Comparison of Two Different Contrast Sensitivity Testing Methods in Patients with Low Vision

PURPOSE: To assess the agreement between two different contrast testing modalities using the index of contrast sensitivity (ICS) in patients with low vision. METHODS: Thirty-eight patients with low vision were included in the study. Contrast sensitivity (CS) was measured binocularly with both the Vector vision-standardized CS test (CSV-1000E, Vector Vision Co, Greenville, Ohio, USA) and the MonPack 3 (Metrovision, France) after refractive correction for each participant. Based on the data from the two tests, the ICS was calculated. The Bland–Altman technique was used to evaluate the agreement between ICSs obtained from different test methods. RESULTS: Range of best corrected visual acuity was 0.50–1.00 logMAR. According to the median logCS values, CS values were highest at 3 cycles per degree (cpd) for the CSV-1000E test and at 1.5 cpd for the Metrovision MonPack 3 test. The median ICS for CSV-1000E was −0.22 (95(th) percentile 4.75), and the median ICS for Metrovision MonPack 3 was 0.08 (95(th) percentile 1.65). The mean difference was 0.655 (between −3.82 and 5.13) within limits of agreement (LoA). The difference and mean values between the two CS test measurements were found to be within LoA range. CONCLUSIONS: An agreement was found between the Metrovision MonPack 3 test and the standard CSV-1000E test results in patients with visual impairment. However, the agreement range was within very wide limits. Therefore, it was thought that they may not be used interchangeability in clinical practice.