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Vital dyes necessary for vitreomacular surgery but may have risks
Vital dyes are used by vitreoretinal specialists to visualize transparent preretinal tissues, to enhance identification and to remove transparent anatomical layers during vitreoretinal surgery, but the dyes can result in irreversible acute toxicity in some cases, according to a review article in Ophthalmic Surgery Lasers & Imaging Retina.
Vitreoretinal specialists most commonly use indocyanine green (ICG), triamcinolone acetonide, trypan blue and brilliant blue G (BBG) as chromovitrectomy dyes to help visualize transparent preretinal tissues such as the epiretinal membrane and vitreous cortex.
“The vital dyes play an important role by facilitating removal of the desired microscopic anatomical layers during vitreoretinal surgery,” OSLI RetinaEditorial Board Member Caroline R. Baumal, MD, told Ocular Surgery News.
Dye preferences Trypan blue and preservative-free triamcinolone acetonide are FDA-approved dyes for intraocular use. According to the 2017 American Society of Retina Specialists Preferences and Trends Survey, 69% of respondents used ICG as their internal limiting membrane (ILM) and epiretinal membrane (ERM) removal dye, with 14.8% preferring BBG and 9.5% preferring triamcinolone acetonide.
However, the use of dyes for ERM removal and ILM peeling could lead to an increased risk for adverse outcomes in some patients. Studies have suggested that ICG, especially if utilized at higher concentrations and for long periods of contact during surgery, may have some degree of toxicity to the retinal pigment epithelium (RPE).
“Safety is the main concern when using a surgical adjuvant. There are concerns regarding dye toxicity to the tissues of the retina and the retinal pigment epithelium. Potential issues may occur during mixing of the dye, be related to direct exposure to the dye or due to dye-potentiated phototoxicity,” Baumal said.
Vitreoretinal specialists can reduce or limit dye-related issues by taking a few steps during a procedure. Specialists should use the “smallest amount of dye possible” with limited retinal exposure time and may consider shielding the central fovea with viscoelastic material. Additionally, mixing a dye such as ICG with dextrose 5% in water and avoiding direct illumination on the fovea when the dye is in the vitreous cavity may limit issues, Baumal said.
Alternative dyes There is an unmet need for safe, versatile dyes that effectively stain both the ILM and the ERM, especially given the transparent nature of the tissues, co-author Thomas A. Ciulla, MD, MBA, told OSN. Several types of dye have been proposed as alternatives to those currently in use. Researchers have attempted to find new alternatives that would minimize the toxicity risk to patients, maximize visualization for specialists and reduce overall costs, according to the review.