CENTRAL RETINAL ARTERY OCCLUSION (CRAO)

As a special emergency in ophthalmology, the disease often occurs in the elderly.

The cause is usually embolism due to high blood pressure, cardiovascular disease. Sometimes it is the result of thrombosis due to inflammation, lupus, Behcet's disease, Horton's disease...

1. CLINICAL SYMPTOMS:

- The patient is completely blind in one eye, suddenly. Sometimes it is discovered after waking up.
- Eye examination:

+ Anterior segment: slightly dilated pupil, loss of reflex to direct light, remaining consensual reflex.

+ Fundus: in the early stages, the arteries are seen to be as small as threads. There is no blood in the lumen of the vessels. At the trunk of the large vessel, there may be reduced blood flow or the image of the blood column being broken into many segments.

After the first hours, retinal edema develops. The milky white retina, mainly at the posterior pole, contrasts with the red color of the macula, a “cherry blossom” appearance due to the macula being nourished by choroidal capillaries.

2. CLINICAL FORMS:

- Transient blindness-arterial spasm: Sudden onset, complete blindness in one eye. Lasts for several minutes. Outside of the attack, vision and fundus are completely normal. Cardiovascular examination is required, often showing signs of carotid artery stenosis or occlusion.

- Occlusion of the central retinal artery: Causes different clinical symptoms depending on the location of the obstruction. Sudden loss of vision, loss of vision corresponding to the area of ​​the damaged artery. Fundus: retinal edema in the area of ​​obstruction due to lack of blood flow. Sometimes the obstruction is seen as a piece of cholesterol or calcium.

- Central retinal artery occlusion in people with cilioretinal artery:
About 20% of the population has an additional cilioretinal artery originating from the choroid, originating from the outer edge of the optic disc, supplying the area between the optic disc and the macula. In this case, vision may be reduced to a greater or lesser extent, but the visual field is
narrowed to a tubular shape. Fundus: a triangular pink retinal area between the optic disc and the macula is still visible, falling between the posterior retinal pole, which is flooded with edema.

- In contrast, isolated cilioretinal artery occlusion: Vision is reduced. The fundus has white edema in an area between the optic disc and the macula, the surrounding retina is not damaged.

3. TREATMENT OF CENTRAL RETINAL ARTERY OCCUPATION

- Locally: change central arterial pressure to move the obstruction by: massaging the eyeball for a few minutes; can puncture the anterior chamber to lower intraocular pressure; inject
vasodilators next to the eyeball.

- Whole body:

• Vasodilators may be used, either orally or by infusion.
• Antiplatelet drugs.
• Anticoagulants and fibrinolytics (only used when there are no contraindications and in young people with good health).

- Treat the root cause:

• If it is high blood pressure: treat high blood pressure.
• Horton's disease: emergency corticosteroid therapy.

- Prognosis: If the patient arrives in time (within 2 hours of illness), vision can be restored, retinal edema disappears after a few days, and arterial circulation returns to normal. In cases of arterial branch occlusion, the lesions are stable, visual field defects in the corresponding retinal area, and there are also cases where the occlusion spreads to the entire retina. Patients rarely arrive in time, so the progression is not good. Vision is completely lost, optic disc atrophy occurs after 1 month, retinal arteries narrow, blood vessels can become white and sclerotic, which can lead to neovascular glaucoma.