What is the best way to measure intraocular pressure (IOP) in a virtual clinic?

Background: Patients with ocular hypertension (OHT) and glaucoma are increasingly reviewed in virtual clinics. As the clinician is not present during the patient's visit it is important that measurements obtained are reliable. The aim of this study was to examine agreement between Goldmann Applanation Tonometry (GAT) intraocular pressure (IOP) measurements (obtained by ophthalmologists and ophthalmic nurses) and a newer automated tonometer-the Ocular Response Analyzer (ORA).
Methods: A prospective study was conducted including 116 eyes of 116 patients with glaucoma and OHT. All subjects had GAT IOP obtained by a nurse and ophthalmologist and ORA IOP by a technician. The order of testing was randomised and previous measurements were masked. Agreement was examined using Bland-Altman plots and 95% limits of agreement (LoA). Intraclass correlation coefficients (ICC) of repeat GAT and ORA measurements were calculated.
Results: Patients had a mean age of 70 ± 13 years. The 95% LoA between ophthalmologist (mean: 14.6 ± 4.3 mmHg) and nurse (mean: 15.0 ± 4.0 mmHg) GAT measurements was ±5.21 mmHg, whereas the 95% LoA between repeat ORA IOPg (mean: 13.8 ± 4.7 mmHg) was ±2.52 mmHg. There was no proportional bias. The ICC was 0.972 for repeat IOPg compared with 0.863 for repeat GAT.
Conclusions: There was only moderate agreement between GAT IOP measurements obtained by nurses working in the virtual clinic and ophthalmologists. Agreement between ORA IOP and ophthalmologists' GAT IOP was better and ORA produced more repeatable measurements, providing evidence it may be a more reliable tool for IOP assessment in virtual clinics.