title: The Effect of Dehydration and Fasting on Corneal Biomechanical Properties and Intraocular Pressure.
abstract: OBJECTIVE
  To evaluate the changes in corneal biomechanical properties and intraocular pressure (IOP) during fasting period in healthy subjects.
  
  
  METHODS
  Seventy-two eyes of 72 fasting subjects (study group), and 62 eyes of 62 nonfasting subjects (control group) were enrolled in this prospective study undertaken at a single university hospital. All subjects underwent complete ophthalmologic examination including ocular biomechanical evaluation with ocular response analyzer. Ocular response analyzer measurement was performed on the right eyes of the subjects between 5.00 and 6.00 PM after approximately 14 hr of fasting for the study group and after a nonfasting period for the control group. The corneal hysteresis, corneal resistance factor, mean corneal compensated IOP (IOPcc), and Goldmann-correlated IOP (IOPg) values were measured with a patented dynamic bidirectional applanation process.
  
  
  RESULTS
  Goldmann-correlated IOP and IOPcc measurements in the study group and the control group were found as 13.8±2.8 mm Hg, 14.6±2.6 mm Hg and 16.3±2.2 mm Hg, 15.7±2.4 mm Hg, respectively. There was statistically significant difference within the two groups in IOPg and IOPcc (P<0.001). In addition, corneal hysteresis and corneal resistance factor significantly decreased in study group compared with control group (P<0.001, P=0.012, respectively).
  
  
  CONCLUSIONS
  Prolonged fasting causes a significant decrease in IOPg, IOPcc, corneal hysteresis, and corneal resistance factor in healthy subjects, altering the biomechanical properties of the cornea.
authors.affiliation: Department of Ophthalmology (R.O., G.S., E.S., M.O., N.Z.), Meram Faculty of Medicine, Necmettin Erbakan University, Konya, Turkey; and Ophthalmology Department (I.E.), 18 March University Faculty of Medicine, Canakkale, Turkey.
authors.forename: Refik
authors.initials: R
authors.lastname: Oltulu
authors.forename: Gunhal
authors.initials: G
authors.lastname: Satirtav
authors.forename: Ismail
authors.initials: I
authors.lastname: Ersan
authors.forename: Erkan
authors.initials: E
authors.lastname: Soylu
authors.forename: Mehmet
authors.initials: M
authors.lastname: Okka
authors.forename: Nazmi
authors.initials: N
authors.lastname: Zengin
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D016022:Case-Control Studies; D003315:Cornea / Q000502:physiology*; D003681:Dehydration / Q000503:physiopathology*; D004548:Elasticity; D005215:Fasting / Q000009:adverse effects / Q000502:physiology*; D005260:Female; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D014065:Tonometry, Ocular; D055815:Young Adult