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Jonathan Hernandez-Siman, Donald Calvin Fletcher, Laura Walker, Manfred MacKeben; Validation of Reduced Contrast SKread Test. Invest. Ophthalmol. Vis. Sci. 2016;57(12):1944. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
To validate a reduced contrast version of the Smith-Kettlewell reading test (SKread) as a functional vision tool in patients with low vision.
59 low vision patients in their initial low vision rehabilitation evaluation had EDTRS visual acuity, LH contrast sensitivity, MNread, SKread and a new 20% low contrast version of the SKread test (20% Michaelson, 11% Weber) performed. Errors per 47 character block of words for the 3 reading tests were calculated and compared. The same measurements were obtained in 11 control subjects with normal vision.
Patient age median/range was 81/43-97 in the low vision group and 57/31-86 in the control group. In the low vision patients, visual acuity median (range) was 20/110 (20/42 to 20/505) and contrast sensitivity (x/30) median (range) was 15 (5-25) shapes. All subjects in the control group had better than 20/40 acuity and 30/30 contrast sensitivity. In the low vision group, error rates per block mean/range were MN Read (high contrast) 0.3/0-2, SK Read (high contrast) 3.4/0-14, and SK Read (low contrast) 4.9/0-15. In the control group, error rates per block mean/range were MNread (high contrast) 0.2/0.1-.3, SKread (high contrast) 0.3/0-0.8, and SKread (low contrast) 0.4/0-0.8. There was good test-retest reliability in the control group. In the low vision group, there were moderate correlations of visual acuity (r = 0.6) and contrast sensitivity (r = 0.4 to 0.6) with error rates in each of the 3 reading tests.
Reduced contrast tests may better simulate real world conditions and reveal functional deficits. This is particularly true for older individuals with declining contrast sensitivity and those with maculopathy. The new low contrast SKread test induces more errors, the patterns of which are useful for understanding how central scotomas interfere with reading function. The control group exhibited stable test-retest reliability on all tests. The unexplained variance in low vision patient performance on the reduced contrast SKread may be related to scotoma interference factors that can be addressed during rehabilitation therapy.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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