A cataract is an opacity or cloudiness in the natural lens of the eye. It is still the leading cause of blindness worldwide and represents an important cause of visual impairment in the United States. The development of cataracts in the adult is related to aging, sunlight exposure, smoking, poor nutrition, eye trauma, systemic diseases, and certain medications such as steroids. A single study has suggested that use of oral vitamin C may help delay the progression of cataracts.

Just as a smudged or dirty camera lens may spoil a photograph, opacity in the natural lens of the eye can result in a blurred image. Patients with cataracts usually complain of blurred vision either at distance, near, or both. This may interfere with tasks such as driving or reading. Other common complaints include glare, halos, and dimness of color vision.

A diagnosis of cataract can only be made by a thorough eye examination including slit lamp (microscopic) evaluation. Other devices are sometimes used to determine if glare interferes with vision. If cataract surgery is being considered, an ophthalmologist will also examine the posterior aspect of the eye, which will include evaluation of the retina and optic nerve. If a cataract is mature (extremely dense) or hypermature (white), an ultrasound device known as a B-scan may be used to rule-out retinal detachment and ocular tumors prior to proceeding with cataract surgery.

The progression of cataracts is highly variable, however, they will invariably worsen in severity. Changing glasses may sometimes be useful in improving vision as the cataract progresses, since cataracts may induce relative nearsightedness. This is the answer as to why some patients with hyperopia (farsightedness) will actually have better vision without glasses in the early stages of cataract development. For most patients, however, changing glasses has minimal impact on overall visual quality. Besides changing glasses, the only other option for treatment of cataracts is cataract surgery.

The decision for cataract surgery is reached only between the EyeMD and the patient. In general, this decision is based on the degree to which the patient's vision is impaired, and the impact that impairment has on his or her quality of life. When a patient is significantly bothered by symptoms of cataract, cataract surgery is usually offered. Many patients will ask if a cataract must be "ripe" before surgery. The answer with today's technology is "no." Before the development of small incision cataract surgery and intraocular lens implants, outcomes with cataract surgery were far inferior to outcomes today. Therefore, ophthalmologists would typically wait until a cataract was very advanced before offering surgery. Today, with advanced surgical techniques and equipment, cataract surgery can be offered at a much earlier stage. In fact, many ophthalmologists will agree that it is safer to proceed with cataract surgery at an earlier stage of development rather than waiting until the cataract is advanced and very dense.

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Congenital Cataract

There are numerous causes of congenital cataracts including a myriad of diseases and syndromes associated with childhood cataracts. However, most congenital cataracts are either sporadic, meaning that no identifiable cause can be found, or are dominantly inherited. The dominantly inherited type will almost certainly result in bilateral cataracts.

Congenital cataracts are almost always initially diagnosed by the pediatrician during the first few weeks or months of life. The patient is then typically referred either to a pediatric or general ophthalmologist. Cataract surgery is usually recommended very early in life, but many factors are important in this decision, including the infant or child's health and whether the cataract is unilateral or bilateral.

Cataract surgery in an infant or child is completed in the operating room under general anesthesia. The cataract is removed and the posterior aspect of the capsule (which contained the opacified lens) is usually removed to prevent opacification. Whether or not an intraocular lens is implanted at that time is controversial. Traditionally, intraocular lens implants were not used in infants or small children and visual rehabilitation was completed with contact lenses or glasses. However, some ophthalmologists prefer to use lens implants even in infants. This decision must be made between the treating physician and the parents or caretakers of the child.

Amblyopia (lazy eye) and strabismus (deviated eyes) are commonly associated with congenital cataracts and these compounding conditions must sometimes be dealt with both before and after cataract surgery in an infant or child. In patients with unilateral congenital cataracts, profound amblyopia may develop. It is now known that these eyes must be treated within the first few months of life if useful vision is to be obtained. Patients with bilateral partial cataracts may, however, undergo surgery at several years of age without the development of amblyopia. For more on amblyopia and strabismus, the reader is referred to the respective conditions detailed elsewhere in this library.

Congenital cataracts are not uncommonly associated with a condition known as persistent hyperplastic primary vitreous (PHPV). This condition, which is characterized by a persistent retrolenticular (behind the cataract) membrane and other ocular malformations, may not be diagnosed until the patient comes to surgery for the cataract. Unfortunately, this condition has a relatively poor prognosis for vision.