This review paper summarises the scientific evidence that supports partial prescribing of spectacles. This is the prescribing of a refractive correction that differs from the subjective refraction and typically involves prescribing a correction that is in between the subjective refraction result and the refractive correction in the patient’s habitually worn spectacles. It is commonly used by very experienced clinicians, but not by those newly qualified. Partial prescribing is likely to reduce cases of patient dissatisfaction with spectacles (non-tolerance cases or ‘non-tols’) and reduce the risk of inducing both dizziness and falls in frail, older patients. The review includes a discussion of the validity and variability of subjective refraction, the degree of tolerance to small changes from the subjective refraction and causes of spectacle adaptation difficulties in the elderly. The latter includes a brief discussion of the vestibulo-ocular reflex, which should be considered when making large changes in refractive correction.