Program in Neuroscience and Mental Health The Hospital for Sick Children

Toronto, Canada

Program in Neuroscience and Mental Health The Hospital for Sick Children

Toronto, Canada
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PubMed | Program in Neuroscience and Mental Health The Hospital for Sick Children and University of Toronto
Type: Journal Article | Journal: Investigative ophthalmology & visual science | Year: 2016

Several behavioral studies have shown that the reaction times of visually guided movements are slower in people with amblyopia, particularly during amblyopic eye viewing. Here, we tested the hypothesis that the initiation of smooth pursuit eye movements, which are responsible for accurately keeping moving objects on the fovea, is delayed in people with anisometropic amblyopia.Eleven participants with anisometropic amblyopia and 14 visually normal observers were asked to track a step-ramp target moving at 15/s horizontally as quickly and as accurately as possible. The experiment was conducted under three viewing conditions: amblyopic/nondominant eye, binocular, and fellow/dominant eye viewing. Outcome measures were smooth pursuit latency, open-loop gain, steady state gain, and catch-up saccade frequency.Participants with anisometropic amblyopia initiated smooth pursuit significantly slower during amblyopic eye viewing (206 20 ms) than visually normal observers viewing with their nondominant eye (183 17 ms, P = 0.002). However, mean pursuit latency in the anisometropic amblyopia group during binocular and monocular fellow eye viewing was comparable to the visually normal group. Mean open-loop gain, steady state gain, and catch-up saccade frequency were similar between the two groups, but participants with anisometropic amblyopia exhibited more variable steady state gain (P = 0.045).This study provides evidence of temporally delayed smooth pursuit initiation in anisometropic amblyopia. After initiation, the smooth pursuit velocity profile in anisometropic amblyopia participants is similar to visually normal controls. This finding differs from what has been observed previously in participants with strabismic amblyopia who exhibit reduced smooth pursuit velocity gains with more catch-up saccades.


PubMed | Program in Neuroscience and Mental Health The Hospital for Sick Children and University of Toronto
Type: Journal Article | Journal: Investigative ophthalmology & visual science | Year: 2015

New behavioral treatment methods, including dichoptic training, perceptual learning, and video gaming, have been proposed to improve visual function in adult amblyopia. Here, we conducted a meta-analysis of these methods to investigate the factors involved in amblyopia recovery and their clinical significance.Mean and individual participant data meta-analyses were performed on 24 studies using the new behavioral methods in adults. Studies were identified using PubMed, Google Scholar, and published reviews.The new methods yielded a mean improvement in visual acuity of 0.17 logMAR with 32% participants achieving gains 0.2 logMAR, and a mean improvement in stereo sensitivity of 0.01 arcsec-1 with 42% of participants improving 2 octaves. The most significant predictor of treatment outcome was visual acuity at the onset of treatment. Participants with more severe amblyopia improved more on visual acuity and less on stereo sensitivity than those with milder amblyopia. Better initial stereo sensitivity was a predictor of greater gains in stereo sensitivity following treatment. Treatment type, amblyopia type, age, and training duration did not have any significant influence on visual and stereo acuity outcomes.Our analyses showed that some participants may benefit from the new treatments; however, clinical trials are required to confirm these findings. Despite the diverse nature of the new behavioral methods, the lack of significant differences in visual and stereo sensitivity outcomes among them suggests that visual attention-a common element among the varied treatment methods-may play an important role in amblyopia recovery.

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