The Repeatability of straylight measurements using the C‐Quant in young and older adults

Abstract

PurposeTo assess the repeatability of retinal straylight measurements using the C‐Quant straylight‐meter and to evaluate the effect of age on repeatability.MethodsTwenty nine young (35.6 ± 9.6 years old) and twenty three older (61.8 ± 8.7 years old) subjects participated in the study. They were examined with the C‐Quant straylight‐meter. Two readings were taken in two different sessions with a time interval between them from 1 to 3 weeks. Inclusion criteria were distance best‐corrected VA of at least 0.8 decimal and without manifest ocular diseases. The repeatability of the straylight was estimated by the Bland‐Altman method whereby the mean difference (MD) and the 95% limits of agreement were determined as the coefficient of repeatability (COR).ResultsMean retinal straylight was 0.97 ± 0.12 log units and 1.21 ± 0.21 in the young and the older group, respectively. Repeatability of straylight measurements in the entire sample was high (MD: −0.003 log units, COR = ±0.21 log units). The repeatability was better in the younger group (MD: +0.024 log units, COR = ±0.15 log units) than in the older group (MD: −0.021 log units, COR = ±0.24 log units). There were not any significant differences between the two repeated measurements in each group and also in the entire sample.ConclusionsThe measurement of retinal straylight using the C‐Quant showed a good repeatability, although was worse in the older group. The impact of changes in straylight caused by intraocular scatter in the older eye should be considered when measuring straylight in age‐related diseases such as cataract.