Abstract
Purpose: :
To compare the results of fixation preference testing and standardized visual acuity testing in White and African-American children aged 30 through 71 months.
Methods: :
The Baltimore Pediatric Eye Disease Study is a population-based cross-sectional evaluation of the prevalence of vision disorders in children aged 6 through 71 months in Baltimore, Maryland, United States. 2,546 preschool children were examined and a total of 1,714 children 30 through 71 months of age were eligible for inclusion in this report. The vision of all eligible children was tested using both the Amblyopia Treatment Study (ATS) visual acuity testing protocol (using single HOTV symbols with surround bars) and fixation preference testing (FPT). 1,435 children (83.7%) were testable by both fixation preference and ATS visual acuity methods.
Results: :
Fifty-three children had two or more lines of inter-ocular differences (IOD) in visual acuity. Seven of them were graded as having "Momentary" or "No Fixation" (sensitivity =13.2% [95% CI = 5.3, 27.2]), while 45 were graded as "Normal" by FPT. In all 7 of the cases of poor FPT, the better-seeing eye was preferred. Low sensitivity and high specificity for detecting an IOD of two or more lines with FPT were seen for both White (33.3% sensitivity [95% CI = 9.5, 57.2)], 99.6% specificity [95% CI = 98.7, 100]) and African American (6.5% sensitivity [95% CI = 0.6, 23.2], 99.3% specificity [95% CI = 98.3, 99.8]) children. When assessing FPT performance for 3 or more lines of IOD, only 5 of the 20 children (sensitivity = 25% [95% CI = 6.0, 44.0]) had FPT grades of "Momentary" or "No Fixation".
Conclusions: :
FPT, when used as part of a population-based research project, does not accurately identify preschool children with two or more lines of interocular difference in presenting visual acuity. The clinical value of this test is poor and its use for diagnosis and monitoring interventions should be reconsidered.
Keywords: visual acuity • amblyopia