I enjoyed reading Dr. Dunbar"s challenging "Retina Quiz" case, "Just How "Interesting" Are Patients" Eyes?" (July 2004). How-ever, I believe this looks remarkably similar to a condition known as peripapillary (pericentral) pigmentary retinal degeneration (PPRD).
PPRD is characterized by a bilateral (usually symmetric) thinning of the retinal pigment epithelium. There is associated bone spicule pigment clumping in a peripapillary distribution that extends nasal to the disc and temporally in an arcuate fashion. In early stages, acuity can be normal. But in later stages, patients can develop a bull"s-eye maculopathy, as seen in Dr. Dunbar"s case.
When the arcuate pigmentary changes meet to form a ring, it is called pericentral retinal pigmentary degeneration (as in this patient"s left eye); if the arcuate areas of degeneration have not yet joined, it is termed "peripapillary." Such pericentral changes have never been documented in Stargardt"s disease.
Noble and Carr examined four asymptomatic patients with PPRD and describe the changes demonstrated by Dr. Dunbar"s case.1 Fluorescein angiography showed marked hyperfluorescence in the affected areas in their patients as well. Visual acuity was normal or nearly normal, and the electro-retinograms were either normal or demonstrated a "slight reduction."
Additionally, Dr. Noble followed three of these four individuals for 13 years and reported a slow progression of the retinal degeneration, with focal choroidal atrophy.2 One of the four patients developed the bull"s-eye maculopathy, as seen in Dr. Dunbar"s patient, and focal choroidal atrophy, seen temporal to the macula of the right eye on fluorescein angiography.
Dr. Dunbar correctly points out that the hallmark angiographic evidence of Stargardt"s disease is a "dark" or "silent" choroid. I am not convinced this is the case from the photos in the "Retina Quiz," but Dr. Dunbar likely has seen other photos of this patient.
Genetic analysis will likely provide us with the correct diagnosis in such cases in which the phenotypic picture is less than classical. It would be interesting if future DNA analysis in Dr. Dunbar"s patient reveals a mutation in the ABCA4 gene on the short arm of chromosome 1, a finding that is diagnostic of Stargardt"s disease.
--Sherry J. Bass, O.D., F.A.A.O., Professor, State University of New York State College of Optometry
1. Noble KG, Carr RE. Peripapillary pigmentary retinal degeneration. Am J Ophthalmol 1978 Jul;86(1):65-75.
2. Noble KG. Peripapillary (pericentral) pigmentary retinal degeneration. Am J Ophthalmol 1989 Dec 15;108(6):686-90.
Dr. Dunbar Responds:
I appreciate your comments and feedback on the case. The patient I presented does look strikingly similar to the cases of peripapillary pigmentary retinal degeneration that were published by Ken Noble. I do not disagree that the patient probably has PPRD; she probably does. However, that does not mean the patient does not have Stargardt"s.
We are now in an age in which genetic testing has resulted in the reclassification of many of the retinal degenerative diseases and dystrophies. Genetic linkage studies were not done on our patient, but the likelihood is that our case and perhaps even some of those published by Dr. Noble would map out to chromosomal 1p involvement and therefore would genetically be classified as Stargardt"s macular disease. I would be curious to know, now that genetic testing is more available, if any testing has been done on any of Noble"s cases to see how they would be classified?
Several fluorescein angiograms have been done on our patient over the years, and the quiet choroid is definitely present outside the zones of RPE atrophy. These are not artifactitious, nor are they from "relative darkening." In fact, the dark choroid is also present in some of the patients that Dr. Noble published in his 1989 paper. Just as one could mistakenly call it a "quiet choroid" because of the "relative darkening" compared to all zones of hyperfluorescence, one could just as easily miss the quiet choroid by not looking carefully due to all the zones of atrophy and hyperfluorescence.
It is an interesting case that is presented, and I had not considered PPRD as a possibility. Thank you for making me aware of it. There is not much new research on this topic. It would be interesting to know if genetic testing has been conducted and what the linkage studies would show. Is it its own genetic disease entity such as PPRD, or does it fall into the Stargardt"s category or some other hereditary condition such as retinitis pigmentosa? Until that is done, we may not really know what the true answer is.
Vol. No: 141:10Issue:
10/23/04
