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Accommodation in infants as measured by photorefraction
H C Howland1, V Dobson, N Sayles
1Section of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853.
Insights
Infant vision accommodation was measured using a new video camera method. Infants adjusted focus appropriately for different distances, showing accommodation speeds similar to adults.
Area of Science:
- Ophthalmology
- Developmental Neuroscience
- Vision Science
Background:
- Accurate visual focus (accommodation) is crucial for infant visual development.
- Previous methods for measuring infant accommodation were limited.
Purpose of the Study:
- To develop and validate a non-invasive video camera photorefractive procedure for on-line monitoring of infant accommodation.
- To investigate infant accommodation responses to various visual targets at different distances.
Main Methods:
- A novel video camera photorefractive technique was employed for remote accommodation measurement (1-2m).
- Twenty-nine infants (2-10 months) were tested with square wave gratings and checkerboard targets at distances from 25cm to 100cm.
- Infants were also exposed to a slowly rotating striped target to assess responses to motion and astigmatism.
Main Results:
- All infants demonstrated appropriate accommodative responses to changes in target distance.
- Infant accommodation speeds reached at least 4.6 Diopters/second, comparable to adult capabilities.
- No systematic accommodative changes were observed in response to the rotating striped target or target type in astigmatic infants.
Conclusions:
- The developed video camera method effectively monitors infant accommodation.
- Infants exhibit robust and adult-like accommodation abilities from an early age.
- Further research is needed to understand specific accommodative responses in infants with astigmatism.
Abstract:
We developed a video camera photorefractive procedure that allows on-line monitoring of accommodation from a distance of 1-2m, and have used it to study accommodation in twenty-nine 2- to 10-month-old human infants. We presented square wave gratings and random checkerboard targets at 25, 33, 50, and 100 cm from the infant. All infants altered their accommodation in the appropriate direction for changing target distances. We also presented infants with a slowly rotating circular striped target. We did not observe any systematic change in accommodation of the astigmatic infants to the rotating striped target, nor any significant change in their accommodation to stationary targets as a function of target type. Measured speeds of accommodation in infants were at least 4.6 D/sec, comparable to that found for adults.