Science: 24-h intraocular pressure patterns measured by Icare PRO rebound in habitual position of open-angle glaucoma eyes
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22 months ago
david 4.1k

This recent scientific publication concludes that monitoring intraocular pressure ("IOP") in both seated and lying positions over a 24 hour period is superior to seated in-office intraocular pressure monitoring. That part of the conclusion is not new. The study also concludes that the Icare PRO rebound tonometer is well-tolerated. This is also not new information.

In this study, the researcher hospitalized the patients overnight in order to perform the 24-hour IOP monitoring. It can be argued that we have sufficient studies of that design. Current technology, such as the Icare tonometers designed for home use, allow a glaucoma patient to perform 24-hour IOP monitoring at home and to safely obtain reliable results. These home-use tonometers feature the same rebound technology as the Pro model and are equally as accurate. Physicians can now offer patients the option to rent a tonometer for period of one week or more at a cost far less than even a single overnight stay in the hospital. Ophthalmologists are finding that home monitoring for a week can be even more informative than a hospital-based diurnal curve. Real life activities do impact a patient's intraocular pressure. Therefore, it can be beneficial to monitor IOP in real life as opposed to the patient being isolated in a hospital.

24-h intraocular pressure patterns measured by Icare PRO rebound in habitual position of open-angle glaucoma eyes - PubMed

Graefes Arch Clin Exp Ophthalmol
2021 Apr 29
PMID: 33914159
DOI: 10.1007/s00417-021-05192-2



To measure the 24-h intraocular pressure (IOP) by the Icare PRO rebound tonometer in healthy and primary open-angle glaucoma (POAG) eyes and compare it with non-contact tonometry (NCT).


Thirty POAG patients, who were under IOP-lowering treatment, and 30 healthy subjects were included. Participants were hospitalized overnight for the 24-h IOP measurement. IOPs were measured by Icare PRO and NCT according to a standard protocol every 2 h during 24 h. The 24-h IOP curve and IOP-related parameters were compared between Icare PRO and NCT groups in POAG and healthy eyes.


The IOPs measured by Icare PRO in habitual position (i.e., sitting during the day and supine at night), increased notably at 22:00 in the normal group and at 20:00 in the POAG group, reached peak at 0:00, stayed high until 4:00, and then decreased in both groups. The POAG patients had higher mean 24-h IOP, peak IOP, IOP fluctuation, and greater IOP change from supine to sitting position in the nocturnal period than those in the normal subjects even after adjusting for eyes, age, gender, CCT, and axial length.


The Icare PRO provides a well-tolerated approach for 24-h IOP monitoring in habitual position. Twenty-four-hour IOP in habitual position is more sensitive for detecting high nocturnal IOP peaks and greater IOP fluctuation for POAG patients.

FitEyes Commentary

There is one potential confounding variable not addressed in any of the hospital-based 24-hour IOP monitoring studies I am aware of. Some patients report a higher awakening IOP (reported as the IOP measurement taken upon awakening and prior to getting out of the bed or engaging in any type of activity while in bed) when they sleep deeply and without awakening during the night. Most hospital-based 24-hour IOP monitoring studies prevent a patient from sleeping deeply without interruption for the entire night, by design.

24-h intraocular pressure patterns measured by Icare PRO rebound in habitual position of open-angle glaucoma eyes | SpringerLink


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This study was funded by the Shanghai Jing’an District Health Commission (2016MS12, 2017QN03, 2019MS12), the State Program of National Natural Science Foundation of China (81570887, 81870692), the State Key Program of National Natural Science Foundation of China (81430007), the subject of major projects of National Natural Science Foundation of China (81790641), the Shanghai Committee of Science and Technology, China (17410712500), and the top priority of clinical medicine center of Shanghai (2017ZZ01020). The sponsor or funding organization had no role in the design or conduct of this research.


  1. Zhaobin Fang
  2. Xiaolei Wang
  3. Siyu Qiu
  4. Xinghuai Sun
  5. Yuhong Chen
  6. Ming Xiao

Corresponding authors

Correspondence to [Yuhong Chen] or [Ming Xiao].

Author information

Author notes

  1. Zhaobin Fang and Xiaolei Wang contributed equally to this work and were regarded as first authors.

  2. Yuhong Chen and Ming Xiao contributed equally to this work and were regarded as corresponding authors.


  1. Department of Ophthalmology, Shanghai Jing’an District Bei Zhan Hospital, Shanghai, 200070, China

    Zhaobin Fang, Siyu Qiu & Ming Xiao

  2. Department of Ophthalmology and Visual Science, Eye, Ear, Nose and Throat Hospital, Shanghai Medical College of Fudan University, Shanghai, 200031, China

    Xiaolei Wang, Xinghuai Sun & Yuhong Chen

  3. NHC Key Laboratory of Myopia, Ministry of Health (Fudan University), Shanghai, 200031, China

    Xiaolei Wang, Xinghuai Sun & Yuhong Chen

  4. Shanghai Key Laboratory of Visual Impairment and Restoration (Fudan University), Shanghai, 200031, China

    Xinghuai Sun

  5. State Key Laboratory of Medical Neurobiology, Institutes of Brain Science and Collaborative Innovation Center for Brain Science, Fudan University, Shanghai, 200032, China

    Xinghuai Sun

Ethics declarations

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.

Informed consent

Informed consent was obtained from all individual participants included in the study.

Conflict of interest

The authors declare no competing interests.

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