Cialis, or tadalafil, is a prescription drug used for the treatment of erectile dysfunction in men. It is classified as a phosphodiesterase-5 enzyme inhibitor, meaning it blocks the function of the phosphodiesterase-5 enzyme and allows the relaxation of smooth muscle in the penis. This leads to the inflow of blood into the penis and produces an erection, but only with sexual stimulation. Cialis may have effects on the eyes or the vision.
Changes in Color
Patients on Cialis may notice a change in vision, particularly loss of blue-green color discrimination. According to "Pharmacotherapy: A Pathophysiologic Approach," changes in color discrimination are reversible when the medication is discontinued, but caution should be used in airplane pilots, who use blue and green lights to land planes.
Blurred Vision
Blurred vision has been reported in post-marketing surveillance of Cialis, explains the "Drug Information Handbook." However, this side effect is rare, occurring in less than 2 percent of patients. If the patient experiences blurred vision, he should avoid driving or operating heavy machinery and inform a health care provider.
Decrease or Lose of Vision
Cialis may cause a sudden decrease or loss of vision. This may be due to a disorder called nonarteritic ischemic optic neuropathy, or NAION, which affects the optic nerve and leads to permanent visual loss. The occurrence of NAION is rare but patients with a history of vision loss are at higher risk. Diabetes, high blood pressure, heart disease, smoking, other eye problems, and being older than 50 also increase the risk of developing NAION, explains the "Drug Information Handbook." If the patient experiences this side effect, he should stop the medication and seek medical attention right away.
Conjunctivitis
Conjunctivitis is the inflammation of conjunctiva, which is the membrane on the inner part of the eyelids and the whites of the eyes. This side effect may be seen in patients using Cialis. Conjunctival hyperemia, an enlargement of the blood vessels that causing red eyes, may also occur. RxList.com states that eye pain, increased tearing and swelling of the eyelids are other side effects seen in the eyes.
References
- "Pharmacotherapy: A Pathophysiologic Approach"; Joseph T. Dipiro, Robert L. Talbert, et al.; 2008
- "Drug Information Handbook"; Charles F. Lacy, Lora L. Armstrong, et al.; 2009
- RxList: Cialis
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