Abstract
Purpose: :
To compare ocular dominance in pediatric versus adult populations in a large sample of healthy volunteers.
Methods: :
Retrospective review of cross-sectional visuomotor testing results from healthy volunteers. An opportunistic sample of 950 healthy volunteers ages 65 and under with normal intelligence and vision were recruited from multiple community sites. Subjects completed ocular dominance testing by sighting a target at ten feet using the Porta (pointing-a-finger) test first with their right hand followed by their left. We divided subjects into pediatric (ages 5-18 years) and adult (19-65 years) groups for analysis.
Results: :
The entire sample population included 448 (47%) males and 502 (53%) females with a mean age (± SD) of 24.2 ± 14.4 years. Of these, 816 (88%) were right-handed. The pediatric group (n = 409; 43%) included 202 (49%) boys and 207 (51%) girls with a mean age of 11.9 ± 2.8 years. The adult group (n = 541; 57%) had 246 (45%) men and 295 (55%) women with a mean age of 33.5 ± 12.5 years. Right-handed Porta testing identified the right eye as dominant in the majority of subjects (58%; P < .001) and statistically similar proportions of the pediatric (57%) and adult (59%) groups (P = .64). Left-handed testing identified the right eye as dominant in a majority of subjects (54%; P = .011) with equivalent proportions in the pediatric (54%) and adult (54%) groups (P = .90). However, 65 (16%) pediatric subjects who tested right dominant with the right hand tested left dominant with the left hand while 52 (13%) reversed from left to right dominant (P < .001 ). Among adult subjects, 89 (16%) tested right dominant initially with the right hand but left with the left hand while 66 (12%) switched from left to right dominant (P < .001 ).
Conclusions: :
The majority of normal subjects showed right eye ocular dominance on one-handed Porta testing without significant change in proportions between pediatric and adult populations. This was only significant with right-handed testing. Interestingly, the act of switching hands during testing resulted in a change in the dominant eye in a significant number of both young people and adults. Further study with other ocular dominance tests will help assess whether this observation is specific to the Porta test, generalizable to one-handed (as opposed to bimanual) testing, or an innate feature of ocular dominance itself.
Keywords: clinical (human) or epidemiologic studies: prevalence/incidence