Test-retest Repeatability of the Ohio Contrast Cards.

SIGNIFICANCE: The Ohio Contrast Cards are a repeatable test of contrast sensitivity, and they reveal higher contrast sensitivity for low-vision patients than is shown by the Pelli-Robson chart. PURPOSE: This study aimed to compare the contrast sensitivity results and test/retest ±limits of agreement for the Ohio Contrast Cards and the Pelli-Robson letter contrast sensitivity chart on two challenging groups of participants, and to compare the Ohio Contrast Card results with grating acuity and the Pelli-Robson results with letter acuity. METHODS: The Ohio Contrast Card and Pelli-Robson tests were each performed twice by two different examiners within one visit on 40 elder patients in Primary Vision Care (>65 years old) and 23 to 27 low-vision school-aged students. Grating acuity was measured using the Teller Acuity Cards (all participants), and letter acuity was measured using ClearChart (elders) or the Bailey-Lovie chart (students). RESULTS: The ±95% limits of agreement were similar for the Ohio Contrast Cards and the Pelli-Robson chart. The elders' limits of agreement were ±0.27 (Ohio Contrast Cards) and ±0.28 (Pelli-Robson); the students' limits of agreement were ±0.42 (Ohio Contrast Cards) and ±0.51 (Pelli-Robson). However, Ohio Contrast Card results were 0.41 log10 Michelson units more sensitive than the Pelli-Robson chart (over one line on the Pelli-Robson chart) for the elders and 0.90 log10 Michelson units (three lines on the Pelli-Robson chart) more sensitive for the elders (0.11 and 0.6 log10 Weber units, respectively). The Pelli-Robson results were correlated with letter acuities and Ohio Contrast Card results for both groups, and the Ohio Contrast Card results were correlated with Teller Acuity Card acuities for the elders. CONCLUSIONS: The Ohio Contrast Cards and Pelli-Robson chart are similarly repeatable. Both contrast sensitivity tests can provide additional clinical information that is not available through visual acuity testing, and Ohio Contrast Card may provide additional information not available from the Pelli-Robson chart.

The Effect of Test Distance on Visual Contrast Sensitivity Measured Using the Pelli-Robson Chart.

Purpose: The Pelli-Robson (PR) chart is widely used to measure clinical contrast sensitivity (CS). It is generally believed that PR testing distance is not critical. Here, we examine whether a closer test distance than the usual 1 meter might be better for patients with low vision. Methods: PR CS was measured on two groups: low-vision students (<20 years old) and elder patients (>65 years old). Student PR was measured at 1 meter and at a closer distance d = visual acuity in log10cy/deg (d = 1.5-logMAR). Elder PR was measured at 1 and 3 meters. Grating CS was also measured using the Ohio Contrast Cards (OCCs). Results: Average CS was 0.398 log10 units (over one line on the PR chart) higher at the closer distance than at 1 meter for the students, but there was no effect of 1 vs. 3 meters test distance for the elders. The equivalent spatial frequencies of the PR letters at 1 meter were near the acuity limits of students with low vision, but were near the peak of the elders' CS functions. Especially for students with low vision, PR CS was below OCC CS, even when PR was tested at a closer distance. Conclusions: PR CS should be measured at a distance in meters that is equal to the patient's letter acuity in cy/deg, or 1.5-logMAR. Translational Relevance: Contrast sensitivity is highly associated with quality of life, and it is important to measure it accurately. Using a closer distance, or measuring grating CS, can reveal visual abilities missed when patients with low vision are tested using PR at 1 meter.