A cataract is an opacity in the normally transparent focusing lens inside the eye that prevents light rays from being focused clearly on the retina. The most common cause, or predisposing factor, for the development of cataracts is aging. Nearly all persons over the age of 60 have some degree of cataract formation. Other causes include intraocular diseases, trauma, drugs and metabolic and endocrine abnormalities (see bottom of page).

Prevention
Several types of medications have been claimed to prevent the development of cataracts. Some of them are routinely prescribed outside the United States; but no medication has been proven to pre- vent the development of the more common types of cataracts. Currently, aspirin and ultraviolet filtering glasses have received attention; and these, as well as other suggestions, are now being studied.

Modern Cataract Surgery
Gone are the days of long hospital stays, strict bedrest and confinement to dark rooms after cataract surgery. The majority of cataract surgery is now performed under local anesthesia on an outpatient basis in the hospital operating room or in a free-standing surgery center. However, inpatient surgery may be required because of the need for complex general and nursing care, multiple ocular conditions, combined cataract surgery with other ocular surgery or the patient's general medical status. Hospitalization may also be necessary for patients who cannot obtain appropriate monitoring and care during the first 48 hours post-operatively.

Intraocular lenses are now routinely implanted during cataract surgery to provide the focusing power necessary after removal of the cataractous lens. Intraocular lenses eliminate the distortion inherent in the traditional "cataract glasses" and the management problems associated with contact lenses. Cataract surgery with an intraocular lens implant is a very safe procedure with successful return of useful vision in over 90 percent of patients.

When to have Cataract Surgery
Nearly all cataract surgery is an elective procedure. It is probably time to consider removing the cataract when decreased vision interferes with the patient's ability to function in his/her daily living pattern, occupation, lifestyle and desired (or required) activities. With a few simple questions you and the patient should be able to determine when surgery is advisable. Surgery is not indicated just because a cataract is present, since it may be mild and well tolerated.

Two circumstances require the physician to recommend removal of the cataract: when the cataract interferes with the diagnosis or treatment of other ocular diseases, such as diabetic retinopathy or potential intraocular malignancy and, in rare cases, when the cataract becomes so advanced that it causes other eye diseases such as uveitis or glaucoma.

Upon referral to an ophthalmologist, a complete ocular exam will be done, including a functional visual exam. It is important to realize that there is no particular acuity level at which cata- ract surgery should be recommended. For example, a small cataract in the center of the lens, which might allow relatively good vision in dim light (such as a testing situation), could render the patient nearly disabled in bright light as the pupil contracts and less light reaches the retina. In addition to the numeric recording of visual acuity, the measurement and evaluation of glare is becoming a widely- used modality for evaluating functional visual loss secondary to cataracts.

While the goal of surgery is to restore sight, "perfect" vision may not always be the result. For example, a patient who has a cataract and a retinal problem (such as macular degeneration with very poor central vision) may not be able to read newspaper print or even drive a car after the cataract is removed. However, this patient may still benefit from cataract surgery if peripheral vision is improved and even a small improvement in central visual acuity is achieved. As long as the patient is informed of what visual improvements can realistically be expected, there may indeed be valid indications for cataract surgery in cases where the outcome is less than "perfect" vision.

In summary, the decision for cataract surgery is based on the patient's visual needs (in all types of situations) and the expectation that visual function will be improved. Just as every patient with a documented cataract does not need surgery, there are many patients with minimal appearing cataracts who can benefit from surgery. Only a discussion with the patient concerning his or her visual requirements can determine when cataract surgery should be performed.

Causes of Cataracts include:

• Aging
• Intraocular Diseases
  • Uveitis
  • Intraocular malignancies
  • Retinitis pigmentosa
  • Retinal detachment
• Trauma Drugs
  • Steroids, topical & systemic
  • Phenothiazines
  • Phospholine iodide eyedrops
• Endocrine & Metabolic
  • Diabetes mellitus
  • Hypoparathyroidism
  • Hypothyroidism
  • Galactosemia
• Congenital

References: American Academy of Ophthalmology