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Incomplete, transient central retinal artery obstruction (CRAO)
can cause a patchy gray discoloration of the retina (due to intracellular
edema). The pattern of retinal whitening resembles that seen in
Purtscher’s retinopathy. Gass (1) noted that this pattern of
retinal whitening after transient CRAO
is more likely in the setting of chronic systemic
hypertension. (Our patient had hypertension.) He postulated
that the pattern is the result of normal regional variations in
arterial perfusion or may result from formation of collateral pathways
of retinal capillary flow caused by focal narrowing of the origin
of the first-order arterioles in hypertensive patients. Gass (1)
also noted that the visual prognosis with this pattern of whitening
is relatively good, as was the case for our patient.
The cause of the transient CRAO for this patient is unknown.
He may have used intravenous drugs (which he denied) and experienced
transient embolic occlusion. He may have compressed the globe
during deep (ie, drug-induced) sleep. Predisposing conditions
that were considered, but for which no supporting evidence was
obtained, include blood dyscrasia, pancreatitis, vasculitis, sickle
cell trait/disease, syphilis, and cardiac abnormalities. The
prolonged arterio-venous transit time probably represents collapse
of the capillary bed in the areas of retinal ischemia.
REFERENCES
1. Gass JDM. Stereoscopic atlas of macular aiseases. 4th ed.
St Louis: Mosby; 1997. p. 444-6.
GENERAL REFERENCES
Oji EO, McLeod D. Partial central retinal artery occlusion. Trans
Ophthalmol Soc UK 98: 156-9; 1978.
Ball CJ. Atheromatous embolism to the brain, retina, and choroid.
Arch Ophthlalmol 76: 690-5; 1966.
Jayam, AV, Hass WK, Carr RE, Kumar AJ. Saturday night retinopathy.
J Neurolog Sci 22: 413-8; 1974. |
