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Adult strabismus (crossed eyes) is when your eyes are not lined up properly and they point in different directions. One eye may look straight ahead while the other eye turns in, out, up, or down. The misalignment can shift from one eye to the other. Strabismus affects vision, since both eyes must aim at the same spot together to see properly.

There Are Six Eye Muscles That Control Eye Movement

One muscle moves the eye to the right, and one muscle moves the eye to the left. The other four muscles move the eye up, down, and at an angle. In order to focus on a single image, all six eye muscles must work together.

What Causes Adult Strabismus (Crossed Eyes)?

To line up and focus both eyes on a single target, all muscles in both eyes must be balanced and working together. The brain controls these muscles. People who have strabismus usually have a problem that can affect eye muscles. Some of those problems may include:

• Health problems such as diabetes, thyroid eye disease (or TED, also known as Graves’ eye disease), Myasthenia gravis, brain tumors, or a stroke
• Accidents or head injury
• Damage to eye muscles during some kind of eye surgery

Most adults with strabismus have had it since they were children. But sometimes it starts later in life.

How Does Adult Strabismus Affect Vision?

With normal vision, both eyes aim at the same spot. The brain combines the two images from our eyes into a single, three-dimensional (3-D) image. This is how we can tell how near or far something is from us (called depth perception).

When one eye is out of alignment, two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the misaligned eye. Instead, it sees only the image from the straight or better-seeing eye. As a result, the child loses depth perception.

Adults who develop strabismus after childhood often have double vision. This is because their brains have already learned to receive images from both eyes. Their brains cannot ignore the image from the turned eye, so they see two images.

What Are the Symptoms of Adult Strabismus (Crossed Eyes)?

The most obvious symptom is having eyes that appear out of alignment. Adults with strabismus also may notice these other symptoms:

• Weakness in or around the eye, or feeling like something is pulling around your eyes.
• Vision changes, such as double vision (seeing two of one image), blurry vision, trouble reading, or a loss of depth perception.
• Constantly tilting or turning your head to see an image clearly.

Strabismus symptoms can be constant, or they can come and go.

Source: American Academy of Ophthalmology | Eye Smart

Myasthenia gravis is a disorder that may cause muscles to weaken and tire easily. The disorder can affect muscles that control eye and eyelid movement. This may cause eyelid drooping or double vision.

Most people who have these eye symptoms of myasthenia may develop weakness in other muscles within one or two years. This broader form affects the muscles of the face, eyes, arms, and legs. It also affects the muscles used for chewing, swallowing, and talking. It can affect muscles used for breathing. When it does, this is a life-threatening situation known as a myasthenic crisis.

With myasthenia gravis it is typical to have periods of muscle weakness followed by periods of few or no symptoms.

What causes myasthenia gravis?

Your body’s own immune system blocks the receptors of the muscles leading to the signs and symptoms of myasthenia gravis with antibodies. This interferes with the connection between the chemical that travels from nerve endings to stimulate the muscle receptors.

Your muscles need this connection for to work correctly. Without this connection the muscles become weak.

What are the symptoms of myasthenia gravis?

The first symptoms of myasthenia gravis often involve the eyes. The most common sign is ptosis, or drooping eyelids. This may affect one or both eyes. If you have myasthenia gravis, you may also feel more tired as the day goes on.

Other myasthenia gravis symptoms include:

• double vision
• weakness in the arms or legs
• difficulty breathing, talking, chewing, or swallowing

Who gets myasthenia gravis?

People with a family history of autoimmune disease or myasthenia gravis may be at greater risk to get the disease. Women are more likely to get myasthenia gravis between the ages of 20 and 40. Men are more likely to get the condition after the age of 60. But myasthenia gravis can occur at any age.

Myasthenia gravis can get worse with stress, illness, and fatigue. If you have myasthenia, check with your doctor before taking any new prescription or over-the-counter medicine. Certain medicines can contribute to worsening myasthenia gravis symptoms.

Source: American Academy of Ophthalmology | Eye Smart

The thyroid is a gland in the front of your neck. It makes hormones that help control your metabolism. Thyroid Eye Disease (or TED, also known as Graves’ eye disease) is an autoimmune condition. It happens when the thyroid gland is not working the way it should. When most people get TED, the thyroid gland makes too much hormone. But others with TED have too little hormone or a normal amount. With TED, the immune system attacks the muscles and tissues surrounding the eyes.

Who is at risk for Thyroid Eye Disease (TED) or Graves' Eye Disease?

While anyone can get TED (or Graves' eye disease), it is more common in:

• smokers
• those with a family history of the disease

What are the symptoms of Thyroid Eye Disease (TED) or Graves' Eye Disease?

Symptoms of TED (or Graves' eye disease) can vary and may come and go. Here are some of them:

• Eye protrusion: TED can cause the muscles in and around the eye to swell and push the eye forward. This eye bulge makes someone look as if they are constantly staring.
• Eyelid retraction: With the eye pushed forward, the upper and lower eyelids retract (pull back). This makes the white part of the eye more visible.
• Dry eye: With TED, the eyes are more exposed to wind and dust. This can make the eyes very dry. Dry eye makes the eyes feel scratchy and uncomfortable, and makes vision blurry. Being very sensitive to light is also a problem.
• Vision changes: Muscle swelling can cause double vision (seeing two images of the same object). Swelling can also pressure and damage the optic nerve (the part of the eye connecting the eye to the brain), which can lead to vision loss.
• Eye “bags”: When the eyelid swells, it can cause tissue around the eye to bulge. This looks like bags around the eyes, and can make someone look older than they are.

Source: American Academy of Ophthalmology | Eye Smart

Ischemic optic neuropathy (ION) is when blood does not flow properly to your eye’s optic nerve, eventually causing lasting damage to this nerve. With ION, you suddenly lose your vision in one or both of your eyes.

The optic nerve carries signals from your eyes to the brain. Your brain then turns these signals into the images you see. When blood flow to the optic nerve is reduced or blocked, the nerve does not get enough oxygen or nutrition. The optic nerve stops working properly, and eventually dies.

ION can affect your central (detail) vision or side (peripheral) vision—or both. Because a damaged optic nerve cannot be fixed, any vision loss from ION is usually permanent. Usually, people with severe ION still have some peripheral vision.

What are symptoms of ION?

If blood flow to your optic nerve is reduced, your vision will darken for a few seconds or minutes then return to normal. This is called a transient ischemic attack (TIA). This kind of attack can happen before ION begins. If you have TIA symptoms, call your ophthalmologist or primary care doctor right away. Finding and treating the problem as soon as possible can help prevent further vision loss from ION.

Who is at risk for ION?

While anyone can get ischemic optic neuropathy (ION), you are more likely to develop it if you:

• have high blood pressure
• have high cholesterol (too much fat or lipid in your blood)
• sleep apnea
• heart disease
• sudden drop in blood pressure or blood loss
• have diabetes
• have clogged arteries
• have glaucoma
• are over 50 years old
• have migraine headaches
• have swelling of arteries in the head (called temporal arteritis), which may be life-threatening and cause massive vision loss

Source: American Academy of Ophthalmology | Eye Smart

The sclera is the white part of the eye. When the sclera is swollen, red, tender, or painful (called inflammation), it is called scleritis. It is common for people with scleritis to have another disease, like rheumatoid arthritis or other autoimmune disease. This underlying disease causes many of the symptoms of scleritis.

There are two main types of scleritis:

• anterior scleritis (occurs at the front of the eye)
• posterior uveitis (occurs at the back of the eye)

Anterior scleritis, is more common than posterior scleritis. There are three types of anterior scleritis. The most common type can inflame the whole sclera or a section of it and is the most treatable. Another type causes tender nodules (bumps) to appear on the sclera, and the most severe can be very painful and destroy the sclera.

Posterior scleritis is the rarer of the two types. People with this type of scleritis may have pain and tenderness. This form can cause problems resulting in retinal detachment and angle-closure glaucoma. Most people only have one type of scleritis, but others can have it at both the front and back of the eye.

What Causes Scleritis?

Scleritis is often linked with an autoimmune disease. Sometimes there is no known cause. Scleritis may be linked to:

• joint swelling and stiffness (arthritis)
• lupus, or other connective tissue disease
• eye infection
• inflammatory bowel disease (IBD)
• Sjogren’s syndrome (causes very dry eyes and other symptoms)
• granulomatosis
• scleroderma

Scleritis may be caused by trauma (injury) to the eye. Rarely, it is caused by a fungus or a parasite.

What Are Symptoms of Scleritis?

Scleritis symptoms include:

• pain
• tenderness of the eye
• redness and swelling of the white part of the eye
• blurred vision
• tearing
• extreme sensitivity to light

There also can be pain of the jaw, face, or head. In some cases, people lose some or all of their vision.

Source: American Academy of Ophthalmology | Eye Smart

Uveitis occurs when the middle layer of the eyeball gets inflamed (red and swollen). This layer, called the uvea, has many blood vessels that nourish the eye. Uveitis can damage vital eye tissue, leading to permanent vision loss.

Three types of uveitis

There are 3 types of uveitis. They are based on which part of the uvea is affected.

Swelling of the uvea near the front of the eye is called anterior uveitis. It starts suddenly and symptoms can last many weeks. Some forms of anterior uveitis are ongoing, while others go away but keep coming back.

Swelling of the uvea in the middle of the eye is called intermediate uveitis. Symptoms can last for a few weeks to many years. This form can go through cycles of getting better, then getting worse.

Swelling of the uvea toward the back of the eye is called posterior uveitis. Symptoms can develop gradually and last for many years.

In severe cases, all layers may be involved.

What causes uveitis?

The cause of uveitis is sometimes unknown. You are more likely to get uveitis if you have or have had:

• infections such as shingles virus, herpes simplex virus, syphilis, Lyme disease, and parasites such as toxoplasmosis.
• a systemic inflammatory disease such as inflammatory bowel disease (IBD), rheumatoid arthritis or lupus
• an eye injury

Smoking (cigarettes, cigars or pipes) also increases your risk of getting uveitis.

Symptoms

Uveitis can develop suddenly. Symptoms can include:

• having a red eye with or without pain
• being very sensitive to bright light
• having blurry vision
• seeing “floaters” (specks or moving clouds in your vision) all of a sudden

Contact one of our eye care specialists right away if you notice any of these symptoms.

Source: American Academy of Ophthalmology | Eye Smart

Because HIV causes a breakdown of your body’s immune system, all areas of the body can get an infection. This includes the eye. People with HIV who are otherwise in good health are not likely to have eye problems related to a suppressed immune system. But an estimated 70 percent of patients with advanced AIDS experience eye disorders.

AIDS-related eye problems due to a suppressed immune system can include the following:

HIV Retinopathy

This is the most common finding in people with AIDS. Cotton-wool spots and blood from broken blood vessels appear on the retina. Ophthalmologists think the HIV virus causes these changes to the small blood vessels in the retina.

CMV Retinitis

CMV retinitis is a more serious eye infection that occurs in about 20 to 30 percent of people with AIDS. A virus called cytomegalovirus (CMV) causes it. It usually happens in people who have more advanced stages of AIDS in which T-cell count is very low. Symptoms include inflammation of the retina, bleeding and vision loss. If left undiagnosed and untreated, CMV can cause severe vision loss within a few months. If you have HIV/AIDS, you should see your ophthalmologist immediately if you see:

• floating spots or “spider-webs”
• flashing lights
• blind spots or blurred vision

CMV retinitis cannot be cured, but medication can slow the progression of the virus.

Detached Retina

CMV can sometimes cause detached retina. This is where the retina pulls away, or detaches, from the back of the eye. A detached retina is a serious problem that causes severe vision loss unless treated. Almost all retinal detachments need detached retina surgery to save the vision. This surgery puts the retina back in its proper position.

Kaposi Sarcoma

Kaposi sarcoma is a rare form of cancer that occurs in AIDS patients. This cancer can cause purple-red lesions to form on the eyelids.  It can also cause a red, fleshy mass to form on the conjunctiva. Kaposi sarcoma may look frightening, but it usually does not harm the eye, and can often be treated.

Squamous Cell Carcinoma of the Conjunctiva

This is a tumor of the conjunctiva. Ophthalmologists believe that this condition is related to several things, including HIV/AIDS infection. It is also related to prolonged sunlight exposure and human papillomavirus (HPV) infection.

Increased Risk of Various Eye Infections

Some eye infections may be more common in patients with HIV. These infections include:

• syphilis
• herpes virus
• gonorrhea
• Chlamydia
• toxoplasmosis
• Candida
• Pneumocystis
• microsporidia

These infections can threaten vision and must be treated by an ophthalmologist.

Source: American Academy of Ophthalmology | Eye Smart