Ophthalmologist and Physician-Scientist
Four Important Facts about the World’s Leading Cause of Blindness

Four Important Facts about the World’s Leading Cause of Blindness

The World Health Organization (WHO) cites more than 250 million people globally are blind or have moderate to severe vision impairment. While some cases are caused by incurable conditions such as glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy, the biggest culprit of vision loss around the world is cataracts. Listed below are four important facts related to what the world is doing to address it.

1. Cataracts are caused by proteins clouding the lens of the eye.

A cataract occurs when the proteins making up part of the lens begin to break down as a result of aging. The lens is the part of the eye that allows light to focus on the retina, facilitating clear vision as well as the ability to see with precision both up close and far away. The proteins in the lens are naturally arranged in such a way to keep the lens clear and allow light to pass through. When the proteins break down, they begin to clump together, clouding the lens and blocking light from entering the retina.

Image by Community Eye Health| Flickr

When cataracts develop, they tend to do so in pairs, though they don’t necessarily advance at the same rate in both eyes. As a cataract grows, a person may begin to experience a range of symptoms. In the beginning, vision may appear vaguely blurred, similar to looking through a dirty window, and bright light may cause more glare than normal. Colors may also appear less vibrant. A cataract may make it more difficult to see in darkness or dim lighting. It may also cause lights to appear with halos surrounding them. Without intervention, a cataract can cause greater vision loss and may eventually lead to blindness.

2. Cataracts are primarily age-related.

Though cataracts may occur in people under the age of 40, they most commonly occur in people aged 40 and older. According to the National Eye Institute (NEI), more than half of Americans aged 80 and older have either undergone cataract surgery or are living with a cataract.

Researchers are not certain exactly what causes the breakdown of proteins in the lens, but a number of risk factors for cataracts have been identified. These include excessive unprotected exposure to the sun’s ultraviolet rays, obesity, smoking, excessive alcohol consumption, diabetes, hypertension and a family history of cataracts.

3. Vision loss from cataracts is treatable.

Vision loss caused by cataracts can be reversed in the vast majority of cases, unlike instances of diabetic retinopathy, glaucoma and AMD. According to the NEI, while a miniscule percentage of patients who undergo cataract surgery may experience complications, approximately 90 percent of people who undergo the procedure experience better vision afterward.

Cataract surgery is usually an outpatient procedure and does not require a hospital stay. The most common form of the surgery is called phacoemulsification (phaco), during which a surgeon uses an ultrasound device emitting high frequencies to break up the cataract. The pieces are gently removed using suction. Afterward, the surgeon implants a foldable intraocular lens (IOL) into the eye, placing it into the same position as the natural lens and restoring clear vision. Laser-assisted cataract surgery (LACS) is a similar process, but performed with the aid of a computer-controlled, high-speed laser that reduces the need for hand-held surgical tools. LACS can be significantly more costly than the standard phaco procedure, but it is not always more effective or safer in every case. 

Though cataract surgery is one of the world’s most effective and safest surgical procedures, an ophthalmologist typically will not recommend it unless a cataract interferes with a patient’s daily activities, such as reading, driving or watching television. Delaying cataract surgery typically does not make the procedure riskier or more complex, nor lead to long-term damage, so there is no need to rush into a decision about surgery.

4. Cataracts can be a debilitating condition in low-income countries.

Many people in the world’s high-income countries have access to cataract treatment, yet in some regions of the world, a cataract diagnosis is devastating and all but hopeless. According to the World Health Organization (WHO), cataracts are responsible for a much larger proportion of blindness and low vision in low- and middle-income nations than in high-income countries. According to the nonprofit Himalayan Cataract Project, approximately 50 percent of avoidable blindness in the world’s least developed countries is due to cataracts. Virtually every one of these cases could be cured with the right medical care.

Those who work or volunteer with vision-based humanitarian organizations recognize that lack of access to quality vision care is a global crisis. Many people from disadvantaged communities struggle with blindness and severe vision loss that could be prevented or even cured with better — or in some cases any — access to qualified eye care professionals. Research from WHO and the United Nations indicates untreated vision problems often have a negative impact on virtually every aspect of a person’s life, including their mental health, education, ability to support their family and even their human dignity.

To learn how you can support the global fight against preventable blindness caused by cataracts and other eye diseases, consider contributing to or becoming involved with the groups See International, the Himalayan Cataract Project or Mission Cataract USA.