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Symptom FAQs

Neuro-visual and vestibular conditions can cause confusing symptoms. To provide some guidance, here are our experts’ answers to some of the most common questions asked by patients.

1. I just got double vision for the first time this week. Is that serious?

Double vision is usually a symptom that results from the two eyes becoming misaligned (so that each eye is pointed to a slightly different view of the world); this is known as binocular diplopia, meaning that the double vision only occurs when both eyes are open, not when just one is open. Occasionally, double vision instead results from trouble with the eye itself, such as due to a cataract; this is known as monocular diplopia, meaning that the double vision occurs when one or each eye is closed. It is important to sort this out by alternately closing each eye. If the double vision disappears with either eye closed, then you have binocular diplopia. If the double vision is still present with just one eye open — regardless of whether that is the right eye, the left eye or either eye — then you have monocular diplopia. You can have monocular diplopia in one (unilateral) or both (bilateral) eyes.

If the issue is monocular diplopia (whether unilateral or bilateral), it is usually due to a cornea problem such as keratoconus, a lens problem such as cataract or lens dislocation, or occasionally a retina problem. If there are other neurological symptoms or loss of vision to one side, it is advisable to seek care with a neurologist or neuro-ophthalmologist right away, and it may be necessary to go to the emergency room if your physician cannot get you an immediate referral. If the monocular diplopia is an isolated symptom, a routine referral by your physician to an ophthalmologist is generally appropriate.

If the issue is binocular diplopia, then typically there is a problem with the movement of one or both eyes. This could result from a complication of diabetes or head injury that causes minor nerve damage (cranial neuropathy). However, strokes in the back part of the brain, brain aneurysms and other dangerous diseases can cause symptoms and physical signs that are identical. If the binocular double vision is new, especially if it is associated with other new neurological symptoms such as dizziness, trouble walking, vomiting, eye pain, headache or neck pain, call 911 or go straight to the emergency room.

2. I temporarily lost vision in one eye. Do I need to worry about that?

Temporary loss of vision in one eye, usually lasting seconds or minutes, is called transient monocular visual losstransient monocular blindness or amaurosis fugax, in Latin. This symptom is often the result of loss of blood flow to the retina or vision nerve of one eye. It should be considered a stroke symptom unless it is known to be due to another condition, such as retinal migraine. If the symptom is new and has not previously been diagnosed, immediately contact your physician or go straight to the emergency room.

3. The doctor said my vision nerves are swollen. Is that serious?

When a neurologist, ophthalmologist, optometrist or other provider looks inside your eye using a bright light (using a device called an ophthalmoscope), they might notice that you have a swollen nerve at the back of your eye. This is called optic nerve edema. If it is only in one eye and you’ve lost some vision in that eye, it is usually the result of optic neuritis or ischemic optic neuropathy. Both conditions require attention from a neuro-ophthalmology specialist right away, since early treatment can sometimes prevent further vision loss or even restore vision. If it is in both eyes, it may be the result of high pressure inside the head (known as raised intracranial pressure or elevated intracranial pressure); if so, the swelling of the eyes would be called papilledema. Papilledema can be due to very serious problems, such as a blockage of fluid around the brain (known as obstructive hydrocephalus, which can be fatal if not treated quickly) or a brain tumor. More often, though, the papilledema is due to a disease known as idiopathic intracranial hypertension (also called pseudotumor cerebri, meaning “there is no brain tumor,” in Latin). It is also important to know that not everything that looks swollen on a casual glance is actually swollen. Sometimes optic nerves can look swollen because they are a little tilted (some people are born that way, and it’s nothing to worry about) or because there are small, non-serious deposits underneath the optic nerve head that cause it to be bunched up (called pseudopapilledema, meaning “there is no real swelling of the vision nerve,” in Latin). If the finding is new and has not previously been diagnosed, immediately contact your physician or go straight to the emergency room.

4. I noticed my pupils aren't the same size. Should I be worried?

Your pupil is the hole inside your eye that opens and closes to let different amounts of light in depending on whether or not you are in a brightly lit environment. In the mirror, it is a black circle in the middle of your iris (the colored part of your eye). In a flash photo, it might appear red from the reflection of light by the back of your eye (think “red eye reduction” in a photo editing software program). Although pupils vary in size between people, most individuals have pupils that are almost exactly the same size in the two eyes (i.e., right versus left). A small number of people have slightly different sized pupils (1-2 millimeters difference); if this has always been the case (sometimes you can tell by looking at an old photo or driver’s license with a magnifying glass), then it is generally nothing to worry about. If it is new, however, is should be taken seriously, especially if the difference between the two pupils changes depending on how bright it is in the environment around you (for example, there is not much difference in size between the right and left pupil in bright light but there is an obvious difference in dim light, or the reverse). This problem can be caused by dangerous conditions like a damaged blood vessel in the neck (carotid artery dissection) or a brain aneurysm. If the finding is new and has not previously been diagnosed, and especially if you have new headaches, eye pain or neck pain, immediately contact your physician or go straight to the emergency room.

5. I've been diagnosed with vertigo. What does that mean?

Vertigo is a symptom, not a disease. Sometimes inner ear diseases that cause vertigo such as benign paroxysmal positional vertigo (BPPV) or vestibular neuritis/labyrinthitis are loosely referred to as vertigo by general physicians. More often, though, when a patient has been told that their diagnosis is vertigo, it suggests that the provider may not know the correct diagnosis. Usually in such cases, it is best to seek further consultation with a specialist.

6. What's the difference between vertigo, dizziness, unsteadiness and lightheadedness?

Different people experience—and describe—balance  symptoms differently. Vertigo is the sensation of motion when no motion is actually occurring; sometimes it feels like a “spinning” sensation, other times more like a “rocking” or “swaying.” Dizziness  is a sense of disorientation to space that does not involve a feeling of motion. Unsteadiness is the sensation of being unstable while sitting, standing or walking. The three sensations often occur together when someone has a problem with their inner ear balance organ or its connections in the brain. The word “lightheadedness” is used differently by different people.

Some people who experience a sense of dizziness describe this as “lightheadedness.” Others specifically use “lightheadedness” to mean they feel faint (the medical term to describe this type of lightheaded feeling is presyncope). People who feel like they are about to faint sometimes have inner ear or brain problems as the cause but, more often, they have low blood pressure or a heart problem.

7. Doctors keep telling me they are looking for nystagmus. What is that?

Nystagmus is an involuntary, rapid, rhythmic, to-and-fro movement of one or both eyes (usually both). Sometimes it is a smooth movement like a pendulum on a grandfather clock (pendular nystagmus) but, more often, it is a movement in which the eye(s) drift slowly in one direction and then jerk back the other way (jerk nystagmus). When prominent, it is not generally a normal finding.

Pendular nystagmus can result from brain diseases such as multiple sclerosis but also from eye problems (like early-life vision loss). This form of nystagmus is usually associated with a disturbing symptom of bouncing or oscillating vision (oscillopsia) but not usually associated with dizziness or vertigo. Unless known to be a longstanding finding since childhood, pendular nystagmus is usually investigated by a neurologist or neuro-ophthalmologist. Although it is not typically a manifestation of acute brain diseases like stroke that require emergent treatment, pendular nystagmus should still be assessed promptly.

Jerk nystagmus usually results from diseases affecting the inner ear balance mechanisms or the back part of the brain (brainstem or cerebellum). This form of nystagmus is often associated with a sense of the world spinning, turning, rotating or rocking (vertigo), but sometimes patients experience no symptoms at all. Other than small amounts of jerk nystagmus lasting a few seconds when looking to the far right or left (physiologic nystagmus), this finding should generally prompt a neurological or neuro-otological assessment. If it is associated with new dizziness or vertigo of unknown cause, that assessment should be immediate.

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