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Gregory Hopkins, Angela Brown, Visual Perception Laboratory; Contrast Sensitivity Measurement in the Pediatric Low Vision Setting. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2763. doi: https://doi.org/.
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A new test of contrast sensitivity (CS), the Stripe Cards of Contrast Sensitivity (SCCS) test, can serve as a simple and efficient means for estimating the maximum contrast sensitivity value of a given patient without having to use multiple spatial frequency gratings, and without knowing the spatial frequency at which maximum sensitivity occurs. This test could be useful for a wide range of patients with various levels of visual acuity (VA), ages, and diagnoses.
We measured VA [Bailey-Lovie (BL), Teller Acuity Cards (TAC)] and CS [Pelli-Robson (PR), SCCS] in counterbalanced order of 26 subjects at the Ohio State School for the Blind. Thus, we tested VA and CS using letter charts (BL, PR) and grating cards (TAC, SCCS). Testing distance was 58 cm for the grating cards, and was adjusted based upon nominal visual acuity for letter charts. Subjects used the dominant or better eye only. Letter chart scoring was letter-by-letter with no substitutions. Time of testing was recorded for each test.
Measurements were obtained on 24 (92%) subjects using all four tests. Two additional subjects could not read letter charts, but were able to complete the TAC and SCCS. Median acuity values were: 1.09 [interquartile range (IQR)=0.71-1.41] for B-L, 0.59 [IQR=0.34-0.82] for TAC. Median log CS was 1.38 [IQR=0.81-1.75] for P-R. The SCCS test showed a ceiling effect, with 65% of subjects scoring the maximum CS (1.65); the upper quartile value was 1.35. The subjects with impaired CS on the PR (according the WHO standards, PR<1.65) showed reliably better sensitivity on the SCCS test than the PR test (sign test, p= 0.002, 2-tailed; nonparametric test required because of the ceiling effect on the SCCS). All subjects had impaired VA, and they showed reliably better TAC acuity than logMAR acuity (Paired t-test, p=0.001, 2-tailed, no ceiling effect). Testing times averaged 54 ± 33 sec (B-L) and 96 ± 65 sec for TAC, averaged 61 ± 42 sec for P-R and 58 ± 46 sec for SCCS.
Both of the grating tests (SCCS and TAC) gave better sensitivity than the corresponding letter charts for subjects with reduced vision. For measuring contrast sensitivity in those with reduced vision, the simpler task and bolder patterns of the SCCS may make it more likely to reveal the maximum performance that a given patient can achieve.
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