The National Eye Institute (NEI) reports that as of the most recent census, 3.3 million Americans aged 40 or older are blind or have moderate to severe vision impairment (low vision). If no changes to eye care are made, the NEI predicts that the number of visually impaired people could be as high as 5.5 million by the year 2020 — a whopping 60% increase largely due to our aging population. Visual impairment and blindness are most often caused by one or a combination of several eye diseases and conditions. The NEI cites the following as the most prevalent eye diseases and conditions:
Age-Related Macular Degeneration (AMD). Age-Related Macular Degeneration (AMD) is the leading cause of permanent impairment of reading and fine or close-up vision among people aged 65 years and older, according to theCenters for Disease Control (CDC). The CDC estimates that 1.8 million Americans aged 40 years and older are affected by Age-Related Macular Degeneration (AMD). Another 7.3 million who have large deposits in the retina called drusen are at increased risk of developing AMD. By 2020, due to our aging populations, the number of Americans with AMD is predicted reach an estimated 2.95 million.
AMD occurs when the macula, an area of the retina that allows you to have detailed central vision, breaks down. It does not affect peripheral vision, which is the ability to see general shapes “out of the corner of your eye” even when you’re looking straight ahead. There are two main types of AMD:
- Dry AMD (atrophic, non-neovascular) is the most common form. In Dry AMD, the tissues of the retina thin over time and small pieces of fatty protein develop under the retina, causing vision loss to occur gradually.
- Wet AMD (exudative) only affects about 10% of patients with AMD. Typically, the condition develops in people who already have dry AMD. Wet AMD creates more damage than dry AMD and progresses more quickly as blood vessels grow under the retina and leak fluid or blood.
Cataracts. A cataract is a clouding of the lens of the eye that causes the lens to lose its ability to properly focus light, resulting in blurry vision. The CDC reports that an estimated 20.5 million (17.2%) Americans aged 40 years and older have a cataract in one or both eyes. Beyond that, 6.1 million (5.1%) have had their lenses removed surgically to eliminate cataracts. By 2020, the total number of Americans who have cataracts is estimated to jump to 30.1 million.
Diabetic Retinopathy. In diabetic retinopathy, uneven blood sugar levels interfere with circulatory function in the retina, causing small blood vessels to swell and rupture. This results in clouded retinal swelling and clouded vision. Diabetic retinopathyis the leading cause of blindness among Americans between the ages of 20 and 74 years. The CDC reports that an estimated 4.1 million people are affected by retinopathy and that an additional 899,000 patients have vision-threatening retinopathy.
Dry Eye. This condition happens if you don’t produce enough tears or a high enough quality of tears to keep your eyes hydrated. Dry eye is uncomfortable and can cause vision to be impaired and interfere with activities of daily living.
Glaucoma. This condition accounts for about one in every eight cases one of blindness in the United States, yet it is treatable if it is caught early. In glaucoma, an excess of ocular (eye) fluid that doesn’t drain properly causes damage to the optic nerve, resulting in blurred vision, a narrowed field of vision with some loss of peripheral vision, and eventually total blindness.
The three main types of glaucoma are:
- Open-angle glaucoma. This is the most common form, also called primary open-angle glaucoma. In open-angle glaucoma, the trabecular meshwork, a spongy tissue near the cornea and iris that drains ocular fluid, slowly becomes less effective at doing its job. When this occurs, intraocular pressure (IOP), rises to dangerous levels. This condition is almost always asymptomatic in the early stages.
- Normal-tension glaucoma. In normal-tension glaucoma, damage occurs to the optic nerve despite an IOP within the normal range, between 10-20 millimeters of mercury (mm Hg).
- Closed-angle glaucoma, also callednarrow-angle glaucoma or angle-closure glaucoma. This less common form of glaucoma happens suddenly, when the iris (colored part of the eye) shifts positions and blocks the flow of fluid through a drainage channel called the drainage angle. This can cause IOP to raise rapidly, necessitating emergency response.
Retinal Detachment. The middle of the eye contains a gel called the vitreous that is connected to the retina. As we age, the vitreous sometimes shrinks and pulls on the retina. This pulling can result in a tear or partial detachment of the retina from the back of the eye. This is painless and results in seeing flashes or floaters, dark spots or shapes that intermittently appear in the line of vision. Retinal tears allow for fluids to seep through torn areas and peel the retina away from the back of the eye, sometimes detaching it entirely, resulting in severe loss of vision or blindness.
In addition to the diseases and conditions cited by the NEI, there are several eye conditions that are less severe, but affect a large amount of people each day.
- Nearsightedness (Myopia)
Early detection of these most common eye diseases and conditions, especially those that are age-related, gives patients much higher chances of retaining their vision.