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G. I. Guber, T. M. Thiel; Reproducibility of Straylight Measurement by C-Quant for Assessment of Retinal Straylight With the Compensation Comparison Method. Invest. Ophthalmol. Vis. Sci. 2010;51(13):3949.
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© ARVO (1962-2015); The Authors (2016-present)
Disability glare gives the appearance of a veil of light thrown over a person’s vision when there is a strong light source present. It is generally accepted that this glare is caused by imperfections in the optical media causing a non-uniform passage of light on its way from its source to the subject’s retina. Because the glare is caused by light incident to the retina, this is termed forward light scatter. Conversely, back scatter is dispersion of light reflected out of the eye and can be seen by an external observer. The C-Quant is a new device for subjective measurement of forward straylight. We examined the reproducibility of the measurements in dependence of the refraction, eye pigmentation and patient's age.
We performed on the subject's dominant eye 5 repeated-measures after refraction was determined. The measurement is based on the "compensation comparison" method whereby the subject's task is a forced-choice comparison between two half fields (one with and one without counterphase compensation light), to decide which half flickers more strongly.
41 healthy subjects, age of 21 to 59y (mean 37,5y) were examined (14 emmetropic, 16 myopic, 7 hyperopic and 4 with astigmatism; 18 with bright and 23 subject with dark eyes). The mean investigation duration of all measurements was 1.37s whereby the duration shortened of initially 1.53s to 1.32s. There was no significant difference between the different groups of refraction, but subjects with bright eyes had significantly higher straylight values.
The importance of testing disability glare in ophthalmic patients is increasing as surgical technology and patient expectations advance. C-Quant is suited for quick and reproducible measurement in patients with complaints caused by straylight.
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