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J. Vernon Odom, William Reuschel; Determinants of Rankings of Small Display Quality in Normally Sighted Persons and Persons with Low Vision Due to Diabetic Retinopathy.. Invest. Ophthalmol. Vis. Sci. 2014;55(13):4152.
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© ARVO (1962-2015); The Authors (2016-present)
To assist development of a simplified metric for small visual displays of use to low vision patients, we evaluated consumers’ rankings of display quality of glucometers under two lighting conditions.
Two groups, 10 normally sighted and 10 low vision patients with diabetic retinopathy ranked the displays of 8 glucometers from best=1 to worst=8 under two light levels, in room light (480 lux) and in sunlight (15,000 lux). The normalized font size (NFS) and contrast (NC) of the 8 devices were assessed under the two lighting conditions. A preliminary metric, DeviceRating (D-R), was calculated using NFS and NC. Subjects’ age, visual acuity (VA; ETDRS) and contrast sensitivity (CS; MARS) were determined. The normally sighted group was aged 68.6 ± 5.97 years with corrected VA of 0.15 ± 0.14 logMAR and log CS of 1.7 ± 0.1. The visually impaired group was aged 59.8 ± 11.74 years with corrected VA of 1.04 ± 0.41 logMAR and log CS of 0.95 ± 0.28. Subjects ranked the visual displays of 8 glucometers. Subjects rankings were evaluated using Spearman Rank Order Correlations (rho), logistic regressions, and a three factor ANOVA (Group, Lighting, and Device) were used to interpret the rankings.
The ANOVA failed to indicate a significant main effect of Group or Lighting as did rho and logistic regression (p>0.50). However, there was a significant main effect of Device (p<0.00005) and significant interaction terms for DevicexLighting (p<0.00005) and DevicexGroup (p=0.001658). Similarly logistic regressions indicated significant effects of Device (p<0.001), D-R (p<0.04) and NC (p<0.05). The only significant correlations with Ranking were D-R and NC (p<0.05).
Subjects rank the displays of glucometers, small panel devices frequently used by low vision patients, differently. Relative rankings are not affected by patient characteristics such as age, VA, or CS. Differences in Device rankings varied by Lighting and by Group, presumably because NC was reduced in higher Lighting and reduced contrast affected the low vision diabetic patients more than the normally sighted.
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