Postural Intraocular Pressure Changes and the Trans-Lamina Cribrosa Pressure Difference: A Systematic Review and Meta-Analysis.

TOPIC: This systematic review and meta-analysis (PROSPERO: CRD42024556443) addresses the magnitude of intraocular pressure (IOP) changes when transitioning from sitting to supine and lateral decubitus positions. It investigates the interaction with intracranial pressure (ICP) to estimate the translaminar cribrosa pressure difference (TLPD). Participants included healthy individuals, glaucoma suspects, and patients with ocular hypertension or glaucoma.

CLINICAL RELEVANCE: Glaucoma management relies on IOP measurements taken upright during clinic hours. This paradigm overlooks nocturnal stressors occurring during recumbency, which occupies one-third of a patient's life. Postural IOP elevations, particularly when coupled with low ICP, may drive disease progression in patients who appear stable during diurnal visits, especially those with normal-tension glaucoma (NTG).

METHODS

We searched Ovid MEDLINE and Embase from inception to July 2024 for observational and interventional studies measuring IOP or ICP in at least two body positions. Eligibility criteria required quantitative reporting in mmHg; studies confounding posture with circadian rhythm were excluded. Risk of bias was assessed using Risk of Bias In Non-randomized Studies - of Interventions for observational studies and the Risk of Bias 2.0 tool for the randomized trial.

RESULTS

Thirty-two cohorts comprising 2,842 eyes and 2,385 patients (weighted mean age 61.5 years) were included; 27 studies contributed quantitative data, including 22 for the supine-versus-sitting analysis. Supine IOP increases were +2.49 mmHg (95% CI, 1.33-3.65) in healthy eyes, +2.89 mmHg (95% CI, 2.27-3.50) in the glaucoma spectrum, and +3.60 mmHg (95% CI, 3.24-3.96) in ocular hypertension (one study). The dependent lateral decubitus eye increased by +3.92 mmHg (95% CI, 3.08-4.75). Qualitative synthesis suggested lower ICP in several glaucoma cohorts, although most IOP and ICP measurements were asynchronous.

CONCLUSION

Recumbency induces significant IOP elevations, pronounced in the dependent eye during lateral decubitus positioning. Current evidence hypothesizes a potential double hit for patients with NTG who may lack cerebrospinal fluid counter-pressure, though this relies largely on inferred, asynchronous measurements. While limited by heterogeneity and reliance on ICP estimates, these findings highlight the necessity of future longitudinal research into nocturnal postural physiology to determine its role in glaucoma management.