Cataracts: Nursing

Cataracts refer to an eye condition in which the normal transparent eye lens becomes cloudy. This distorts the image projected onto the retina and causes cloudy vision.

Okay now, let’s go over some physiology. Normally, the lens is a transparent biconvex structure that lies behind the iris, dividing the anterior and posterior segments of the eye. The lens is held in place by the ciliary processes, which are tiny projections from a structure called the ciliary body. The ciliary body also controls the degree to which the lens becomes flatter or rounder. And this in turn bends the light entering the eye to focus images onto the retina. If we zoom into the lens, we’ll see that it’s composed of three layers: the capsule, cortex, and nucleus. The nucleus is made up of concentric layers of transparent proteins called crystallins.

Now, cataracts are caused by the opacification or clouding of the lens. When this occurs at birth, it's called congenital cataracts. So, risk factors for congenital cataracts include congenital infections, such as toxoplasmosis and rubella, as well as genetic conditions, such as trisomy 13, which causes Down syndrome, Wilson’s disease, in which extra copper is stored in the body tissues, and myotonic dystrophy, which is characterized by progressive muscle weakness and loss. Other risk factors for congenital cataracts include inborn errors of metabolism, like galactosemia, which is a hereditary condition that impairs the conversion of galactose to glucose in newborns.

Now, cataracts can also develop later in life, in which case it's acquired. Acquired cataracts are often associated with advanced age, usually above 60, smoking, excessive alcohol use, penetrating eye trauma, and infections. Other risk factors for acquired cataracts include exposure to UV light, prolonged use of medications like glucocorticoids, and diabetes mellitus.

Regardless of the cause, the pathological outcome is a change in the structure and composition of the lens. So, crystallins start clumping together, which causes decreased transparency of the lens, making it cloudy. At the same time, the lens becomes stiffer, which reduces its ability to refract light and focus images on the retina.