TY - JOUR
T1 - Analysis of saccades and peak velocity to symmetrical convergence stimuli
T2 - Binocularly normal controls compared to convergence insufficiency patients
AU - Alvarez, Tara L.
AU - Kim, Eun H.
N1 - Copyright:
Copyright 2013 Elsevier B.V., All rights reserved.
PY - 2013
Y1 - 2013
N2 - PURPOSE. To assess the potential peak velocity asymmetry between the left-eye and right-eye movement responses stimulated by symmetrical vergence steps in those with normal binocular vision and those with convergence insufficiency (CI) before and after vergence training. This study also evaluated whether vergence training influenced convergence peak velocity and the prevalence of saccades within the first second of the response. METHODS. The peak velocities of the left-eye, right-eye, and combined vergence response evoked from symmetrical 28, 48, and 68 convergence step stimuli were assessed in 10 controls and 7 CI subjects. Four of the CI subjects participated in vergence training. An asymmetry ratio was calculated as the peak velocity of the slower eye movement response divided by the peak velocity of the faster eye movement response. RESULTS. Controls were significantly more symmetrical (left-eye peak velocity was approximately equal to right-eye peak velocity) compared to CI subjects (P < 0.001). After vergence training, the CI subjects' left-eye and right-eye movements became significantly more symmetrical, convergence peak velocity increased, and the prevalence of saccades within the first 1 second decreased (P < 0.01). Peak convergence velocity was significantly correlated to the prevalence of saccades observed within the first second of the response (r =0.8; P < 0.05). CONCLUSIONS. Data suggest that vergence training improves the symmetry between the left-eye and right-eye movements, increases convergence peak velocity, and decreases the prevalence of saccades within the first second of the response, which facilitates binocular coordination in CI patients. Saccades may be a compensatory mechanism used by CI subjects when convergence peak velocity is reduced.
AB - PURPOSE. To assess the potential peak velocity asymmetry between the left-eye and right-eye movement responses stimulated by symmetrical vergence steps in those with normal binocular vision and those with convergence insufficiency (CI) before and after vergence training. This study also evaluated whether vergence training influenced convergence peak velocity and the prevalence of saccades within the first second of the response. METHODS. The peak velocities of the left-eye, right-eye, and combined vergence response evoked from symmetrical 28, 48, and 68 convergence step stimuli were assessed in 10 controls and 7 CI subjects. Four of the CI subjects participated in vergence training. An asymmetry ratio was calculated as the peak velocity of the slower eye movement response divided by the peak velocity of the faster eye movement response. RESULTS. Controls were significantly more symmetrical (left-eye peak velocity was approximately equal to right-eye peak velocity) compared to CI subjects (P < 0.001). After vergence training, the CI subjects' left-eye and right-eye movements became significantly more symmetrical, convergence peak velocity increased, and the prevalence of saccades within the first 1 second decreased (P < 0.01). Peak convergence velocity was significantly correlated to the prevalence of saccades observed within the first second of the response (r =0.8; P < 0.05). CONCLUSIONS. Data suggest that vergence training improves the symmetry between the left-eye and right-eye movements, increases convergence peak velocity, and decreases the prevalence of saccades within the first second of the response, which facilitates binocular coordination in CI patients. Saccades may be a compensatory mechanism used by CI subjects when convergence peak velocity is reduced.
KW - Convergence
KW - Convergence insufficiency
KW - Eye movements
KW - Saccade
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U2 - 10.1167/iovs.13-11797
DO - 10.1167/iovs.13-11797
M3 - Article
C2 - 23674758
AN - SCOPUS:84879184234
VL - 54
SP - 4122
EP - 4135
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
SN - 0146-0404
IS - 6
ER -