Functional characteristics of patients with retinal dystrophy that manifest abnormal parafoveal annuli of high density fundus autofluorescence; a review and update.
OBJECTIVE
To examine the presence and functional significance of annular fundus autofluorescence abnormalities in patients with different retinal dystrophies.


METHODS
Eighty one patients were ascertained who had a parafoveal ring of high density on fundus autofluorescence imaging. Sixty two had had a clinical diagnosis of retinitis pigmentosa (RP) or Usher syndrome with normal visual acuity. Others included a case of Leber congenital amaurosis and genetically confirmed cases of cone or cone-rod dystrophy (GUCA1A, RPGR, RIMS1), "cone dystrophy with supernormal rod ERG" (KCNV2) and X-linked retinoschisis (RS1). International-standard full-field and pattern electroretinography (ERG; PERG) were performed. Some patients with rod-cone or cone-rod dystrophy underwent multifocal ERG (mfERG) testing and photopic and scotopic fine matrix mapping (FMM).


RESULTS
In patients with RP, the radius of the parafoveal ring of high density correlated with PERG P50 (R = 0.83, P < 0.0005, N = 62) and encircled areas of preserved photopic function. In the other patients, AF rings either resembled those seen in RP or encircled an area of central atrophy. Ring radius was inversely related to the PERG P50 component in 4 of 18 cases with a detectable response. FMM showed that arcs of high density were associated with a gradient of sensitivity change.


CONCLUSIONS
Parafoveal rings of high density autofluorescence are a non-specific manifestation of retinal dysfunction that can occur in different retinal dystrophies. Electrophysiology remains essential for accurate diagnosis. The high correlation of autofluorescence with PERG, mfERG and FMM demonstrates that AF abnormalities have functional significance and may help identify suitable patients and retinal areas amenable to future therapeutic intervention.
Robson
Anthony G
AG
Department of Electrophysiology, Moorfields Eye Hospital, 162 City Road, London EC1 2PD, UK. anthony.robson@moorfields.nhs.uk
Michaelides
Michel
M
Saihan
Zubin
Z
Bird
Alan C
AC
Webster
Andrew R
AR
Moore
Anthony T
AT
Fitzke
Fred W
FW
Holder
Graham E
GE
D004596:Electroretinography; D005453:Fluorescence; D005584:Fovea Centralis / Q000378:metabolism / Q000503:physiopathology*; D005654:Fundus Oculi; D005838:Genotype; D006801:Humans; D008062:Lipofuscin / Q000378:metabolism; D010641:Phenotype; D012174:Retinitis Pigmentosa / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*; D052245:Usher Syndromes / Q000175:diagnosis / Q000378:metabolism / Q000503:physiopathology*
D008062:Lipofuscin