Increased plasma free cortisol in ocular hypertension and open angle glaucoma
B. Schwartz, G. McCarty and B. Rosner
Values of plasma free cortisol (not bound to plasma proteins), total plasma
cortisol, and percent free cortisol were determined in normal, ocular
hypertensive, and open angle glaucomatous subjects. Median total plasma,
plasma free, and percent free cortisol levels were higher in ocular
hypertensive and glaucomatous individuals. The most significant differences
occurred with percent free cortisol values between normal and glaucomatous
subjects. There was a significant positive correlation between percent free
cortisol and total cortisol levels in normal subjects only. For subjects
with glaucoma and hypertension, the percent free cortisol values were
independent of the total cortisol values. Multilinear regression analysis
also indicated that besides diagnosis and level of total plasma cortisol,
male sex, blood sampling late in the day, and increased diastolic blood
pressure were the only variables significantly related to increased values
of plasma free cortisol and percent free cortisol. Ocular medication for
glaucoma and use of beta-blockers were not found to be significant
independent variables in the regression models for either plasma free
cortisol or percent free cortisol. These observations further suggest that
a disorder of the pituitary adrenal axis and/or a binding of plasma
cortisol is associated with ocular hypertension and open angle glaucoma.
