The role of the disc damage likelihood scale in glaucoma detection by community optometrists

Abstract

Purpose: Recent guidelines recommend disc damage likelihood scale (DDLS) is recorded for all referrals of suspected glaucoma from community optometrists to hospital eye services (HES) in Scotland. This study aimed to determine whether lower DDLS grades were associated with higher rates of discharge at the first visit to HES. Methods: A retrospective analysis of 618 consecutive new referrals from community optometrists to a university hospital glaucoma service. 65 (10.5%) included DDLS graded by the community optometrist. A comprehensive eye examination and optical coherence tomography (OCT) was performed in the hospital glaucoma clinic and first visit discharge rate (FVDR) for different grades of DDLS compared. The relationship between DDLS and retinal nerve fibre layer (RNFL) thickness on OCT was also examined. Results: The FVDR for patients with DDLS recorded in the referral was 27.7% (18 of 65) compared to 25% (138 of 553) in those without DDLS (p = 0.631). The FVDR was 50% for those with a DDLS of 3 in the worse eye, decreasing to 32% and 21% for DDLS grades of 4 and 5 respectively. No patient with a DDLS ≥ 6 was discharged at the first visit and none with a DDLS < 4 (the cut off for consideration of referral in Scottish guidelines) were found to have glaucoma. There was a significant but weak inverse relationship between DDLS and RNFL thickness. The strongest relationship was with average RNFL thickness (r = À0.378, p < 0.01) followed by superotemporal (r = À0.359, p < 0.01) and inferotemporal (r = À0.353, p < 0.01) RNFL thickness. Conclusions: In patients referred to HES with DDLS information included, lower DDLS grading was associated with higher odds of being discharged at the first visit. DDLS grading by community optometrists had a poor correlation with RNFL thickness measured using OCT.

Referrals from community optometrists in England and their replies: A mixed methods study

“…In Scotland, where the NHS eyecare provided by community optometrists is more comprehensive and better funded, the proportion of referrals discharged at the first visit to glaucoma clinic was 25% for cases of suspected open angle glaucoma or ocular hypertension and 12% in those referred for narrow angles 19 . Another study of CO glaucoma referrals in Scotland found a first visit discharge rate of 25%–27.7%, depending on the information in the referral 18 20 …”

“…Previous research on the accuracy of optometric referrals has mostly studied glaucoma, [17][18][19][20][21][22][23][24][25] which is challenging to diagnose because the signs of early glaucoma are subtle, even to an eye specialist. 26 National Institute for Health and Care Excellence (NICE) glaucoma guidelines in 2009 27 and 2017 28 had a major impact; therefore, this summary of previous literature on optometric referral accuracy concentrates on research published since 2009 in the UK.…”

“…19 Another study of CO glaucoma referrals in Scotland found a first visit discharge rate of 25%-27.7%, depending on the information in the referral. 18 The challenges of diagnosing glaucoma were highlighted in a pan-European study which found that optometrist-initiated referrals in the UK have similar accuracy to ophthalmologist-initiated referrals in other European countries. 20 Optometric referrals for other conditions show variable performance, with high diagnostic concurrence (99%) for posterior capsular opacification 33 and orthoptic referrals (87%), 34 but in one study, low accuracy for wet macular degeneration, with only 37% of patients referred with a rapid access form having neovascular age-related macular degeneration.…”

Spotlight on the Disc-Damage Likelihood Scale (DDLS)

“…However, a further study of glaucoma referrals in Scotland found the first visit discharge rate was lower in patients with higher DDLS scores, decreasing from 50% in those with a DDLS of 3, to 0% in those with a DDLS ≥6. 74 No patients with a DDLS of less than 4 were diagnosed with glaucoma at their first visit. This study though was limited by the small number of patients in which DDLS had been recorded.…”

RimNet: A Deep Neural Network Pipeline for Automated Identification of the Optic Disc Rim

“…5 It is commonly accepted and has been incorporated into eye health guidelines for optometrists and ophthalmologists. 7 , 8 The DDLS is limited as a diagnostic tool by the need for expert time to accurately grade images. Automated high-efficacy DDLS grading could offer a powerful screening method.…”