Preclinical Evaluation of the Efficacy and Safety of Vital Dyes for Inner Limiting Membrane Staining

Removal of the internal limiting membrane (ILM) during vitrectomy is thought to relieve tangential traction on the fovea in various macular pathology, especially in macular holes. The ILM is a very thin and transparent membrane on the surface of retina and is difficult to identify during removal, therefore, it could cause damage on macula and disturb vision while peeling this membrane without staining. However, its complete removal is essential to ensure successful macular hole surgery. The intravitreous injection of dyes has been reported to allow better visualization of ILM and to contribute to safer peeling by providing a clear contrast between the membrane and the remaining retina. Initially, indocyanine green (ICG) dye was shown to stain avidly the internal limiting membrane (ILM). However, numerous reports have raised concerns over retinal toxicity after intravitreous ICG injection. Subsequently, trypan blue (TB), triamcinolone acetonide and patent blue arose as newer alternative vital dyes. However, the exact risk of these chemical to retinal tissue is under investigation. Furthermore, subretinal dyes have been reported to cause retinal cell degeneration at lower concentrations than vitreous dyes in both humans and experimental animals. Yet, many surgeons report that dye-assisted ILM peeling is indispensable. Thus, there is a great need to develop new dyes for effective and safe staining to facilitate ILM removal The safest vital dye to the retina with high affinity for the acellular ILM and ERM is yet to be determined. In the previous studies of chromovitrectomy, most dyes are from industrial chemicals. For this study, a total of six vital dyes, were selected from the anthocyanins. They included Malvidin, Delphinidin, Cyanidin, Peonidin, Pelargonidin, and Luteolinidin, all are extracts from the natural plants. They are essential intergradient in our daily food. Some reports also demonstrated intake of anthocyanins is good for retina. The aim of this study was to investigate in vitro and in vivo the retinal biocompatibility of these six dyes in cell culture, and injected intravitreally or subretinally into rats’ eyes with clinical examination, fluorescein angiography, histology and, transmission electron microscopy (TEM), and electroretinography (ERG). The pre-clinical results will find out the potentially dyes which have better retinal biocompatibility for ILM peeling in the future clinical applications.

Project ID:PC10101-1775
External Project ID:NSC99-2314-B182-020-MY3