Anisometropia can cause problems for patients, particularly if its onset is sudden, for example after cataract surgery. 

A survey of 140 clinical leads in England and Northern Ireland conducted by the Royal College of Ophthalmologists showed that – of the 87 who replied – 62 per cent applied thresholds of moderate visual acuity (VA) reduction (6/9 or 6/12 or worse) before cataract surgery was undertaken. It also found that for second-eye surgery, the access requirements were often stricter, further restricting those in need of cataract surgery (RCOphth, 2017). These issues are likely to become less widespread given the new NICE guidelines on cataract (2017), but second-eye surgery is not suitable (or may not be desired) in all cases, so the issue of anisometropia is still likely to arise in optometric practice.