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ABIGAIL R. KRAFT, Alyssa M Gehring, Richard W Hertle, Tawna L Roberts; Repeatability of Contrast Sensitivity in Patients with Infantile Nystagmus Syndrome Using the CSV-1000R. Invest. Ophthalmol. Vis. Sci. 2019;60(9):532. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To assess the test-retest reliability of contrast sensitivity in patients with Infantile Nystagmus Syndrome (INS).
Test-retest contrast sensitivity (CS) was measured binocularly in 20 INS patients (17.8 years; 8-64) and 20 age-matched visually normal control subjects (19.6 years, range 8-62) using the CSV-1000R. CS was evaluated at four spatial frequencies (3, 6, 12, and 18 cycles per degree [cpd]). Each spatial frequency had 8 contrast levels with an average inter-stimulus decrease of 0.15 log units. Spatial frequencies were displayed in 2 rows with the test pattern in the top or bottom row (2 alternative forced choice). All levels were presented to each subject. Contrast threshold was defined as the level immediately prior to the first misidentified pattern. Test-retest reliability was assessed using Bland-Altman plots and the 95% limits of agreement (LOA) and intraclass correlation coefficients (ICC).
The absolute difference in test-retest in CS scores for each spatial frequency (3, 6, 12, 18 cpd) was 0.2±0.2, 0.3±0.3, 0.3±0.3, and 0.1±0.2 log units for INS subjects and 0.1±0.1, 0.1±0.2, 0.2±0.3, and 0.1±0.3, log units for control subjects, respectively. INS subjects had a greater absolute difference in test-retest than controls at 3 cpd (p=0.047). The upper and lower limits of the 95% LOA for each spatial frequency were greater in INS subjects for 3 [INS: -0.40, 0.56; CS: -0.28, -0.35], 6 (INS: -0.90, 0.80; CS: -0.31, 0.46), and 12 (INS: -0.78, 0.83; CS: -0.55, 0.66) cpd. Control subjects had slightly greater 95% LOAs at 18 cpd (INS: -0.41, 0.53; CS: -0.44, 0.59). ICCs were moderate at 3 (0.66) and 6 (0.68) cpd, and high at 12 (0.79) and 18 (0.86) cpd.
INS subjects had a significantly greater absolute difference in contrast sensitivity test-retest compared to control subjects at 3 cpd. Despite having moderate to high reliability measures using ICC, the 95% LOA was ≥0.94 log units for INS patients and ≥0.63 log units for control subjects, which equates to approximately 6 and 4 levels on the chart, respectively. Our results suggest that despite INS patients and control subjects having similar test-retest reliability, CS testing using the commercially available CSV-1000R has larger 95% LOA than desired as a measure of CS in a potential clinical trial.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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