Hansen, RonaldMoskowitz, AnneBush, Jennifer N.Fulton, Anne2016-12-022016Hansen, Ronald M., Anne Moskowitz, Jennifer N. Bush, and Anne B. Fulton. 2016. “Increment Threshold Functions in Retinopathy of Prematurity.” Investigative Ophthalmology & Visual Science 57 (6): 2421-2427. doi:10.1167/iovs.16-19294. http://dx.doi.org/10.1167/iovs.16-19294.0146-0404http://nrs.harvard.edu/urn-3:HUL.InstRepos:29626011Purpose 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. Methods: 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). Results: 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. Conclusions: 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.en-USretinopathy of prematurityincrement thresholdretinal adaptationphotoreceptorsvisual psychophysicsJournal Article2016-12-0210.1167/iovs.16-19294