Feasibility and comparison of visual acuity testing methods in children with neurofibromatosis type 1 and/or optic pathway gliomas.

PURPOSE: Longitudinal ophthalmologic clinical trials in young children require multiple visual acuity (VA) testing methods-especially when the subjects have cognitive and developmental delay. This study evaluated the success rate and comparability of two different VA testing methods in children with neurofibromatosis type 1 (NF1) and/or optic pathway gliomas (OPGs).

METHODS

Two institutions prospectively enrolled children 10 years or younger with NF1 and/or an OPG. Both Teller grating acuity (TAC) and recognition acuity using the computerized version of the Amblyopia Treatment Study VA testing protocol that limits responses to four letters (H, O, T, or V) were attempted in all subjects. The association of age and diagnosis of NF1 on success rate was analyzed. Differences in grating and recognition acuity were compared.

RESULTS

One hundred twenty-seven children met inclusion criteria (median age = 5.58 years). Of 127 subjects, 11 (8.7%) could not complete monocular TAC testing in either eye; 39 (30.7%) could not complete HOTV testing and were younger than those able to complete HOTV testing (mean = 2.9 vs. 7.0 years, respectively; Z = -8.3, P < 0.01). Older age was associated with successful HOTV testing and remained significant in all regression analyses (P < 0.01). The within-subject logMAR values for TAC and HOTV testing results were significantly correlated (r = 0.69, P < 0.01).

CONCLUSIONS

Young children with NF1 and/or OPGs were frequently unable to complete recognition acuity testing. These factors are important to consider when designing a clinical trial for children with NF1 and/or OPGs.