Purpose: The accommodation and vergence systems are used to enable individuals to have clear and single vision. These two systems are underdeveloped at birth but undergo rapid maturation during the first year of life. The primary aim of this study was to determine if the association between accommodation and vergence motor responses is adult-like during the first 10 months of life.
Methods: Eighty subjects were recruited to be followed longitudinally at 4 consecutive study visits for the following age windows: 3- to 4.5-months (VW1), 7- to 10-months (VW2), 18- to 20-months (VW3) and 36- to 40-months of age (VW4). Data from VW1 and VW2 were analyzed for the purpose of this effort, as all subjects have not aged up to the final two visit windows. Accommodation and vergence were measured simultaneously using eccentric photorefraction and Purkinji image eye tracking, while the subjects tracked a moving age-appropriate cartoon movie between positions at 1.10 diopters (D) or meter angles (MA) and 2.85 D or MA during binocular viewing. Correlations between the two motor systems were calculated at each visit window and compared to 5 adult control subjects with normal binocular vision.
Results: Mean calculated correlations increased between the two infant study visits but were not adult-like by 7- to 10-months of age (VW1: x-bar = 0.50, SD = 0.17; VW2: x-bar = 0.62 (SD = 0.15); adult controls: x-bar = 0.83, SD = 0.05). Regression analysis suggested that refractive error was not predictive of the calculated correlations, R2 = 0.045 at VW1 and R2 = 0.016 at VW2.
Conclusions: The accommodation and vergence systems in human infants mature rapidly during the first year of life. However, by 10-months of age the association between the two systems is not adult-like for moving stimuli during binocular viewing. The infant subjects experienced more drifts in accommodation, increased instability of both accommodation and vergence, and more prominent under- and over-shoots.
|Advisor:||Candy, T. Rowan|
|Commitee:||Burns, Stephan A., Lyon, Don W.|
|School Location:||United States -- Indiana|
|Source:||MAI 52/06M(E), Masters Abstracts International|
|Subjects:||Ophthalmology, Developmental biology|
|Keywords:||Accommodation, Pediatric, Vergence|
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