Retinal tolerance of an implantable light source for use during vitrectomy surgery

To assess for the possible development of a phototoxic lesion, we exposed five Dutch belted rabbit retinas to constant illumination with an implantable "chandelier" light source at maximal intensity for 1 hour. No clinically apparent lesion developed in any of the experimentally treated eyes by 48 to 72 hours posttreatment. Light and electron microscopic examination failed to reveal any of the characteristic changes of retinal phototoxicity. A control eye treated with a 20-minute exposure to a standard endoiluminator probe at maximal intensity held 2 mm from the retinal surface demonstrated typical light and electron microscopic phototoxic abnormalities, whereas a retina similarly treated with a 5-minute exposure was normal. We have confirmed that a standard endoilluminator probe can create a phototoxic lesion in the experimental setting. Furthermore, no phototoxicity from the sustained retinal exposure to a fixed, implantable light source for a clinically relevant duration could be demonstrated.