Accommodation Response in Hypermetropic Anisometropia (ARIHA Study)

Anisometropic amblyopia is when one eye has a much stronger glasses prescription than the other, causing poor vision in one eye, even with glasses, because the brain favours the better-seeing eye. With standard care treatment (glasses plus either patching or atropine drops given to the better seeing eye), 35% of children with anisometropic amblyopia do not have any significant visual improvements, and will have reduced vision in one eye for life. There is no consensus for the reasons why some children do not respond as well as others. Recent research using the Plusoptix PowerRefractor (PR3), which quickly measures eye focusing (accommodation), suggested that in children with anisometropic amblyopia, the focusing of the amblyopic eye might influence treatment success. However, such measurements weren't previously common due to equipment limitations in clinics. The investigators aim to use the non-invasive PR3 to assess accommodation in hypermetropic anisometropic amblyopia, at the University of Sheffield. This will be a two-phase study of children aged 4-10 years who have hypermetropic anisometropia. The investigators will recruit participants attending the Ophthalmology Department at Sheffield Children's NHS Foundation Trust (SCH). The investigators will take repeated measurements of accommodation at points during standard care treatment (phase 1) and conduct a pilot intervention study (phase 2) to determine whether adjusting glasses prescriptions based on accommodation responses with amblyopia treatment can improve vision in the weaker eye. The goal is to gather evidence to inform a future larger multicentre RCT to improve the visual outcomes for anisometropic amblyopic children in the future.

This is a two-phase study of children aged 4-10 years who have hypermetropic anisometropia: 1. Phase 1 is a cohort observational study. It will involve repeated measurements of accommodation response (using the PR3) of hypermetropic anisometropic children during their standard care treatment at SCH. PR3 measurements (all non-invasive) will be taken at various stages of their treatment to track if accommodation responses change over time. 2. Phase 2 is a pilot intervention study. It will recruit hypermetropic anisometropic children who have finished their standard care treatment at SCH but have not achieved equal (or nearly equal) vision for initial screening. Those who are found to have asymmetrical accommodation responses, and also have residual amblyopia (unequal vision in the two eyes) will be invited to the intervention study. Bespoke glasses will be issued, based on accommodation response, and children will restart occlusion (patching) for 12 weeks while wearing the bespoke glasses. This is to assess whether a glasses adaptation based on accommodation response will help to further improve vision in their amblyopic eye.