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Visual impact of artificially induced intraocular scatter with a liquid crystal phase modulator


Purpose : Various ocular pathologies, including cataracts, increase the amount of intraocular scattering, which impairs visual function. We developed a procedure to induce realistic and controlled intraocular scatter investigating its impact on Contrast Sensitivity Function (CSF) at the presence of glare.

Methods : The instrument introduces phase masks with controlled spatial properties at the eye’s pupil plane. It is based on the use of a liquid crystal on silicon spatial light modulator (LCOS-SLM) conjugated to the pupil plane of the eye by means of a telescope with angular magnification of 6. This setup allows to induce phase structures at the pupil plane with a high resolution (1.3-μm) while providing a field of view of 27 degrees. Subjects viewed monocularly through the system visual stimuli with size of 8 degrees. All experiments were performed with quasi-monochromatic light at 550±40 nm. CSF was measured for different amounts of induced scatter with and without a glare source consisting of a fluorescent ring lamp with equivalent angle radius of 5.6 degrees.

Results : The phase introduced at the pupil plane was calculated to produce a wide-angle point spread function (PSF) similar to the CIE (Commission internationale de l’éclairage) glare function. The amplitude of the generated phase mask controled the amount of added scatter. The area under the logarithm of the CSF (AULCSF) used as a metrics decreased linearly with the amount of induced scatter (straylight parameter S).

Conclusions : A instrument to induced non-invasively and realistically controlled amounts of scatter has been developed. It also permitted to establish the relationship between stray-light and contrast reduction under normal viewing and glare conditions.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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