Supine positioning during sleeping hours is associated with decreased blood pressure and increased IOP, which results in decreased perfusion to the eye, including the optic nerve. It has been theorized that this reduced ocular perfusion pressure (OPP) may increase optic nerve damage and associated vision loss.
Fluctuation in IOP over a 24-hour period is attributed to autonomic or humoral control, changes in vascular tone, and bodily postural changes.
A pilot study to evaluate and compare the 24-hour habitual fluctuations in IOP and OPP in glaucoma patients treated with medical therapy, selective laser trabeculoplasty (SLT) or trabeculectomy was performed by Ruparelia and colleagues from the Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, NS, Canada.
Recruited patients were admitted to the sleep lab for 24-hour serial habitual IOP and blood pressure measurements. IOP and OPP fluctuation among the 3 treatment groups were compared.
The IOP measurements were obtained using Goldmann applanation tonometry and with the patient in upright position. Nocturnal (8 pm, 12 am, 4 am) IOP measurements were obtained via Perkins applanation tonometry and with the patient in the supine position for at least 30 minutes prior to measurement. Brachial blood pressure (BP) was measured using an automated sphygmomanometer.
Thirty three (33) eyes from 33 patients were recruited in this study, including 11 patients in the medical therapy group, 11 patients in the SLT group, and 11 patients in the trabeculectomy group.
The medical therapy group was found to have significantly higher 24-hour IOP fluctuation (8.3 ± 1.6 mmHg) than the SLT (3.5 ± 1.9 mmHg) and trabeculectomy (4.3 ± 1.3 mmHg) groups (P < 0.001).
Mean 24-hour OPP fluctuation was also significantly higher in the medical therapy group (18.5 ± 4.0 mmHg) than the SLT (11.9 ± 7.3 mmHg) and trabeculectomy (14.1 ± 3.9 mmHg) groups (P < 0.05).
No difference in IOP or OPP fluctuation was found between SLT and trabeculectomy groups (P > 0.05).
Therefore, both SLT and trabeculectomy may be more effective in reducing 24-hour IOP and OPP fluctuation than medical therapy alone. IOP and OPP fluctuation was comparable between SLT and trabeculectomy cohorts.
REFERENCE:
Ruparelia S, Bonatti R, Murphy JA, Nicolela MT, Eadie BD, Chauhan BC, Dyachok OM, Shuba LM. Twenty four-hour intraocular pressure fluctuation in treated glaucoma patients: a pilot study. Can J Ophthalmol. 2025 Aug;60(4):216-221. doi: 10.1016/j.jcjo.2024.11.010. Epub 2025 Jan 14. PMID: 39719016.
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