Binocular Vision Anomalies: An Update on Prevalence, Impact, Technological and Treatment Developments and Current Challenges

PURPOSE: To identify key recent research in the field of binocular vision anomalies, highlight important advances and identify where new developments are emerging. This allows identification of gaps in our knowledge, which may inform future research efforts. METHODS: A narrative review of the peer-reviewed literature on amblyopia, strabismus and non-strabismic binocular vision anomalies (NSBVA) was carried out under the following headings: prevalence, impact and new developments (e.g., in technology, treatment and disease understanding). RESULTS: The prevalence of amblyopia and strabismus continues to be studied intensively in different geographical regions and amongst different ethnicities, with results revealing large variations in rates of esotropia versus exotropia. Studies of NSBVA prevalence frequently suffer from major methodological limitations, leaving uncertainty about their prevalence and impact. This stems from variability in diagnostic criteria and an uncertain link between the conditions and the symptoms generated. There has been an upsurge in evaluations of the impact of strabismus and amblyopia. Along with their effect on vision, changes are seen in visuomotor and other functional task performance (e.g., reading). Additionally, there are important psychosocial impacts (e.g., in self-confidence), particularly when strabismus is present. Digital applications are emerging for both detecting and treating binocular anomalies, although much remains to be done to establish their acceptability to patients and overall usefulness. The quality of the research evidence guiding amblyopia treatment is much stronger than for strabismus, where evidence for the treatment of the condition is still lacking. CONCLUSIONS: With greater awareness of the need for robust research evidence, the knowledge gaps concerning binocular vision anomalies are becoming clearer. As high-quality research evidence emerges and armed with a greater understanding of their prevalence and impact, it is hoped that future management of these visual anomalies will be based more upon robust research evidence and less upon clinical consensus.