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Cataract Surgery - Symptoms & Treatment

A common cause of vision loss, a cataract is a gradually developing opacity of the lens or lens capsule of the eye. Cataracts commonly occur bilaterally, with each progressing independently. Exceptions are traumatic cataracts, which are usually unilateral, and congenital cataracts, which may remain stationary.

Cataracts are most prevalent in persons over age 70, as part of aging. Surgical intervention improves vision in 95% of affected people.

Causes Cataracts have various causes: Senile cataracts develop in elderly patients, probably because of degenerative changes in the chemical state of lens proteins. Congenital cataracts occur in neonates as genetic defects or as a sequela of maternal rubella during the first trimester.

• Traumatic cataracts develop after a foreign body injures the lens with sufficient force to allow aqueous or vitreous humor to enter the lens capsule.
• Complicated cataracts develop as secondary effects in a patient with uveitis, glaucoma, retinitis pigmentosa, or a detached retina or in the course of a systemic disease, such as diabetes, hypoparathyroidism, or atopic dermatitis. They can also result from exposure to ionizing radiation or infrared rays.
• Toxic cataracts result from prolonged exposure to drug or chemical toxicity with prednisone, ergot alkaloids, naphthalene, or phenothiazines; they also result from excessive exposure to sunlight.

What Are the Different Types of Cataract?

There are three types of cataracts that affect different parts of the lens, have different symptoms and cause different vision problems.

1. Nuclear cataract occurs in the center of the lens. This type is the most common form of cataract and is associated with the natural aging process.
2. Cortical cataract begins with spoke-like formation extending from the outside of the lens into the center. When the spokes reach the center, blurring and glare result in loss of vision. Diabetics commonly develop this type of cataract.
3. Subcapsular cataract develops very slowly and starts at the back of the lens. Symptoms may not appear until the opacity is well developed. Subcapsular cataracts are often found in patients with diabetes, high myopia, retinitis pigmentosa, and people taking steroids for extended periods.

Signs and symptoms

Here are some signs and symptoms of cataract:

• Cloudy, fuzzy, foggy, or filmy vision.
• Colors appearing faded or changed in hue.  Blue may appear to be green and yellow may look white.
• Problems driving at night because headlights seem too bright.
• Print appearing faded and lacking in contrast.
• Problems with glare from lamps or the sun.
• Frequent changes in your eyeglass prescription.
• Double vision.
• Better near vision for a while only in farsighted people.

These symptoms also can be signs of other eye problems.

Diagnosis

When shining a penlight on the pupil, observation of a white area behind the pupil suggests an advanced cataract. Ophthalmoscopy or a slitlamp examination confirms the diagnosis by revealing a dark area in the normally homogeneous red reflex.

Treatment

Cataracts require surgical extraction of the opaque lens and intraoperative correction of visual deficits with a lens implant (intraocular lens) for best visual results. This procedure is most frequently performed as same day surgery.

Surgical procedures

The following procedures are used to correct cataracts:

• Extracapsular cataract extraction removes the anterior lens capsule and cortex, leaving the posterior capsule intact. Typically, this is done using phacoemulsification equipment, which fragments the lens with ultrasound. The fragments are then removed by irrigation and aspiration. With this procedure, a posterior chamber intraocular lens (IOL) is implanted where the patient's own lens used to be. (A posterior chamber IOL is currently the most common type used in the United States .) This procedure can be used with patients of all ages.

Some patients who have an extracapsular cataract extraction develop a secondary membrane in the posterior lens capsule (which has been left intact) that causes decreased visual acuity. But this membrane can be removed by the Nd: YAG laser, which cuts an area out of the center of the membrane, thereby restoring vision. However, laser therapy alone can't be used to remove a cataract.

• Intracapsular cataract extraction removes the entire lens within the intact capsule by cryoextraction (the moist lens sticks to an extremely cold metal probe for easy and safe removal with gentle traction).

Possible complications of surgery include the loss of vitreous (during surgery), wound dehiscence from loosening of sutures and flat anterior chamber or iris prolapse into the wound, hyphema, pupillary block glaucoma, retinal detachment, and infection.

Correction of visual deficits

A patient with an IOL implant may experience improved vision almost immediately if the retina is intact. The IOL implant usually only corrects for distance. To protect the eye postoperatively, some patients wear an eye patch for 6 to 8 hours, while others may have a collagen shield (similar to a contact lens) that dissolves in 24 hours. The patient will then need either corrective reading glasses or a corrective contact lens, which will be fitted 4 to 8 weeks after surgery.

If no IOL has been implanted, the patient may be given temporary aphakic cataract glasses; in about 4 to 8 weeks, he'll be refracted for his own glasses.

Prevention

The primary prevention involves controlling associated diseases and avoiding exposure to factors known to promote cataract formation.

• Wearing sunglasses when you are outside during the day can reduce the amount of UV light your eyes are exposed to. Some sunglasses do not filter out the harmful UV. An optician should be able to tell you which sunglasses filter out the most UV. For patients who smoke cigarettes, quitting will decrease the risk of cataracts.
• Regular intake of antioxidants (such as vitamin C and E) is theoretically helpful, but this is also not proven.