Cataracts, a clouding of the lens of the eye, develop for many reasons. There are several types of cataracts: nuclear cataracts, which form in the center of the lens and are most often associated with aging; posterior subcapsular cataracts (PSC), often seen in diabetics and people taking certain medications; and cortical cataracts, which form at the outer edge of the lens and grow inward. Several medications cause cataracts and others are implicated in increasing the risk of cataract development.
Steroids
Steroid medications have a clear connection to cataract formation. Steroid medications increase the risk of PSC, particularly if given in the form of eye drops to treat inflammation in the eye, the University of Illinois Eye and Ear Infirmary explains. Oral steroids in the form of prednisone in doses of 15 mg per day over one year resulted in cataract formation in 75 percent of patients.
According to the same source, 765 steroid drops given over 10.5 months, or a little over two drops a day, ended in cataract formation in half the patients studied. Inhaled steroids for asthma can also increase the risk, especially if 28 puffs or more are used. The risk of cataract development was three times higher in people using inhaled steroids four times a day or more.
Antipsychotics
Older antipsychotic drugs such as phenothiazide-derived medications, including Mellaril, Stelazine, and chlorpromazine (Thorazine) were associated with cataract formation. One study reported by lead author Sajida Shahzad, M.D., in an article published in 2002 in "Psychomatics" titled "Cataract Occurrence with Antipsychotic Drugs," stated that up to 33 percent of 384 patients taking chlorpromazine had deposits on the anterior lens. Newer antipsychotic medications have not been proved to have the same risk of cataract formation, Shahzad reports.
Other Medications
A number of medications are weakly linked to cataract formation, the University of Maryland Medical Center states. These include allopurinol, amiodarone, tricyclic antidepressants, potassium-sparing diuretics, thyroid hormone, tamoxifen and tetracyclines. Certain glaucoma medications and psoralen, used in conjunction with light therapy to treat psoriasis, may cause cataracts as well.
