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Grzegorz Labuz, Nicolaas Reus, Thomas J T P Van Den Berg; Forward light scattering by implant lenses extracted from donor eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2714.
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© ARVO (1962-2015); The Authors (2016-present)
Clinical studies have found that in 10% of pseudophakic eyes straylight can be considered a serious hindrance for patient’s vision. Straylight is the visual effect of forward light scattering. Increased straylight results in unwanted light phenomena, such as glare. This could be due to implanted intraocular lenses (IOLs). Such IOL-related complications have, however, been rarely reported, possibly because scatterers in the IOL can be missed, as slit-lamp evaluation assesses only backscattered light. We therefore studied in vitro forward-scattering effects of IOLs extracted from donor eyes, and determined potential sources of straylight in the IOLs.
Seventy-seven IOLs removed from donor eyes were analyzed. Straylight was measured using the C-Quant device (Oculus) adapted for in vitro evaluation of IOLs. To study straylight-angular dependence, measurements were performed at a 2.5 deg and 7 deg scatter angle. Results were compared to normal straylight levels of the crystalline lens at the age of 20 and 70 years, and to a cataractous lens. To identify potential scattering sources, the IOLs were examined with light microscopy.
The average straylight parameter s (±SD) at 2.5 deg was 6.5 ±6.0 deg^2/sr; at 7 deg it was 5.7 ±5.2 deg^2/sr. Straylight was found to be below the level of the 20yo crystalline lens in 39% of the IOLs; 13% showed straylight higher than that of the 70yo lens. Three IOLs showed straylight levels close to that of the cataractous lens. We identified 8 groups of 5 till 11 IOLs each, which accounted for 81% of the studied lenses. Median straylight (at 7 deg) for these 8 IOL groups ranged from 1.7 to 11.6 deg^2/sr. Light microscopy revealed that increased straylight is associated with the presence of surface deposits, snowflake degeneration, and glistenings.
We found that 13% of the studied IOLs showed seriously increased straylight levels. The results correspond to in vivo studies reporting straylight elevation in pseudophakic patients. The mentioned IOL-related complications appear to be significant sources of forward light scattering. Straylight-angular dependence was more or less in correspondence with the Stiles-Holladay approximation, suggesting that the responsible particles are of wavelength size or larger.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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