This prospective study found that a new visual acuity test that uses hand gesture optotypes could be a viable option for pediatric patients.
The authors tested the Handy Eye Chart in 16 consecutive patients between the ages of 6 and 18 years presenting for eye examinations at a university-based pediatric ophthalmology center. All patients were deemed capable of undergoing visual acuity testing with the ETDRS chart and had visual acuity of 20/16 to 20/200 in at least one eye as determined by the ETDRS chart.
To follow the recognized standard, the new eye chart was designed in the logarithmic linear format of the ETDRS chart. Four symbols representing the "thumbs-up," "circle," "palm," and letter "C" hand gestures were used as optotypes. Each row on the new chart contains five optotypes, including at least one of each of the four symbols. The order in which the symbols are presented on each line was randomized. The optotypes are spaced proportionally, and the lines progress in 0.1 log unit steps from 20/16 logMAR to 20/200 at a viewing distance of 10 feet. Therefore, the optotypes on each line are approximately 1.26 times the height of the optotypes on the next lower line. The vertical distance between adjacent rows is equal to the height of the row below (e.g., the smaller of the two rows).
Distance visual acuity was determined monocularly using both the gold-standard ETDRS chart and the new chart, alternating the order of administration between patients. The worse-seeing eye of each patient was tested to obtain a sample across a wide range of visual acuities without fatiguing the children. Visual acuity was measured on both charts by a single examiner who was not masked to the results of the first test when conducting the second. The chart stand was positioned at a distance of 10 feet from the examination chair.
For both charts, the tester asked the subject to identify the optotypes on a single line two lines larger than the most recently recorded acuity, from left to right. Acuity was scored as the total number of optotypes identified correctly. In addition, for each optotype identified incorrectly, both the symbol that was given as a response and the symbol that was missed were noted.
There was a strong linear correlation of 0.95 between the charts. On average, children scored 0.03 ± 0.08 logMAR (1.5 letters) better on the ETDRS than on the new chart over the range of acuities tested.
The authors conclude that although this study demonstrated potential for use of the new eye chart in children aged 6 to 18 years, additional study is required to see how the optotypes perform when presented in isolated fashion and when introduced to the population of children for whom they were intended (younger, nonverbal, and developmentally delayed children.