July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Comparison of straylight in cataracts to the CIE PSF model
Author Affiliations & Notes
  • Thomas J T P Van Den Berg
    Ophthalmic Research, Netherlands Inst for Neurosci, Royal Acad, Amsterdam, Netherlands
  • Footnotes
    Commercial Relationships   Thomas Van Den Berg, Oculus (P)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 5930. doi:
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      Thomas J T P Van Den Berg; Comparison of straylight in cataracts to the CIE PSF model. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5930.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The international standards committee CIE (Commission Internationale d'Éclairage) has formulated a standard for the peripheral part of the Point-Spread-Function (straylight) as means to specify disability glare. This standard has age as parameter, based on population studies assessing the angular dependency of straylight for different ages. The present study evaluates whether this PSF model can be applied to cataract patients. The results will also be compared to in vitro light scattering data on human eye lenses isolated from donor eyes. An important application would be how in vivo straylight measurement such as with the C-Quant instrument from Oculus can be used for overall assessment of the peripheral part of the PSF also in cataracts. As the CIE PSF model has age as parameter, the straylight effect of a cataract could then be expressed as “equivalent age”.

Methods : Data are used from an earlier study on the angular dependency of straylight in cataract patients. The study included 34 controls (mean age 65y), 16 cortical (69y), 19 nuclear (73y), and 17 posterior subcapsular (60y) cataract patients. Mixed cataracts were excluded. In order to test for potential effects of cataract severity on angular dependency all groups were divided into two halves, with higher, and lower straylight values. For comparison with in vitro light scattering data from another earlier study, known physical theory for light scattering particles was fitted to the data, and the resulting angular distribution was used for the comparison.

Results : Surprisingly, no differences in angular dependency of straylight were found between the 4 groups (controls and 3 cataract groups). There was a statistically significant difference though as function of severity. The 8 angular functions fitted closely to the CIE function using different values for the age parameter, with residual errors about 0.06 log units. Correspondences with the in vitro scattering results are equally close. The equivalent ages for the 4 groups were (low/high subgroup): controls 56y/66y, cortical cat. 67y/86y, nuclear cat. 81y/89y, and post. subc. cat. 86y/98y.

Conclusions : The CIE standard for the (peripheral part of the) PSF can also be used for describing the angular distribution of straylight for cataract patients. The single straylight value measured clinically at 7 degrees can be used to predict the total amount of light scattered in the eye in case of normal aging as well as cataracts.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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