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Retinal vascular occlusion (Lecture)

Patient with retinal artery occlusion will present as → a 74-year-old man presents with sudden vision loss in his right eye. He has a medical history of hypertension and coronary artery disease and new-onset atrial fibrillation. On physical exam, a carotid bruit is auscultated. His visual acuity is light perception. Confrontational visual fields reveal a dense scotoma, and a penlight examination shows an afferent pupillary defect. Dilated funduscopic examination shows retinal whitening with a cherry-red spot in the fovea.

Patient with retinal vein occlusion will present as → a 65-year-old woman who presents to the ED with the sudden onset of painless vision loss in her left eye. Her past medical history includes hypertension and hyperlipidemia. The patient’s temperature is 98°F (36.7°C), blood pressure is 145/86 mmHg, pulse is 62/min, and respirations are 12/min with an oxygen saturation of 98% O2 on room air. An ophthalmology consult is called, and the fundoscopic examination reveals a swollen optic disc with extensive retinal hemorrhages.

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Central retinal artery and retinal vein occlusion

  • Both cause a monocular painless vision loss

When a patient presents with monocular vision loss you need to be thinking of four things:

Central retinal artery occlusion is characterized by sudden, painless acute visual loss usually attributed to ischemia or thrombus to the major retinal arterial blood supply

  • Caused by an embolism resulting from atrial fibrillation, cardiac vegetation, or a patent foramen ovale, but might be also due to thrombosis of the retinal artery, usually as a result of atherosclerosis
    • Commonly results from ruptured plaque from the same-sided (ipsilateral) carotid artery
  • Typically, the patient presents with sudden, painless onset of markedly decreased unilateral loss of vision (amaurosis fugax)
  • Physical examination findings include a significant decrease in visual acuity, relative afferent pupillary defect (ie, Marcus Gunn pupil)
  • Fundoscopy reveals a cloudy, pale retina with attenuated vessels and a cherry-red spot in the fovea
    • The cherry-red spot is seen because the macula receives its blood supply from the choroid, which remains unaffected, while the surrounding retina is pale and ischemic due to the retinal artery occlusion

Retinal vein occlusion

  • This manifests as a sudden acute monocular vision loss
  • Can be further divided into non-ischemic and ischemic subtypes
  • Compression of the central retinal vein or one of its branches due to a thrombus, a narrow vein, or from an atherosclerotic artery crossing it
  • For diagnosis, look for a history of cardiovascular risk factors, such as diabetes mellitus and hypertension, or hypercoagulable states like polycythemia vera
  • Fundoscopic examination may reveal optic disc swelling, retinal hemorrhages, and dilated veins that give a characteristic “blood and thunder appearance

Fundoscopy of retinal artery occlusioncherry-red spot on the macula and pale retina

Fundoscopy of retinal vein occlusion optic disc swelling, retinal hemorrhages, and dilated veins that give a characteristic “blood and thunder appearance

Central retinal artery occlusion is an ophthalmologic emergency ⇒ immediate treatment is indicated if occlusion occurred within 24 h of presentation

  • Reduction of intraocular pressure with ocular hypotensive drugs (eg, topical timolol 0.5%, acetazolamide 500 mg IV or PO)
  • Intermittent digital massage over the closed eyelid or anterior chamber paracentesis may dislodge an embolus and allow it to enter a smaller branch of the artery, thus reducing the area of retinal ischemia
  • If patients present within the first few hours of occlusion, some centers catheterize the carotid/ophthalmic artery and selectively inject thrombolytic drugs
  • Treatment may include hyperbaric oxygen therapy, which involves the inhalation of 100% oxygen at a pressure that’s higher than the atmospheric pressure

Retinal vein occlusion is treated with laser photocoagulation, and steroid or anti-VEGF injections

Picmonic
Retinal artery and vein occlusion

Central retinal artery occlusion (CRAO) can cause ischemia to the retina’s sensitive tissue, resulting in vision loss that can be permanent. Etiologies for CRAO are mostly based in thromboembolic phenomena from diseases such as atherosclerosis, atrial fibrillation, and giant cell (temporal) arteritis. Sudden, painless monocular vision loss or a “descending curtain” view are classic symptoms described by patients. There may be retinal plaques on fundoscopy, a grayish discoloration to the retina, or a cherry-red spot on the macula. Ultrasound is helpful in diagnosis. Management includes immediate ocular massage and lowering of intraocular pressure to prevent permanent damage.

Central retinal artery occlusion (CRAO)
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Central retinal vein occlusion
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Question 1
In a patient with amaurosis fugax what is the most appropriate initial diagnostic study?
A
Ophthalmoscopy
Hint:
Ophthalmoscopy provides visualization of retina but does not help elucidate the source of the plaque.
B
Schiotz tonometry
Hint:
Schiotz tonometry is used to measure intraocular pressure.
C
MR angiography
Hint:
MR angiography is a useful test to identify retinal vascular anatomy but is not the first choice in the search for causes of amaurosis fugax.
D
Carotid ultrasound
Question 1 Explanation: 
The most common cause of amaurosis fugax is an atherosclerotic plaque in the carotid artery which can be identified with ultrasound.
Question 2
45-year-old woman presents to the ED with acute painless loss of vision, photophobia associated with a smaller unilateral pupil on the involved side. Which of the following is the most likely diagnosis?
A
central retinal vein occlusion (CRVO)
Hint:
Central retinal vein occlusion (CRVO) is characterized by painless, unilateral vision loss of varying severity, slower onset of decreased vision than with arterial occlusion, retinal hemorrhages, cotton wool spots, and macular edema.
B
iritis/uveitis
Hint:
See E for explanation
C
retrobulbar hemorrhage or hematoma
Hint:
Retrobulbar hemorrhage is associated with decreased ocular range of motion, decreased vision, ptosis of the lid, and increased pressure in the globe raising intraocular pressure. The high pressure decreases retinal artery perfusion, which results in retinal ischemia. The patient presents with decreased visual acuity, proptosis, and a dilated nonreactive pupil.
D
hyphema
Hint:
A hyphema is caused by bleeding from the vasculature of the iris usually precipitated by trauma. Blood is often visualized in the anterior chamber and can be seen via slit lamp evaluation. Symptoms usually consist of pain, photophobia, and decreased vision. Intraocular pressures may increase as well. The major clinical consideration is the potential of reoccurring bleeding.
E
central retinal artery occlusion
Question 2 Explanation: 
Central retinal artery occlusion is characterized by acute visual loss usually attributed to ischemic or thrombus to the major retinal arterial blood supply. Typically, the patient presents with sudden, painless onset of markedly decreased unilateral loss of vision. Physical examination findings include significant decrease in visual acuity, relative afferent pupillary defect (ie, Marcus Gunn pupil), and a pale retina with a red spot that is visible on funduscopic examination. Central retinal vein occlusion (CRVO) is characterized by painless, unilateral vision loss of varying severity, slower onset of decreased vision than with arterial occlusion, retinal hemorrhages, cotton wool spots, and macular edema. Physical examination findings include ciliary flush (ie, circumcorneal perilimbal injection of the episcleritis and scleral vessels) conjunctival injection and cells may be present in the anterior chamber. The pupil on the affected side is often small and irregular. Direct and consensual light reflex will cause pain on the affected side to increase. Retrobulbar hemorrhage is associated with decreased ocular range of motion, decreased vision, ptosis of the lid, and increased pressure in the globe raising intraocular pressure. The high pressure decreases retinal artery perfusion, which results in retinal ischemia. The patient presents with decreased visual acuity, proptosis, and a dilated nonreactive pupil. A hyphema is caused by bleeding from the vasculature of the iris usually precipitated by trauma. Blood is often visualized in the anterior chamber and can be seen via slit lamp evaluation. Symptoms usually consist of pain, photophobia, and decreased vision. Intraocular pressures may increase as well. The major clinical consideration is the potential of reoccurring bleeding.
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