Optometrists are required to refer patients with any abnormality of the eye, excluding normal changes due to age, to a General Practitioner. It can be difficult to decide when a cataract ceases to be a normal age-related change and becomes an ocular abnormality. This questionnaire-based study examines the criteria adopted by Optometrists and GPs for referring patients with cataract and compares this to the referral criteria suggested by Ophthalmologists. For all professions, the main factors influencing referral are visual acuity, subjective visual impairment and the need to drive. Optometrists and GPs generally refer patients with cataract at a VA level of 6/18-6/24, whilst most Ophthalmologists would be willing to see patients with cataract at a VA of 6/9-6/12. However, Ophthalmologists report that sometimes patients are referred too soon, regardless of their acuity level, because the patient is not yet impaired by their level of vision or does not want surgery. Suggestions for improvements in the referral of cataract are discussed. It is important for Optometrists to make clear whether a letter to a GP is for information only or for referral. If referral is warranted, information in addition to acuity will assist an Ophthalmologist in prioritizing appointments, including age, occupation, brief description of disability and the need to drive without contravening any laws.