title: Effect of head and eye positions on fixation disparities, phorias, and ductions at near.
abstract: This study evaluated the effects of head and gaze position on near fixation disparity, phoria, and duction findings. A population of 104 non-complaining subjects divided by age into 3 groups participated in the study. The primary head and gaze position along with two others approximating the positions used for reading by nonbifocal and bifocal wearers were used. A statistically significant effect was found for the phoria data from the young group, but the magnitude was clinically insignificant. Changes in head and/or gaze positions did not significantly affect fixation disparities or duction recovery ranges. Phorias and fixation disparities showed statistically significant increases in exo deviation with increasing age regardless of head and/or gaze position. Nine of 23 presbyopic subjects gave erratic findings during fixation disparity testing and this casts doubt upon the clinical usefulness of this procedure with presbyopes.
authors.affiliation: College of Optometry, Pacific University, Forest Grove, Oregon.
authors.forename: M C
authors.initials: MC
authors.lastname: McKee
authors.forename: D A
authors.initials: DA
authors.lastname: Young
authors.forename: P
authors.initials: P
authors.lastname: Kohl
authors.forename: A R
authors.initials: AR
authors.lastname: Reinke
authors.forename: R L
authors.initials: RL
authors.lastname: Yolton
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D005260:Female; D005403:Fixation, Ocular; D006257:Head; D006801:Humans; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology*; D011187:Posture; D011305:Presbyopia / Q000503:physiopathology; D013285:Strabismus / Q000503:physiopathology*