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Editors Selection IGR 17-4
Intraocular Pressure: Effects of surgery on circadian IOP patterns
Comment by Kaweh Mansouri on:
48953 Dampening of Diurnal Intraocular Pressure Fluctuation by Combined Trabeculotomy and Sinusotomy in Eyes With Open-angle Glaucoma, Matsuoka M; Ando A; Minamino K et al., Journal of Glaucoma, 2013; 22: 290-293
Matsuoka et al. show that a combined glaucoma procedure (modified trabeculotomy + sinusotomy) may be able to lower intraocular pressure (IOP) in a consistent manner throughout the 24-h cycle. They found that mean IOP, maximum IOP, delta IOP were reduced by 15.1%, 26.3%, and 41.3%, respectively. Most interestingly, they found a flattening of the 24-h IOP pattern after surgical intervention, including during the nocturnal period. This retrospective study included 14 eyes of eight patients who had significant pre-operative IOP fluctuations, defined as IOPs above 20 mmHg during office hours despite regular IOPs < 17 mmHg. Goldmann applanation tonometry measurements were taken every three hours with the patients in the upright position.
At present, this article represents the closest to a study on 24-h IOP-lowering characteristics of incisional glaucoma surgery. However, there are several important shortcomings that may limit its findings. Most importantly, the fact that patients were awakened from sleep and IOP measurements were taken in the sitting position will have influenced IOP measurements. Other investigators have previously conducted diurnal tension curves combined with a water-drinking test and suggested that glaucoma surgery provides more consistent 24-h IOP control than medications.1,2 The mechanisms behind this are insufficiently known. By creating an enhanced outflow pathway independent of episcleral venous pressure, surgery may be able of blunting the generally observed nocturnal IOP rise in the recumbent body position.
Our group3,4 and others5 have previously reported on the use of new technology for continuous 24-h IOP monitoring. An increasing body of work shows that IOP is a highly dynamic parameter. Therefore, current methods of static tonometry fail to reflect the true nature of an individual's IOP. Glaucoma is a 24-h disease and the absence of data on circadian IOP-lowering effects of glaucoma surgery constitutes a gaping deficit in our knowledge. Future research evaluating the circadian effect of glaucoma surgical procedures is eagerly awaited.
References
- Mansouri K, Orgül S, Mermoud A, et al. Quality of diurnal intraocular pressure control in primary open-angle patients treated with latanoprost compared with surgically treated glaucoma patients: a prospective trial. Br J Ophthalmol 2008; 92: 332-336.
- Medeiros FA, Pinheiro A, Moura FC, et al. Intraocular pressure fluctuations in medical versus surgically treated glaucomatous patients. J Ocul Pharmacol Ther 2002; 18: 489-498.
- Mansouri K, Shaarawy T. Continuous intraocular pressure monitoring with a wireless ocular telemetry sensor: initial clinical experience in patients with open angle glaucoma. Br J Ophthalmol 2011; 95: 627-629.
- Mansouri K, Medeiros FA, Tafreshi A, Weinreb RN. Continuous 24-Hour Monitoring of Intraocular Pressure Patterns With a Contact Lens Sensor: Safety, Tolerability, and Reproducibility in Patients With Glaucoma. Arch Ophthalmol 2012: 13:1-6.
- De Smedt S, Mermoud A, Schnyder C. 24-hour Intraocular Pressure Fluctuation Monitoring Using an Ocular Telemetry Sensor: Tolerability and Functionality in Healthy Subjects. J Glaucoma 2011; 21: 539-544.
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