Sudden painless monocular visual loss

This article was designed to be viewed and distributed as a PDF. Please download the PDF for easiest reading.

‌History

‌A 58-year-old African-American female presented to the ophthalmology clinic from the local emergency department with a history of right eye (OD) sudden visual loss since 9:00 am that morning, when she woke up. The patient described her vision as “complete blackness.” The first episode lasted 10 minutes followed by an additional three episodes within the first hour of awakening. The patient denied any other associated symptoms—pain, photophobia, flashes of light, floaters, headache, jaw claudication, weight loss, scalp tenderness, or trauma.

Previous history

The patient’s past medical history included uncontrolled hypertension. She was taking lisinopril. She had an allergy to penicillin and tetracycline. Her past surgical history in- cluded a total abdominal hysterectomy with bilateral oo- pherectomy. Her family history included diabetes mellitus no acute processes. The ophthalmology clinic was notified at 2:55 pm of the patients’ complaint and was sent over to the clinic with the instruction to perform digital massage. Upon arrival, the patient was subsequently diagnosed with a branch retinal artery occlusion (BRAO) (Figure 1a). She was admitted to the hospital for a vascular work up, ma- gentic resonance imaging/angiography, and an echocardio- gram.

Discussion

The purpose of this case report is to review an ophthalmo- logic emergency that may present to your primary care office or emergency department including the natural his- tory, typical presentation and management of a BRAO and also central retinal artery occlusion (CRAO).

Blood supply to the retina originates from the ophthalmic artery. The ophthalmic artery is the first intracranial branch off of the internal carotid artery. The ophthalmic artery supplies the eye via two branches: the central retinal artery and ciliary arteries. The central artery supplies the retina via the superior and inferior intraretinal branches. A notable variant is the presence of a cilioretinal branch from the short posterior ciliary artery that gives collateral flow to the fo- veal area. This variant is present in approximately 14% of the United States population. An embolism occurs when an object migrates from one blood vessel and causes an occlu- sion of another vessel. This is in contrast to a thrombus, or clot, which forms at the blockage point within a blood vessel and is not carried from somewhere else. Several types of embolism exist—thromboembolus, an embolism of thrombus or blood clot, an embolism from a cholesterol plaque often resulting from atherosclerosis, and others such as fat, air, and septic emboli.

CRAO is a somewhat rare event, with an incidence of approximately 1 to 10 in 100,000.1 Symptomatic BRAO is even less common. Demographic characteristics of patients with CRAO and BRAO are consistent with those seen for other vascular disorders.

CRAO usually presents with sudden, complete, painless visual loss in one eye. The retina becomes opaque and edematous and the intact choroidal vasculature beneath the foveola stands out in contrast to the surrounding opaque neural retina, thus producing a cherry red spot (Figure 2). In time, the central artery recanalizes and the retinal edema resolves. Visual outcome is dependent on presence of a cilioretinal artery that spares the central macula and time to treatment.2

‌BRAO is also a fairly rare ocular disorder. It can be grouped in several ways including permanent or transient, via location, and by the produced visual field defect. A BRAO occurs when an embolus flows from the central retinal artery to a more distal branch. Of recurring occlu- sions, BRAO is less common (38%) than CRAO (57%).

The patient presentation can vary; however, the most common presenting complaint is acute painless visual loss, which is only in a section of the peripheral vision depending on the location of the occlusion. The visual symptoms may originate with central visual loss and change depending on the final location of the emboli. The defect may be an altitudinal defect affecting the upper or lower hemifield but never respecting the vertical axis.

Fundus examination reveals an edematous opacification and whitening of the retina along the distribution of the occluded vessel within hours to days. Cotton-wool spots may be present and are limited to the area of the retina supplied by the occluded vessel. Emboli can be seen in approximately 20% to 40% of patients. Boxcarring is a sign of severe occlusion and slowing circulation. In the acute phase, the blood column in the artery becomes segmented with separation of serum from Rouleau stacking of the red corpuscles, leading to a boxcarring appearance of the blood column (Figure 1b). As with CRAO, the affected vessel recanalizes over time and perfusion returns, and the edema resolves with the visual field defect remaining.

Once a CRAO/BRAO is diagnosed, a work-up should be done to determine the etiology of the cause, although the yield is relatively low. A complete blood count, erythrocyte sedimentation rate, C-reactive protein (giant cell arteritis accounts for 1–2% of CRAO cases), prothrombin time, partial thromboplas- tin time, fasting lipid panel and, if indicated, blood cultures should be ordered.3 Imaging studies are also helpful in determining the etiology (e.g., echocardiogram to look for vegetations, valvular disease, and thrombi). Carotid Dop- plers or magnetic resonance imaging should be ordered to evaluate the carotid circulation for atherosclerosis. An elec- trocardiogram should be done, or a 24-hour Holter monitor worn, to rule out atrial fibrillation.4‌

Treatment

Prognosis is related to the timeliness of treatment and the presenting visual acuity.5,6 Depending on the location of the emboli, certain intervention may be beneficial, but efficacy is questionable.7 Most patients (80%) with BRAO recover normal vision, whereas spontaneous clinical improvement from CRAO is rare.8

Hayreh studies concluded that in young healthy rhesus monkeys, CRAO retinal damage was reversible if the du- ration lasted for 97 to 98 minutes, but the retina suffers irreversible damage after 105 minutes.9

The retina of old, atherosclerotic, and hypertensive rhe- sus monkeys suffers no detectable damage with CRAO of

97 minutes duration, but suffers progressively more irre- versible damage with increased duration. These findings are counterintuitive and may relate to the type of anesthesia used or hypoxic preconditioning.

The study suggested that a CRAO lasting 240 minutes results in massive, irreversible retinal damage.10

The general consensus from an evidence-based and med- ical legal aspect is to intervene by 90 minutes.2 Ocular massage can be performed by applying direct pressure for 5 to 15 seconds, releasing, and repeating several times. In- creased intraocular pressure causes a reflexive dilation of retinal arterioles by 16%. A sudden drop in intraocular pressure with release increases the volume of flow by 86%. Ocular massage may dislodge the embolus to a point farther down the arterial circulation and improve retinal perfusion, but the efficacy in improving visual outcome is unknown. Anterior chamber paracentesis is advocated when visual loss has been present for less than 24 hours. Early paracen- tesis is thought to increase visual recovery by decreasing the intraocular pressure and allowing greater perfusion and pushing emboli farther down the vessel. This can be per- formed with a 27- to 30-gauge needle, with removal of 0.1 to 0.4 mL of aqueous humor, without decreasing the pres- sure lower than 4. There may be a marginal visual benefit associated with local intra-arterial fibrinolysis compared with conventional management of CRAO,11-13 and hyper- baric oxygen may be of benefit. The data suggest that anterior chamber carbogen therapy offer little benefit for treating acute nonarteritic CRAO.14

Presence of a cilioretinal artery with foveolar sparing increases improvement in end outcome visual acuity. Isch- emic retinal damage also may arise from oxidative damage and membrane damage once retinal tissue is reperfused.2

Long-term management focuses on preventing recurrent vascular events. Our patient’s work-up revealed uncon- trolled hypertension, dyslipidema, and diabetes. Her electro- cardiogram, magnetic resonance imaging/angiogram were normal. Although no definitive etiology was evident we counseled the patient to control her hypertension and dys- lipidemia, with the hope of decreasing the likelihood of future occurrences.

References

1. Rumelt S, Dorenboim Y, Rehany U: Aggressive systematic treatment for central retinal artery occlusion. Am J Ophthalmol 128:733-738, 1999

2. Regillo R: Basic and clinical science course. Retina and vitreous. San Francisco: American Academy of Ophthalmology pp. 159-164, 2008

3. Fineman MS, Savino PJ, Federman JL, Eagle RC Jr: Branch retinal artery occlusion as the initial sign of giant cell arteritis. Am J Oph- thalmol 53:721-748, 1996

4. Rhee DJ, Pyfer M: Central retinal artery occlusion. In: Rhee DJ, Pyfer MF, eds. The Wills Eye Manual: Office and Emergency Room Diag- nosis and Treatment of Eye Disease, 5th ed. Philadelphia: Lippincott Williams & Wilkins, 2008, pp 282-284

5. Hayreh SS, Podhajsky P, Zimmerman B: Branch retinal artery occlu- sion; natural history of visual outcome. Ophthalmology 116:1188- 1194, 2009

   
   

6. ‌Mason JO III, Shah AA, Vail RS, et al: Branch retinal artery occlusion; visual prognosis. Am J Ophthalmol 46:455-457, 2008

7. Atebara NH, Brown GC, Cater J: Efficacy of anterior chamber para- centesis and Carbogen in treating nonarteritic central retinal artery occlusion. Ophthalmology 102:2029-2034, 1995

8. Yuzurihara D, Iijima H: Visual outcome in central retinal and branch retinal artery occlusion. Jpn J Ophthalmol 48:490-492, 2004

9. Hayreh SS, Zimmerman MB, Kimura A, Sanon A: Central retinal artery occluison: retinal survival time. Exp Eye Res 78:723-736, 2004

10. Hayreh SS, Kolder HE, Weingeist TA: Central retinal artery occlusion and retinal tolerance time. Ophthalmology 87:75-78, 1980

11. Beatty S, Eong K: Local intra-arterial fibrinolysis for acute occlusion of the central retinal artery: a meta-analysis of the published data. Br J Ophthalmol 84:914-916 2000

12. Richard G, Lerche RC, Knospe V, Zeumer H: Treatment of retinal arterial occlusion with local fibrinolysis using recombinant tissue plas- minogen activator. Ophthalmology 106:768-773, 1999

13. Schmidt DP, Schulte-Mönting J, Schumacher M: Prognosis of central retinal artery occlusion: local intraarterial fibrinolysis versus conser- vative treatment. Am J Neuroradiology 23:1301-1307, 2002

14. Atebara NH, Brown GC, Cater J: Efficacy of anterior chamber para- centesis and Carbogen in treating nonarteritic central retinal artery occlusion. Ophthalmology 102:2029-2034, 1995