3D Movie Viewing vs Occlusion for Treating Amblyopia in Children

Amblyopia is the leading cause of monocular visual impairment in children, with a prevalence of approximately 2-3%. It is commonly associated with strabismus and/or anisometropia and is characterized by reduced visual acuity and deficits in binocular vision, particularly stereopsis. While conventional treatments such as refractive correction and occlusion therapy are effective in improving visual acuity, many patients retain residual deficits in stereopsis and binocular function.

Recent advances in amblyopia treatment have focused on binocular approaches, including perceptual learning, dichoptic training, and virtual reality-based interventions. These methods aim to stimulate binocular interaction and reduce suppression of the amblyopic eye. Among these approaches, 3D movie viewing represents a naturalistic and engaging stimulus that introduces large binocular disparities and may promote binocular integration in a child-friendly environment.

Preliminary evidence from a pilot study conducted by our group demonstrated that a single 3D movie session can produce significant and sustained improvements in stereopsis and visual acuity in children with a history of amblyopia. However, this study lacked a control group and involved only a single exposure session.

The present study is a prospective, randomized, controlled, single-center clinical trial designed to evaluate the efficacy of repeated 3D movie viewing sessions combined with occlusion therapy compared to occlusion therapy alone. Participants will be randomly assigned to either an experimental group (3D viewing plus occlusion) or a control group (occlusion alone). The intervention will consist of 3 to 6 weekly sessions of 3D movie viewing, each lasting approximately 90-120 minutes.

The study includes two phases: an initial comparative phase in which outcomes between groups are assessed after three sessions, and a second phase in which all participants are exposed to additional 3D sessions to evaluate cumulative effects. Assessments will be conducted at baseline (T0), after the first phase (T1), and after completion of all sessions (T2).

Primary outcome measures include stereopsis (measured in log arcseconds), visual acuity (logMAR), and ocular deviation (prism diopters). Secondary outcomes include sensory and motor characteristics (fusion, suppression, retinal correspondence), treatment adherence, and patient-reported satisfaction and quality of life.

Outcome assessors will be masked to group allocation to reduce bias. The study also aims to explore factors influencing treatment response, including age and type of amblyopia.

This trial seeks to determine whether 3D movie viewing can serve as an effective, engaging, and non-invasive adjunct to conventional amblyopia treatment, with potential implications for improving both visual function and patient adherence.

Inclusion criteria

Children aged 4 to 14 years Diagnosis of unilateral amblyopia (anisometropic, strabismic, or mixed) Interocular visual acuity difference ≥ 0.2 logMAR (equivalent to ≥ 2 Snellen lines) Ability to understand and follow age-appropriate instructions Written informed consent from parents or legal guardians Child assent obtained when applicable

Exclusion criteria

Previous treatment for amblyopia Ocular surgery within the last 6 months Strabismus with deviation greater than 10 prism diopters Presence of other ocular pathologies affecting vision (e.g., cataract, nystagmus, ptosis, corneal opacity, retinal disease, optic neuropathy) Neurological or cognitive impairment preventing compliance with study procedures Prior intensive exposure to 3D movies or virtual reality/3D video games that could act as a confounding factor Refusal of the child or family to participate