Extraocular non-invasive transscleral LED-Endoilluminator for Eye Speculum Integration

Abstract

Purpose: To introduce an extraocular non-invasive transcleral eye speculum with integrated light-emitting diode (LED) - Endoilluminator which increases the efficacy of performing pars plana vitrectomy (PPV) procedures.

Methods: A white LED is incorporated as a light source. The speculum which has the integrated LED applies appropriate pressure to the sclera. A prototype has been developed incorporating the relevant international standards for endoillumination. Tests were performed with enucleated porcine eyes.

Results: This new instrument efficiently illuminates the vitreous cavity in the porcine eyes. We could demonstrate that all parameters are well within their limits required by the international standards for endoillumination of the eye. Considering a distance of 18 mm (light delivered through pars plana) and 1 mm (light delivered through sclera from behind the retina) irradiance values of 6,22E-05 and 1,28E-03 (W/cm²) allow exposure time of 44 hrs respectively 2 hrs with no phototoxicity risk from the short wavelength light.<br /> The thermal relevant irradiance E_VIS-R of 11,7mW/cm² is significantly lower than the clinically relevant threshold value of 0,7 W/cm². The measured maximum temperature of 27.8° C is far below the threshold of between 47° C and 57° C which is considered to be relevant for potential thermal damage.

Conclusions: Conventional chandelier endoilluminators for PPV consist of a light-fibre which is introduced into the eye through an incision. A novel extraocular LED-Endoilluminator was developed. This illuminator is attached to a speculum and does not require connection to a light source or a light fibre. The transmitted and diffused light results in an incision free and complete illumination of the vitreous cavity. Compared to standard illumination systems, the possible exposure time to light of all wavelengths becomes significantly longer. This is also true in cases when the illumination is not applied at the PP but more posterior through the retina. Neither the amount of ultraviolet radiation nor thermal effects are clinically relevant.<br /> Peyman, G. A. Improved vitrectomy illumination system. AJO 81: 99 -100 (1976). Koch F, et al. Multiport illumination system (MIS) for panoramic bi-manual vitreous surgery. Graefe's Arch 229:425-429 (1991). Bashkatov, A et al. Optical properties of human sclera in spectral range 370-2500 nm. Optics and Spectroscopy 109, 2, 197-204 (2010).