title: Increment Threshold Functions in Retinopathy of Prematurity.
abstract: To assess scotopic background adaptation in subjects with a history of preterm birth and retinopathy of prematurity (ROP). Retinopathy of prematurity is known to have long-term effects on rod photoreceptor and rod mediated postreceptor retinal function.
  
  
  
  Rod-mediated thresholds for detection of 3° diameter, 50 ms stimuli presented 20° from fixation were measured using a spatial forced choice method in 36 subjects (aged 9-17 years) with a history of preterm birth and 11 age similar term-born subjects. Thresholds were measured first in the dark-adapted condition and then in the presence of 6 steady background lights (-2.8 to +2.0 log scot td). A model of the increment threshold function was fit to each subject's thresholds to estimate the dark-adapted threshold (TDA) and the Eigengrau (A0, the background that elevates threshold 0.3 log unit above TDA).
  
  
  
  In subjects with a history of severe ROP, both TDA and A0 were significantly elevated relative to those in former preterms who never had ROP and term-born control subjects. Subjects who had mild ROP had normal TDA but elevated A0. Neither TDA nor A0 differed significantly between former preterms who never had ROP and term-born controls.
  
  
  
  The results suggest that in severe ROP, threshold is affected at a preadaptation site, possibly the rod outer segment. In mild ROP, changes in the Eigengrau may reflect increased intrinsic noise in the photoreceptor or postreceptor circuitry or both.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Hansen
authors.forename: Anne
authors.initials: A
authors.lastname: Moskowitz
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Bush
authors.forename: Anne B
authors.initials: AB
authors.lastname: Fulton
mesh_terms: D000293:Adolescent; D002648:Child; D003623:Dark Adaptation; D018450:Disease Progression; D004596:Electroretinography / Q000379:methods; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010775:Photic Stimulation; D012160:Retina / Q000503:physiopathology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D012178:Retinopathy of Prematurity / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000502:physiology*