How Does the Eye Work?
Before we begin the discussion about cataracts and cataract surgery, we'd like to first introduce you to the way the eye works. We find it most helpful to think of the eye as a video camera hooked up to a TV monitor.
A video camera has a lens to focus the light, film (or electronic sensors) to capture the image, and a cable to transmit the image to the monitor or recording device.
In a similar manner, the eye has two surfaces that focus light: the cornea, or clear surface of the eye; and the lens which sits behind the iris, or pupil. The cornea and lens, together, focus light onto the retina which is similar to the film or electronic sensors in a camera.
The retina then converts light into a signal that is transmitted to our brains through the optic nerve, which is similar to the cable that connects a video camera to the TV or VCR.
What Are Cataracts and What Are the Different Types?
There are several eye conditions that can cause blurry or foggy vision, dimming of lights or colors, sensitivity to light, and trouble with night vision, and cataracts are one of these.
Cataracts are a condition that obscures the lens of the eye, ultimately preventing light from refracting through it and onto the retina. Trauma to the eye, illness in the eye, disease or trauma to a fetus in utero, or simply age can all lead to the development of cataracts. Essentially, anything that breaks down proteins in the lens, leading them to clump together, will cause cataracts.
Different Types of Cataracts
All cataracts occur because of damaged proteins in the lens clumping together and obstructing vision; however, there are several kinds of cataracts that lead to different symptoms, have different root causes, and will look different in the eye.
Nuclear cataract: This type of cataract forms in the center of the lens, often darkening as it spreads, leading to hazy, blurry, or yellowed vision.
Anterior polar cataract: This is a dot near the center point of the front of the lens, which eventually spreads out.
Cortical cataract: This kind is the opposite of nuclear cataracts, beginning on the outer edges of the lens and spreading inward, looking like spokes on a wheel.
Lamellar cataract: This occurs in the layers between the nuclear and cortical parts of the lens, creating striations.
Posterior capsular cataract: These cataracts form faster, and they are more likely to occur in younger people. They occur when proteins settle at the back of the lens and begin to form a hazy area. There are a few different types of posterior cataracts.
Posterior subcapsular cataract: This involves a thin layer of clouding and protein clumps affecting the back surface of the lens. Posterior polar cataract: These are like the anterior polar cataract, but at the back of the lens rather than the front.
Diabetic Cataract: Adults who have diabetes are two to five times more likely to develop cataracts than those people who don’t have diabetes. Cataracts may also form among younger-aged people with diabetes.
Congenital cataract: These are formed in utero or just after a baby is born, and they are most often caused by illness or trauma during fetal development; however, in some instances, the cataract develops due to genetics.
Trauma-induced cataract: Damage to the lens leads to damaged proteins clumping and forming cataracts, and if the eye is hit, diseased, under intense pressure, or undergoes surgery like LASIK, a cataract may form.
Radiation cataract: This type of cataract forms after exposure to radiation, either in a radioactive area or after long-term exposure to UV radiation.
Some patients have multiple types of cataract occurring simultaneously. While cataracts are a progressive disease that can cause blindness when they are untreated, they are easy to diagnose and treat in the United States.