Abstract
Purpose: :
The aged human lens contains chromophores that absorb and scatter incoming light to an extent which may interfere with visual function. The aim of the present study was to produce photochemical bleaching of the age-related lens yellowing by two-photon photolysis.
Methods: :
Ten human donor lenses were exposed to ultrashort infrared laser pulses from a femtosecond Ti:Sapphire laser emitting at 800 nm. Age range of the donors was 46 to 75 years of age. Pulse duration was 200-300 femtoseconds. Pulse energy was approximately 0.5 µJ. A focusing lens of f=85 mm was used yielding a theoretical spotsize of 14 µm.
Results: :
Two-photon absorption was evident as emission of blue autofluorescence upon exitation by pulsed infrared light at 800 nm. Photobleaching was observed as an increased transmission of light in the blue-green range of the spectrum and as a macroscopically visible reduced yellow coloration of the aged human donor lenses whilst lens transparency was maintained.
Conclusions: :
We found that exposure to ultrashort pulsed infra-red laser light lead to bleaching the chromophores through twophoton absorption. This leaves hopes for a new non-invasive treatment of age-related lens disorders.
Keywords: cataract • laser • crystallins