Visual acuity lower when tested at home rather than clinic

Visual acuity (VA) is better when tested in the clinic versus at home, according to a research letter published online Aug. 18 in JAMA Ophthalmology.

Michael D. Crossland, Ph.D., from University College London, and colleagues compared at-home and in-clinic VA using data from the next clinic visit after the home assessment (mean time, 8.8 months) to determine whether differences are due to disease progression. The analysis included 79 adults (mean age, 55 years).

The researchers found that mean VA was 0.80 logMAR (Snellen equivalent 20/125) at home and 0.75 logMAR (Snellen equivalent 20/112) in the clinic. The mean difference between the at-home and in-clinic tests was −0.056 logMAR, with no systematic change observed with level of vision.

“We hypothesized that the poorer home VA values found by ourselves and others might be due to differences in lighting levels, differences in glare or light adaptation, difficulties in understanding the test, differences in motivation without a clinician being present, or perhaps by some psychological effect of being in their own home,” the authors write.

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