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R.F. Melendez, N. Kumar, S.M. Maswadi, K. Zaslow, R.D. Glickman; Photodynamic Actions of Indocyanine Green and Trypan Blue on Human Lens Epithelial and Retinal Pigment Epithelial Cells . Invest. Ophthalmol. Vis. Sci. 2004;45(13):364.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Various dyes have been utilized to stain the anterior lens capsule for better visualization during surgery for mature cataracts. Two common dyes, Indocyanine Green (ICG) and Trypan Blue (TryB) have been used in this procedure. Residual lens epithelial cells after cataract surgery contribute to the development of posterior capsule opacification (PCO). The purpose of this study was to evaluate the toxicity and photodynamic activity of these dyes on cultured human lens epithelial and retinal pigment epithelial cells, which could be exploited for clinical applications. Methods: Human–derived lens epithelial cells (ATCC CRL–11421) and retinal pigment epithelial cells (hTERT–RPE: Geron Corp.) were exposed to ICG at concentrations of 0.025 to 5 mg/mL, and to TryB at concentrations of 0.025 to 4.0 mg/mL. Incubation times were 5, 30, and 60 minutes. The cells were exposed to diode laser (806 nm, irradiance=55 mW/cm2) with respective controls. Cell viability was assessed after incubation in the dyes by the uptake of Sytox Orange nucleic acid stain (Molec. Probes). Results: At ICG concentrations below 0.1 mg/ml, there was >50% cell viability of the human lens epithelial cell; at a higher ICG concentration there was a significant photodynamic–induced loss of viability. TryB had little cytotoxicity to the human lens epithelial cells: >70% cells were viable irrespective of the dye concentration or laser treatment (except at 4 mg/ml, which may be due to a selective photothermal effect). In contrast, ICG was toxic to hTERT–RPE cells at all concentrations (<20% cell viability). TryB was also toxic to hTERT–RPE cells at all concentrations (< 10% cell viability), with no indication of laser–induced phototoxicity. Incubation time was not a factor for cytotoxicity for either dye. Conclusions: Both ICG and TryB were more toxic to the hTERT–RPE cells than to the lens epithelial cells. TryB did not have photosensitizing properties. ICG, however, acted as a photosensitizer in a dose dependent manner in both cell types. The data indicate these dyes are potentially useful in the eradication of residual lens epithelial cells after cataract surgery and other ophthalmic procedures, thus reducing the incidence of PCO. Additional studies need to be done to assess the toxicity of these agents to the corneal endothelial cells.
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