title: Diurnal variation in retinal thickening measurement by optical coherence tomography in center-involved diabetic macular edema.
abstract: OBJECTIVE
  To evaluate diurnal variation in retinal thickness measured with optical coherence tomography (OCT) in patients with center-involved diabetic macular edema.
  
  
  METHODS
  Serial OCT3 measurements were performed in 156 eyes of 96 subjects with clinically diagnosed diabetic macular edema and OCT central subfield retinal thickness of 225 microm or greater at 8 am. Central subfield thickness was measured from OCT3 retinal thickness maps at 6 points over a single day between 8 am and 4 pm. A change in central subfield thickening (observed thickness minus mean normal thickness) of at least 25% and of at least 50 microm at 2 consecutive points or between 8 am and 4 pm was considered to have met the composite outcome threshold.
  
  
  RESULTS
  At 8 am, the mean central subfield thickness was 368 microm and the mean visual acuity was 66 letters (approximately 20/50). The mean change in relative central subfield retinal thickening between 8 am and 4 pm was a decrease of 6% (95% confidence interval, -9% to -3%) and the mean absolute change was a decrease of 13 microm (95% CI, -17 to -8). The absolute change was significantly greater in retinas that were thicker at 8 am (P<.001) but the relative change was not (P = .14). The composite threshold of reduction in central subfield thickening (as defined above) was observed in 5 eyes of 4 subjects (3% of eyes; 95% CI, 1% to 8%) while 2 eyes of 2 subjects (1%; 95% CI, 0% to 5%) had an increase in central subfield thickening of this same magnitude. The maximum decrease was observed at 4 pm in all 5 eyes.
  
  
  CONCLUSIONS
  Although on average there are slight decreases in retinal thickening during the day, most eyes with diabetic macular edema have little meaningful change in OCT central subfield thickening between 8 am and 4 pm.
authors.affiliation: Jaeb Center for Health Research, Tampa, FL 33647, USA. drcrnet@jaeb.org
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Danis
authors.forename: Adam R
authors.initials: AR
authors.lastname: Glassman
authors.forename: Lloyd Paul
authors.initials: LP
authors.lastname: Aiello
authors.forename: Andrew N
authors.initials: AN
authors.lastname: Antoszyk
authors.forename: Roy W
authors.initials: RW
authors.lastname: Beck
authors.forename: David J
authors.initials: DJ
authors.lastname: Browning
authors.forename: Antonio P
authors.initials: AP
authors.lastname: Ciardella
authors.forename: James L
authors.initials: JL
authors.lastname: Kinyoun
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Murtha
authors.forename: Trexler M
authors.initials: TM
authors.lastname: Topping
authors.forename: Michel
authors.initials: M
authors.lastname: Shami
authors.forename: George S
authors.initials: GS
authors.lastname: Sharuk
authors.forename: John A
authors.initials: JA
authors.lastname: Wells
mesh_terms: D000886:Anthropometry; D002940:Circadian Rhythm; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008269:Macular Edema / Q000175:diagnosis*; D008297:Male; D008875:Middle Aged; D012160:Retina / Q000473:pathology*; D013997:Time Factors; D041623:Tomography, Optical Coherence; D014792:Visual Acuity