Relationship Between Sleep Position and Glaucoma Progression

Kevin Kaplowitz; Justin Dredge; Robert Honkanen

Disclosures

Curr Opin Ophthalmol. 2019;30(6):484-490. 

In This Article

Risk Factors for Positional Intraocular Pressure Increase

The cause of the positional IOP increase is not yet clear. A common theory focuses on alterations in ocular perfusion such as poor autoregulation near the optic nerve head which may be more common in normal-tension glaucoma.[30] However, one study found no changes in the blood pressure and ocular perfusion pressure between lying flat and at 30 degrees of head of bed elevation.[31] Other theories consider the cerebral venous volume as well.[32,33] The effect of increased gravity[34] in the horizontal position is thought to contribute to an increase in the episcleral venous pressure by perhaps 1–2 mmHg which could also reduce scleral rigidity and increase choroidal filling.[35,36] For lateral asymmetry, some theories revolve around the right atrium being lower in the right LDP, resulting in increased venous return and lower sympathetic output.[37]

A reported risk factor for greater positional IOP increase is higher baseline IOP, although the data is contradictory. One study found that lower baseline IOP leads to higher positional increases,[38] one found the opposite,[39] and more studies found no relationship between sitting IOP and positional increase.[17,36,40,41,42] Hetland-Eriksen[39] noted that significantly larger positional increases can be seen with very high baseline IOP's (i.e., baseline IOP over 40 mmHg), which are less commonly studied.

Other risk factors for greater positional increases include older age[9,43] and thinner corneal pachymetry.[6] Although some studies found that eyes with shorter axial lengths have higher nocturnal fluctuations,[44] some studies on LDP found no association between axial length and postural increase,[6,17] whereas one found that longer eyes have more elevations.[9] One study found larger positional increase in patients with shorter distances between the corneal apex to the tip of the nose or from the temple to the eye.[45] Another study investigated the relationship between obesity and positional increase in LDP but found no association.[18]

Although most studies focus on presenting mean changes in IOP, larger studies with distributional data may help to identify risk factors by identifying cases with unusual positional changes. For instance, one study showed a large positional increase of 4 mmHg from sitting to LDP in the dependent eye, but further analysis showed that while 7% of patients had a positional increase of 11–12 mmHg, 15% of cases had a lower IOP in the LDP as compared to sitting.[46]

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