title: A comparison of the circadian rhythm of intraocular pressure in primary phronic angle closure glaucoma, primary open angle glaucoma and normal eyes.
abstract: OBJECTIVE
  To evaluate the circadian rhythm of intraocular pressure (IOP) in primary chronic angle closure glaucoma (PCACG), primary open angle glaucoma (POAG), and normal eyes.
  
  
  METHODS
  Cross-sectional study of newly diagnosed patients of POAG (60 eyes), PCACG following laser iridotomy (75 eyes), and age and sex matched normal controls (75 eyes). All subjects underwent applanation tonometry at 7 a.m., 10 a.m., 1 p.m., 4 p.m., 7 p.m., and 10 p.m. by a masked observer. Circadian rhythms were classified based upon the timing and presence of peak pressure.
  
  
  RESULTS
  Age and gender in all three groups were comparable. Diurnal IOP fluctuations were significantly higher in PCACG (7.69+3.03 mmHg) and POAG (8.31+2.58 mmHg) groups compared to normal controls (4.83 + 2.46 mmHg). PCACG eyes and controls had similarly timed circadian rhythms, with PCACG eyes having a consistently higher IOP. At 7 and 10 a.m., IOP peaked more often in POAG eyes compared to PCACG eyes. A plateau type of circadian rhythm was most common in normal eyes. The timing of peak IOP could be significantly correlated with the type of primary glaucoma examined.
  
  
  CONCLUSIONS
  Afternoon peaks were more common in postiridotomy PCACG eyes, similar to the rhythm in normal eyes. Morning peaks were more frequent in POAG eyes. Diurnal fluctuation > 6 mmHg, associated with an IOP of 21 mmHg or more was never seen in a normal eye.
authors.affiliation: Dr. Rajendra Prasad Centre for ophthalmic science, All India Institute of Medical Science, New Delhi. drsihota@hotmail.com
authors.forename: Ramanjit
authors.initials: R
authors.lastname: Sihota
authors.forename: R
authors.initials: R
authors.lastname: Saxena
authors.forename: M
authors.initials: M
authors.lastname: Gogoi
authors.forename: A
authors.initials: A
authors.lastname: Sood
authors.forename: V
authors.initials: V
authors.lastname: Gulati
authors.forename: R M
authors.initials: RM
authors.lastname: Pandey
mesh_terms: D016022:Case-Control Studies; D002908:Chronic Disease; D002940:Circadian Rhythm; D005260:Female; D015812:Glaucoma, Angle-Closure / Q000503:physiopathology*; D005902:Glaucoma, Open-Angle / Q000503:physiopathology*; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged