[Diurnal variability of intraocular pressure].
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.
Jaén-Díaz
J I
JI
Centro de Salud Docente Santa M.a de Benquerencia, Toledo, Spain. ijd02@hotmail.com
Cordero-García
B
B
López-de-Castro
F
F
de-Castro-Mesa
C
C
Castilla-López-Madridejos
F
F
Berciano-Martínez
F
F
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D035843:Biomedical Research; D002940:Circadian Rhythm; D003627:Data Interpretation, Statistical; D005194:Family Practice; D005260:Female; D005901:Glaucoma / Q000175:diagnosis*; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008365:Manometry; D008875:Middle Aged; D009798:Ocular Hypertension / Q000175:diagnosis; D011320:Primary Health Care; D012737:Sex Factors; D013997:Time Factors