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Updated: Jul 10, 2026

Trabecular Meshwork Response to Pressure Elevation in the Living Human Eye
Published on: June 20, 2015
[Diurnal variability of intraocular pressure]
J I Jaén-Díaz1, B Cordero-García, F López-de-Castro
1Centro de Salud Docente Santa M.a de Benquerencia, Toledo, Spain. ijd02@hotmail.com
Objective:
To assess whether there are variations in the intraocular pressure (IOP) between the morning and afternoon in healthy subjects.
Methods:
This study was carried out in a Primary Care Health Center among usual patients of general practitioners. Two measurements of the intraocular pressure were assessed on the same day (between 8 and 9 a.m. and between 5 and 6 p.m.) using a Perkins applanation tonometer. The subjects (119 females and 101 males) had a mean age of 46.3 years, with ages ranging between 14 and 83 years. They were proportionally distributed among 4 age groups (14-24, 25-44, 45-64 and >65 years).
Results:
The IOP mean values were: right eye, morning time and afternoon, 13.29 and 11.81 mm Hg, respectively (p<0.001); left eye, morning time and afternoon, 13.48 and 12.04 mm Hg (p<0.001). The IOP was significantly higher in males than in females, and showed a weak association with age.
Conclusions:
We found a diurnal variation of IOP of approximately 1.5 mm Hg. The time of day when the IOP is measured needs to be considered as a variable in research in ocular hypertension and glaucoma.
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