Pattern ERG correlates of abnormal fundus autofluorescence in patients with retinitis pigmentosa and normal visual acuity.
OBJECTIVE
To examine the functional significance of central abnormalities present in fundus autofluorescence (AF) images in patients with rod-cone dystrophy and good visual acuity.


METHODS
Thirty patients were selected according to three criteria: a clinical diagnosis of retinitis pigmentosa (RP) confirmed with International Society for Clinical Electrophysiology of Vision (ISCEV) standard ERGs, a parafoveal ring of increased high density on fundus AF imaging, and a visual acuity of 20/30 or better. Macular function was assessed with pattern electroretinography (PERG) to checkerboard stimuli of different field sizes. Fundus AF imaging was performed with a confocal scanning laser ophthalmoscope.


RESULTS
The radius of the parafoveal ring of high density varied between 1.5 degrees and 9 degrees. The PERG P50 amplitude correlated highly with the radius of the ring of increased autofluorescence (r = 0.80, P < 0.0005, n = 30). PERGs to smaller circular field sizes were present, but increasing field size to beyond that of the high-density autofluorescence ring did not produce further increases in P50 amplitude. There was a high correlation between the minimum stimulus size required to elicit a maximum-amplitude PERG and the radius of the ring (r = 0.87).


CONCLUSIONS
The high correlation between AF imaging and PERG, an established technique in the assessment of central retinal function, demonstrates the likelihood that autofluorescence abnormalities have functional significance and may therefore be a valuable additional parameter in the monitoring of these patients.
Robson
Anthony G
AG
Department of Electrophysiology, Moorfields Eye Hospital, London, United Kingdom. anthony.robson@moorfields.nhs.uk
El-Amir
Ahmed
A
Bailey
Claire
C
Egan
Catherine A
CA
Fitzke
Frederick W
FW
Webster
Andrew R
AR
Bird
Alan C
AC
Holder
Graham E
GE
D000293:Adolescent; D000328:Adult; D002648:Child; D004596:Electroretinography; D005453:Fluorescence; D005654:Fundus Oculi; D006801:Humans; D008875:Middle Aged; D009887:Ophthalmoscopy; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology*; D012174:Retinitis Pigmentosa / Q000503:physiopathology*; D014792:Visual Acuity / Q000502:physiology*