye for chromovitrectomy. BBG produced a non-significant decrease in optical quality, which will require further investigation to determine its safety in chromovitrectomy. BPB caused a significant persistent decrease in optical quality, decreasing its likelihood for use in future chromovitrectomy procedures.
Keywords: vitreoretinal surgery • ocular irritancy/toxicity testing • retinal pigment epithelium