Eye and vision care

What are cataracts?

The crystalline lens of the eye is normally clear. However, when the lens becomes clouded or opaque, a patient is said to have cataracts. Cataracts impair vision (see photographs below). Although often compared to a window that's frosted or to a film covering the eye, cataracts are not a film over the eye, nor are they a growth or tumor. Contrary to common belief, cataracts are not caused by overuse of the eyes. They cannot spread from one eye to the other; a cataract may develop in one eye, and not the other. Cataracts can be corrected, and patients should have no reason to believe that cataracts lead to irreversible blindness.

As the lens becomes increasingly cloudy, light has difficulty passing through it to reach the retina. (See Anatomy of the Eye, also in this section.) As a result, images on the retina are blurred or dimmed, colors may appear yellowed or faded, and vision is decreased. Many patients compare cataracts to looking through a dirty or frosted window. (See photographs below.)

The lens consists of a central nucleus and the surrounding cortex, and it is enclosed by a capsule. Each of these parts, independently or together, may cloud or become opaque, resulting in a cataract. The rate at which cataracts develop varies from one individual to another, and it may even be different between a patient's two eyes. While some cataracts (such as those that affect younger people and those with diabetes) can progress rather quickly, others (such as age-related cataracts) progress slowly over several years or not at all.

Similarly, some cataracts affect near vision, others affect far vision, and still others may affect both. Some patients with early cataracts report that their vision is affected in certain lighting conditions—some are particularly sensitive to glare and bright light while others report poor night vision and the appearance of haloes around lights. (See more under Symptoms, below.)

Who gets cataracts?

Cataracts most commonly affect adults between the ages of 50 and 70, but symptoms may first appear at a younger age, particularly if systemic diseases associated with cataracts (i.e. glaucoma, retinitis pigmentosa, diabetes, Marfan's syndrome) are present. Congenital cataracts may be dense enough to prevent normal vision at birth.¹

Although researchers are learning more about cataracts, it's still unclear just what causes age-related cataracts. Some studies suggest the following risk factors may predispose certain individuals to cataracts and other eye diseases:²

• premature birth or developmental delay
• smoking
• exposure to sunlight/UV rays
• family history of cataracts or eye disease
• Black
• previous serious eye injury, particularly one in which the eye was cut or punctured
• use of certain medications such as cortisone-steroids
• pre-existing diseases such as diabetes or HIV

If you have any of the above-listed risk factors, consult your ophthalmologist to determine how often you should have an eye exam. It's recommended that adults between 40 and 64 have their eyes examined every two to four years. Adults 65 or older should have their eyes checked every one to two years.

What causes cataracts?³

The vast majority of cataracts are considered to be the result of age-related change in the crystalline lens of the eye—change unassociated with other disease processes. As people age, the structure and function of the lens begin to degenerate, and through a series of complex chemical changes, the lens gradually becomes opaque or clouded.

Cataracts may be secondary to other eye diseases associated with lens opacity, including intraocular inflammation, retinitis pigmentosa and glaucoma. Other systemic diseases such as diabetes, Down Syndrome, myotonic dystrophy, Marfan's syndrome, and allergic dermatitis have also been linked to cataracts.

Cataracts may be induced by drugs such as cortisone-type steroids.

Rapidly developing cataracts may form as the result of a penetrating injury to the eye.

Congenital or infantile cataracts can occur spontaneously or secondary to systemic diseases. Maternal infection with rubella (German measles) metabolic disturbances, hereditary disorders, neurologic diseases, and in rare cases, birth injury are all conditions associated with congenital or infantile cataracts.

What are the symptoms of cataracts?

Symptoms usually start with a gradual and painless blurring or decrease in vision. Glare, either from sunlight or nighttime driving, can be a major problem.

Other symptoms may include:

Poor night vision Increased nearsightedness Double vision in one eye Sensitivity to light and glare Changes in the color of the pupil Cloudy, filmy, or fuzzy vision Blurred vision

Requiring brighter light to read Fading or yellowness of colors Frequent changes in eyeglass prescription Cloudy lens at birth Distorted images in either eye

Of course, the amount of cloudiness within the lens may vary, and patients may not be aware they have a cataract, particularly if the cloudiness is not in the center of the lens.

How are cataracts diagnosed and treated?

There are no medications or homeopathic treaments to prevent or reverse cataracts. Be wary of pundits and ads promising reversal through eyedrops, dietary supplements, naturopathy, and herbal remedies—there is no evidence to indicate these are in any way effective.

At present, surgery is the only means of removing a cataract; the crystalline lens is removed and replaced with an intraocular lens implant. Intraocular lens implants may be made of plastic, acrylic, or silicone.

A thorough examination by an ophthalmologist can detect the presence of cataracts and any other conditions that may be linked to blurred vision or other eye conditions. Your ophthalmologist will also be able to detect problems with other structures of the eye (i.e., cornea, retina, optic nerve) which may be responsible for vision loss and advise you whether these problems may impact upon cataract surgery. If these problems are such that improvement of your vision after cataract surgery is unlikely, surgical cataract removal may not be recommended. In addition, if it's unlikely a cataract will significantly impact your daily activities, removal may not be necessary; a simple change in your eyeglass prescription may be all that's needed. Your ophthalmologist will be able to tell you whether cataract surgery is needed and whether surgery will improve your vision. He or she will also determine the power of the intraocular lens implant that will be placed in your eye.⁴

Cataracts are not removed simply because they are present; they are removed only if they significantly interfere with a person's daily activities, such as reading or driving.

Cataract procedures are generally performed under local anesthetic, on an outpatient basis. Removal of a cataract is done using microsurgical techniques in which a small incision is made into the eye. In most cases, the incision is small enough that it is self-healing and doesn't require stitches. Using delicate instruments, an ophthalmic surgeon breaks apart and removes the cloudy lens. The back membrane of the lens, called the posterior capsule, is left in place. It serves to anchor the new, clear intraocular lens implant.⁵

A more sophisticated method of cataract removal places an ultrasound probe into the cataract; the probe's high-speed vibration breaks the cataract into tiny pieces.⁶

Patients may worry that they will be able to "see" what is happening around them during surgery or that surgery will be painful. This need not be a concern: when they arrive for surgery, patients are given eyedrops and sedative medications to help them relax. During surgery, the eyelids are held open by an eyelid speculum, but because the nerves of the eye are numbed by a local anesthetic, the patient sees little more than light and movement; he or she is not able to see the surgery while it's happening. Patients don't experience any pain, and cataract procedures generally last between 30 and 45 minutes.

Following surgery, a day of rest is recommended, with patients quickly returning to normal activities. You will need to take eyedrops and medications as prescribed by your surgeon. Avoid rubbing or pressing on your eyes; your surgeon may give you a metal shield to place over your eye, particularly at night or while napping to prevent you from doing this. Avoid bending, lifting, and any other strenuous activities until you are told you can safely resume them.

Cataract surgery boasts an excellent success rate, with improved vision achieved in the majority of patients. Only a small number of patients continue to experience problems following surgery. Some complications may include infection, bleeding, swelling, or retinal detachment.

The difficulty with modern cataract procedures is that they do not have any effect on the underlying causes which led to the cataract(s). Although the procedures are successful, some patients may not experience improved vision. Problems such as age-related macular degeneration, glaucoma, or diabetic retinopathy may limit vision after surgery.⁷

Furthermore, research at Hubei Medical College in Wuhan, China in 1991 reported six cases of mental complications as a result of cataract procedures. These complications included confusion, agitation, schizophrenia, aberant behaviour, and nervousness, some of which required sedative drugs and psychotherapy.⁸

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1. Cataract. Internet Health Library. (1999–2001)
2. Age-Related Cataracts American Academy of Ophthalmology®. (2003)
3. Cataract. Internet Health Library. (1999–2001)
4. Cataract. American Academy of Ophthalmology®. (2003)
5. What is Cataract Surgery? Bluestreak Media. (2004)
6. What is Cataract Surgery? Bluestreak Media. (2004)
7. Cataract Surgery. American Academy of Ophthalmology®. (2003)
8. Report of six cases of mental complications after cataractopiesis. Jiang S Department of Ophthalmology, First Affiliated Hospital, Hubei Medical College Wuhan, China. Yen Ko Hsueh Pao (CHINA) Jun 1991, 7 (2) p77–8