Título

Experimental model to evaluate the benefits of light-emitting diode (LED) source to prevent retinal phototoxicity during pars plana vitrectomy

Introdução

In vitreoretinal surgery, the use of an intraocular illumination is necessary and the phototoxic effects of surgical endoillumination lights on the retinal pigment epithelium (RPE) and other retinal cells have long been a matter of debate increasing light exposure to the vitreous, retina and subretinal space. Light-emitting diode (LED) is now currently available for vitreoretinal surgery to help the surgeons during the surgery. The purpose of the study is evaluate retinal phototoxicity of the LED sources during vitrectomy surgery.

Método

Thirty-two rabbits (16 Dutch belted rabbits and 16 big-ear white rabbits) with weighing 1.5 to 2 kg were used in this study. All rabbits were submitted to similar lighting used in vitreoretinal surgery. A single experimental procedure was performed only on the right eye of each rabbit with a specific light to study the effects of light phytotoxicity. The chosen lights were: xenon 420nm (white-blue) or xenon 475nm (white-green) or pure white LED or white LED with a 20% of yellow filter. All rabbits were submitted to a macular surgery simulating during the experimental procedure, with the 23-gauge endoillumination placed near the retina with a 30 minutes of light expose. All rabbits were submitted to optical coherence tomography (OCT), color fundus photo and fluorescein angiography (FA) preoperative and 7th postoperative day. Then the animals were scarified and the eyes were removed for histological study.

Resultados

The maximum intensity of the light sources and endoillumination probe did not exceed those used commercially. All pigmented animals were submitted to the experiment had some degree of phototoxicity regardless of light source. Retinal damage was evident as the FA presented areas of hyperfluorescence, OCT disclosed increase reflective areas of the inner and/or outer retina layers and RPE and histology show some disorganization of the retinal layers. White LED and 475nm wavelength had minor degree damage in pigmented rabbits when compared to others lighting simulations group. Albino rabbits had no phototoxicity, except xenon 420nm filter group.

Conclusões

The use of LED as light source for endoillumination in pars plana vitrectomy shows similar retinal damage compare to the others light sources. Thermal irradiation and photochemical toxicity expose to the EPR is prone to the injury. EPR can absorbers light from different wavelengths and still a roll player to generate retinal toxicity.