title: Intraocular pressure changes and ocular biometry during Sirsasana (headstand posture) in yoga practitioners.
abstract: OBJECTIVE
  To study the intraocular pressure (IOP) changes in Sirsasana (headstand posture) done by experienced yoga practitioners and correlate the ocular biometric parameters with the IOP changes, and to screen for the prevalence of ocular hypertension in this group of subjects.
  
  
  METHODS
  Prospective case observational series.
  
  
  METHODS
  Seventy-five subjects (50 Asian Indians and 25 Caucasians) from a yoga training institute volunteered for the study.
  
  
  METHODS
  All participants underwent a detailed ophthalmic examination along with ocular biometry and corneal pachymetry. Intraocular pressure was recorded using a Tonopen before, during, and after the Sirsasana. Changes were compared using the paired t test. Age, axial length, anterior chamber depth, lens thickness, corneal curvature, corneal thickness, race, and the length of time for which the practitioner was performing yoga were correlated with the induced IOP difference in a randomly selected eye using Pearson's correlation coefficient with Bonferroni correction for multiple comparisons.
  
  
  METHODS
  Ocular biometry and induced IOP difference.
  
  
  RESULTS
  The mean increase in IOP at baseline and immediately after assuming Sirsasana was 15.1+/-4.1 mmHg (R = 0.07; P = 0.999) and after 5 minutes was 15.8+/-4.6 mmHg (R = -0.25; P = 0.357). The induced increase in IOP during the posture was twice the baseline IOP. There was no correlation between age, ocular biometry, and ultrasound pachymetry when compared with the induced IOP difference. One subject (1.33%) was found to have baseline IOP of more than 21 mmHg.
  
  
  CONCLUSIONS
  There was a uniform 2-fold increase in the IOP during Sirsasana, which was maintained during the posture in all age groups irrespective of the ocular biometry and ultrasound pachymetry. We did not demonstrate a higher prevalence of ocular hypertensives in this cohort of yoga practitioners nor did the risk factors contributing to glaucoma show any correlation with magnitude of IOP raise during the posture.
authors.affiliation: Medical and Vision Research Foundation, Sankara Nethralaya, Chennai, India. drmbsn@rediffmail.com
authors.forename: Mani
authors.initials: M
authors.lastname: Baskaran
authors.forename: Krishna
authors.initials: K
authors.lastname: Raman
authors.forename: Krishna Kumar
authors.initials: KK
authors.lastname: Ramani
authors.forename: Joseph
authors.initials: J
authors.lastname: Roy
authors.forename: Lingam
authors.initials: L
authors.lastname: Vijaya
authors.forename: Sengamedu S
authors.initials: SS
authors.lastname: Badrinath
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001699:Biometry; D005123:Eye / Q000033:anatomy & histology* / Q000000981:diagnostic imaging; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D011187:Posture / Q000502:physiology*; D011446:Prospective Studies; D012016:Reference Values; D013997:Time Factors; D014463:Ultrasonography; D015013:Yoga