An analysis of patients discharged from a hospital-based glaucoma case-finding clinic over a 3-year period.

PURPOSE: To analyse the false positive referrals by community optometrists to a glaucoma case-finding clinic over a 3-year period. METHODS: A retrospective study was undertaken of the 531 patients who were referred by community optometrists and discharged after their first visit to the glaucoma case-finding clinic at the Oxford Eye Hospital between 2003 and 2005. The number of patients who were referred on the basis of one, two or three abnormal parameters was determined. The specific reason why the presumed abnormal parameter was considered normal by a glaucoma specialist was determined from the patients' records. RESULTS: The referral was based on only one presumed abnormal parameter in 65.5-74.3% of patients (minimum-maximum percentage per year, 2003-2005). Physiological cupping was present in 21.5-29.5%, asymmetrical cupping because of asymmetrical disc size in 6.4-8.2% and asymmetrical cupping in the presence of similar disc size in 1.9-5.1%. An intraocular pressure (IOP) within the normal range was measured in 17.6-20.8% and an IOP between 22 and 25 mmHg in association with a central corneal thickness of >588 microm was found in a further 11.5-15.4%. In 11.5-16.1% of patients who were referred because of an abnormal visual field, no field defect was found when the test was repeated. A cause other than glaucoma was responsible for an abnormal visual field defect in 1.2-6%. CONCLUSION: This study identifies the factors responsible for false positive referrals to a hospital-based glaucoma case-finding clinic. By considering these factors and by combining test data, the number of unnecessary referrals could be reduced in the future