title: Longitudinal stability of the diurnal rhythm of intraocular pressure in subjects with healthy eyes, ocular hypertension and pigment dispersion syndrome.
abstract: BACKGROUND
  The diurnal fluctuation of intraocular pressure may be relevant in glaucoma. The aim of this study was to find out whether the timing of diurnal fluctuation is stable over the years.
  
  
  METHODS
  Long-term IOP data from the Erlangen Glaucoma Registry, consisting of several annual extended diurnal IOP profiles for each patient, was retrospectively analyzed. Normal subjects, patients with ocular hypertension and with pigment dispersion syndrome were included because these subjects had not been treated with antiglaucomatous medications at the time of data acquisition. A cosine curve was fitted to the IOP data and the stability of individual rhythms over the years was tested using the Rayleigh test. To compare the peak times among groups, means were calculated only from subjects with a significant Rayleigh test.
  
  
  RESULTS
  Of the fifty-two eligible subjects, a total of 364 extended diurnal IOP profiles measured in a sitting position had been collected over a period of 114 ± 39 months. The Rayleigh test indicated intraindividual stability of phase timing only in 19 subjects (36%). In subjects with pigment dispersions syndrome, peak IOP occurred on average two hours and seven minutes later during the day compared with subjects without this condition (p = 0.05).
  
  
  CONCLUSIONS
  Fitting of cosine curves to the clinical IOP profiles was generally feasible, although careful interpretation is warranted due to lack of measurements in supine position and between midnight and 7 am. The interesting observation of a phase lag in eyes with pigment dispersion syndrome warrants confirmation and exploration in future prospective studies. The analysis of the IOP data showed no stable individual rhythm in the long term in a majority of patients.
authors.affiliation: Department of Ophthalmology, University Hospital Erlangen, Friedrich-Alexander-University Erlangen-Nuremberg, Schwabachanlage 6, 91054 Erlangen, Germany. cord.huchzermeyer@uk-erlangen.de.
authors.forename: Cord
authors.initials: C
authors.lastname: Huchzermeyer
authors.forename: Udo
authors.initials: U
authors.lastname: Reulbach
authors.forename: Folkert
authors.initials: F
authors.lastname: Horn
authors.forename: Robert
authors.initials: R
authors.lastname: Lämmer
authors.forename: Christian Y
authors.initials: CY
authors.lastname: Mardin
authors.forename: Anselm G M
authors.initials: AG
authors.lastname: Jünemann
mesh_terms: D000328:Adult; D000368:Aged; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009798:Ocular Hypertension / Q000503:physiopathology*; D011187:Posture; D012189:Retrospective Studies; D014065:Tonometry, Ocular