Vision changes are common as we age. However, problems with eyesight also can be an early indicator of a more serious injury or condition. How do you know when to seek out medical advice? Neuro-ophthalmologist Steven Newman, MD, provides clarification on some of the more common vision problems and possible causes below.
When your eyes don’t work together as a team to focus on an object, you’ll likely see two images of the same object instead of one clear image. This is known as double vision or diplopia.
Double Vision: Probable Causes
According to Newman, structural abnormalities of the eye muscles or the nerves that stimulate them may cause double vision. When one eye sees a second image (often a ghost image) while the other eye is covered, this is known as monocular diplopia. It is most commonly caused by astigmatism (a defect in the curvature of the cornea or shape of the lens) or early formation of cataracts (clouding of the eye lens).
Double Vision: Possible Causes
Any condition that impairs the muscles or nerves controlling the eyes also can result in double vision. Some of these conditions are:
- Myasthenia gravis, an autoimmune disorder that interrupts transmission between the motor nerves and the eye muscles. This weakens the muscles that move the eyes and often the eyelids (resulting in a drooping eyelid).
- Graves’ disease, a thyroid condition that causes inflammation in and around the eyes. It can produce double vision by interfering with the ability of the enlarged muscle to relax. Typically, this results in vertical double vision, which worsens while looking up.
- Multiple sclerosis (MS), a disease that attacks the central nervous system and causes optic neuritis or inflammation of the optic nerve in 50 percent of MS patients. It often leads to decreased or blurry vision. When the brainstem is affected, it also may cause an abnormality in eye movements. The most common result is an inability to move an eye in (toward the nose).
- Miller Fisher syndrome, a variant of Guillain-Barre syndrome that causes weakness of the eye muscle.
- Diabetes and high blood pressure, which can cut off blood flow to one of the nerves that control eye muscles. This is referred to as a microvascular cranial nerve palsy or ophthalmoplegia.
- A brain tumor, which may directly affect one of the motor nerves going to the muscles that move the eye or lead to increased intracranial pressure, which may produce a cranial nerve palsy or paralysis that inhibits eye movement.
When Double Vision Is Serious
Double vision is most concerning when it comes on suddenly, or is prolonged, recurrent or progressive. However, it’s always a good idea to consult a doctor any time you experience double vision.
Some of the conditions mentioned above may resolve on their own or may be treatable. But double vision may be a sign of a life-threatening problem. For example, if double vision is accompanied by paralysis of the eye and there is an enlarged pupil, then you may have an aneurysm or a bulging artery that can rupture.
“An aneurysm is one of those things you don’t want to miss because it has a 30 percent mortality risk,” says Newman.
Sudden Vision Loss
Sudden vision loss may occur in one or both eyes. It may happen in minutes or over the course of a couple of days. Your eyesight may diminish entirely or it may just become foggy or blurry. Symptoms may be temporary or, in some cases, permanent.
Sudden Vision Loss: Probable Causes
Conditions that cause increased pressure within the eye are the most common causes of optic nerve dysfunction. This can lead to vision loss. Most often, these conditions cause slow but progressive peripheral visual field loss, but occasionally there may be sudden, temporary vision loss.
Migraine headache sufferers, for example, may experience blurry vision, periods of darkness or even visual disruptions often described as flashing, or zigzagging lights. But the symptoms will typically diminish, and vision will return to normal. If the symptoms do not resolve on their own, you should be evaluated for other possible causes.
Sudden Vision Loss: Possible Causes
Diabetes is one of the most common causes of not only temporary vision loss or impairment but permanent blindness. In fact, diabetes-related complications are the leading cause of preventable or treatable blindness among adults in the U.S., according to the Centers for Disease Control and Prevention.
High blood sugar can damage blood vessels in the retina, which causes diabetic retinopathy. This condition leads to fluid build-up in the retina, the development of scar tissue in the eye or detachment of the retina, all of which negatively impact your ability to see. Thus, if you are a diabetic, it’s imperative that you receive regular eye exams.
When Sudden Vision Loss Is Serious
According to Newman, eye problems, including vision loss, may signal a problem within the brain. “Many common neurological problems have eye manifestations,” he says. Depending on where it’s located in the brain, a tumor may cause double vision, as mentioned above, abnormal eye movements or decreased vision. Acting on these visual cues may allow you to catch problems like cancer sooner and have a better shot at treating the underlying condition and improving symptoms.
Another rare but serious cause of sudden vision loss is stroke. Should a bleed or interruption of circulation occur in the portion of the brain responsible for visual processing, you may experience vision loss in one eye or, more commonly, trouble seeing to one side.
Even if symptoms subside, you may still have had a ministroke or transient ischemic attack (TIA), so be sure to talk to your doctor.
“It is sometimes possible to limit the effect of a stroke or even reverse the symptoms if the patient is seen immediately at an emergency room with a stroke team available,” says Newman.
“Floaters” in the Eye
The small specks or spots that travel across your field of vision are often referred to as “floaters.”
Floaters: Probable Cause
As we age, the vitreous or clear, jelly-like substance that makes up the middle of the eye begins to shrink. “When the vitreous jelly shrinks, it may pull away tissue from the back of the eye that then floats across the visual pathways,” says Newman. “These often persist, but most patients get used to them and ignore them.”
When Floaters Are Serious
Should the vitreous pull away from the retina, this can cause a retina tear, which can then lead to a retinal detachment. Permanent vision loss may follow if not treated. Fortunately, this is uncommon.
However, if you see persistent flashing lights, hundreds of floaters and especially a curtaining coming up or down over your vision, you should see your healthcare provider promptly. “If caught early, retinal tears and even developing detachments can be treated,” says Newman. “Once the center part of the eye is involved, the chance of an excellent result following surgery decreases.”
The cornea, the layer that makes up the front of the eye, has the body’s second highest number of pain receptors, according to Newman. “This is why eye pain due to corneal injury or pathology can be quite troublesome or even debilitating,” he says.
Eye Pain: Probable Causes
“Anything that affects the surface of the eye will usually lead to eye pain,” says Newman. This may include a scratch, overuse of contact lenses, chemical irritant, infection or a foreign object hitting the eye surface.
Inflammation in the eye due to a specific infectious agent or a particular immune system response can also cause eye pain, says Newman.
Eye Pain: When It’s Serious
Some symptoms suggest a more serious problem, such as a tumor at the base of the skull or a sudden rise in eye pressure. These can cause permanent vision loss if not treated immediately. They include:
- Vision loss
- Numbness of the face or eye
“Our eyes are very valuable to us. Any symptoms of visual loss or double vision should be investigated,” says Newman.
Our bodies do all kinds of weird things. How do you know when to ignore something and when to get to the doctor ASAP? We break down what’s normal and what’s not in this occasional series.