Central Retinal Artery Occlusion (CRAO)

Central Retinal Artery Occlusion (CRAO)
SYMPTOMS Sudden painless vision loss (typically counting fingers to light perception)
May report a history of amaurosis fugax
SIGNS Typically unilateral
Acute occlusion: Immediate APD, Superficial retina opacification, Cherry red spot at the fovea, Boxcarring, Cotton wool spots, Few intraretinal hemorrhages (Dot/Blot/Flame), Paracentral acute middle maculopathy (PAMM), Optic nerve edema, Cystoid macular edema
With acute central retinal artery occlusion, retinal signs typically show up in 15 minutes to a few hours
Chronic/Resolved occlusion: The opacified inner retina will resolve and instead Atrophy of the RNFL,GCL,INL,IPL will be present (leads to an overall thinner inner retina). Retina color will eventually go back to normal with Optic nerve head pallor and Vessel attenuation. Other signs include NVD, NVE, NVI, NVA, Subhyaloid hemorrhages, Preretinal hemorrhages, Intravitreal hemorrhages, Intraretinal hemorrhages (Dot/Blot/Flame), Neovascular glaucoma
Signs associated with chronic/resolved central retinal artery occlusions typically appear in 4-6 weeks following the initial onset of the central retinal artery occlusion
WORK-UP Pupils, EOMs, Full eye exam with dilated retinal exam (look closely at the pupillary ruff for NVI especially before dilating), Gonioscopy, OCT analysis of the macula (acute CRAO: increased reflectivity and thickness of the GCL,RNFL,INL,IPL / chronic CRAO: atrophy and thinning of the inner retina / signs of cystoid macular edema are best seen with an OCT ), OCT analysis of the optic nerve, OCT-Angiography, Fluorescein Angiography, Fundus photos, B-scan ultrasound (if unable to view the retina), Electrodiagnostic testing (Multifocal ERG: presence of a significantly diminished or absent B-wave), Watzke-Allen test, Macular photostress test, Amsler grid
TREATMENT Refer to PCP/ER STAT (patient has a high risk of developing a stroke or heart attack especially within the first week of central retinal artery occlusion onset)
Patient needs to use caution with any strenuous exercise or activities in the presence of retinal neovascularization
Patient should sleep with their head elevated in presence of a preretinal, subhyaloid, and/or intravitreal hemorrhage
Typically irreversible damage occurs 90-100 minutes after the initial onset of the CRAO and any treatment should be done within 24 hours of the initial onset of the CRAO
Treatments that can be attempted in office
Ocular massage (needs to be done for at least 1 hour) while patient lies in a supine position
Begin Diamox 250mg QID for the first 24 hours along with topical glaucoma agents (Beta blockers and Alpha-2 Agonists) in order to quickly lower IOP (Always keep in mind the contraindications and side effects before prescribing these medications)
Have patient breath in a paper bag
Other treatments to consider include paracentesis and a hyperbaric oxygen therapy
There is no particular order to all the treatment options. These are treatments that can be attempted but there is no definitive proof that any of the treatments actually work. Visual prognosis is still will be poor despite any treatment
Refer to a retinal specialist ASAP after attempting in office treatments especially if there is retinal neovascularization, subhyaloid hemorrhages, preretinal hemorrhages, intravitreal hemorrhages, and/or cystoid macular edema
NVI and/or NVA with normal IOP and no evidence of glaucomatous optic nerve damage: Refer to retinal specialist within 48 hours
NVI and/or NVA with elevated IOPs but no evidence of glaucomatous optic nerve damage or with associated secondary open angle glaucoma: Begin treatment with topical and oral glaucoma medications. Refer to retinal specialist within 48 hours
NVI and/or NVA with secondary angle closure with or without glaucoma: The goal is to lower the IOP as quickly as possible in office and then refer to a retinal specialist ASAP. A glaucoma specialist will most likely be involved as well as patient will need a trabeculectomy and/or shunt
FOLLOW-UP Acute central retinal artery occlusion without evidence of retinal neovascularization, neovascular glaucoma, subhyaloid hemorrhages, preretinal hemorrhages, intravitreal hemorrhages, and/or cystoid macular edema: Should see back in 1-2 months in order to monitor for development of cystoid macular edema, worsening of ischemia, retinal neovascularization, and neovascular glaucoma. If stable, patient should be seen in 4-6 months
Once retinal neovascularization becomes involutional or quiescent and the retina and macula is stable, patient should be seen back every 4-6 months
Neovascular glaucoma: Patient will most likely continue care with a retinal specialist and/or glaucoma specialist. If condition is stable and patient is no longer seeing a retinal specialist and/or glaucoma specialist, the patient should be seen every 2-4 months
ADDITIONAL LAB | TESTS The patient needs to follow-up with their PCP for additional testing if not already done which includes the following: Blood pressure, Fasting blood sugar, HbA1c, Lipid panel, CBC with differential, ESR, ANA, Plasma protein electrophoresis, Thrombophilia screening (PT, TT, BT, PTT, INR, Protein C, Protein S, Anticardiolipin antibodies), Carotid duplex, Cardiac evaluation
ETIOLOGY Blockage of blood flow within the central retinal artery leads to loss of blood flow to the inner retina and subsequent ganglion cell death, RNFL loss, and inner retina atrophy
DIFFERENTIAL DX Acute Ophthalmic Artery Occlusion, Tay-Sachs Disease, Commotio Retinae
NOTES The etiologies of a CRAO include the following: Plaques, Giant cell arteritis, Talc, Thrombosis, Migraine, Fat emboli, Air emboli, Increase in IOP or Glaucoma, Cosmetic facial fillers, Strangulation, Chiropractic manipulation of the neck
The systemic disease that is most commonly associated with a CRAO is hypertension
The three main types of plaques include the following: Hollenhorst (most common plaque seen in older patients, typically from the carotid arteries, glistening/yellowish/thin/focal in appearance, most malleable type of plaque and blood can usually flow around it) Platelet-Fibrin (typically from the carotid arteries or cardiac valves, dull/white-gray/long in appearance) Calcific (least common plaque to be seen in older patients, typically from the cardiac valves, dull/white-yellow/large/focal in appearance, not very malleable so most likely to lead to an occlusion and remain in the retinal vasculature for years)
It is more common to see NVI/NVA instead of NVD/NVE in patients with central retinal artery occlusions
Typically only the posterior pole is involved with a CRAO because the RNFL and GCL is so thin in the periphery that the inner retina layers in the periphery can be maintained by choroidal circulation
If the patient has a cilioretinal artery, which connects the choroidal vasculature to retinal vasculature, there may be sparing of the fovea, foveola, and papillomacular bundle if a CRAO occurs. If this is the case, VA will typically be better than 20/50 but there still will be the presence of severe visual field loss (cilioretinal artery occlusions can also occur but are rare)
Tay-Sachs disease or Niemann-Pick disease should be considered if a child presents with bilateral retinal cherry red spots
Central Retinal Artery Occlusion (CRAO): Fundus photo demonstrating the presence of a cherry red spot in the posterior pole https://imagebank.asrs.org/file/1683/central-retinal-artery-occlusion