Central retinal artery occlusion

Abstract

The pathogeneses, clinical features, and management of central retinal artery occlusion (CRAO) are discussed. CRAO consists of the following four distinct clinical entities: non-arteritic CRAO (NA-CRAO), transient NA-CRAO, NA-CRAO with cilioretinal artery sparing, and arteritic CRAO. Clinical characteristics, visual outcome, and management very much depend upon the type of CRAO. Contrary to the prevalent belief, spontaneous improvement in both visual acuity and visual fields does occur, mainly during the first 7 days. The incidence of spontaneous visual acuity improvement during the first 7 days differs significantly (P < 0.001) among the four types of CRAO; among them, in eyes with initial visual acuity of counting finger or worse, visual acuity improved, remained stable, or deteriorated in NA-CRAO in 22%, 66%, and 12%, respectively; in NA-CRAO with cilioretinal artery sparing in 67%, 33%, and none, respectively; and in transient NA-CRAO in 82%, 18%, and none, respectively. Arteritic CRAO shows no change. Recent studies have shown that administration of local intra-arterial thrombolytic agent not only has no beneficial effect but also can be harmful. Investigations to find the cause and to prevent or reduce the risk of any further visual problems are discussed. Prevalent multiple misconceptions on CRAO are discussed.

Keywords: Central retinal artery occlusion; retinal arteries; retinal artery occlusion; retinal vessels.

Figure 1

Fundus photograph of the left eye with non-arteritic CRAO (NA-CRAO), and two patent cilioretinal arteries (arrows). It shows cherry-red spot, retinal opacity of posterior fundus – most marked in the macular region, cattle-trucking in the retinal vessels

Figure 2

Fundus photograph and fluorescein fundus angiogram of left eye with transient NA-CRAO.(a) Fundus photograph shows large number of cotton wool spots, maximum in the macular region. (b) Fluorescein angiogram, during retinal arterial phase, shows almost normal but slightly sluggish retinal circulation, except for the absence of filling in the foveal region, and cotton wool spots at places mask the background choroidal fluorescence

Figure 3

Right eye with arteritic CRAO and arteritic anterior ischemic optic neuropathy. (a) Fundus photograph shows chalky-white optic disk edema, some mild cattle-trucking in the retinal vessels, and cherry red spot with perifoveolar retinal opacity.(b) Fluorescein fundus angiogram, during the early phase, shows posterior ciliary artery occlusion with a few small patches of choroidal filling, and early filling of the central retinal artery.(c) Fluorescein fundus angiogram during the late phase shows cattle-trucking in the retinal vessels, with almost no disk staining

Figure 4

Schematic representation, showing the course of central retinal artery and its branches and anastomoses. A = Arachnoid; C = choroid; CRA = central retinal artery; Col. Br. = Collateral branches; CRV = central retinal vein; D = dura; LC = lamina cribrosa; ON = optic nerve; PCA = posterior ciliary artery; PR = prelaminar region; R = retina; S = sclera; SAS = subarachnoid space

Figure 5

A transverse section of the human optic nerve, showing the central retinal artery (CRA) inferiorly lying within the substance of dural sheath of the optic nerve (ON)

Figure 6

An example of a common trunk of origin of central artery of the retina and posterior ciliary arteries arising from the ophthalmic artery, as seen from below. CAR = Central artery of the retina, LPCA = lateral posterior ciliary artery, MPCA = medical posterior ciliary artery, OA = ophthalmic artery, ON = optic nerve. PPS = point of penetration into the sheath by the central retinal artery.*Common trunk of origin of CAR and MPCA

Figure 7

Fluorescein fundus angiograms (a, c, d) and a fundus photograph (b) of right eye of an atherosclerotic monkey before and after intravenous infusion of serotonin.(a) Baseline angiogram during retinal arteriovenous phase, showing normal filling of the central retinal artery, the retinal vasculature, and the choroid, one week before (b, c). (b, c) During infusion of serotonin (b) is a black and white fundus photograph about 2 min after the start of serotonin infusion, showing evidence of CRAO, including pale optic disk, retinal opacity, and cherry red spot at fovea. (c) An angiogram about 4 min, after the start of serotonin infusion, shows normal filling of the choroidal circulation but complete occlusion of the central retinal artery. (d) An angiogram during regression phase shows once again normal filling of the central retinal artery and the choroid

Figure 8

A 24-h ambulatory blood pressure recording in a woman, starting at about 11:00 a.m. and ending at about 10:00 a.m. next day. Note that during the waking hours the blood pressure is perfectly normal but shows a marked drop during the sleeping hours (nocturnal arterial hypotension)

Figure 9

Visual fields of right eye with NA-CRAO, plotted with a Goldmann perimeter, show a large absolute central scotoma, with almost normal peripheral visual field with I-4e and V-4e

Figure 10

Fundus photograph of the right eye with NA-CRAO, and a patent cilioretinal artery in the macular region. The retinal supply by the patent cilioretinal artery passes through the foveal region (arrow)

Figure 11

Fundus photograph and fluorescein fundus angiogram of left eye four day after the onset of transient NA-CRAO. (a) Fundus photograph shows retinal opacity of posterior fundus – most marked in the macular region, a small cherry red spot, a few retinal hemorrhages a small patent cilioretinal artery (arrow), and normal-looking peripheral retina.(b) Fluorescein fundus angiogram, during the retinal arteriovenous phase, shows slightly delayed filling of the retinal arteries and veins, with central macular region showing no retinal capillary filling due to no-reflow phenomenon caused by thick ischemic retina in that region

Figure 12

(a) Fundus photograph of the left eye with multiple cilioretinal collaterals on and around the optic disk in an eye with old NA-CRAO. (b) Fluorescein fundus angiogram of the right eye, during retinal arterial phase, with multiple cilioretinal collaterals on and around the optic disk in an eye with old NA-CRAO. Note that, unlike neovascularization, the collateral shows no fluorescein leak

Figure 13

Fluorescein fundus angiogram of the left eye of a rhesus monkey, immediately after experimentally cutting of the central retinal artery at its site of entry into the optic nerve. It shows slow filling of the central retinal artery and the retinal vascular bed, in spite of cutting of the central retinal artery

Figure 14

Fluorescein fundus angiogram of the left eye of a patient with NA-CRAO, 29 s after injection of the dye, shows normal filling of the choroid and optic disk vessels (supplied by the posterior ciliary artery circulation), but no filling of the central retinal artery at all as yet. The retinal vessels show typical “cattle-trucking”

Figure 15

Fluorescein fundus angiogram of the left eye with NA-CRAO with cilioretinal retinal sparing. It shows the area supplied by the cilioretinal artery and retrograde filling the adjacent retinal circulation