Very low risk of light‐induced retinal damage during Boston Keratoprosthesis surgery

Abstract

AbstractPurpose To assess the possibility of light damage to the retina by a surgical microscope during implantation of a Boston Keratoprosthesis (B‐KPro) in rabbits.Methods The retinal irradiance from a Zeiss OPMI Lumera S7 operating microscope was measured at its working distance (16.5 cm). Light transmittance through an isolated B‐KPro (made of PMMA) was measured. A B‐KPro was implanted into one eye of each of 12 rabbits with the optic of the device initially covered during the procedure. Retinoscopy was performed after the implantation, and external additional lenses were used when needed to focus the light on the retina. The operated eyes were then continuously exposed to a fixed light intensity under the microscope for 1 hour. After the exposure, the rabbits were monitored for 9 days and fluorescein angiography (FA) was carried out at days 2 and 9.Results Light transmittance of the B‐KPro revealed blockage of short wavelengths (from 0.001% at 200nm to 42% at 390nm) and of long wavelengths (12‐35% at 1660‐1750nm). In addition, the surgical microscope blocked part of the blue, ultraviolet (UV), and infrared (IR) wavelengths of light. FA showed no leak of dye or other morphological changes. Histological examination with H&E staining showed no morphological retinal changes.Conclusion Our results show that the PMMA of the B‐KPro has a very low transmittance of phototoxic wavelengths of light, mostly UV. In addition, modern surgical microscopes have filters for UV and IR wavelengths of the light spectrum. No morphologic damage to the retina from the light exposure from our microscope could be demonstrated. Thus, there should be very low risk of light damage to the retina during routine B‐KPro surgery.