Cataracts

Long-term use of prednisone could cause cataracts to develop.

Another side effect of high doses or prolonged use of prednisone (or other steroids) is the development of cataracts. Cataracts are generally thought of as a condition of older persons. However, because prednisone accelerates the natural aging process, it can cause cataracts to develop in younger people. Unlike some side effects, such as facial “mooning,” increased appetite, hair growth, and acne, a cataract will not abate after the course of steroid treatment is complete. However, if the steroid dosage is lessened or discontinued, an existing cataract may not get any larger.

Prevalence of cataracts

In the general United States population, 50% of persons between the ages of 65 and 74 years, and 70% of persons over the age of 75 years have at least one cataract. Congenital cataracts can occur in newborns (at a rate of 10,000 per year), but are generally the result of an infection, or drug or alcohol abuse during the pregnancy.

How cataracts form

After light passes through the pupil of the eye, it passes through the lens, which is comprised primarily of water and proteins. The lens functions much like a camera, focusing that light onto the retina. The lens of your eye can actually change shape to focus on objects that are close, or far away. During the normal aging process, some of the proteins in the lens may clump together, causing an area of opacity—a cataract. The area will become larger and more opaque over time, clouding the lens and making it difficult to see.

Types of cataracts

There are three types of cataracts: nuclear, cortical and posterior subcapsular. Prednisone, either oral or in eye drops, may cause posterior subcapsular cataracts.

Nuclear: This type of cataract develops slowly, is more common in older persons, and gives the eye a yellow tinge.

Cortical: This type of cataract is common in persons with diabetes. A cortical cataract forms in the lens cortex, and eventually extends outward like the spokes on a wheel.

Posterior subcapsular: This type of cataract may be caused by high doses or prolonged use of prednisone, extreme farsightedness, and retinitis pigmentosa. This type of cataract forms at the back of the lens, and symptoms tend to develop relatively quickly (in months, rather than years). As light passes through the portion of the back of lens with the cataract, it is scattered rather than focused. A person with an early posterior subcapsular cataract may have more trouble seeing close objects.

How would you know if you had a cataract?

Symptoms of cataracts include:

• Blurry vision.
• Colors (especially blue) appear faded.
• Difficulty seeing in bright light or dimly lit rooms.
• Double vision.
• Film over vision (similar to looking through a dirty windshield).
• Frequent eyeglass prescription changes.
• Increased nearsightedness.
• Seeing halos around lights.
• Reduced night vision.

Other cataract risk factors

Prednisone, administered in high doses or prolonged use is a risk factor for cataracts. However, there are several other risk factors, including age, prior eye surgery or trauma, chronic conditions, and certain medications. Chronic conditions:

• Diabetes.
• Down’s syndrome.
• Galactosemia.
• Juvenile rheumatoid arthritis.
• Muscular dystrophy.
• Myotonic dystrophy.
• Retinitis pigmentosa.
• Uveitis.
• Wilson’s disease.

Medications:

• Amiodarone (antiarrhythmic).
• Chlorpromazine (sedative).
• Lovastatin (cholesterol-lowering drug).
• Phenytoin (antiseizure).

Cataract risk factors

There is no medication known to prevent cataracts. However, it is thought that a diet high in antioxidants (beta-carotene, and Vitamins C and E) may help prevent cataracts, as well as other health conditions. Ultraviolet light is a known risk factor; wear sunglasses or a hat with a brim to reduce exposure. Eye trauma is also a risk factor; wear protective eyewear when engaging in activities where eye injury is possible.

Treating cataracts

In the early stages of a cataract, sight can be improved through the use of eyeglasses, appropriate lighting, and a magnifying lens for reading or other close work. However, if the cataract progresses to a point where everyday activities become difficult, surgery may be necessary. Fortunately, cataract surgery is common and safe, with 90% of patients reporting improved eyesight and quality of life afterwards.

There are two different types of cataract surgery: phacoemulsification and extracapsular. In phacoemulsification surgery, a small probe that emits ultrasound waves is inserted into the eye through an incision. The ultrasound waves cause the cataract to break into pieces, which are then suctioned away from the eye.

In extracapsular cataract surgery, the lens with the cataract is removed from the eye and replaced with an artificial intraocular lens. The artificial lens looks and feels normal, though it can not change shape like a natural lens. Persons with an intraocular lens will need eyeglasses for reading or close work.