Abstract
Purpose: :
To obtain the spectral transmittance curves of different intraocular lenses (IOL) having either UV or blue-light filters, including yellow and orange IOLs, and to compare results with the spectral emission curves of natural and artificial light sources.
Methods: :
Ten IOLs were evaluated, using a Perkin-Elmer Lambda 800 UV/VIS spectrometer. Different simulations of filtering were made using the following illuminants: a) the NASA standard data of spectral irradiance (W m-2 µm-1) for the solar disk at the earth’s surface at air mass 2, b) the ratio of UV to global broad band irradiation in Mediterranean latitude and c) the relative spectral power distribution curves of daylight, incandescent lamps and fluorescent bulbs as defined in CIE illuminants.
Results: :
All the studied IOLs provide good UVC (200-280 nm) and UVB (280-315 nm) protection, but the Artisan, which has a noticeable window at 270 nm. Nevertheless, neither natural nor artificial sources have emission under 300 nm. In the UVA range (315-380 nm) the different IOLs manifest different degrees of absorption.
Conclusions: :
The absorption filters of the IOLs must affect mainly the UVA spectral zone, because there is a noticeable component of this radiation in daylight. All the studied IOL filters perform well enough, although differently in the UVA and the blue zones, being the yellow and orange filters the ones with best absorption in those short wavelengths. However, the maximum emission in daylight spectrum is located at about 470 nm, and the yellow and orange filters have absorptions of about 40% and 60% respectively for this wavelength. Thus, it is important to appropriately choose the transmission curve of the IOL in order to preserve the retina from harmful radiations without reducing the amount of visible light reaching it.
Keywords: radiation damage: light/UV • optical properties • intraocular lens