Updated: Feb 12, 2009
In 1859, Van Graefe first described central retinal artery occlusion (CRAO) as an embolic event to the central retinal artery in a patient with endocarditis. In 1868, Mauthner suggested that spasmodic contractions could lead to retinal artery occlusion. There is a multitude of causes of CRAO, but patients typically present with sudden, severe, and painless loss of vision.
Visual loss from CRAO occurs from the loss of blood supply to the inner layer of the retina. The ophthalmic artery is the first branch of the internal carotid artery and enters the orbit underneath the optic nerve through the optic canal. The central retinal artery is the first intraorbital branch of the ophthalmic artery, which enters the optic nerve 8-15 mm behind the globe to supply the retina. Short posterior ciliary arteries branch distally from the ophthalmic artery and supply the choroid. Anatomical variants include cilioretinal branches from the short posterior ciliary artery, which gives additional supply to the macula from the choroidal circulation. A cilioretinal artery occurs in approximately 14% of the population.
Acutely, obstruction of the central retinal artery results in inner layer edema and pyknosis of the ganglion cell nuclei. Ischemic necrosis results, and the retina becomes opacified and yellow-white in appearance. The opacity is most dense in the posterior pole as a result of the increased thickness of the nerve fiber layer and ganglion cells in this region. Furthermore, the foveola assumes a cherry-red spot because of a combination of 2 factors: (1) the intact retinal pigment epithelium and choroid underlying the fovea, and (2) the foveolar retina is nourished by the choriocapillaris. The late stage shows a homogenous scar replacing the inner layer of the retina.
Approximately 14% of the general population has cilioretinal arteries and 25% of eyes with acute CRAO have cilioretinal artery. The cilioretinal artery supplies part or all of papillomacular bundle. In 10% of eyes, the cilioretinal artery supplies some or all of the foveola. In such an eye, the visual acuity generally returns to 20/50 or better in 80% of eyes over a 2-week period.
The opacification takes as little as 15 minutes to several hours before becoming evident and resolves in 4-6 weeks. The resulting anatomy reflects a catastrophic insult to the inner retinal layers with attenuated retinal arterioles and optic nerve pallor. Pigmentary changes are typically absent since the retinal pigment epithelium remains unaffected. Boxcar appearance of the blood column can be seen in both arteries and veins. Hayreh has shown that irreversible cell injury occurs after 90-100 minutes of total CRAO in the primate model.1 Controversy exists regarding the optimal window of treatment in humans, but the conservative approach involves treatment up to 24 hours.
CRAO is found in 1 per 10,000 outpatient visits. Of these patients, 1-2% present with bilateral involvement.
Patients with visualized retinal artery emboli, whether or not obstruction is present, have a 56% mortality rate over 9 years, compared to 27% for an age-matched population without retinal artery emboli. Life expectancy of patients with CRAO is 5.5 years compared to 15.4 years for an age-matched population without CRAO.
Men are affected slightly more frequently than women.
The mean age of presentation is in the early 60s, although a few cases have been reported in patients younger than 30 years. The etiology of occlusion changes depending on the age of presentation.
Causes of CRAO vary depending on the age of the patient. A detailed analysis of comorbid disease is necessary to elucidate the cause of the acute visual loss.
Retinopathy, Purtscher
Inadvertent intraocular injection of gentamicin
Arteritic ischemic optic neuropathy
Other causes of cherry-red spot
Tay-Sach disease or other storage disease
Carbonic anhydrase is an enzyme found in many tissues of the body, including the eye. The reversible reaction it catalyzes involves the hydration of carbon dioxide and the dehydration of carbonic acid.
Reduces rate of aqueous humor formation by inhibiting enzyme carbonic anhydrase, which results in decreased IOP. Used most frequently as single diuretic agent in acute management of CRAO. Other diuretics may be added if sufficient decrease in IOP is not attained.
250-500 mg IV; repeat in 2-4 h prn; not to exceed 1 g/d
10-15 mg/kg/d PO divided q6-8h
5-10 mg/kg/dose IV/IM q6h
Can decrease therapeutic levels of lithium and alter excretion of drugs (eg, amphetamines, quinidine, phenobarbital, salicylates) by alkalinizing urine
Documented hypersensitivity; hepatic disease; severe renal disease; adrenocortical insufficiency; severe pulmonary obstruction
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Patients with impaired hepatic function may go into coma; may cause substantial increase in blood glucose in some diabetic patients
Used concomitantly with other topical ophthalmic drug products to lower IOP. If more than one ophthalmic drug is being used, administer the drugs at least 10 min apart. Reversibly inhibits carbonic anhydrase, reducing hydrogen ion secretion at renal tubule and increases renal excretion of sodium, potassium bicarbonate, and water to decrease production of aqueous humor.
1 gtt tid in affected eye(s)
Not established
Coadministration with high-dose salicylate therapy may increase toxicity; may have additive systemic effects if patient is already on oral CA inhibitors
Documented hypersensitivity
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Local ocular adverse effects, primarily conjunctivitis and lid reactions, may occur with long-term administration of dorzolamide (discontinue therapy and evaluate patient before restarting therapy)
Lower IOP by creating an osmotic gradient between the ocular fluids and plasma (not for long-term use).
Reduces elevated IOP when the pressure cannot be lowered by other means. Initially assess for adequate renal function in adults by administering a test dose of 200 mg/kg, given IV over 3-5 min. It should produce a urine flow of at least 30-50 mL/h of urine over 2-3 h. In children, assess for adequate renal function by administering a test dose of 200 mg/kg, given IV over 3-5 min. It should produce a urine flow of at least 1 mL/h over 1-3 h.
1.5-2 g/kg IV as a 20% solution (7.5-10 mL/kg) or as a 15% solution (10-13 mL/kg) over a period as short as 30 min
Initial dose: 0.5-1 g/kg IV
Maintenance dose: 0.25–0.5 g/kg IV q4-6h
None reported
Documented hypersensitivity; anuria; severe pulmonary congestion; severe dehydration; active intracranial bleeding; progressive renal damage; progressive heart failure
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Carefully evaluate cardiovascular status before rapid administration of mannitol since a sudden increase in extracellular fluid may lead to fulminating CHF; avoid pseudoagglutination, when blood given simultaneously, add at least 20 mEq of sodium chloride to each liter of mannitol solution; do not give electrolyte-free mannitol solutions with blood
Used in glaucoma to interrupt acute attacks. Oral osmotic agent for reducing IOP. Able to increase tonicity of blood until finally metabolized and eliminated by the kidneys. Maximum reduction of IOP usually occurs 1 h after glycerin administration. Effect usually lasts approximately 5 h.
1-2 g/kg PO; repeat q5h prn
Alternatively, 1 mL/kg PO as a 50% solution in juice
Administer as in adults
None reported
Documented hypersensitivity; frank or impending acute pulmonary edema; anuria; severe dehydration; severe cardiac decompensation
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Administer orally, never parenterally; for oral use only; avoid in acute urinary retention in preoperative period; continued use may result in weight gain; caution in hypervolemia, diabetes, severely dehydrated individuals, confused mental states, congestive heart disease, and cardiac, renal, or hepatic disease
Lower IOP mainly by increasing outflow and reducing the production of aqueous humor. The combination of a miotic and a sympathomimetic has additive effects in lowering IOP. Each may be added in rotation after a 5-minute interval, until target IOP is reached.
Reduces elevated, as well as normal, IOP whether or not accompanied by glaucoma. Apraclonidine is a relatively selective alpha-adrenergic agonist that does not have significant local anesthetic activity. Has minimal cardiovascular effects.
Solution (0.5%): 1-2 gtt in affected eye(s) tid; since apraclonidine 0.5% will be used with other ocular glaucoma therapies, use an approximate 5-min interval between instillation of each medication to prevent washout of previous dose; do not inject into the eye
Solution (1%): 1 gtt in affected eye 1 h before initiating anterior segment laser surgery; second gtt into the same eye immediately upon completion of surgery
Not established
Monitor pulse and BP frequently when giving cardiovascular drugs; not for use concurrently with MAOIs
Documented hypersensitivity; patients on MAOIs or have taken them in the past 14 d
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
Caution in coronary insufficiency, chronic renal failure, recent myocardial infarction, cerebrovascular disease, Raynaud disease, thromboangiitis obliterans, and depressed patients
Converted to epinephrine in eye by enzymatic hydrolysis. Appears to act by decreasing aqueous production and enhancing outflow facility. Has same therapeutic effect as epinephrine with fewer local and systemic side effects. May be used as an initial therapy or as an adjunct with other antiglaucoma agents for the control of IOP.
1 gtt into eye(s) q12h
Not established
Increased or synergistic effects when used concurrently with agents that lower IOP
Documented hypersensitivity; narrow angles; dilation of pupil may predispose patient to attack of angle-closure glaucoma
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Macular edema occurs in up to 30% of aphakic patients treated with epinephrine; discontinuation of treatment generally results in reversal of maculopathy; caution in vascular hypertension
Lower IOP by decreasing the rate of aqueous humor production and possibly outflow. They may be more effective than either pilocarpine or epinephrine alone and have the advantage of not affecting pupil size or accommodation.
May reduce elevated and normal IOP, with or without glaucoma by reducing the production of aqueous humor or by outflow.
1 gtt of 0.25% or 0.5% in affected eye(s) bid; if IOP is maintained at satisfactory levels, change the dosage to 1 gtt in affected eye(s) qd; if clinical response is not adequate, change dosage to 1 gtt of 0.5% solution in affected eye(s) bid; if IOP is still not at a satisfactory level, consider concomitant therapy
Administer as in adults
Coadministration of ophthalmic timolol may cause bradycardia and asystole when used in combination with systemic beta-blockers; rechallenge studies have confirmed these effects; use topical beta-blockers with caution if the patient is already on systemic beta-blockers
Documented hypersensitivity; bronchial asthma; sinus bradycardia; second- and third-degree AV block; severe chronic obstructive pulmonary disease; overt cardiac failure; cardiogenic shock
C - Fetal risk revealed in studies in animals but not established or not studied in humans; may use if benefits outweigh risk to fetus
May contain sulfites, which may cause allergic-type reactions in susceptible patients
Used in arterial occlusion only when temporal arteritis (GCA) is the suspected or confirmed etiology.
Useful in the treatment of inflammatory and allergic reactions. May decrease inflammation by reversing increased capillary permeability and suppressing polymorphonuclear lymphocyte activity.
5-60 mg PO qd or divided bid/qid; not to exceed 80 mg/d; taper over 2 wk as symptoms resolve
Once giant cell arteritis is suspected, administer methylprednisolone, 250 mg IV q6h for 12 doses; then, switch to prednisone, 80-100 mg PO qd; adjust dose clinically
4-5 mg/m2/d PO
Alternative: 1-2 mg/kg PO qd; taper over 2 wk as symptoms resolve
Coadministration with estrogens may decrease prednisone clearance; concurrent use with digoxin may cause digitalis toxicity secondary to hypokalemia; phenobarbital, phenytoin, and rifampin may increase metabolism of glucocorticoids (consider increasing maintenance dose); monitor for hypokalemia with coadministration of diuretics
Documented hypersensitivity; viral infection; peptic ulcer disease; hepatic dysfunction; connective tissue infections; fungal or tubercular skin infections; GI disease
B - Fetal risk not confirmed in studies in humans but has been shown in some studies in animals
Caution in hypertension; known to cause cataract formation with long-term use; in prolonged use, withdraw treatment by gradually decreasing frequency of applications to avoid adrenal insufficiency
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central retinal artery occlusion, central retina artery occlusion, CRAO, ophthalmic artery occlusion, central retinal artery, retinal artery occlusion, RAO, branch retinal artery occlusion, BRAO, embolism of the retinal artery, retinal artery emboli, ocular stroke, retina, visual loss, vision loss, loss of vision, blindness
Robert H Graham, MD, Senior Associate Consultant, Department of Ophthalmology, Mayo Clinic, Scottsdale, Arizona
Robert H Graham, MD is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, and Arizona Ophthalmological Society
Disclosure: WebMD/eMedicine Salary Employment
Shehab A Ebrahim, MD, Assistant Professor, Department of Ophthalmology, Tulane University; Vitreoretinal Surgeon, The Retina Institute, LLC
Shehab A Ebrahim, MD is a member of the following medical societies: American Academy of Ophthalmology, American Medical Association, American Society of Retina Specialists, and Association for Research in Vision and Ophthalmology
Disclosure: Nothing to disclose.
V Al Pakalnis, MD, PhD, Professor of Ophthalmology, University of South Carolina School of Medicine; Chief of Ophthalmology, Dorn Veterans Affairs Medical Center
V Al Pakalnis, MD, PhD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and South Carolina Medical Association
Disclosure: Nothing to disclose.
Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.
Steve Charles, MD, Director of Charles Retina Institute; Clinical Professor, Department of Ophthalmology, University of Tennessee College of Medicine
Steve Charles, MD is a member of the following medical societies: American Academy of Ophthalmology, American Society of Retina Specialists, Club Jules Gonin, Macula Society, and Retina Society
Disclosure: Alcon Laboratories Consulting fee Consulting; OptiMedica Ownership interest Consulting
Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri
Disclosure: Nothing to disclose.
Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences
Hampton Roy Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, and Pan-American Association of Ophthalmology
Disclosure: Nothing to disclose.
The authors and editors of eMedicine gratefully acknowledge the contributions of previous coauthors, Enoch Huang, MD, MPH, and DooHo Brian Kim, BA, to the development and writing of this article.
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