title: Daytime levels of melatonin in patients with age-related macular degeneration.
abstract: OBJECTIVE
  Melatonin (N-acetyl-5-methoxytryptamine) (MT) is a hormone that acts as an antioxidant. It is produced by the pineal gland and within the retina; its release is blocked by light entering the eye. We examined whether MT daytime levels differ between pseudophakic patients with age-related macular degeneration (ARMD) and pseudophakic subjects without any ocular pathology of the same age.
  
  
  METHODS
  A prospective, cross-sectional, observational study was performed. Pseudophakic patients of the same age group were included. Patients underwent complete ophthalmic examinations and blood sampling between 08:00 and 10:00 hr. MT daytime value in the serum was the main outcome measure.
  
  
  RESULTS
  Sixty-nine pseudophakic patients were included. Fifty patients with exudative and non-exudative ARMD were in the study group while 19 patients were controls. Patients with ARMD had significantly higher daytime levels of MT (P = 0.003). There were significant differences in MT daytime levels between the exudative and non-exudative forms (P = 0.009). MT values also correlated with the best-corrected visual acuity (r = -0.285, P = 0.019).
  
  
  CONCLUSIONS
  These data indicate that pseudophakic patients with ARMD produce more MT during the day compared to pseudophakic subjects without ARMD. This may be caused by the reduced visual acuity in patients with ARMD, whereby less light reaches the photoreceptors, allowing MT secretion to continue during the day. Because MT also acts as an antioxidant and daytime levels are higher in patients with ARMD, these results might be interpreted as a rescue factor.
authors.affiliation: Department of Ophthalmology, The Ludwig Boltzmann Institute for Retinology and Biomicroscopic Lasersurgery, Vienna, Austria. katharina.schmid-kubista@wienkav.at
authors.forename: Katharina E
authors.initials: KE
authors.lastname: Schmid-Kubista
authors.forename: Carl G
authors.initials: CG
authors.lastname: Glittenberg
authors.forename: Melanie
authors.initials: M
authors.lastname: Cezanne
authors.forename: Klaus
authors.initials: K
authors.lastname: Holzmann
authors.forename: Beatrix
authors.initials: B
authors.lastname: Neumaier-Ammerer
authors.forename: Susanne
authors.initials: S
authors.lastname: Binder
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002940:Circadian Rhythm / Q000502:physiology*; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008268:Macular Degeneration / Q000097:blood*; D008297:Male; D008550:Melatonin / Q000097:blood*; D008875:Middle Aged; D011446:Prospective Studies; D019591:Pseudophakia / Q000097:blood; D012621:Seasons; D014792:Visual Acuity / Q000502:physiology
chemical_list: D008550:Melatonin