Circadian rhythm of intraocular pressure in healthy subjects and glaucoma patients

Abstract

Abstract Purpose: Intraocular pressure (IOP) varies and depends on many factors. Intraocular pressure variations throughout the nycthemeron (the full 24‐period of a night and a day) are the most interesting for studying. Methods: With present techniques, it is impossible to measure continuously without waking the subject up. Thus, IOP must be hourly measured during 24 hours with a portable tonometer which allows short measurements in any posture, without requiring the subjects or patients to rise during the night. Results: Intraocular pressure depends on a nyctohemeral rhythm, being higher at night than during the day in healthy subjects, with a nocturnal peak value (acrophase). In the same normal individual, several 24‐hour monitorings are identical. Each individual has his own 24‐hour pattern of IOP.In glaucoma patients, however, the 24‐hour rhythm of IOP was reversed, with values being higher during the day (a midday peak in IOP) than during the night. Conclusions: The time course of the nyctohemeral curve of intraocular pressure is considered to play a role in the prognosis of glaucoma and allows to classify the type of glaucoma (POAG, NTG). Lowering of IOP is still the only option that is available for treating patients with glaucoma. Variations encountered in the individual’s nyctohemeral IOP pattern must be taken into consideration to manage the most efficient treatment.