Endoillumination during vitrectomy and phototoxicity thresholds

Abstract

Aim-To assess the retinal phototoxicity hazards of and to provide safety margins for endoillumination during vitrectomy. Methods-The absolute power and spectral distribution from various light sources and filter combinations that are commercially available for vitreous surgery were measured. The maximal exposure times based on the ICNIRP safety guidelines for photochemical and thermal injury of the aphakic eye were calculated. Additionally, the eVect of various measures that reduce the risk of phototoxicity was evaluated. Results-Measurements of the spectrum and energy indicated that the ICNIRP safety guidelines for photochemical retinal damage are exceeded within 1 minute for nine out of 10 combinations tested. With an additional 475 nm long pass filter, light levels below 10 mW, and a distance from light probe to retina of at least 10 mm, the allowable exposure time can be increased up to 13 minutes. Thermal damage can be anticipated when the light probe touches the retina. Conclusion-Commercially available light sources for endoillumination during vitrectomy are not safe with respect to photochemical retinal damage. Even with maximal precautions macular phototoxic damage remains a factual danger during vitrectomy. (Br J Ophthalmol 2000;84:1372-1375

Light damage to the retina: an historical approach

“…The maximum exposure time, as defined by ICNIRP, is reached within a minute. 24 A filter that blocks the short wavelengths lengthens the maximum permissible exposure time but hampers color vision. A more extensive treatment of the subject is given by Wolffe.…”

Material Properties of the Internal Limiting Membrane and Their Significance in Chromovitrectomy

“…Yellow and orange filters have been described to increase contrast perception by a reduction of ocular media light scatter and decreased chromatic aberration [60]. Spectral filters are available in many commercially available endoilluminator devices, as they allow the attenuation of retinal and retinal pigment epithelium light toxicity by the reduction of the endoillumination short-wavelength spectrum [61]. Only few surgeons rely on the use of spectral filters for chromovitrectomy, and a Medline search reveals only 2 publications on the protective effects of endoillumination filters in the last 3 decades [61,62].…”

“…Spectral filters are available in many commercially available endoilluminator devices, as they allow the attenuation of retinal and retinal pigment epithelium light toxicity by the reduction of the endoillumination short-wavelength spectrum [61]. Only few surgeons rely on the use of spectral filters for chromovitrectomy, and a Medline search reveals only 2 publications on the protective effects of endoillumination filters in the last 3 decades [61,62]. We used chromaticity analysis to examine the influence of spectral light filters in connection with intraoperative endoillumination on intraoperative ILM contrast.…”

Inflammation induced by photocoagulation laser is minimized by copper chelators

“…Inflammation of retinal tissues may also occur after intense light exposure, such as during endoillumination during vitreoretinal surgery, and during cataract surgery when the removal of the lens causes a temporary, unobstructed light axis to the retina [17]. As intense light exposure, even for brief periods, will result in an increased chemical generation of ROS, it is possible that secondary inflammation after vitreoretinal or cataract surgery may result in a compromised therapeutic outcome due to the proliferative cellular events triggered by excess ROS or free radicals in the surrounding tissues.…”