What is leprosy?
Leprosy, also known as Hansen’s disease, is a curable infection caused by a bacteria called Mycobacterium leprae. The infection mainly targets your skin cells, eyes and peripheral nerves — the nerves that aren't in your brain or spinal cord.
Some of the serious eye-related issues that can result from Hansen’s disease include uveitis, corneal damage and cataracts.
Around 250,000 people worldwide are diagnosed with leprosy every year, but only about 225 of those cases are in the United States. It's more common in Asia, Africa and South America.
Leprosy isn't very contagious from person to person. Most people can't get infected because they are naturally immune to the bacteria that causes the disease. In rare cases, Hansen’s disease can be spread by coming into contact with infected armadillo blood or meat.
How does leprosy affect the eyes?
Leprosy and the eyes are connected in several ways. About three-quarters of all leprosy patients have at least one eye problem related to the disease.
Leprosy often affects the eyes in one or both of these ways:
- Bacteria infect an area near the front of the eye and cause inflammation or other issues.
- Bacteria damage the nerves that keep the eyes and eyelids working well.
Treatment can be an important part of protecting your eyesight. Some leprosy-related eye conditions can lead to permanent vision damage, especially if you don't get prompt treatment for the eye problem or overall infection.
Leprosy eye problems near the front of the eye
In many cases, leprosy bacteria prefer the front part of the eye and surrounding tissue because it's cooler and easier to reach.
This means the following areas are more likely to be affected:
- Eyelids, brows and lashes
- Natural lens of the eye
- Cornea
- Sclera
- Iris
- Lacrimal gland
If Hansen’s disease affects these parts of the eye, it can lead to the following conditions:
Trichiasis
Trichiasis is an eye condition in which the eyelashes are pointed the wrong way.
Eyelashes that grow inward can rub and scrape against the clear, front part of the eye (the cornea) and the see-through lining of the white part of your eye and inner eyelid (the conjunctiva).
Ingrown lashes can scar the cornea and damage your eyesight if they aren't managed. Trichiasis can cause:
- Eye redness
- The feeling that something is stuck in your eye
- Eye watering
- Sensitivity to light
- Vision loss
Cataracts
Leprosy can triple the average risk of developing a cataract (when the normally clear lens of the eye is cloudy).
While a cataract can be treated with surgery, it's one of the leading causes of blindness among leprosy patients. This is largely because many affected people don't have access to the surgical care they need.
Keratitis
Keratitis is when the cornea gets inflamed. There are several different kinds of keratitis and leprosy can cause more than one type.
People with keratitis can experience these and other symptoms:
- Eye pain
- Blurry vision
- Red eyes
- Sensitivity to light
- Reduced vision (if the cornea is scarred a lot)
Madarosis
Madarosis is a loss of eyebrows and eyelashes. It can happen when leprosy bacteria invade the hair follicles and damage them to the point where they fall out.
Episcleritis
Episcleritis is inflammation between the conjunctiva and the white part of the eye (the sclera).
It makes your eye look red but it shouldn't cause severe pain. Pain could be a sign of a more serious problem.
Uveitis
Uveitis is an inflammation of the middle layer of the eye (the uvea). The colored part of your eye (the iris) is part of the uvea.
When it's caused by leprosy, uveitis often affects the iris and the structure behind it (the ciliary body). This is called iridocyclitis. It's the most common eye problem in people who have a severe form of the disease called lepromatous leprosy.
Iridocyclitis can cause symptoms like:
- Blurry vision
- Eye redness
- Eye pain
- Light sensitivity
- Vision loss (if left untreated)
Dry eyes
Leprosy can damage the gland that helps produce the tear film on your eye (the lacrimal gland). Your eyes may feel dry if they don't have enough tears, or if the tear film is unhealthy.
People with dry eyes can have symptoms like:
- Blurry vision
- Burning or itching
- Gritty feeling
- Blinking more than usual
- Sensitivity to light
Dacryocystitis
Dacryocystitis is inflammation of the lacrimal sac, which helps drain tears from your eyes into your nose. It can be a short-term or long-term issue.
Its symptoms can include:
- Pain, redness and swelling around the inner corner of your eye
- Blurry vision
- Watery eyes
Glaucoma
Glaucoma is a group of eye diseases that damage the information pathway between your eye and brain (the optic nerve). Many times, glaucoma is related to high pressure inside your eye.
It's known as secondary glaucoma when it's caused by leprosy or another health condition. People with leprosy can develop glaucoma as a result of chronic inflammation from uveitis. It can also be caused by long-term use of steroid medications used to treat both leprosy and uveitis.
Corneal leproma
A corneal leproma is a clump or nodule of leprosy bacteria that collects near the edge of the cornea. It's relatively rare.
The nodule is painless early on, and it can cause vision loss as it progresses.
Iris atrophy
The breakdown of some parts of the iris is called iris atrophy. This rare condition is more common with advanced disease.
Sometimes this breakdown can continue even after people complete the multidrug treatment for leprosy.
Phthisis bulbi
Leprosy can lead to phthisis bulbi if someone has had the disease for a long time. This untreatable condition makes the eyeball look shrunken and collapsed.
The most notable symptom of phthisis bulbi is permanent vision loss.
Nerve-related eye problems from leprosy
Eye problems can also be related to nerve inflammation and damage caused by leprosy.
Nerves in your head called cranial nerves are especially important to your eyes since they control these and other important functions:
- Blinking
- Eye movement
- Tear production
When these nerves aren't working right, it can lead to eye problems such as:
Lagophthalmos
Lagophthalmos is when your eyelids don't close all the way. It can happen when leprosy bacteria invade the facial nerve and weaken the eyelid muscles.
When your eyes don't close all the way, it can affect the health of your tears and the surface of your eyes. This can lead to dry eyes and even corneal injury and damage.
Ectropion and entropion
Leprosy bacteria can affect the area around your eyes and weaken the eyelids. This makes it harder for the eyelids to work like they should.
These two conditions typically affect the lower eyelids:
- Ectropion (the eyelid turns outward)
- Entropion (the eyelid curls inward)
Both can make the eye red and teary. Ectropion can also cause dry eyes.
Neurotrophic keratitis
The trigeminal nerve, one of your cranial nerves, sends all the nerve sensations to your cornea.
These sensations help your body decide when to make tears and blink automatically. Leprosy can hurt the trigeminal nerve's ability to help with these functions.
This can make you lose feeling in your cornea, which is called neurotrophic keratitis. It can lead to:
- Breakdown of the cornea (corneal melting)
- Open sores on the cornea (corneal ulcers)
Neurotrophic keratitis is rare, but it can damage your vision if it's not diagnosed and treated.
Exposure keratopathy
Exposure keratopathy is cornea damage that happens when another issue unnaturally exposes the eye to the environment.
Leprosy-related eye problems like these can lead to exposure keratopathy:
- Lagophthalmos
- Neurotrophic keratitis
- Ectropion
- Entropion
Common symptoms include burning, tearing, blurry vision and a feeling that something is stuck in your eye. If it progresses, it can lead to cornea scars and vision loss.
Treatment for eye conditions caused by leprosy
Many times, the best way to treat these eye problems is to treat leprosy with antibiotics as early as possible. This will cure the disease and help prevent future complications.
The risk of severe vision loss from leprosy is generally low if you start taking antibiotics early on.
However, some eye changes may continue or worsen after leprosy is cured. This is why eye doctors are vital to medical care during and after a leprosy infection.
The treatment for each eye problem depends on the condition. Some eye conditions require treatments like eye drops or other prescription medication, while others may need surgery.
Your eye doctor will help you form a care plan to improve your symptoms and protect your eyesight.
When to see a doctor
Leprosy is rare in developed nations, but it's still important to see a doctor if you have symptoms or if:
- You may have been exposed to someone who has the disease.
- You're concerned about being exposed to armadillo blood or tissue.
Always use caution if you think you've been exposed to leprosy bacteria.
There are several links between leprosy and the eye, and the disease can affect your eyes and vision in many ways. It's important to work closely with your eye doctor and care team to diagnose, manage and treat these problems as needed.
if your primary care doctor rules out leprosy and you still have concerning or severe eye symptoms, schedule an eye exam. Your eye doctor can help you find the underlying cause of your symptoms and provide appropriate treatment.
