Background Optimal utilisation of investigations in glaucoma management remains unclear. We aimed to assess whether a temporal association exists between such testing and management changes.

Methods Retrospective observational study using nationwide healthcare insurance claims database. Glaucoma outpatient encounters from patients aged ≥40 years with/without Humphrey visual field (HVF) and/or optical coherence tomography (OCT) were identified. An encounter was considered associated with an intervention if surgery occurred within 90 days, or if medication change or laser trabeculoplasty (LT) occurred within 30 days.

Results 12 669 324 outpatient encounters of 1 863 748 individuals from 2003 to 2020 were included. HVF and OCT was performed during 32.8% and 22.2% of encounters respectively. Of the 36 763 (0.3%) encounters preceding surgery, 28.1% included HVF, 11.9% had OCT and 8.5% both. 79 181 (0.6%) visits preceded LT, of which 28.2% had HVF, 13.2% OCT and 9.3% both. Of the 515 899 (4.5%) encounters preceding medication changes, 29.1% had HVF, 16.7% OCT and 12.2% both. Compared with encounters with no investigations, those with HVF and/or OCT were associated with a 49% increased odds of a management change (p<0.001). In multivariate analyses, compared with encounters without investigations, visits with HVF alone had higher odds of subsequent surgery and LT, while HVF and/or OCT were associated with higher odds of medication change (p<0.001 for all).

Conclusion Glaucoma therapeutic changes occurred following approximately 5% of outpatient encounters. Surgery and LT were more likely to occur following a visit with a HVF rather than an OCT, while either investigation was associated with a higher odds of medication change.