Abstract
Purpose: :
To evaluate psychophysically the absorption of blue light by the crystalline lens and by tinted and and non-tinted IOLs after cataract surgery.
Methods: :
The absorption of blue light was assessed in 29 patients (mean age 68, range 41-79) with variant density of nuclear senile cataract (0 to 3+), by measuring the parafoveal relative sensitivity of blue-green radiation using Heterochromatic Flicker Photometry (HFP) (MPS 9000 QuantifEYETM, ZeaVision©). 15 patients among them (mean age 66, range 41-78) underwent cataract or clear lens extraction. Tinted and not tinted IOL was implanted in a group of 6 patients (mean age 67, range 45-76) and 9 patients (mean age 65, range 41-78), respectively. At the 15th postoperative day HFP was repeated and the results were analyzed by non-parametric statistical tests.
Results: :
A significant positive correlation was found between lens absorption and cataract density (r=0.5, p=0.006), at the pre-op group. At the follow-up measurements, there was a significant reduction in blue light absorption at the not tinted IOL group, compared to pre-op measurements (p=0.01), whereas at the tinted IOL group no significant difference was found (p=0.75). A significant difference in blue light absorption between the two different IOL groups (p=0.01) was also found postoperatively.
Conclusions: :
The human crystalline lens absorbs more at the blue spectrum with the progression of cataract density. The tinted IOLs appears to mimic the light-attenuating characteristics of the ageing & cataractous lens This may offer protection to the retina from the photochemical damage caused by high energy short wavelength radiation.
Keywords: cataract • intraocular lens • radiation damage: light/UV