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Retinal vessel occlusion

Last updated: March 24, 2021

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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.

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

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).

Epidemiological data refers to the US, unless otherwise specified.

Retinal artery occlusion

Retinal vein occlusion

The exact cause of thromboembolic retinal vein occlusion is unknown, but risk factors include:

Retinal artery occlusion

Clinical features of central vs. branch retinal artery occlusion
Clinical features
  • 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
  • Box-carring of retinal vessels during the acute phase in the affected retinal quadrant
  • Narrow retinal vessels in the affected retinal quadrant
  • Retinal emboli/plaques (∼ 60–70% of cases)
General physical examination

Retinal vein occlusion

Clinical features of central vs. branch retinal vein occlusion [1]
Non-ischemic CRVO Ischemic CRVO
Clinical features
  • 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
  • Many dot-and-blot and/or flame-shaped hemorrhages in all four retinal quadrants and venous thickening (blood and thunder appearance)
  • Cotton wool spots
    • Characterized by yellow-white deposits on the retina
    • Caused by swelling of retinal nerve fibers due to ischemia
  • Severe macular edema
  • Severe papilledema
  • Dot-and blot and/or flame-shaped hemorrhages in the retinal quadrant drained by the affected vein

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


Retinal artery occlusion [3][4]

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 [1][3]

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.

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

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.


  1. Central Retinal Vein Occlusion. http://eyewiki.aao.org/Central_Retinal_Vein_Occlusion. Updated: December 21, 2014. Accessed: February 18, 2017.
  2. Douglas J Covert. Retinal vein occlusion: Epidemiology, clinical manifestations, and diagnosis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/retinal-vein-occlusion-epidemiology-clinical-manifestations-and-diagnosis.Last updated: January 25, 2020. Accessed: August 17, 2020.
  3. Mirshahi A, Feltgen N, Hansen LL, Hattenbach LO. Retinal Vascular Occlusions: An Interdisciplinary Challenge. Dtsch Arztebl Int. 2008; 105 (26): p.474-479. doi: 10.3238/arztebl.2008.0474 . | Open in Read by QxMD
  4. Cugati S, Varma DD, Chen CS, Lee AW. Treatment Options for Central Retinal Artery Occlusion. Curr Treat Options Neurol. 2012; 15 (1): p.63-77. doi: 10.1007/s11940-012-0202-9 . | Open in Read by QxMD
  5. Douglas J Covert. Retinal vein occlusion: Treatment. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/retinal-vein-occlusion-treatment.Last updated: June 21, 2018. Accessed: August 17, 2020.
  6. Christina J. Flaxel, Steven T. Bailey, Jennifer I. Lim, Ron A. Adelman, Amani Fawzi, G. Atma Vemulakonda, Gui-shuang Ying. Retinal Vein Occlusions PPP 2019. Ophthalmology. 2019 .
  7. Kooragayala LM. Central Retinal Vein Occlusion. Central Retinal Vein Occlusion. New York, NY: WebMD. http://emedicine.medscape.com/article/1223746-overview. Updated: June 29, 2016. Accessed: March 15, 2017.