Riboflavin (vitamin B2) is important in the maintenance of many tissues of the body.

Photrexa (for the eyes) is a "photosensitive" solution used during a procedure to treat progressive keratoconus in adults and adolescents who are at least 14 years old.

Keratoconus (KER-a-toe-KOE-nus) is a degenerative eye disease that affects the cornea, the outermost layer on the surface of your eye. The cornea works by directing light toward the back of your eye to help you focus your vision. In people with keratoconus, the cornea becomes thin and weak, and then bulges outward. This causes incoming light to be channeled in too many directions, causing distorted vision. Progressive keratoconus can cause vision problems that may eventually lead to vision loss or a corneal transplant.

Photrexa is used together with ultraviolet (UV) light as part of a procedure called corneal collagen crosslinking.

Corneal collagen crosslinking is a method of applying riboflavin eye drops and UV light to the cornea. In this procedure, riboflavin eye drops are placed into the eyes over several minutes. Then a UV light is directed over the cornea. The riboflavin enhances the light, causing a reaction in collagen fibers inside the cornea. This procedure helps stiffen and strengthen your cornea to slow or stop the progression of keratoconus.

Photrexa may also be used for purposes not listed in this medication guide.

Avoid rubbing your eyes for at least 5 days after your corneal procedure.

A surgeon or other healthcare provider will give you Photrexa as part of your corneal collagen crosslinking procedure.

You will be given numbing eyedrops to prepare you for the procedure. You may also be given a sedative or anesthesia to help you relax. Although you will most likely be awake during the procedure, you should feel little or no discomfort. A special device will be placed around your eyelids to keep them open during the procedure.

Your eye surgeon will place Photrexa drops into your eyes about every 2 minutes during the procedure.

After the procedure, the surgeon will place a contact lens on the treated eye to protect it for a short time.

Call your doctor right away if the contact lens falls out or feels like it is out of place inside your eye.

You may also need to use antibiotic or steroid eyedrops to prevent infection and reduce swelling after your procedure. Carefully follow all after-care instructions and do not miss any follow-up appointments.

To make sure Photrexa is safe for you, tell your doctor about all your medical conditions or allergies, and all the medicines you are using.

Also tell your doctor if you are pregnant or breast-feeding a baby.

Because Photrexa is given as part of a medical procedure, this medicine has no daily dosing schedule.

Since Photrexa is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.

Avoid rubbing your eyes for at least 5 days after your procedure.

Your eyes may be more sensitive to light after your procedure. Wear sunglasses when you are exposed to bright light.

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Photrexa may cause serious side effects. Call your doctor at once if you have:

• eye redness or watering;

• severe eye pain; or

• sudden change in your vision.

Common side effects of Photrexa may include:

• feeling like something is in your eye;

• increased tearing;

• blurred vision, hazy vision;

• increased glare in your vision; or

• headache.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.