Types of Senile Cataracts
What is a Cataract?
The word cataract is used to describe the hardening of the lens of the eye.
The lens gives the eye 30 percent of its focusing power and is the part that focuses light onto the retina. It allows us to see at all different distances including distance and near.
The lens is suspended in a bag, known as a capsule, by tiny ligaments called zonular fibers. These fibers are the muscles that do all the focusing.
Anatomy of the Eye
Types of Cataracts
There are three main types of cataracts: traumatic, congenital and senile. Traumatic cataracts occur as a result of injury to the eye, usually from a blunt trauma such as a baseball or punch to the eye. Congenital cataracts form just after or before birth. Senile cataracts are a result of the aging process.
There are three main types of senile cataracts:
- Nuclear Sclerotic
- Posterior Subcapsular
Most people have a combination of these three types of cataracts, but let’s look at each type individually.
Nuclear Sclerotic Cataracts
Nuclear sclerotic cataracts, or NS cataracts, are the most common type. The center of the lens is called the nucleus.
As the lens grows, it constantly produces new fibers. The old fibers are pushed toward the center of the lens, and form the nucleus. When a person hits the age of 30 this process begins to cause the nucleus to harden.
After the age of 45, the nucleus continues to harden (called sclerosis) and begins to yellow. The sclerosis can cause the patient to become nearsighted, or myopic.
The yellowing of the lens can cause the loss of vibrancy in color. Most patients will notice a dramatic change in color perception after having the cataract removed.
Symptoms of nuclear sclerotic cataracts:
- Poor night vision
- Glare from oncoming headlights when driving at night or in rain
- Blurry vision, especially at distance, although near vision will also be affected
- Monocular diplopia (double vision in one eye)
- Decreased sensitivity to color variations
Anatomy of the Human Lens
The cortex is the area that surrounds the nucleus. When this area hardens and becomes difficult to see through, it is termed a cortical cataract. The proximity of the cortical opacity to the nucleus determines how the central vision is affected. These cataracts are typically associated with nuclear sclerotic cataracts which leads to dramatic changes in vision. Cortical cataracts usually progress very slowly, although there are exceptions.
Symptoms of cortical cataracts:
- Glare at night, especially from headlights
- Loss of visual clarity at both distance and near
- Loss of contrast sensitivity
Posterior Subcapsular Cataracts
This type of cataract is unique. It is thought that these cataracts are an attempt by the lens to regenerate because they are dynamic in nature (constantly changing). They form just in front of the capsule and are usually the result of trauma, ionizing radiation or the over use of corticosteroids. Posterior subcapsular, or PSC, cataracts are often found in diabetics who have had several Kenalog injections to treat macular edema.
Symptoms of PSC cataracts:
- Rapid onset of visual deterioration
- Glare, specifically from bright sunlight (vision is actually good in dim light)
- Decreased visual acuity at both distance and near
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Morgagnian cataracts are the result of liquefaction of the cortex that allows the nucleus to float freely within the lens. The cortex becomes a milky, white fluid which can cause the lens capsule to rupture and leak causing excessive inflammation.
This can also cause phacomorphic glaucoma which is a form of angle-closure glaucoma caused by the forward bowing of the iris by the lens. This bowing cuts off the trabecular meshwork blocking the drainage system of the eye.
Symptoms of Morgagnian cataracts:
- Glare from bright lights, especially headlights
- Poor night vision
- Decreased overall visual acuity
- Hazy or cloudy vision
- Sudden onset pain
- Sudden onset nausea or vomiting
Morgagnian cataracts are quite rare. I have only seen one in my 18 years in ophthalmology.
Although this article is specific to senile cataracts, traumatic cataracts can affect people of all ages. In order to be thorough, a brief discussion of traumatic cataracts is necessary.
Traumatic cataracts, as their name suggests, are triggered by trauma to the eye. Blunt trauma is the most common form of injury to cause this type of cataract, although lacerations and foreign bodies can also trigger this reaction. These types of cataracts typically form rapidly; there are rare cases in which they form more slowly, however.
Symptoms of traumatic cataracts include:
- Sudden loss of vision
- Sudden appearance of hazy or cloudy vision
- Sudden onset of glare at night while driving
- Sudden onset of glare from sunlight
- Sensation of an obstruction in the vision
Treatment and Prevention
Cataract surgery is the only “treatment” once a cataract becomes bothersome. Glasses can clarify the vision for a while; however, they will only be effective for so long. The cataract will eventually need to be removed, and an artificial lens will need to be implanted.
Although senile cataracts can’t be prevented, their formation can be slowed. Eating a healthy diet rich in leafy green vegetables, nuts, and fruits and increasing the intake of Omega 3-6-9 complexes as well as vitamins can help slow the process dramatically.
It is also imperative to wear sunglasses anytime you go outside. The UV rays from the sun can also cause cataracts to grow more rapidly.
Lastly, quit smoking. Smoking is one of the major risk factors for the premature development of cataracts. If you smoke, you should make every effort to quit now!
As always, this article is no substitute for medical advice. If you feel your vision is failing for any reason, see your ophthalmologist right away.
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© 2012 Melissa Flagg OSC