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Abstract #3458 Published in IGR 4-2
Twenty-four-hour pattern of intraocular pressure in young adults with moderate to severe myopia
Liu JHK; Kripke DF; Twa MD; Gokhale PA; Jones EI; Park EH; Meehan JE; Weinreb RNInvestigative Ophthalmology and Visual Science 2002; 43: 2351-2355
PURPOSE: To characterize the 24-hour change of intraocular pressure (IOP) in young adults with moderate to severe myopia. METHODS: Nineteen young adults, aged 18-25 years old, with moderate to severe myopia (myopia group) and 17 age-matched volunteers with emmetropia or mild myopia (control group) were housed for one day in a sleep laboratory. An eight-hour accustomed sleep period was assigned to each volunteer. Twelve measurements of IOP, axial length, blood pressure, and heart rate were taken at two-hour intervals. In the wake period, blood pressure and heart rate were measured after a five-minute bed rest. Axial length and IOP were measured in supine volunteers. Volunteers then sat for five minutes, after which IOP was measured. In the sleep period, measurements were taken in supine volunteers in bed. RESULTS: In both the myopia and control groups, the average supine IOP in the sleep period was higher than the average sitting IOP in the wake period. However, the magnitude of this IOP elevation at night was significantly less in the myopia group. In the sleep period, IOP was less in the myopia group than in the control group. When only the 24-hour supine IOP data were considered, the trough occurred at 1:30 a.m., and the peak occurred around noon in the myopia group. In the control group, the trough was at 9:30 p.m., and the peak at 5:30 a.m. Least-square cosine fits showed 24-hour rhythms of supine IOP in both groups, but their phase timings were different. Axial length remained unchanged throughout the day and night in both groups. There was no difference in the 24-hour rhythms of mean blood pressure and heart rate between the two groups. CONCLUSIONS: Considering habitual body positions, IOP increases at night in young adults with moderate to severe myopia, but the magnitude of the increase is significantly less than that in the age-matched control subjects. There is a 24-hour rhythm of supine IOP in the myopic group, but the phase timing is different from that in the control subjects. These variations of IOP in young adults with moderate to severe myopia are not related to changes in cardiovascular parameters.
Dr. J.H.K. Liu, Department of Ophthalmology, University of California-San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0946, USA. joliu@ucsd.edu
Classification:
6.1 Intraocular pressure measurement; factors affecting IOP (Part of: 6 Clinical examination methods)
8.1 Myopia (Part of: 8 Refractive errors in relation to glaucoma)