Which medication may be prescribed to treat an eye infection?

Gatifloxacin is an antibiotic that belongs to the fluoroquinolone class and is specifically used to treat bacterial eye infections. Its mechanism of action involves inhibiting bacterial DNA replication, which effectively helps in controlling and eliminating the infection. This medication is formulated for ophthalmic use and is particularly suited for treating conditions like bacterial conjunctivitis or corneal ulcers.

The other medications listed do not serve the same purpose as antibiotics. Cyclosporine is primarily used as an immunosuppressant, often for dry eye conditions. Homatropine is an anticholinergic used to dilate pupils and for its effects on managing inflammation. Tetryzoline, on the other hand, is a decongestant used for temporary relief of eye redness due to irritation but does not have antibacterial properties. Thus, Gatifloxacin is the appropriate choice for effectively addressing bacterial infections in the eye.