Detecting Intraocular Pressure Harmonic Frequencies in Glaucoma and the Sampling Targets Needed to Identify Them With Self-Tonometry
5 affiliations
- 1Lions Eye Institute, University of Western Australia, Royal Perth Hospital, Perth, Western, Australia
- 2School of Health and Clinical Sciences, University of Western Australia, Perth, Western, Australia
- 3School of Population Health, Curtin University, Perth, Western, Australia
- 4International Centre for Radio Astronomy Research, The University of Western Australia, Crawley, Western, Australia
- 5International Space Centre, The University of Western Australia, Crawley, Western, Australia
Abstract
Purpose: The purpose of this study was to determine the detectability and occurrence of circadian and ultradian rhythms in patient-acquired intraocular pressure (IOP) measurements with sampling targets for reliable harmonic detection.
Methods: A multi-harmonic non-uniform discrete Fourier transform (NDFT), with bootstrap amplitude confidence intervals and independent Lomb–Scargle periodogram (LSP) confirmation, was applied to 286 home-tonometry monitoring blocks from 137 eyes of 69 patients with glaucoma. Integer harmonic frequencies (F) from 1 to 10 cycles per day were tested. Characterized frequency was defined when noise-threshold significance, amplitude lower 95% confidence bound >0, and phase 95% confidence interval met prespecified criteria. Detection probability was modeled by a logistic generalized additive model (GAM) accounting for total observation count, clock-hour coverage, and the longest sparse-data gap.
Results: The 24-hour rhythm (F1) was characterized in 35.7% of blocks; at least one of F1, F2, F3, or F4 was characterized in 44.8% (128/286). Of these 128 blocks, 34% (43) had 2 or more harmonics simultaneously characterized and 7% (9) had 3 or more. Detected periodicities were almost exclusively integer harmonics. Non-integer LSP peaks arose in only 3.1% of blocks (9/286). Where 15 or more clock-hours contained at least 2 observations and no more than 2 consecutive clock-hours contained one or none, approximately 100 to 130 observations over 4 weeks gave a model-predicted detection probability of 75% to 85%, rising to 90% at approximately 150 observations.
Conclusions: One or more characterizable 24-hour integer IOP harmonic rhythms could be detected with an appropriate self-tonometry protocol in nearly half of treated patients with glaucoma.
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BibTeX
@article{morgan2026detecting,
title = {{Detecting Intraocular Pressure Harmonic Frequencies in Glaucoma and the Sampling Targets Needed to Identify Them With Self-Tonometry}},
author = {William H. Morgan and Chiau-Ni (Charlene) Chiu and Andrew Turpin and Danail Obreschkow and Allison M. McKendrick},
journal = {Investigative Ophthalmology \& Visual Science},
year = {2026},
month = oct,
doi = {10.1167/iovs.67.12.37},
url = {https://doi.org/10.1167/iovs.67.12.37},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Detecting Intraocular Pressure Harmonic Frequencies in Glaucoma and the Sampling Targets Needed to Identify Them With Self-Tonometry
AU - William H. Morgan
AU - Chiau-Ni (Charlene) Chiu
AU - Andrew Turpin
AU - Danail Obreschkow
AU - Allison M. McKendrick
PY - 2026
DA - 2026/10/21
JO - Investigative Ophthalmology & Visual Science
DO - 10.1167/iovs.67.12.37
UR - https://doi.org/10.1167/iovs.67.12.37
AB - Purpose: The purpose of this study was to determine the detectability and occurrence of circadian and ultradian rhythms in patient-acquired intraocular pressure (IOP) measurements with sampling targets for reliable harmonic detection. Methods: A multi-harmonic non-uniform discrete Fourier transform (NDFT), with bootstrap amplitude confidence intervals and independent Lomb–Scargle periodogram (LSP) confirmation, was applied to 286 home-tonometry monitoring blocks from 137 eyes of 69 patients with glaucoma. Integer harmonic frequencies (F) from 1 to 10 cycles per day were tested. Characterized frequency was defined when noise-threshold significance, amplitude lower 95% confidence bound >0, and phase 95% confidence interval met prespecified criteria. Detection probability was modeled by a logistic generalized additive model (GAM) accounting for total observation count, clock-hour coverage, and the longest sparse-data gap. Results: The 24-hour rhythm (F1) was characterized in 35.7% of blocks; at least one of F1, F2, F3, or F4 was characterized in 44.8% (128/286). Of these 128 blocks, 34% (43) had 2 or more harmonics simultaneously characterized and 7% (9) had 3 or more. Detected periodicities were almost exclusively integer harmonics. Non-integer LSP peaks arose in only 3.1% of blocks (9/286). Where 15 or more clock-hours contained at least 2 observations and no more than 2 consecutive clock-hours contained one or none, approximately 100 to 130 observations over 4 weeks gave a model-predicted detection probability of 75% to 85%, rising to 90% at approximately 150 observations. Conclusions: One or more characterizable 24-hour integer IOP harmonic rhythms could be detected with an appropriate self-tonometry protocol in nearly half of treated patients with glaucoma.
SN - 0146-0404
SN - 1552-5783
ER -