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Jessica Maslin, Nisha Chadha, Christopher C Teng, Ji Liu; Does Supine Body Position Affect Central Corneal Thickness?. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):2038.
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© ARVO (1962-2015); The Authors (2016-present)
Central corneal thickness (CCT) is an important factor in intraocular pressure (IOP) measurement and glaucoma management. While IOP is known to increase in supine body position, it remains unknown whether body position has any effect on CCT. This prospective study evaluated the effect of supine body position on CCT in glaucoma patients and in healthy subjects.
Open-angle glaucoma patients (N=18, age 51-85) and healthy subjects (N=18, age 25-76) were evaluated. Exclusion criteria for both groups included a history of corneal disease or corneal surgery. CCT was measured using an ultrasound pachymeter, Pachmate (DGH Technology, Inc.). Three consecutive measurements in each eye were first taken in the sitting position, and repeated after 10 minutes and 30 minutes in a supine position. CCT values for each eye were obtained by averaging these three measurements at each time interval. The CCT values of right and left eyes were then averaged to obtain a single data point for each patient. Patients were instructed not to sleep or close their eyelids during the supine positioning time. Results were analyzed using repeated measures analysis of variance.
In the glaucoma group, CCT decreased with supine positioning at 30 minutes (mean= -13.0 μm, P<0.05). The decrease in CCT at 10 minutes of supine positioning in the glaucoma group (mean= -8.3 μm) was not statistically significant (P=0.09). In healthy subjects, CCT decreased with supine positioning at 10 minutes (P<0.05) and at 30 minutes (P<0.01). The mean decrease was -5.2 μm (CI= -0.1 to -10.4) at 10 minutes supine and -7.4 μm (CI=-2.1 to -12.8) at 30 minutes supine. There was no statistically significant difference between the CCT at 10 minutes supine and at 30 minutes supine in the glaucoma (P=0.21) and healthy groups (P=0.45).
Our results demonstrate that a decrease in CCT occurs after 30 minutes of supine positioning in glaucoma patients and in healthy subjects. Like IOP, CCT may be a dynamic measurement subject to postural changes. Further evaluation of CCT at extended periods of supine positioning is indicated to further investigate this relationship.
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