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Introduction to straylight as quality measure for ophthalmic procedures
Author(s) -
VAN DEN BERG TJTP
Publication year - 2008
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.1755-3768.2008.4441.x
Subject(s) - glare , optometry , mesopic vision , medicine , ophthalmology , contrast (vision) , visual acuity , capsulotomy , scotopic vision , visual field , optics , photopic vision , intraocular lens , retinal , physics , materials science , composite material , layer (electronics)
Purpose Often patients complain about halos, glare, hazy vision and blinding at night, but while doing regular tests like visual acuity, contrast sensitivity and slit lamp examination little unusual can be found. Most probably, the patient’s complaints are caused by increased large angle light scattering in the eye media which can not be detected by common tests, but straylight degrades the image projected on the retina, thus decreasing the quality of vision. Usually the variable for increasing ocular straylight is the crystalline lens and a cataract may cause a significant increase. Increased ocular straylight may also be caused by refractive surgery and pathological changes. Methods A forced choice psychophysical assessment technique was developed ("Compensation Comparison"), which resulted in a commercial product (C‐Quant from Oculus). The task of the patient is to make 25 short observations, comparing flicker strength in two half fields, and indicate with push buttons wich half field flickers most strongly. The straylight value is obtained including a reliability estimate. Added value in comparison to visual acuity was assessed in 2400 subjects in the European GLARE study. Results Straylight gives the part of the point‐spread‐function outside 1 degree. In contrast, visual acuity and contrast sensitivity relate to the psf within 0.3 degrees. Consequently, straylight assesses a part of the visual spectrum that is missed with the classical visual function measures. Patient studies have been performed on normal aging, cataract and cataract surgery, refractive surgery, YAG capsulotomy, etc. In all those studies straylight was often much increased, corresponding to complaints, while visual acuity was good. Conclusion Straylight is important to assess quality of vision.Commercial interest