title: Diurnal Alterations of Refraction, Anterior Segment Biometrics, and Intraocular Pressure in Long-Time Dehydration due to Religious Fasting.
abstract: OBJECTIVE
  To investigate the effects of dehydration due to fasting on diurnal changes of intraocular pressure, anterior segment biometrics, and refraction.
  
  
  METHODS
  The intraocular pressures, anterior segment biometrics (axial length: AL; Central corneal thickness: CCT; Lens thickness: LT; Anterior chamber depth: ACD), and refractive measurements of 30 eyes of 15 fasting healthy male volunteers were recorded at 8:00 in the morning and 17:00 in the evening in the Ramadan of 2013 and two months later. The results were compared and the statistical analyses were performed using the Rstudio software version 0.98.501. The variables were investigated using visual (histograms, probability plots) and analytical methods (Kolmogorov-Smirnov/Shapiro-Wilk test) to determine whether or not they were normally distributed.
  
  
  RESULTS
  The refractive values remained stable in the fasting as well as in the control period (p = 0.384). The axial length measured slightly shorter in the fasting period (p = 0.001). The corneal thickness presented a diurnal variation, in which the cornea measured thinner in the evening. The difference between the fasting and control period was not statistically significant (p = 0.359). The major differences were observed in the anterior chamber depth and IOP. The ACD was shallower in the evening during the fasting period, where it was deeper in the control period. The diurnal IOP difference was greater in the fasting period than the control period. Both were statistically significant (p = 0.001). The LT remained unchanged in both periods.
  
  
  CONCLUSIONS
  The major difference was shown in the anterior chamber shallowing in the evening hours and IOP. Our study contributes the hypothesis that the posterior segment of the eye is more responsible for the axial length alterations and normovolemia has a more dominant influence on diurnal IOP changes.
authors.affiliation: a Department of Ophthalmology , Sifa University Medical Faculty , Izmir , Turkey.
authors.forename: Gonen
authors.initials: G
authors.lastname: Baser
authors.affiliation: a Department of Ophthalmology , Sifa University Medical Faculty , Izmir , Turkey.
authors.forename: Hakan
authors.initials: H
authors.lastname: Cengiz
authors.affiliation: a Department of Ophthalmology , Sifa University Medical Faculty , Izmir , Turkey.
authors.forename: Murat
authors.initials: M
authors.lastname: Uyar
authors.affiliation: a Department of Ophthalmology , Sifa University Medical Faculty , Izmir , Turkey.
authors.forename: Emine
authors.initials: E
authors.lastname: Seker Un
mesh_terms: D000328:Adult; D000869:Anterior Eye Segment / Q000503:physiopathology*; D058452:Axial Length, Eye; D001699:Biometry; D002940:Circadian Rhythm / Q000502:physiology*; D003681:Dehydration / Q000503:physiopathology*; D005215:Fasting / Q000502:physiology*; D064368:Healthy Volunteers; D006801:Humans; D007429:Intraocular Pressure / Q000502:physiology*; D007514:Islam; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology*; D012068:Religion and Medicine
keywords: Anterior chamber depth; anterior segment biometrics; axial eye length; dehydration; diurnal intraocular pressure