The term cataract refers to a clouding or loss of transparency within the lens of the eye. As the clouding process progresses, light has difficulty passing through the lens. This results in dim, distorted or blurred images on the retina and decreased vision. The visibility can be compared to looking through a dirty window.
Understanding Your Body
To understand cataracts, it may be helpful to learn some basic facts about the structure of the eye. When one looks at an object, light radiates from it and passes through the window of the eye, the clear transparent cornea (front surface of the eye). After then passing through the black central pupil, the light then passes through the crystalline lens. This lens, normally a crystal clear structure, focuses light onto the retina, similar to the way a camera lens focuses light onto film. From the retina, the image is transmitted along the optic nerve and to the brain where the actual process of seeing takes place.
The crystalline lens consists of three parts: the outer membrane envelope (or capsule) which surrounds the lens, the center (or nucleus), and the cortex which surrounds the nucleus in layers similar to an onion. The lens is suspended in place by small ligaments which are attached to a ring of muscle which helps focus light images onto the retina.
It is important to realize that cataracts do not grow; they are not a skin covering the eye, nor are they a tumor. A cataract develops as a result of increasing cloudiness within the lens itself. There is no way to predict how rapidly a cataract will progress. Some develop slowly over a period of years and some progress rapidly over months. A sudden change in one’s vision should not be attributed to a cataract.
Treatment and Management of Cataracts
At present, there is no medical therapy for cataracts such as pills, eye drops, or eye exercises. The only current treatment is surgery, usually on an elective basis.
Because many people have early cataracts yet are unaware of them, the mere diagnosis of a cataract does not indicate the need for surgery. If one can see well enough to pursue one’s occupation, hobbies and lifestyle, then there is no need for surgery. If on the other hand, the patient’s decreased vision is interfering with the necessities and pleasures in one’s life, such as driving, then surgery should be considered. Thus the decision to have an operation is made by the patient after a thorough eye exam and discussion with the ophthalmologist. There are though certain circumstances where the cataract may need to be removed for medical reasons. An example would be if the cataract is making it difficult for the physician to see the retina in patients with diabetes, or the optic nerve in patients with glaucoma. In such cases the eye surgeon may encourage the patient to have cataract surgery in order to follow the eye for these diseases.
Types of Cataract Operations
Years ago, a cataract had to “ripen” or harden before removal. Now with new surgical procedures, a cataract can be removed at any stage in which significant visual impairment is evident. The two most commonly used methods to remove a cataract are the phacoemulsification technique and the extracapsular technique.
In the phacoemulsification technique, an ultrasound probe breaks up the cloudy lens into pieces and then vacuums them out through a tiny incision. A plastic intraocular lens implant is then carefully inserted. Because the incision is as small as three to four millimeters, suturing may not be necessary and visual recovery occurs rapidly.
With the extracapsular technique, the cataract is removed as one entire piece. This requires a larger incision and sutures. A lens implant is also placed, but visual recovery can take a few more weeks because of the larger incision.
Both techniques are usually performed on an outpatient basis with the patient heading home within a few hours following the surgery. The procedure generally takes less than an hour and is nearly painless. Restrictions in activities after surgery vary; the larger incision extracapsular technique usually has more restrictions such as avoiding lifting heavy objects for several weeks. Once healed though, either technique can provide an outstanding visual result. The patient should consult with the ophthalmologist on which technique is best and safest for him or her.
With both of these techniques, the backside of the outer capsular membrane of the lens is left undisturbed. This helps support the lens implant. Each implant is especially selected for the patient and has the potential of correcting preexisting nearsightedness and farsightedness. This is why many patients don’t require glasses as much after cataract surgery.
Can a cataract come back once it is removed? No, but the backside of the outer capsular membrane can become cloudy months to years following surgery. The vision slowly blurs during this process. A quick and painless procedure in the office called a YAG laser clears away the cloudy membrane and the vision rapidly returns to the level it was following surgery.
New surgical procedures such as laser removal of cataracts are being refined. Incisions continue to be made smaller as instrumentation changes. Lens implants are being developed that can correct for astigmatism and possibly even eliminate glasses all together. Although cataract surgery has become an extremely successful surgery, research is being done to find ways of preventing the development of cataracts.
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