Evaluation of the effect of modifying indocyanine green solvent on its toxicity to the corneal endothelial cells

Abstract

Purpose : Ensuring optimal visibility of the anterior capsule is crucial in continuous curvilinear capsulorhexis (CCC) during cataract surgery, particularly in advanced cataracts with diminished red reflex from the retina. Furthermore, the unavailability of the commonly proposed agents trypan blue and Brilliant blue G in some operating theaters prompts exploration of indocyanine green (ICG) as a viable vital dye, given its ability to stain the lens capsule. In the index retrospective study, we assessed the effects of modifying the ICG solvent on reducing its toxicity.

Methods : Eyes undergoing phacoemulsification and intraocular lens implantation performed by a single surgeon between September 2017 and March 2018 at National Cheng Kung University Hospital were reviewed. Patients were categorized into three groups: a control group without ICG, a group with ICG dissolved in distilled water (ICGDW), and a group with ICG dissolved in 5% glucose water (ICGGW). ICG concentration was 0.25% in both solutions. The primary endpoint was a change in endothelial cell density (ECD), measured at postoperative 1- or 3-months. In vitro experiments involved harvesting rabbit corneal endothelium cells treated with different solutions for one minute, with cellular toxicity assessed using a lactate dehydrogenase assay.

Results : After inverse probability of treatment weighting adjustments, one hundred eyes of 63 patients with similar cataract grading across the three groups were included. There are 26, 43, and 31 eyes in the ICGDW, ICGGW, and control groups, respectively. Preoperative ECD and central corneal thickness and cumulative dissipated energy were comparable among the group (Figure 1). ECD reduction at the 1- and 3-month postoperative visits was significantly higher in the ICGDW group compared to the control or ICGGW group (p<0.05 for both time points). Eyes operated using ICGDW presented a higher risk of more than 5% endothelial cell density loss at three months (OR 75.13, 95% CI: 7.46-756.06). Cellular experiments demonstrated significantly lower cellular survival after treatment with distilled or ICGDW (Figure 2).

Conclusions : The study indicates that the toxicity of the ICG solution is partially attributed to the solvent, with 5% glucose water being a safer solvent than distilled water. This finding can assist surgeons in selecting vital dyes for selected cases of advanced cataract.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.