Purpose
<br /> Contrast sensitivity is a fundamental measure of visual function, and obtaining quick and reliable estimates of contrast sensitivity is vital in clinical settings. The quick CSF is an adaptive method that uses Bayesian inference and a trial-to-trial information gain strategy to obtain rapid measurements of contrast sensitivity and to produce an estimate of the entire contrast sensitivity function (CSF) (Lesmes et al Journal of Vision 2010, ARVO 2012 and 2013).The purpose of the present study was to evaluate short term repeatability of CSF parameter estimates using the quick CSF method.
Methods
<br /> Twenty four individuals with normal or mild impaired vision (glaucoma, cataract or age related macular degeneration) participated in the study. Measurements were performed twice with the quick CSF technique in binocular viewing conditions. The CSF was measured with 50 trials and estimates of area under the log CSF (AULCSF), high spatial frequency cutoff (CSF acuity), and contrast sensitivity at 1, 1.5, 3, 6, 12 and 18 cycles per degree (cpd) were obtained (see figure 1). Altman and Bland plots were performed to evaluate the limits of agreement and paired t-tests were performed to assess difference between the first and second measurements.
Results
<br /> The median age of the study participants was 32 years (range 22-76). The figure 2 provides the contrast sensitivity measures obtained in first and second measurement and the limits of agreement as assessed by the Altman and Bland plots. The AULCSF had upper limit of agreement (ULA) -0.18 and lower limit of agreement (LLA) +0.22. The CSF acuity had ULA -7.0 and LLA +10.9 cpd. The t-tests revealed that all parameters, including AULCSF and CS at various cpd, were not significantly different between the first and second sets of measurement (paired t-test p>0.05). However, CSF acuity was significantly higher in the second measurement compared to the first measurement (mean difference 1.95 cpd; paired t-test t-statistic -2.09, p= 0.04).
Conclusions
<br /> The quick CSF provides contrast sensitivity parameters that are repeatable in groups with normal and mild impaired vision.