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Assessment of visual processing functions and disorders
Published in John Ravenscroft, The Routledge Handbook of Visual Impairment, 2019
Processing functions of pictures of concrete objects (LEA symbols, used in early examinations) and letters are processed in different networks and thus VA values can be different if these networks are differently damaged. Visual acuity should be measured with both types of tests with abstract optotypes: letter and number optotypes, as soon as the child learns them. This is now possible with the visual acuity test: “FOUR tests in ONE” with tests based on the four Sloan letters, the four LEA numbers, and the four LEA symbols and the international reference optotype, four Landolt-Cs.
Contrast Sensitivity in Early to Intermediate Age-Related Macular Degeneration (AMD)
Published in Current Eye Research, 2022
William H. Ridder, George Comer, Caren Oquindo, Pat Yoshinaga, Michael Engles, James Burke
A recent report which agrees with our results has suggested that intermediate AMD patients may have a decrease in CS under mesopic (0.9 cd/m2) and photopic conditions (90 cd/m2).18 Early AMD patients were not investigated. This study used band-pass filtered Sloan letters with the quick CSF system to measure CS. The qCSF algorithm employed to estimate the CS function resulted in a much lower overall CS for subjects than our method. The peak CS for normal subjects was 32 compared to 94.6 in the present study. Because of the different methods employed, direct comparisons between the present results and this publication are not possible.
Does Early Glasses Wear Improve Visual Outcome in OCA1A?
Published in Journal of Binocular Vision and Ocular Motility, 2021
Laura May, Kimberly Merrill, John E. Connett, C. Gail Summers
Binocular BCVA was measured with a logMAR chart with Sloan letters as monocular testing with occlusion or fogging can increase nystagmus and diminish acuity; it also produces an artificial environment. Binocular BCVA was recorded at distance only as near convergence and accommodation may vary by patient and age at follow up leading to variation in measurement of near acuity. All patients were wearing glasses with most recent cycloplegic refraction at examination and were allowed to use their preferred head posture.
Instant vision assessment device for measuring refraction in low vision
Published in Clinical and Experimental Optometry, 2021
The Lighthouse Modified ETDRS with Sloan letters charts l, 2 and 3 were used to measure visual acuities at 4 m and were randomised among the refraction methods. If the subjects did not see any letters at 4 m, the charts were moved to 2 m. The subjects read from the first line of the chart until the smallest letter that could not be seen. The visual acuities were scored as logMAR units with each letter equal to 0.02 logMAR units.