title: Temporal summation in children with a history of retinopathy of prematurity.
abstract: OBJECTIVE
  To assess temporal summation in children with a history of retinopathy of prematurity (ROP) by determining the critical duration (tCRIT) for complete temporal summation under rod-mediated conditions. From prior ERG studies, it is known that the kinetics of activation of phototransduction are prolonged in the ROP rod photoreceptor.
  
  
  METHODS
  Dark-adapted thresholds for detecting 10° diameter stimuli with durations from 10 to 640 ms were measured. A two-alternative, spatial, forced-choice psychophysical procedure was used. The tCRIT for complete summation was estimated in former preterm subjects with a history of severe ROP (n = 7), mild ROP (n = 23), and no ROP (n = 15). The subjects ranged in age from 10.4 to 17.6 (median 15.6) years. Age-similar term-born control subjects (n = 5) were also tested.
  
  
  RESULTS
  Critical duration was significantly longer in subjects with a history of ROP than in subjects who never had ROP or who were born at term. Mean tCRIT in the mild ROP group [127.5 (SD = 19.9) ms] and severe group [147.6 (SD = 18.9) ms] did not differ significantly, but both were significantly longer than in former preterms who never had ROP [101.1 (SD = 16.5) ms] and in term-born controls [101.0 (SD = 19.5) ms].
  
  
  CONCLUSIONS
  In ROP subjects, tCRIT is significantly prolonged. This is likely due to abnormal kinetics in the rod outer segment.
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Ronald M
authors.initials: RM
authors.lastname: Hansen
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Anne
authors.initials: A
authors.lastname: Moskowitz
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Jena L
authors.initials: JL
authors.lastname: Tavormina
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Jennifer N
authors.initials: JN
authors.lastname: Bush
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Garima
authors.initials: G
authors.lastname: Soni
authors.affiliation: Department of Ophthalmology, Boston Children's Hospital and Harvard Medical School, Boston, Massachusetts, United States.
authors.forename: Anne B
authors.initials: AB
authors.lastname: Fulton
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003623:Dark Adaptation / Q000502:physiology*; D004596:Electroretinography / Q000379:methods; D005260:Female; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D010775:Photic Stimulation; D011379:Prognosis; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology*; D012178:Retinopathy of Prematurity / Q000503:physiopathology*; D012684:Sensory Thresholds / Q000502:physiology*
keywords: photoreceptors; psychophysics; retinopathy of prematurity; scotopic visual threshold; temporal summation