Intraocular pressure following 18 hours of systemic dehydration in ocular normotensive healthy subjects

Abstract

Aim: To investigate the effect of dehydration on intraocular pressure (IOP). Subjects: The study population comprised 50 subjects (27 men and 23 women) with a mean age of 42.84 ± 2.64 years.Method: The subjects dehydrated for 18 hours. IOP was assessed in both eyes using the Perkins handheld applanation tonometer. Baseline measurement of IOP was taken before the subjects dehydrated for 18 hours and repeated after dehydration. Blood samples were taken before and after dehydration for the determination of plasma osmolality and plasma antidiuretic hormone (ADH) concentrations.Results: A statistically significant (p < 0.001) reduction in the mean weight of subjects occurred after dehydration. There was a significant reduction in IOP from 16.68 mmHg ± 0.32 mmHg to 13.08 mmHg ± 0.31 mmHg after dehydration (p < 0.001). Mean plasma osmolality showed a statistically significant increase (p < 0.05) from baseline of 290.02 mOsmol/kg ± 1.25 mOsmol/kg to 294.96 mOsmol/kg ± 1.33 mOsmol/kg after dehydration. There was also a significant increase (p < 0.05) in mean plasma ADH concentration from 5.36 pg/mL ± 0.21 pg/mL to 6.40 pg/mL ± 0.20 pg/mL after dehydration. There were no significant differences in both systolic and diastolic blood pressures before and after dehydration.Conclusion: Dehydration decreases IOP in healthy humans; this decrease probably results from an increase in plasma osmolality and plasma ADH concentrations.