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John Robson, Raju Sapotka, John Kidd, Douglas Newman, Shahina Pardhan; Self-assessment of visual function using new single-use printed charts.. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© 2017 Association for Research in Vision and Ophthalmology.
It is desirable that the progress of degenerative retinal diseases should be continuously monitored so that therapeutic intervention can be instituted in a timely manner. We are investigating the possibility that this could be achieved by self-assessment of contrast sensitivity (or other visual function) using simple printed paper charts that can be used by subjects in their own homes.
Subjects view at reading distance a printed paper chart that displays a series of round patches whose Weber contrast progressively reduces by 0.05 log units. Subjects are required to show which patches they can see by correctly marking the location of the patches on the chart. Once the chart has been marked it is scored using a transparent template showing the correct locations. Contrast sensitivity is reported as the reciprocal of the contrast of the faintest patch whose location is marked correctly. The variability of contrast sensitivity measurements has been examined in many subjects (both normal and impaired vision) who made two contrast sensitivity estimates (test/retest), or a smaller number of normal subjects making multiple estimates (12) on different versions of the chart with patches placed in different randomised locations.
Test/retest measurements indicate that there is only a negligible learning effect (the mean retest contrast sensitivity is less than 0.02 log units greater than the initial test value) while the standard deviation of the differences between the test and retest values is less than about 0.08 log units, indicating an underlying standard deviation of less than 0.06 log units for single determinations of contrast sensitivity. This value is consistent with the variability seen with multiple repeated measurements in normals. Comparison of the contrast sensitivity and visual acuity of a group of patients with AMD at various stages shows a high degree of correlation between these two measures of visual function indicating that, in this case, a measurement of contrast sensitivity could be at least as useful in assessing progression as a measurement of acuity.
Contrast sensitivitycan be satisfactorily measured in the home using the 'NuBlobs' charts. Measurements of contrast sensitivity are preferred to acuity measurements because they are less dependent upon the subject's refractive state and working distance. The charts can be used for different visual conditions.
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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