Abstract
Purpose: :
To determine if changes in accommodation in young children can be measured with the Pediatric Wavefront Evaluator (PeWE), an open field Shack-Hartmann sensor based continuously recording aberrometer.
Methods: :
Non-cycloplegic measurements of refractive error were obtained with the PeWE open field wavefront sensor while 68 children (mean age 4.7 years, range 3.0 to 7.0 years) binocularly viewed a cartoon at near (50 cm) and at distance (200 cm). The difference between spherical equivalent (M), J0, and J45 measurements for near and distant fixation were calculated for the right eye of each subject to determine if the children were viewing targets through the instrument as instructed, to determine if PeWE is sensitive enough to measure their changes in accommodation with viewing distance, and to determine if viewing distance influenced astigmatism measurements. With a change in target distance from 50cm to 200cm, a change of 1.50D in M would be expected if subjects are accurately changing their accommodation with viewing distance. Change in astigmatism would not be expected.
Results: :
For the sample, mean right eye M, J0, and J45 was -1.11 (SD 1.27), 0.62 (SD 0.38), and -0.17 (SD 0.17) for near fixation measurements and -0.08 (SD 1.5), 0.58 (SD 0.37), and -0.16 (SD 0.14) for distant fixation measurements. Mean difference between M for near vs distant fixation was significant (mean difference 1.03 D (SD 0.88), p < 0.001). Mean difference between near and distant measurements of J0 (-0.04) and J45 (0.01) were not significant.
Conclusions: :
Comparison of measurements at near and distance indicates that children are viewing stimuli through the open field instrument and that the PeWE is sensitive enough to detect changes in accommodation with changes in target distance. Ongoing research is utilizing the PeWE to examine the relation between lower order aberrations, higher order aberrations, and patterns of accommodation in astigmatic and non-astigmatic infants and children from age 6 months through 7 years.
Keywords: astigmatism • refraction • accommodation