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Abstract #46413 Published in IGR 13-3
Diurnal variations in axial length, choroidal thickness, intraocular pressure, and ocular biometrics
Chakraborty R; Read SA; Collins MJInvestigative Ophthalmology and Visual Science 2011; 52: 5121-5129
PURPOSE: To investigate the pattern of diurnal variations in axial length (AL), choroidal thickness, intraocular pressure (IOP), and ocular biometrics over 2 consecutive days. METHODS: Measurements of ocular biometrics and IOP were collected for 30 young adult subjects (15 myopes, 15 emmetropes) at 10 different times over 2 consecutive days. Five sets of measurements were collected each day at approximately 3-hour intervals, with the first measurement taken at ~9 AM and final measurement at ~9 PM. RESULTS: AL underwent significant diurnal variation (P < 0.0001) that was consistently observed across the 2 measurement days. The longest AL was typically observed at the second measurement session (mean time, 12:26) and the shortest AL at the final session of each day (mean time, 21:06). The mean diurnal change in AL was 0.032 ± 0.018 mm. Choroidal thickness underwent significant diurnal variation (mean change, 0.029 ± 0.016 mm; P < 0.001) and varied approximately in antiphase to the AL changes. Significant diurnal variations were also found in vitreous chamber depth (VCD; mean change, 0.06 ± 0.029 mm; P < 0.0001) and IOP (mean change, 3.54 ± 0.84 mm Hg; P < 0.0001). A positive association was found between the variations of AL and IOP (r(2) = 0.17, P < 0.0001) and AL and VCD (r(2) = 0.31, P < 0.0001) and a negative association between AL and choroidal thickness (r(2) = 0.13, P < 0.0001). There were no significant differences in the magnitude and timing of diurnal variations associated with refractive error. CONCLUSIONS: Significant diurnal variations in AL, choroidal thickness, and IOP were consistently observed over 2 consecutive days of testing.
Contact Lens and Visual Optics Laboratory, School of Optometry, Queensland University of Technology, Brisbane, Queensland, Australia.
Classification:
6.1.2 Fluctuation, circadian rhythms (Part of: 6 Clinical examination methods > 6.1 Intraocular pressure measurement; factors affecting IOP)
2.2 Cornea (Part of: 2 Anatomical structures in glaucoma)
2.12 Choroid, peripapillary choroid, peripapillary atrophy (Part of: 2 Anatomical structures in glaucoma)
