Abstract
Purpose: It is now well accepted that contrast sensitivity (CS) is the most comprehensive single measure of human spatial vision and an emerging clinical tool, especially for assessing patients undergoing refractive surgery and those with retinal and neuro-ophthalmic pathology. Despite its scientific and clinical merits, there are few data on the metrics of CS measurement, perhaps most critically, the stability of assessment across time. Here we provide these results for two of the most predominant sine wave based tests of spatial CS. Methods: Using a standard staircase procedure, right eyes from 15 healthy emmetropic adults (18- 53 yr.) were tested 5-10 times repeatedly (M = 2.4 days between tests) with both the FACT (Vistech) and Vector Vision tests under standard photopic conditions. Contrast thresholds at each spatial frequency (1.5 to 18 c/deg) were obtained, with both test and SF order counterbalanced across trials. Given the repeated tests, participants were not given feedback at any point during the procedure. Results: Performance across tests was very consistent for both tests, especially at mid spatial frequencies. On average, adults differed by 0.30, 0.13, 0.15, 0.22 and 0 .29 CS octaves (an octave is a halving or doubling of CS) at 1.5, 3.0, 6.0, 12.0 and 18.0 cy/deg, respectively. ANOVA and post hoc analyses revealed that there were differences between spatial frequency (p < 0.01), with relatively greatest stability at 3.0 and 6.0 cy/deg. Conclusions: At least among those with normal vision, multiple measurements of contrast sensitivity yield highly consistent and stable estimates of spatial vision. In addition to the implications for measurements of contrast sensitivity in lab settings, this result is of critical importance for clinicians as it implies that patient changes in CS during the course of assessment and treatment likely reflects true degradations or improvements in the underlying optical and neural substrate.
Meeting abstract presented at VSS 2017