Background adaptation in children with a history of mild retinopathy of prematurity.
OBJECTIVE
In children with a history of mild retinopathy of prematurity (ROP), test the hypothesis that elevation of the parafoveal over peripheral dark-adapted threshold is due to photoreceptor rather than postreceptor dysfunction.


METHODS
A forced choice procedure was used to measure thresholds, for detection of 2 degrees diameter, 50 msec, blue stimuli presented 10 degrees (parafoveal) or 30 degrees (peripheral) eccentric in the dark and in the presence of steady red backgrounds (-4 to +2 log scot td). Four ROP and four control subjects were tested at both eccentricities. A model of the increment threshold function was fit to the data to calculate the eigengrau and dark-adapted threshold.


RESULTS
Both ROP subjects with elevated parafoveal thresholds also have elevated parafoveal eigengraus. On the other hand, parafoveal and peripheral eigengraus are equal in ROP subjects without parafoveal threshold elevation. Nevertheless, the dark-adapted thresholds of all ROP subjects are higher than those of any control subject at both sites.


CONCLUSIONS
The parafoveal threshold elevation is due to rod dysfunction. There is also evidence of peripheral rod photoreceptor involvement in the subjects with ROP.
Hansen
R M
RM
Department of Ophthalmology, Children's Hospital and Harvard Medical School, Boston, Massachusetts 02115, USA. hansen_r@a1.tch.harvard.edu
Fulton
A B
AB
D000293:Adolescent; D000328:Adult; D002648:Child; D003623:Dark Adaptation; D004594:Electrophysiology; D005584:Fovea Centralis / Q000503:physiopathology; D006801:Humans; D007231:Infant, Newborn; D017948:Retinal Rod Photoreceptor Cells / Q000503:physiopathology*; D012178:Retinopathy of Prematurity / Q000503:physiopathology*; D012684:Sensory Thresholds