What Do Infrequent Goldmann Applanation Tonometry Measurements Reveal About Intraocular Pressure Profiles After Nonpenetrating Glaucoma Surgery?

Purpose: To evaluate how reliably single Goldmann applanation tonometry (GAT) measurements reflect the preceding month's intraocular pressure (IOP) profile in operated open-angle glaucoma. Methods: This longitudinal study included 24 patients with a suprachoroidal telemetric IOP sensor analyzing 156 in-hospital GAT measurements, 154 simultaneous telemetric readings, and 13,734 at-home measurements across follow-up visits. Telemetric data from the 30 days prior to each visit were stratified by time of day and matched to corresponding GAT measurements, which, in turn, were ranked relative to the interquartile range (IQR) of the preceding at-home measurements. Peak-and-trough analyses were performed using hourly aggregated data. Results: The GAT and telemetric IOP measurements showed good agreement (mean ΔIOP = -0.1 ± 3.0 mm Hg). However, 59.7% of the GAT-measured IOP values exceeded the IQR, and 14.3% fell below the IQR of the corresponding telemetric distributions; only 26.0% were within the IQR. Deviations from the telemetric median were 4.2 ± 2.4 mm Hg (above IQR), -2.3 ± 1.5 mm Hg (below IQR), and 0.5 ± 1.2 mm Hg (within IQR). Of the 99 statistically significant extrema (45 peaks and 54 troughs), most peaks occurred within 3 hours before GAT measurements. Troughs were observed both before and after GAT, but with larger nyctohemeral misalignment to GAT. Conclusions: Single GAT measurements frequently failed to represent the underlying 30-day IOP profile and often missed clinically relevant peaks and troughs, despite good pointwise agreement with telemetric measurements. Translational Relevance: High-frequency telemetric monitoring provides a more comprehensive assessment of IOP dynamics and may improve individualized glaucoma management compared with infrequent GAT snapshot measurements.