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Comparison of optical and psychophysical methods to measure intraocular straylight
Author(s) -
PENNOS A,
GINIS HS,
ARTAL P
Publication year - 2014
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2014.1777.x
Subject(s) - optics , contrast (vision) , emmetropia , logarithm , glare , mathematics , computer science , physics , materials science , refractive error , visual acuity , mathematical analysis , layer (electronics) , composite material
Abstract Purpose To quantify intraocular forward scattering (straylight) by using three different methods in a group of normal subjects. Methods Intraocular straylight was measured in the dominant eye of 10 emmetropic subjects without any known ocular pathology (30±5 years).Two different, commercially available, scatter filters (Black Pro‐Mist ¼ and Black Pro‐Mist ½ from Tiffen)where used in order to recreate the effects of higher scattering. Three measurement techniques were used:a commercially available straylight meter (C‐quant, Oculus),a prototype of an optical double‐pass based method (Sigma) and a psychophysical method that we developed.We used a Bayesian method (quick‐CSF) in a range of spatial frequencies (2 to 20 cycles/degree) with 50 2‐alternative forced choice trials.Each set of trials was repeated 2 times for each condition (with and without glare).As a glare source, a fluorescent lamp was positioned concentrically to the test area where the sinusoidal gratings were projected.All tests were presented on a screen placed at 1 meter distance from the subject and the test area was covering a total of 6.4 degrees of visual field.For Sigma and C‐Quant tests,the logarithm of Scatter coefficient was determined, whereas for the q‐CSF measurements the difference between the areas below the log contrast sensitivity curves was used as scatter metrics. Results In the three methods, the effects of straylight were accordingly increasing with the addition of the scatter filters. A correlation between all three methods was verified. Conclusion These results suggest the potential use of an even simplified method based on the q‐CSF to evaluate straylight complementing other existing methods.