title: Vitamin D and intraocular pressure--results from a case-control and an intervention study.
abstract: OBJECTIVE
  To study the associations between serum 25-hydroxy-vitamin D (25(OH)D) levels, vitamin D administration and intraocular pressure (IOP).
  
  
  METHODS
  The design of the study included a nested case-control study and a randomized controlled intervention trial. In the first part, healthy Caucasians with high or low serum 25(OH)D levels were recruited from a population-based study. IOP of the right eye was measured by the use of a rebound tonometer. In the second part, those with low serum 25(OH)D levels were randomized to receive either capsules of vitamin D3 20,000 IU twice per week or placebo for 6 months before IOP was measured again.
  
  
  RESULTS
  Intraocular pressure in the 87 participants with low serum 25(OH)D levels (mean 40.1±12.9 nm) did not differ from IOP in the 42 participants with high serum 25(OH)D levels (mean 85.1±14.0 nm) (15.9±3.3 mmHg versus 15.6±3.1 mmHg, p= 0.56, independent t-test). After intervention, IOP decreased by -0.8± 2.1 mmHg (p = 0.017, paired t-test) in the vitamin D group (n= 39) and -0.8±2.5 mmHg (p= 0.059) in the placebo group (n= 39), but the change was not significantly different between the groups (p= 0.92, independent t-test).
  
  
  CONCLUSIONS
  This study in healthy participants revealed no associations between serum 25(OH)D levels and IOP, and administration of vitamin D3 to participants with low levels of 25(OH)D did not affect IOP. These results do not support a role of vitamin D in the regulation of IOP.
authors.affiliation: Department of Ophthalmology, University Hospital of North Norway, Tromsø, NorwayDepartment of Clinical Medicine, Tromsø Endocrine Research Group, University of Tromsø, Tromsø, NorwayDivision of Internal Medicine, University Hospital of North Norway, Tromsø, NorwayDepartment of Clinical Medicine, Brain and Circulation Research Group, University of Tromsø, Tromsø, Norway.
authors.forename: Einar Andreas
authors.initials: EA
authors.lastname: Krefting
authors.forename: Rolf
authors.initials: R
authors.lastname: Jorde
authors.forename: Terje
authors.initials: T
authors.lastname: Christoffersen
authors.forename: Guri
authors.initials: G
authors.lastname: Grimnes
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002112:Calcifediol / Q000097:blood; D002214:Capsules; D016022:Case-Control Studies; D002762:Cholecalciferol / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008163:Luminescent Measurements; D008297:Male; D008875:Middle Aged; D014065:Tonometry, Ocular; D014808:Vitamin D Deficiency / Q000097:blood / Q000188:drug therapy*; D014815:Vitamins / Q000008:administration & dosage*
chemical_list: D002214:Capsules; D014815:Vitamins; D002762:Cholecalciferol; D002112:Calcifediol
keywords: glaucoma; intraocular pressure; randomized controlled trial; vitamin D