Abstract
Purpose:
To compare performance of astigmatic students on the Beery VMI Developmental Test of Visual Perception while wearing best correction and while uncorrected.
Methods:
Subjects were third through eighth grade Tohono O'odham students, who have a high prevalence of astigmatism. An eye examination which included measurement of refractive error (subjectively refined cycloplegic autorefraction) was performed on each student. The Beery VMI Developmental Test of Visual Perception was administered on two separate dates once with best correction and once uncorrected. Order of testing was randomly selected. Testing was conducted binocularly. Standardized testing forms were used and administration and scoring was conducted per the BEERY VMI Manual. Raw scores were converted to age based standardized score (mean = 100, SD = 10). Students were categorized as having moderate (1 to < 3D) or high (>/= 3D) astigmatism based on astigmatism magnitude in their least astigmatic eye. Repeated measures analysis of variance compared performance with correction vs. without correction across astigmatism groups while controlling for test order.
Results:
The final sample included 195 students (109 moderate astigmats, 86 high astigmats). There was a significant effect of correction, with students scoring better with than without the spectacles (97.82 (SD 12.2) vs 95.01 (SD 14.25), p = 0.006). There was no significant effect of astigmatism magnitude. However, there was a significant interaction between correction and testing order. For students who completed the test with their correction first, there was no significant difference between performance when corrected and when uncorrected (98.75 (SD 11.12) vs. 99.09, (SD 12.14)). For students who completed the test uncorrected first, performance when corrected (97.00, SD 12.74) was significantly better than when uncorrected (91.43, SD 15.04, p < 0.001).
Conclusions:
The results indicate that uncorrected refractive error, particularly astigmatism, may significantly reduce scores on the BEERY VMI Developmental Test of Visual Perception. However, when correction was worn, average scores in the astigmatic sample approached the standardized score mean of 100. Strategies students developed while performing the test first with their best-correction may have improved performance when uncorrected.