gms | German Medical Science

32. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

Deutschsprachige Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII)

15.02. - 17.02.2018, Dresden

Keynote lecture: Effect of straylight on vision

Meeting Abstract

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  • Tom J. van den Berg - Amsterdam/NL

Deutschsprachige Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie. 32. Kongress der Deutschsprachigen Gesellschaft für Intraokularlinsen-Implantation, Interventionelle und Refraktive Chirurgie (DGII). Dresden, 15.-17.02.2018. Düsseldorf: German Medical Science GMS Publishing House; 2018. Doc18dgii027

doi: 10.3205/18dgii027, urn:nbn:de:0183-18dgii0279

Published: February 22, 2018

© 2018 van den Berg.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

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Early complaints from cataract often derive from increased straylight. Straylight is defined as the visual phenomenon of light perceived to radiate around bright lights against a dark background. The straylight phenomenon causes blinding while driving at night or against a low sun, but also complaints such as difficulty with face recognition. The CIE has decided that straylight should be used as standard to quantify disability glare.

As light enters the pupil of the eye to form an image on the retina, part of that light is scattered in different structures, such as the cornea and crystalline lens. This causes a veil of light on top of the more or less proper retinal image, reducing visibility, and degrading quality of vision. Added to this veil is light back scattered from the fundus, and light diffusely transmitted by the iris and exposed part of the sclera. The scattered light forms part of the functional point-spread-function, in particular its peripheral part for angles >1degree. It is quantified by its so called equivalent luminance value. Straylight increases with aging, also if no cataract is diagnosed, and with different other adverse conditions. In particular several corneal dystrophies can have large straylight effects. Straylight can be measured precisely on the basis of the equivalent luminance principle using psychophysical techniques. To evaluate patient complaints in routine clinical setting the C-Quant from Oculus is used. A straylight increase by a factor of 3x can be used as indication for cataract surgery. At an elevation of 4x driving at night is considered dangerous. The straylight value has been found to correspond in one-to-one fashion to optically defined light scatter. This was tested using artificial scatter filters because of lack of instruments to measure functional light scatter optically.