The cone electroretinogram in retinopathy of prematurity.
OBJECTIVE
To test the hypothesis that retinopathy of prematurity (ROP) affects the cone photoreceptors less than the rod photoreceptors.


METHODS
Electroretinogram (ERG) responses to a 1.8-log-unit range of red flashes on a white, rod-saturating background were recorded in 42 subjects with a history of preterm birth and ROP (28 untreated; 6 treated) or no ROP (n = 8). The sensitivity (S(CONE)) and saturated amplitude (R(CONE)) of the cone photoresponse were calculated by fit of a model of the activation of cone phototransduction to the a-waves. The cone-driven b-wave amplitude was evaluated as a function of stimulus intensity. S(CONE) and R(CONE) were compared to the rod response parameters (S(ROD), R(ROD)) recorded from the same preterm subjects. Responses in the former preterm subjects were compared to those in control subjects.


RESULTS
The values of S(CONE) and R(CONE) in the preterm subjects overlapped broadly with those in the control subjects. The shapes of the b-wave stimulus-response functions did not differ between preterm and control subjects. The relative value of S(CONE) was significantly greater than that of S(ROD).


CONCLUSIONS
ROP has less effect on the cone than on the rod photoresponses, suggesting that cones are more resistant to the ROP disease process. The similar shape of the b-wave stimulus-response function in preterms and control subjects is evidence that ROP does not alter the balance of ON and OFF signals in the cone pathway.
Fulton
Anne B
AB
Department of Ophthalmology, Children's Hospital and Harvard Medical School Boston, MA 02115, USA. anne.fulton@childrens.harvard.edu
Hansen
Ronald M
RM
Moskowitz
Anne
A
D004596:Electroretinography; D005865:Gestational Age; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D010775:Photic Stimulation; D047928:Premature Birth; D017949:Retinal Cone Photoreceptor Cells / Q000502:physiology*; D017948:Retinal Rod Photoreceptor Cells / Q000502:physiology; D012178:Retinopathy of Prematurity / Q000503:physiopathology*; D014785:Vision, Ocular / Q000502:physiology