• Clinical science

Retinal vessel occlusion

Summary

Retinal artery occlusion refers to occlusion of the central retinal artery and/or its branches, usually as a result of thromboembolic phenomena. Central retinal artery occlusion (CRAO) is characterized by sudden, painless loss of vision and a relative afferent pupillary defect. Ophthalmoscopy reveals a pale, edematous retina and a cherry-red spot in the foveal region. Branch retinal artery occlusion (BRAO) presents with specific patterns of visual field defects depending on which branch is involved. Treatment is usually ineffective because of irreversible ischemic damage to the retina. The prognosis is especially poor if the macula is involved. Retinal vein occlusion is more common than retinal artery occlusion and follows a less fulminant course. Branched retinal vein occlusion (BRVO), which is more common than central retinal vein occlusion (CRVO), is usually asymptomatic unless the macula is involved. CRVO may be either non-ischemic or ischemic. Fluorescein angiography is required in order to differentiate between ischemic and non-ischemic retinal vein occlusion. The prognosis of ischemic CRVO is less favorable since it is associated with neovascular glaucoma and retinal detachment. While BRVO and non-ischemic CRVO usually do not require any treatment, ischemic CRVO requires laser therapy.

Definition

Retinal vessel occlusion causes retinal ischemia. Based on the site of occlusion, retinal vessel occlusion can be classified into the following entities:

Epidemiology

Retinal artery occlusion

  • Age of onset: > 60 years
  • Sex: >

Retinal vein occlusion

  • Age of onset: > 80 years
  • Sex: =

Retinal vein occlusion is much more common than retinal artery occlusion. Retinal vein occlusion is the second most common vascular disease of the retina (after diabetic retinopathy)!

References:[1][2][3][4][5]

Epidemiological data refers to the US, unless otherwise specified.

Etiology

Retinal artery occlusion

Retinal vein occlusion

References:[1][6][7]

Clinical features

Retinal artery occlusion

CRAO BRAO
Symptoms
  • Sudden, painless loss of vision in one eye (often described as a “descending curtain”)
  • A past history of amaurosis fugax may be present.
Relative afferent pupillary defect
  • Present
  • Absent
Ophthalmoscopic findings
  • Grayish-white discoloration of the retinal quadrant supplied by the affected vessel
  • Retinal emboli/plaques (∼ 60–70% of cases)
General physical examination

Retinal vein occlusion

CRVO BRVO
Non-ischemic CRVO Ischemic CRVO
Symptoms
  • Subacute, mild to moderate loss of vision in the affected eye
  • Sudden, severe loss of vision in the affected eye
  • Usually asymptomatic
Relative afferent pupillary defect
  • Absent
  • Present
  • Absent
Ophthalmoscopic findings
  • A few dot-and-blot and/or flame-shaped hemorrhages in all four retinal quadrants
  • Dot-and blot and/or flame-shaped hemorrhages in the retinal quadrant drained by the affected vein

References:[1][6][7]

Amaurosis fugax

Diagnostics

Retinal vessel occlusion is primarily a clinical diagnosis (based on the patient's history and fundus examination). Additional investigations are usually performed to identify underlying risk factors, to differentiate between subtypes (e.g., in the case of CRVO).

Retinal artery occlusion

Retinal vein occlusion

References:[6][1]

Treatment

Retinal artery occlusion

Retinal artery occlusion is an ophthalmologic emergency.

Treatment should be initiated as soon as possible, as permanent retinal damage occurs within 1.5 hours of central retinal artery occlusion.

Retinal vein occlusion

References:[6][8][9][10][1]

Complications

Release of vasoproliferative substances (e.g., VEGF) from the ischemic retina causes:

Of all types of retinal vessel occlusion, ischemic CRVO is most commonly associated with neovascularization!
References:[1][7]

We list the most important complications. The selection is not exhaustive.

Prognosis

Retinal artery occlusion

Retinal vein occlusion

  • Rule of thirds: Visual acuity improves in one-third of cases, remains the same in another third, and worsens in the remaining third.
  • The prognosis is especially poor in the case of ischemic CRVO.

References:[6][7]