Do locally agreed guidelines for optometrists concerning the referral of glaucoma suspects influence referral practice?

Purpose To assess whether the issuing of local guidelines for glaucoma dete ction including a protocol for the referral of suspects can improve the qua lity and accuracy of referrals from optometrists. Methods Universally agreed guidelines, which included a protocol for referr ing glaucoma suspects, were circulated to all optometrists in the catchment area of a major teaching hospital ophthalmic unit. Data on 207 new patient s referred to one glaucoma clinic were collected from GOS18 forms and hospi tal records covering two 12 month periods spanning the guideline disseminat ion. Referral accuracy was calculated and the reasons for protocol violatio ns and referral of normal individuals were determined. Where possible, data were compared with a similar study relating to referrals made to the same clinic in 1988 and 1993. Results The mean (SD) intraocular pressure (IOP) at which optometrists refe rred patients was 22.5 (6.6) in 1997 and 21.9 mmHg (6.6) in 1998/9, both si gnificantly less than in 1988. A statistically significant upward trend wit h time was found in the number of patients referred with an assessment of c up/disc ratio and in those with details of a visual field assessment. The o verall 'true positive diagnosis' was 40% (42/105) in 1997 and 32.3% (33/102 ) in 1998/9 after the guidelines (p = 0.32), both of which were significant ly lower than the 1988 rate of 56% (34/75) (p = 0.03 and 0.003). Fifty per cent of false positive referrals in both 1997 and 1998/9 were associated wi th an assessment by the optometrist of the optic disc(s) that was at varian ce with the ophthalmologist's. False positive visual fields were associated with 22% and 35% of non-true positive referrals in 1997 and 1998/9. Protoc ol violations were observed in 48% of referrals after the guidelines had be en disseminated. When the referral was both a false positive and the guidel ine protocol was not followed, 88% of violations were associated with IOP m easurement in 1997 and 73% in 1998/9. The equivalent figures for visual fie ld violations were 70% in 1997 and 76% in 1998/9. Normal individuals referr ed as suspects were significantly (p = 0.001) less likely to be referred on IOP grounds if their optometrist followed the referral protocol. Conclusion Local dissemination of glaucoma screening guidelines with a prot ocol for referral did not appear to improve the diagnostic accuracy of opto metrists in our area. Optometrists who follow the guidelines refer fewer no rmal individuals on IOP grounds, but false positive visual fields and optic disc interpretation difficulties remain a factor in such referrals. Additi onal strategies will be necessary to improve the quality and accuracy of re ferrals for suspect glaucoma by optometrists.