British optometrists played effective roles in glaucoma screenings when referring to ophthalmologists, specifically in their track record of low false-negative (FN) and false-positive (FP) referrals, according to a study in the British Journal of Ophthalmology.

In the study, researchers evaluated the clinical effectiveness of the Manchester Glaucoma Enhanced Referral Scheme (GERS) for both FP and FN rates.

To determine the false-positive rate (referred patients subsequently discharged at their first visit), investigators collected outcome data for patients who were newly referred through GERS and were assessed in usual-care clinics. For the false-negative rate, glaucoma suspects deemed as not requiring referral following GERS assessment were invited to take a reference standard exam by a glaucoma specialist OD. Additionally, two glaucoma specialist consultant ophthalmologists independently reviewed 33 separate cases that compromised randomly selected referred and non-referred cases.

In the study, 1,404 patients were evaluated through GERS. Of these, 651 (46.3 percent) were referred to Hospital Eye Service and 753 (53.6 percent) were discharged. Investigators found a 15.5 percent false-positive rate in 307 assessable patients referred to Hospital Eye Services. They also reviewed 131 (17.4 percent) of those patients not referred to Hospital Eye Services through GERS. Researchers noted 117 (89.3 percent) were confirmed as not requiring hospital follow-up. Additionally, 14 (10.7 percent) required follow-up, including five (3.8 percent) who were offered treatment. Only one patient met the GERS referral criteria and was not referred, which represented a true FN.

When comparing the optometrist’s and the two consulting ophthalmologists’ decisions in the case reviews, the study found agreements between the consultants on management in 23-of-30 non-referred cases versus 25-of-30 and 24-of-30 cases where the glaucoma specialist optometrist and the individual consultant were in agreement. “This finding suggests that the glaucoma specialist optometrist’s decision making demonstrated non-inferiority when compared with consultant-consultant agreement,” researchers said. There were only two cases (seven percent) where both consultants agreed, and their decision was different than that of the optometrists. In each case, the consultant would have discharged the patient, whereas the glaucoma specialist optometrists considered follow-up or treatment.

Researchers reported no cases of missed glaucoma or non-glaucomatous pathology identified within the sample.

“It is clear that GERS is highly successful in reducing the FP rate from community referrals for suspect glaucoma. The FN evaluation in this study shows that GERS is clinically effective and very safe, offering reassurance to commissioners wishing to implement community pathways,” the study stated. 

Gunn PJG, Marks, JR, Konstantakopoulou E, et al. Clinical effectiveness of the Manchester glaucoma enhanced referral scheme. Br J Ophthalmol. October 11, 2018. [Epub, ahead of print].