Assessment of visual acuity in the supine position

Abstract

Objective: To determine whether a modified Snellen eye chart could be used to accurately assess visual acuity (VA) in the supine position. Method: This was a prospective study involving ED staff volunteers comparing VA on a standard Snellen eye chart with VA on a size-reduced ceiling-mounted modified Snellen eye chart. Results: Fifty-six volunteers participated. VA ranged from 20/10 to 20/200 on both of the charts, but 87% of the volunteers had VA of 20/50 or better. The VA results for the 2 charts were highly correlated; right eye r = 0.931 and left eye r = 0.953. Weighted κs showed substantial agreement for both eyes; κ = 0.63 and 0.79 for the right and left eyes, respectively. In only 4 of 112 paired measurements did the VA recorded with the ceiling chart differ by >1 line from that recorded on the Snellen chart. Conclusion: There is an excellent correlation between VAs determined in the erect and the supine positions using the standard Snellen eye chart and the modified ceiling-mounted version. Substantial agreement exists between readings using the 2 charts. Although additional testing is warranted in an ophthalmologically diverse patient population, use of this chart for the assessment of VA in the supine ED patient may allow for earlier VA evaluation.