Understanding Cataract

What causes Cataract?

The following conditions may cause cataract formation:

• Congenital

• Trauma

• Aging Process

• Associated with diseases (metabolic and connective tissue diseases)

Congenital Cataract

A cataract is a marked opacity of the lens. This may be present at birth or may become apparent in early childhood. It can occur as a result of trauma to the eye if the lens is injured. Some are dominantly inherited, so are familial. When the opacity is on the anterior surface of the lens, the cause is thought to be birth injury or possibly contact between the lens and the cornea during intrauterine life. When the opacity is located at the edge of the lens, it may be the result of nutritional deficiency during intrauterine life, such as rickets or hypocalcemia. Infants who contract rubella prenatally may develop central cataracts. Some central cataracts are hereditary.

Eye Trauma and Injury

These include burns, contact trauma, and penetrating injuries. Chemical burns such as those causes by acid or alkali must be treated immediately to prevent the possibility of permanent visual impairment from damage to eye structure possibly the lens. Lacerations to the lens cause by contact trauma may cause opacity of the lens. Blurring of vision may occur immediately following trauma. The predominant symptom is progressive loss of vision.

Metabolic Diseases

Of the metabolic diseases affecting the eye, diabetes is the most common. Diabetes may affect any of the structure of the eye. Senile cataracts occur earlier in persons who have diabetes and progress more rapidly than in most elderly people. Diabetic retinopathy produces characteristic changes in the retina that can cause severe visual damage and eventually result in blindness. This condition often causes blindness due to recurrent hemorrhage and retinal detachment.

Connective Tissue Diseases

Persons with connective tissue diseases commonly have eyed involvements. One or more frequent eye manifestation is dry eyes. Patients complain of a scratchy burning sensation, with possible redness of the eye and photophobia (sensitivity to light). Any eye structure can be involved; the tissues of the eye that are affected are, in general, of the same type as the tissue involved in the primary manifestation of the disease.

Aging Process

Cataracts resulting from aging or disease usually develop gradually. Both eyes may develop cataracts, but they usually develop at different rates. Changes in vision associated with aging to include the obvious changes around the eye, such as shrunken appearance of the eyes due to loss of orbital flat, the slowed blink reflex, and poor eye muscle tone. The degenerative changes in the eyes beginning in the middle age lead to the relative inflexibility of the lens, called presbyopia. During the latter, it could result to opacity of the lens or cataract. The person with presbyopia may find that reading without glasses is possible in the early stage of cataract formation due to artificial myopia caused by the greater convexity of the lens. To diagnose cataract(s), the pupil is dilated and the lens of the eye is examined with the ophthalmoscope and the slit lamp.