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Canthaxanthine Retinopathy
Alejandro Espaillat, MD;
Lloyd Paul Aiello, MD, PhD;
Paul G. Arrigg, MD;
Robert Villalobos, MD;
Philip M. Silver, OD;
Robert W. Cavicchi, CRA
Arch Fam Med. 2000;9:121-122.
AN asymptomatic 34-year-old man was seen for a routine eye examination. Medical history was noteworthy for a 1-month history of type 2 diabetes mellitus treated with oral hypoglycemic agents. His visual acuity was correctable to 20/15 OU and the intraocular pressure by applanation was 17 mm Hg OD and 16 mm Hg OS. Findings on external ocular examination revealed a normal anatomy with dark tanning of the skin. Findings from the eye examination were completely normal except for numerous bilateral inner retinal crystalline deposits arranged in a doughnut-shaped pattern surrounding the macula (Figure 1). The observed crystalline deposits appeared more pronounced and numerous when evaluated using red-free fundus photography (Figure 2). A fluorescein angiogram showed a perifoveolar ring of blocked fluorescence corresponding to the area of the crystalline deposits (Figure 3). On further discussion with the patient, it was ascertained that he had been taking four 30-mg capsules a day of oral canthaxanthine (Orobronze; DeWitte, Greenville, SC) for the purpose of bronzing his skin.
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Figure 1. Left, Fundus photograph of the right eye of a 34-year-old man following daily ingestion of the artificial tanning agent, canthaxanthine. The inner retina exhibited numerous 30-µm-diameter crystalline deposits in a bilateral ringlike distribution. The remainder of the macula, retinal arteries, retinal veins, and the optic nerve were unremarkable. Right, Magnified view of the temporal macula.
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Figure 2. Red-free fundus photograph of the same eye as in Figure 1 demonstrating improved visualization of the crystalline retinal deposits as compared with color fundus photography.
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Figure 3. Fluorescein angiogram of the same eye as in Figure 1 revealing a subtle perifoveolar ring of intraretinal hypofluorescence presumably due to obstruction of the background fluorescence by the crystalline deposits in the nerve fiber layer.
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COMMENT
Canthaxanthine is one of more than 400 naturally occurring carotenoid substances that has been used extensively as an artificial food-coloring agent.1 Canthaxanthine may be present in some crustaceans, chanterelle mushrooms, and as a minor component of the flesh pigmentation in wild salmon and trout.2 The bronzing of the skin induced by oral ingestion of this carotenoid has led to its use as an artificial tanning agent3 and as a medical therapy for erythropoietic protoporphyria.1
The development of the retinal precipitates has been correlated with the total dose consumed.2 Patients who have ingested at least 37 g demonstrate retinal deposits 50% of the time while those who ingest at least 60 g universally have maculopathy present.4 These deposits are a reversible consequence of the canthaxanthine ingestion.5 The approximately 30-µm, goldlike particles have been localized at the level of the nerve fiber layer of the macular region in humans6 and, more recently, at the level of the ganglion cell, inner plexiform, and inner nuclear layers in a 2.5-year study of cynomolgus monkeys ingesting canthaxanthine.7 Although the affected individual is usually asymptomatic, the retinal deposits may cause diminished retinal sensitivity with subnormal dark adaptation and electroretinographic responses.3 Subtle alterations of retinal function can often be revealed by static perimetry.4
AUTHOR INFORMATION
Selected from Arch Ophthalmol. 1999;117:412-413. Photo Essay.
REFERENCES
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1. McGuinnes R, Beaumont P. Gold dust retinopathy after the ingestion of canthaxanthine to produce skin bronzing. Med J Aust. 1985;143:622-623.
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2. Sharkey JA. Idiopathic canthaxanthine retinopathy. Eur J Ophthalmol. 1993;3:226-228.
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3. Lonn LI. Canthaxanthine retinopathy. Arch Ophthalmol. 1987;105:1590-1591.
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4. Harnois C, Cortin P, Samson J, et al. Static perimetry in canthaxanthine maculopathy. Arch Ophthalmol. 1988;106:58-60.
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5. Harnois C, Samson J, Malenfant M, Rousseau A. Canthaxanthine retinopathy: anatomic and functional reversibility. Arch Ophthalmol. 1989;107:538-540.
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6. Daicker B, Schiedt K, Adnet JJ, Bermand P. Canthaxanthine retinopathy: an investigation by light and electron microscopy and physiochemical analysis. Graefes Arch Clin Exp Ophthalmol. 1987;225:189-197.
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7. Goralczyk R, Buser S, Bausch J, Bee W, Zuhlke U, Barker FM. Occurrence of birefringent retinal inclusions in cynomolgus monkeys after high doses of canthaxanthin. Invest Ophthalmol Vis Sci. 1997;38:741-752.
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