2020–2021 BCSC Basic and Clinical Science Course™
12 Retina and Vitreous
Part II: Disorders of the Retina and Vitreous
Chapter 06: Retinal Vascular Diseases Associated With Cardiovascular Disease
Arterial Occlusive Disease
The blood supply to the inner layers of the retina is derived entirely from the central retinal artery, unless a cilioretinal artery is present (20%–25% of eyes). Retinal ischemia results from disease processes that affect the vessels anywhere from the common carotid artery to the intraretinal arterioles. The signs and symptoms of arterial obstruction depend on the vessel involved: occlusion of a peripheral arteriole may be asymptomatic, whereas an ophthalmic artery occlusion can cause total blindness.
Capillary Retinal Arteriole Obstruction (Cotton-Wool Spots)
Acute obstruction in the distribution of the radial peripapillary capillary net leads to the formation of a nerve fiber layer (NFL) infarct, or cotton-wool spot, which causes impaired axoplasmic transport in the NFL (Fig 6-15). These inner retinal ischemic spots are superficial, white, and typically one-fourth optic disc area or less in size. They usually fade in 5–7 weeks, although spots present in association with diabetic retinopathy often remain longer. A subtle retinal depression caused by inner retinal ischemic atrophy may develop in an area of prior ischemia. The effect on visual function, including loss of visual acuity and field defects, is related to the size and location of the occluded area.
Figure 6-15 Fundus photograph shows a cotton-wool spot.
(Courtesy of Gary C. Brown, MD.)
The most common cause of cotton-wool spots is diabetic retinopathy (discussed in Chapter 5). Other causes include
systemic arterial hypertension
sickle cell retinopathy
cardiac embolic disease
carotid artery obstructive disease
collagen vascular disease
If even 1 cotton-wool spot is discovered in the fundus in an otherwise apparently healthy eye, the clinician should initiate a workup for the most likely underlying etiologies.
Brown GC, Brown MM, Hiller T, Fischer D, Benson WE, Magargal LE. Cotton-wool spots. Retina. 1985;5(4):206–214.
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.