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

Jules-Gonin Eye Hospital, University of Lausanne, Avenue de France 15, 1000 Lausanne 7, Vaud, Switzerland.
Albrecht von Graæes Archiv für Ophthalmologie (Impact Factor: 1.91). 05/2011; 249(9):1367-71. DOI: 10.1007/s00417-011-1704-y
Source: PubMed


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.
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.
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 dark-colored irises when correcting for age. The intraclass correlation coefficient (ICC) of repeated measurements was 0.83 (95%CI 0.76 to 0.90).
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.

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Available from: Ivo Guber, Jun 26, 2014
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    • "Cerviño et al. [8] reported that the mean log(s) of the intrasession SD in the 10 consecutive measurements and that of the intersession SD in the 5 sessions were 0.07 and 0.05, respectively, suggesting that the C-Quant straylight meter measurements are repeatable and reliable for the assessment of the log measurements. Guber et al. [9] showed that the ICC of 5 repeated measurements was 0.83, which was comparable with our current ICC findings. With regard to the PSF meter, Saad et al. [10] showed, in a study of normal, cataractous, and postrefractive surgery eyes, that the repeatability limit "
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    • "The equivalent luminance is estimated by means of fitting an appropriate psychometric function to the subjects' responses. The compensation comparison method has been used in numerous studies (Guber, Bachmann et al., 2011; van den Berg, Franssen et al., 2009). One limitation related to the psychophysical nature of the tasks is the possible complexity for some subjects. "
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