title: Diurnal Variation in Choroidal and Retinal Thickness of the Early Treatment of Diabetic Retinopathy Study Macular Subfields Determined Using Swept-Source Optical Coherence Tomography.
abstract: OBJECTIVE
  To describe diurnal variation in choroidal thickness (CT) and retinal thickness (RT) of the nine Early Treatment of Diabetic Retinopathy Study (ETDRS) macular subfields determined using swept-source optical coherence tomography.
  
  
  METHODS
  A prospective study was conducted on 24 healthy Korean volunteers who underwent two sequential measurements of a randomly selected eye at 9 a.m., 1 p.m., and 6 p.m. The radial scan mode was used. To determine the repeatability and reliability, we applied intragrader agreement using the intraclass correlation coefficient (ICC).
  
  
  RESULTS
  Significant diurnal variation in CT was observed. The highest mean CT was found at 9 a.m. The lowest mean CT occurred at 1 p.m. There was excellent intragrader agreement, with the ICC ranging from 0.961 to 0.997. There was no significant diurnal variation in RT.
  
  
  CONCLUSIONS
  There was significant diurnal variation in CT. The choroid was thinner at 1 p.m. than at 9 a.m. and 6 p.m.
authors: Department of Ophthalmology, Gyeongsang National University College of Medicine, Jinju, Republic of Korea.
authors: Yong-Seop
authors: YS
authors: Han
authors: Hyung-Bin
authors: HB
authors: Lim
authors: Soo-Hyun
authors: SH
authors: Lee
authors: Jung-Yeul
authors: JY
authors: Kim
mesh_terms: D000328:Adult; D002829:Choroid / Q000033:anatomy & histology*; D002940:Circadian Rhythm / Q000502:physiology*; D003930:Diabetic Retinopathy / Q000175:diagnosis; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008297:Male; D009929:Organ Size; D011446:Prospective Studies; D015203:Reproducibility of Results; D012160:Retina / Q000033:anatomy & histology*; D041623:Tomography, Optical Coherence / Q000592:standards*; D014792:Visual Acuity / Q000502:physiology