Effect of vision-based treatments on visual acuity and motor function in children with amblyopia
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Purpose: To investigate existing as well as novel vision-based treatments in children with amblyopia and determine the utility of motor function as a potential outcome measure. Methods: Three experiments were conducted. Experiment 1 was a meta-analysis that initially found 3346 articles through a comprehensive literature search in Ovid Embase, PubMed, the Cochrane Library, Vision Cite, and Scopus. The search was for randomized clinical trials (RCTs) from 1975 to June 2020 and investigated improvement in visual acuity (VA) of the amblyopic eye. The population was patients aged 4 – 17 years old with amblyopia undergoing vision-based treatment. Two independent reviewers narrowed the results to 36 articles. Meta-analyses and a meta-regression were conducted on a subset of these RCTs in order to determine if any one vision-based treatment was superior at improving VA of the amblyopic eye. The goal of Experiment 2 was to characterize the types of motor function deficits seen in children (aged 3 - >7) with amblyopia and binocular vision problems (anisometropia without amblyopia, and strabismus without amblyopia), compared to controls. A total of 64 participants were recruited. Visual acuity (HOTV), stereopsis (Randot Preschool Stereoacuity Test), suppression (Worth 4 dot test) and motor function scores were assessed (Movement Assessment Battery for Children 2nd edition). Experiment 3 involved developing a binocular video treatment for use in a multi-site RCT. This treatment aimed for children aged 3 – 6 with amblyopia was created by transforming an existing cartoon (Q Pootle 5, provided by the British Broadcasting Corporation) into a dichoptic format. The goal was to create a video treatment that inspired high adherence rates and could separate specific, key characters between the eyes. Results: In Experiment 1, of the 3346 studies identified, 36 were included in a narrative synthesis. A random effects meta-analysis (five studies) compared the efficacy of binocular treatments versus patching: mean difference −0.03 logMAR; 95% CI 0.01 to 0.04 (p<0.001), favouring patching. An exploratory study-level regression (18 studies) showed no statistically significant differences between vision-based treatments and a reference group of 2–5 hours of patching. Age, sample size and pre- randomisation optical treatment were not statistically significantly associated with changes in amblyopic eye acuity. A network meta-analysis (26 studies) comparing vision-based treatments to patching 2–5 hours found one statistically significant comparison, namely, the favouring of a combination of two treatment arms comparing combination and binocular treatments, against patching 2–5 hours: standard mean difference: 2.63; 95% CI 1.18 to 4.09. However, this result was an indirect comparison calculated from a single study. A linear regression analysis (17 studies) found a significant relationship between adherence and effect size, but the model did not completely fit the data: regression coefficient 0.022; 95% CI 0.004 to 0.040 (p=0.02). In Experiment 2, An ANCOVA did not find a significant main effect of patient group on total motor function standard scores F(2, 51) = 1.59, p = 0.82). None of the covariates (visual acuity and stereopsis) were significantly associated with total motor function scores (lowest p = 0.42). When investigating the sub-categories of the MABC-2, one-way ANOVAs showed no significant effect of group for manual dexterity, catching and throwing, and balance scores. A novel binocular treatment was developed from the ground up for Experiment 3. The resulting treatment separated key characters and/or items between the eyes, to ensure that the use of the amblyopic eye was essential for the patient to understand each scene. The cartoon was successfully ported to the New Nintendo 3DS XL, a handheld device that allows dichoptic videos to be shown without the need for glasses. This treatment is distinct from previous video treatments in the literature and we hypothesize that it will improve visual acuity of the amblyopic eye, stereopsis and fine and gross motor function skills in children with amblyopia. Conclusion: Clinicians have many available options for treatment that are just as efficacious as patching for 2-5 hours. This includes the possibility of binocular treatments, which may also improve stereopsis. More research on symptoms other than just visual acuity, such as motor function, should be further investigated in patients with amblyopia in order to provide a complete healthcare plan.
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Taylor Brin (2021). Effect of vision-based treatments on visual acuity and motor function in children with amblyopia. UWSpace. http://hdl.handle.net/10012/17222