Diplopia

Richard C. Mauer

Diplopia, or true double vision, not simply blurred vision, can be a very useful clinical symptom. A range of problems can be limited to the eye or be as severe as an intracranial aneurysm. Evaluation in a systematic manner is critical in coming to the correct underlying cause (1).

Approach

It is critical on evaluation of diplopia to determine if the problem is monocular or truly binocular, as the range of seriousness is directly proportional to whether it falls into one or the other category. It is also important to ascertain whether it is true diplopia or double imaging, simply blurred vision or hazy vision, or floaters in the field of vision. Unless the patient can positively state that actual double imaging is occurring, there is no diplopia (2).

A. Monocular diplopia. Usually eye-related conditions are the underlying cause here (e.g., cataracts, corneal opacities, and occasionally intravitreous opacity). Monocular diplopia is present when the patient notices diplopia with either the right or left eye being covered.

 B. Binocular diplopia. This is usually secondary to intracranial abnormalities (e.g., aneurysm, stroke, hemorrhage, or increase in intracranial pressure). Binocular diplopia is present when double vision is noted only with both eyes being opened. When the patient closes either eye separately and the diplopia goes away, with each of the right and left eye being occluded, then binocular diplopia is present. In other words, it takes two eyes functioning properly to have binocular diplopia.

History

 A. Characteristics of the diplopia. Is it true double vision or simply just blurred or hazy vision? Patients often confuse double vision with blurry vision. Close one eye or the other to test the double vision. If, in the process of covering one or the other eye, double vision is still noted, under the occluded condition, this defines monocular diplopia, a non–life-threatening cause. If double vision goes away when covering the left eye, and again when covering the right eye separately, this is binocular diplopia and the index of severity increases substantially for the underlying cause. Does diplopia get worse looking at a distance and improve when looking up close (i.e., probably a sixth nerve palsy)? Are there any recent headaches associated with this? Is there a problem with balance, coordination, nausea or vomiting, or drooping of the eyes? Is double vision separated horizontally or vertically? A vertical separation suggests either a third or fourth nerve palsy. If there is ptosis with the diplopia, it suggests a third nerve palsy. Is the diplopia sudden in onset? This suggests a vascular event if the headache is binocular.

 B. Concurrent conditions. Microvascular ischemia is often secondary to diabetes, hypertension, or peripheral vascular disease, which can often cause a third, fourth, or an acute sixth cranial nerve palsy (Chapters 7.8 and 14.1). Thyroid disease can cause a gradually worsening binocular diplopia with a waxing and waning symptom (Chapter 14.8). This is usually associated with obvious proptosis in one or both eyes.

C. Duration of diplopia. A chronic subacute intermittent diplopia, with some blurred vision or floaters with decreased vision, usually suggests an eye-related problem such as cataracts, corneal opacity, irregular astigmatism, or vitreous opacity. An acute intermittent diplopia usually represents a cranial nerve palsy and often represents an intracranial condition.

Physical examination. Focused physical examination (PE)

This should include a visual acuity test for each eye. Ask the patient about diplopia being present when covering each eye. If double vision is still present while having one or the other eye covered, by definition, this is monocular diplopia. A rare patient will complain of triplopia, or triple vision. This usually is malingering, but occasionally can be caused by corneal surface irregularity. Other parts of the examination are important: check the ocular rotations; lack of abduction or external rotation of the eye would suggest a sixth nerve palsy. Check for monocular ptosis; if it is present, then a third nerve palsy is suggested. Pupillary responses, if fixed and dilated, suggest an acute pupillary-involving third nerve palsy. An optic nerve where papilledema is present suggests an intracranial-involving process. A red fundus reflex test showing an opacity in the red reflex suggests an ocular cause, such as cataracts or corneal opacity.

Testing

A. Clinical laboratory tests. For most diplopia workups, no blood, urine, or clinical laboratory tests are needed. The only tests that might be suggested would be a glucose and hemoglobin A1c for those cases in which a suspicion of diabetes exists. An elevated erythrocyte sedimentation rate with temporal tenderness present would suggest temporal arteritis.

 B. Diagnostic imaging. In monocular diplopia, no diagnostic imaging is necessary. However, with binocular diplopia, diagnostic imaging with a computed tomography scan with and without contrast should be done. With a third nerve palsy present with pupillary involvement, then a magnetic resonance imaging scan would be preferred to look for an aneurysm of the posterior communicating artery. All cases of untreated diplopia should be referred to an ophthalmologist for evaluation. If the diplopia is binocular, the patient needs to be seen on the same day. If monocular, the evaluation should be undertaken within 1 to 3 days.

Diagnostic assessment

 It is critical in the evaluation to determine whether the problem is monocular or binocular diplopia. In monocular diplopia, there is usually a more vague history; blurred vision is often present, or occasional floaters or lines are noted in the vision. More chronicity is expected of weeks to months with an intermittent presentation. The patient is often more vague about the description of the condition. In true binocular diplopia, the patient classically notes the problem suddenly, is definitely noting two images, which are either vertically or horizontally separated; when covering one and then the other eye, it goes away in each occlusion state. The level of seriousness is markedly increased in binocular diplopia. An ophthalmologic examination is mandated in either scenario (3).

References

1. Brazis PW, Lee AG. Binocular vertical diplopia. Mayo Clin Proc 1998:73:55–66.

2. Richardson LD, Joyce DM. Diplopia in the emergency department. Emerg Med Clin North Am 1997;15(3):649–664.

3. Spector RH. Vertical diplopia. Surv Ophthalmol 1993;38(1):31–62.

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Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

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More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X