Computerized method of visual acuity testing: adaptation of the amblyopia treatment study visual acuity testing protocol1☆,

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Abstract

PURPOSE: To report a computerized method for determining visual acuity in children using the Amblyopia Treatment Study visual acuity testing protocol.

METHODS: A computerized visual acuity tester was developed that uses a programmed handheld device that uses the Palm operating system (Palm, Inc, Santa Clara, California). The handheld device communicates with a personal computer running a Linux operating system and 17-inch monitor. At a test distance of 3 m, single letters can be displayed from 20/800 to 20/12. A C program on the handheld device runs the Amblyopia Treatment Study visual acuity testing protocol. Using this method, visual acuity was tested in both the right and left eyes, and then the testing was repeated in 156 children age 3 to 7 years at four clinical sites.

RESULTS: Test-retest reliability was high (r = .92 and 0.95 for and right and left eyes, respectively), with 88% of right eye retests and 94% of left eye retests within 0.1 logarithm of minimal angle of resolution (logMAR) units of the initial test. The 95% confidence interval for an acuity score was calculated to be the score ± 0.13 logMAR units. For a change between two acuity scores, the 95% confidence interval was the difference ± 0.19 logMAR units.

CONCLUSIONS: We have developed a computerized method for measurement of visual acuity. Automation of the Amblyopia Treatment Study visual acuity testing protocol is an effective method of testing visual acuity in children 3 to 7 years of age.

Section snippets

Methods

The Electronic Visual Acuity Tester consists of a handheld device that uses the Palm operating system version 3.5.0 (Palm, Inc, Santa Clara, California) and a personal computer running a Linux operating system and the Super VGA Graphics Library version 1.4.3. The handheld device and personal computer are connected by a serial cable (Figure 1). Stimuli are high-contrast black-and-white letters with luminance of 85 to 105 candelas/m2 and contrast of 98%. Both HOTV and Sloan letter sets are

Results

One hundred fifty-six children were included in the study. One site contributed data on 95 children (61%) and the remaining three secondary sites data on 61 children (39%). The mean age of the children was 5.6 ± 1.4 years; 51% were males and 78% were Caucasian. Seventy-three of the children (47%) had no ocular cause for decreased acuity in both eyes, 60 (38%) had amblyopia in one eye, and the rest had other specified causes for decreased acuity. Most of the amblyopic eyes had only a mild

Discussion

We have developed a personal computer-based visual acuity testing system controlled by a handheld device running the Palm operating system and programmed to run the Amblyopia Treatment Study visual acuity testing protocol. Our results indicate that this testing procedure has very good reliability for the measurement of visual acuity in children 3 to 7 years old. These results are similar to those we obtained when the Amblyopia Treatment Study acuity testing protocol was evaluated with manual

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This work was supported by grants from the National Eye Institute (EY11155, EY11751, EY13095) and Research to Prevent Blindness, Inc, New York, New York, (J.M.H. as R.P.B. Olga Keith Wiess Scholar and an unrestricted grant to the Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota).

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Additional technical information about the Electronic Visual Acuity Tester and the Amblyopia Treatment Study visual acuity testing protocol application can be obtained from the lead author ([email protected]).

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