How Do I Manage Transient Monocular Visual loss In a Young, otherwise Healthy PatIent? Question

Abstract

A 27-year-old woman reports having had 3 episodes of transient " darkening" of vision in her right eye. Each episode lasted 3 to 5 minutes without any associated symptoms. Her general health is excellent; her only medication is an oral contraceptive. She has no history of migraine. Her examination, including visual fields, is entirely normal. What evaluation and therapy should be undertaken? Transient monocular vision loss (TMVL) of abrupt onset typically represents a focal retinal, choroidal, or optic nerve functional deficit due to ischemia. Historical clues are important, such as asking your patient what area of the visual field was lost; the duration of the loss; and the pres-ence of any neurological symptoms, such as headache, numbness, or weakness. In your patient, the absence of scintillations and headaches and the fact that the vision loss is monocular makes a diagnosis of migraine less likely. A careful history, asking for associated systemic symptoms, is important, although none are reported by your patient. The differential diagnosis of TMVL in young individuals includes several entities. Vasospasm in the eye is thought to be due to spasm involving the retinal circulation and often affects the same eye every time. These patients have a stereotypical pattern of "patchy darkening" of vision for approximately 1 minute, followed by poor acuity for 1 to 5 minutes, followed by a return to base-line. There are no scintillations and no neurological abnormalities on examination. In my opinion, the best "investigation" is a thorough history and neuro-ophthalmic examination. Vasospasm is a benign condition that rarely leads to any permanent visual damage. I have found that the fre-quency of the TMVL events can sometimes be reduced by the use of calcium channel blockers.

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32
How Do I Manage TransIenT
Monocular VIsual loss In a
Young, oTHerwIse HealTHY PaTIenT?

Lee AG, ed.
Curbside Consultation in Neuro-Ophthalmology:
49 Clinica l Questions, Secon d Edition (pp 133 -136).
© 2015 SLACK Incorporated.
Rosa Ana Tang, MD, MPH and Roberto A. Cruz, MD
A 27-year-old woman reports having had 3 episodes of transient “darkening” of vision in her
right eye. Each episode lasted 3 to 5 minutes without any associated symptoms. Her general
health is excellent; her only medication is an oral contraceptive. She has no history of migraine.
Her examination, including visual fields, is entirely normal. What evaluation and therapy
should be undertaken?
Transient monocular vision loss (TMVL) of abrupt onset typically represents a focal retinal,
choroidal, or optic nerve functional deficit due to ischemia. Historical clues are important, such
as asking your patient what area of the visual field was lost; the duration of the loss; and the pres-
ence of any neurological symptoms, such as headache, numbness, or weakness. In your patient,
the absence of scintillations and headaches and the fact that the vision loss is monocular makes
a diagnosis of migraine less likely. A careful history, asking for associated systemic symptoms, is
important, although none are reported by your patient.
The differential diagnosis of TMVL in young individuals includes several entities. Vasospasm
in the eye is thought to be due to spasm involving the retinal circulation and often affects the
same eye every time. These patients have a stereotypical pattern of “patchy darkening” of vision for
approximately 1 minute, followed by poor acuity for 1 to 5 minutes, followed by a return to base-
line. There are no scintillations and no neurological abnormalities on examination. In my opinion,
the best “investigation” is a thorough history and neuro-ophthalmic examination. Vasospasm is
a benign condition that rarely leads to any permanent visual damage. I have found that the fre-
quency of the TMVL events can sometimes be reduced by the use of calcium channel blockers.

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In the past, TMVL in young patients had been termed retinal migraine. This designation
appears no longer correct for at least 2 reasons. First, most of the reported patients diagnosed with
retinal migraine have not met strict International Head Society criteria. Second, there are no stud-
ies in humans to suggest that the retina is subject to “spreading depression,” the process believed
to underlie the binocular visual aura emanating from the visual cortex in migraine.
Transient monocular visual loss can be caused by reversible (by anticoagulation) retinal artery
thrombi associated with heritable thrombophilia. These ocular vascular thrombotic events have
opened a diagnostic window for screening and treatment of a variety of disorders, including fac-
tor V Leiden, prothrombin gene mutations, and hypofibrinolysis. Hypercoaguable/hyperviscosity
syndromes are a consideration, especially in patients with a normal MRI of the brain who also lack
signif icant ipsilateral internal carotid artery stenosis, atrial fibrillation, or cardiac thrombus. The
patient in question is taking birth control pills; if she is a smoker and has history of migraine, she
is at risk for both ocular and brain stroke.
In other cases involving changes in intermittent systemic blood pressure (too high or too low),
TMVL may be associated with changes in posture, bright light exposure, heavy exercise, or eating
a large meal. If paroxysmal hypertension related to renal artery stenosis or pheochromocytoma is
the cause, the patient may also experience episodic dizziness, as well as palpitations, sweating, and
pallor. Cardiac emboli or arrhythmia related to valvular disease, such as patent foramen ovale or
endocarditis in drug addicts, is characterized by erratic pulse, heart murmur, or both on physical
examination.
Less likely is the presence of premature atherosclerosis, carotid dissection, or fibro muscular
dysplasia. Carotid artery dissection (CAD) is a common cause of stroke in previously healthy
young individuals. About 75% of CADs lead to ischemic events, making it imperative that they
be recognized and treated as soon as possible.
Rare causes of TMVL are orbital tumors and posterior vitreous detachment. The latter gives
rise to a typical “one-time event” of monocular TMVL in the majority of patients. Ocular coher-
ence tomography is the instrument of choice to study the vitreoretinal interface and will image the
presence of vitreoretinal traction in these patients.
A standard algorithm for the assessment of young patients (below 50 years of age) with TMVL
does not exist; diagnostic evaluation is determined by the history and specific examination find-
ings, such as ocular inflammation, retinal venous or arterial changes, presence of a carotid bruit,
level of blood pressure, pulse, heart murmurs, and any neurological deficits. A thorough ophthal-
mic examination is essential, especially dilated funduscopy and visual field testing.
In a healthy young patient with an isolated single episode of TMVL and no other associated
symptoms and signs, I would conclude that the condition is due to retinal vasospasm and not do
any further workup. Both visual and systemic prognoses are excellent. However, our patient has
had 3 occurrences of TMVL; therefore, studies to exclude an embolic source (eg, heart disease),
carotid dissection (look for ipsilateral Horner’s syndrome) vasculitis, or a hypercoagulable state
need to be considered (Table 32-1). If all studies are normal, I would reassure the patient of the
benign nature of the disorder and perhaps offer treatment with a calcium channel blocker. If
the patient experiences a change in these stereotypical visual events or new signs and symptoms
develop, reevaluation is indicated.

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Summary
 Many otherwise healthy young patients with an isolated single episode of TMVL and no other
associated symptoms and signs have retinal vasospasm.
 Selected patients might require testing to exclude heart disease, vasculitis, and possibly a
hypercoaguable state.
 A dramatic change in prior stable and stereotypical visual events or the development of new
neurological signs or symptoms should prompt reevaluation as indicated.
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Hypercoagulable State Testing
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