Clear PMMA versus yellow intraocular lens material. An electrophysiologic study on pigmented rabbits regarding "the blue light hazard"

Abstract

Pigmented rabbits were exposed for 3.5 h to light (retinal irradiance 60-70 mW/cm2, i.e. below the level of thermal damage) from a Xenon lamp, passing IR filters and a fiber optic system as well as a Perspex CQ (clear PMMA) IOL material in front of one of the eyes (the "PER" eye) and a yellow (blue light absorbing) filter (potential IOL material) in front of the other eye (the "YEL" eye). The difference in spectral distribution of light transmitted by the two filters may be important. Does the yellow filter offer significant protection against "the blue light hazard"? DC ERG recordings were performed before, 1 day after and 4-6 days after exposure. The c- (mainly pigment epithelium (PE)) and b-wave (neuroretina) amplitudes were measured and the cPER/cYEL as well as the bPER/bYEL ratios calculated. Both ratios were found to be reduced after exposure, for the c-wave 30-33% (p less than 0.05 - 0.001), and for the b-wave 12-20% (p less than 0.01 - 0.02). This means that both the PE and the neuroretina were injured in the PER eye, the PE more than the neuroretina. At day 4-6 the c- and b-wave ratios were found to have returned to initial levels, indicating that the damage was reversible to a large extent. Thus, the yellow filter offered a better protection than the Perspex material. There were no ophthalmoscopic fundal changes 1-2 h after exposure. After 1 day minimal changes were seen in 3/16 YEL eyes and somewhat more pronounced changes in 8/16 PER eyes, all in the central fundus. The conclusion is that in acute experiments and under the conditions applied the yellow filter protected the PE and the retina against photochemical light injury (mainly "the blue light hazard") significantly better than the Perspex material. Furthermore, the yellow filter was found to protect significantly better than a UV absorbing IOL material.