Measles infections can harm the front or back of the eye, possibly causing vision loss or blindness
Though measles is just re-emerging as a threat in developed countries, the disease has long been a leading cause of childhood blindness worldwide. One study estimates that measles causes up to 60,000 cases of blindness a year globally. Poor access to measles vaccination and malnutrition often correlate with higher rates of blindness in the most affected countries.
The extremely contagious virus continues to plague countries in East Africa and Asia, with the latest large outbreak involving 58,000 people in the Philippines. As new cases of this disease emerge in Europe and the United States (where the disease was once considered eradicated), the American Academy of Ophthalmology is informing the public as well as clinicians — who may be caring for measles patients for the first time — about different ways the virus can harm eyes and affect vision:
- Conjunctivitis: Redness and watery eyes from conjunctivitis occur in nearly all measles patients. This type of pink eye usually develops early on in the disease and is a hallmark symptom along with fever, cough and a runny nose, often occurring before the telltale rash. This condition usually abates on its own as the disease runs its course.
- Keratitis: Keratitis is an infection of the cornea, the window of the eye. In comparison with conjunctivitis, keratitis has more severe symptoms and far more dangerous consequences. Symptoms include pain, redness, tearing and light sensitivity. It can feel as though foreign particles are lodged in the eye. Often treated with medicated drops, keratitis will cause temporary blurred vision, but if it leads to scarring the loss of vision can be permanent.
- Corneal scarring: Corneal ulcers are open sores on the front of the eye that can occur when infected, either via the measles virus or from a bacterial infection that develops secondary to measles. Ulcers may appear as white dots on the front of the eye and are usually treated with topical antiviral or antibiotic drops. When the ulcers heal, they can scar over and leave opaque scar tissue that may inhibit vision and cause blindness.
- Retinopathy: While rare, there are documented cases where the measles virus destroys the retina, a layer of cells in the back of the eye that convert light energy into electrical impulses that go to the brain. Retinitis can cause temporary and, in some cases permanent, vision loss.
- Optic neuritis: This inflammation affects the optic nerve that sends signals from the back of the eye to the brain. This complication is relatively rare but can occur in measles patients who also develop encephalitis, or brain swelling, though cases without encephalitis have also surfaced. Acute cases may be treated with corticosteroids. Like retinitis, vision loss from optic neuritis can be temporary or permanent.
- Blindness: Measles is a leading cause of childhood blindness in developing countries where immunization programs for this disease are less established or often interrupted by conflict. When compounded by malnutrition, particularly vitamin A deficiency, measles is associated with corneal scarring from ulceration and keratitis, two of the most likely reasons for blindness from measles. Blindness from optic neuritis has also been noted.
There is no specific anti-viral treatment for measles, making vaccination the best means of limiting the spread of this disease. The Centers for Disease Control and Prevention (CDC) and the World Health Organization recommend measles vaccination (often administered in the United States through a shot for measles, mumps and rubella, or "MMR") to children age 1 and older and adults born in 1957 or later who do not display measles immunity. For more details, visit www.cdc.gov/measles.
Treatment with Vitamin A
For children with severe cases (including those requiring hospitalization), the World Health Organization suggests treatments of vitamin A on the day of diagnosis and day after to prevent vision loss from eye complications:
- 50,000 IU for infants younger than 6 months of age
- 100,000 IU for infants 6 to 11 months of age
- 200,000 IU for children 12 months of age and older
A comparative analysis of avoidable causes of childhood blindness in Malaysia with low income, middle income and high income countries, International Ophthalmology, March 2014
Measles in the Philippines, CDC, Feb 2015
Measles Blindness, Survey of Ophthalmology, 2004
The Clinical Significance of Measles: A Review, Journal of Infectious Diseases, 2004
Bilateral anterior optic neuritis in adult measles infection without encephalomyelitis, American Journal of Ophthalmology, 2002
Measles Vaccine: WHO position paper, Weekly Epidemiological Record, 2009