Amblyopia is a common visual disorder that is treatable in childhood. However, therapies have limited efficacy in adult patients with amblyopia. Fluoxetine can reinstate early-life critical period-like neuronal plasticity and has been used to recover functional vision in adult rats with amblyopia. We conducted a Phase 2, randomized (fluoxetine vs. placebo), double-blind, multicenter clinical trial examined whether or not fluoxetine can improve visual acuity in amblyopic adults. This interventional trial included 42 participants diagnosed with moderate to severe amblyopia. Subjects were randomized to receive either 20 mg fluoxetine (n = 22) or placebo (n = 20). During the 10-week treatment period, all subjects performed daily computerized perceptual training and eye patching. At the primary endpoint, the mean treatment group difference in visual acuity improvement was only 0.027 logMAR units (95% CI: −0.057 to 0.110; p = 0.524). However, visual acuity had significantly improved from baseline to 10 weeks in both fluoxetine (−0.167 logMAR; 95% CI: −0.226 to −0.108; p < 0.001) and placebo (−0.194 logMAR; 95% CI: −0.254 to −0.133; p < 0.001) groups. While this study failed to provide evidence that fluoxetine enhances neuroplasticity, our data support other recent clinical studies suggesting that improvement of vision can be accomplished in adults with amblyopia.
(1) Strabismus has an impact on individuals’ health-related quality of life. The impact should be assessed with valid patient-reported outcome measures such as the Adult Strabismus Questionnaire (AS-20). The AS-20 was further refined using a Rasch analysis for the American population. The aims of the study were to translate and culturally adapt the AS-20 into Finnish and to evaluate the psychometric properties of the Finnish AS-20. (2) The guidelines of the Professional Society for Health Economics and Outcomes Research steered the process and four items were added from the original data as Finnish additions. The construct and convergent validity and internal consistency were evaluated via psychometric testing for three potential Finnish AS-20 structures. The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) checklist was applied. (3) The participants (n = 137) reported that the translation was clear and understandable. All structures showed high reliability and internal consistency as measured using Cronbach alpha values. The convergent validity assessed using Spearman’s correlation coefficients between the structures and one item of Satisfaction with Life Scale indicated very low to moderate positive correlations. The construct validity evaluated using a confirmatory factor analysis revealed the refined AS-20 structure to be satisfactory. (4) The refined AS-20 can be used in clinical practice and research, but further validation is recommended.
Amblyopia is a developmental disorder associated with abnormal visual experience during early childhood commonly arising from strabismus and/or anisometropia and leading to dysfunctions in visual cortex and to various visual deficits. The different forms of neuronal activity that are attenuated in amblyopia have been only partially characterized. In electrophysiological recordings of healthy human brain, the presentation of visual stimuli is associated with event-related activity and oscillatory responses. It has remained poorly understood whether these forms of activity are reduced in amblyopia and whether possible dysfunctions would arise from lower- or higher-order visual areas. We recorded neuronal activity with magnetoencephalography (MEG) from anisometropic amblyopic patients and control participants during two visual tasks presented separately for each eye and estimated neuronal activity from source-reconstructed MEG data. We investigated whether event-related and oscillatory responses would be reduced for amblyopia and localized their cortical sources. Oscillation amplitudes and evoked responses were reduced for stimuli presented to the amblyopic eye in higher-order visual areas and in parietal and prefrontal cortices. Importantly, the reduction of oscillation amplitudes but not that of evoked responses was correlated with decreased visual acuity in amblyopia. These results show that attenuated oscillatory responses are correlated with visual deficits in anisometric amblyopia.
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