Reproducibility of straylight measurement by C-Quant for assessment of retinal straylight using the compensation comparison method

Abstract

Background Straylight gives the appearance of a veil of light thrown over a person's retinal image when there is a strong light source present. We examined the reproducibility of the measurements by C-Quant, and assessed its correlation to characteristics of the eye and subjects' age. Participants and Methods Five repeated straylight measurements were taken using the dominant eye of 45 healthy subjects (age 21-59) with a BCVA of 20/20: 14 emmetropic, 16 myopic, eight hyperopic and seven with astigmatism. We assessed the extent of reproducibility of straylight measures using the intraclass correlation coefficient. Results The mean straylight value of all measurements was 1.01 (SD 0.23, median 0.97, interquartile range 0.85-1.1). Per 10 years of age, straylight increased in average by 0.10 (95%CI 0.04 to 0.16, p<0.01]. We found no independent association of refraction (range −5.25 dpt to +2 dpt) on straylight values (0.001; 95%CI −0.022 to 0.024, p=0.92). Compared to emmetropic subjects, myopia reduced straylight (−.011; −0.024 to 0.02, p=0.11), whereas higher straylight values (0.09; −0.01 to 0.20, p=0.09) were observed in subjects with blue irises as compared to darkcolored irises when correcting for age. The intraclass correlation coefficient (ICC) of repeated measurements was 0.83 (95%CI 0.76 to 0.90). Conclusions Our study showed that straylight measurements with the C-Quant had a high reproducibility, i.e. a lack of large intra-observer variability, making it appropriate to be applied in long-term follow-up studies assessing the long-term effect of surgical procedures on the quality of vision.

Qualité de vision étudiée par mesure comparative de la diffusion de la lumière

“…La reproductibilité de cette plateforme a également été prouvée dans la littérature par Guber et al [10] et Cervino et al [23]. Elle permet l'analyse de la diffusion antérograde de la lumière et a essentiellement été utilisée pour l'étude de la qualité de vision après chirurgie réfractive (après Epilasik et Lasik par Li et al [24], pour mesurer l'effet d'implants de chambre postérieure par Ehmer et al [25] et Xing et al [26], l'étude de glistennings sur les implants de chambre postérieure par Colin et al [27].…”

“…Elle est basée sur le principe de comparaison subjective psychophysique de stimuli générés par ordinateur. Cet examen, reproductible [10], nécessite une participation active de plusieurs minutes du patient ainsi qu'une absence de troubles des fonctions supérieures. L'indice mesuré est le log(s), permettant de quantifier la diffusion antérograde de la lumière.…”

Double-pass technique and compensation-comparison method in eyes with cataract

“…Besides the former experimental systems, in recent years a new commercial instrument (C-Quant, Oculus GmbH, WetzlarDutenhofen, Germany) has gained acceptance for controllable assessment of straylight in the clinical setting [6][7][8][9] . It is based on the so-called compensation-comparison method which uses a central test field subdivided into two half fields: one with and one without counterphase compensation light.…”

Ocular straylight in the normal pseudophakic eye

“…This instrument has been shown to have good reliability and repeatability. [15][16][17] In the management of cataract, visual acuity is still considered the primary criterion for quality of vision. 18 However, disability glare has been accepted as a criterion as well.…”