Treatment of Eye Infections

Abstract

The quinolone antimicrobials are commonly prescribed as eye drops for the therapy of anterior eye infections such as conjunctivitis and keratitis. Ophthalmic drops containing 3 mg of norfloxacin, ciprofloxacin, ofloxacin, and levofloxacin per ml (0.3% solutions) are available. Bacterial infections of the eye and contiguous tissues include conjunctivitis, keratitis, blepharitis, preseptal cellulitis, orbital cellulitis, cavernous sinus thrombosis, uveitis, and endophthalmitis. The discussion in this chapter is limited to the use and pharmacology of quinolones for the treatment of bacterial infections of the conjunctiva (conjunctivitis), cornea (keratitis), and aqueous and vitreous humors (endophthalmitis). Conjunctivitis is the most common bacterial infection of the eye and is also often caused by viruses. Although it causes local symptoms including irritation and tearing, it is rarely sight threatening and often resolves without antimicrobial therapy. Treatment of keratitis requires antibiotic penetration into the corneal stroma, and endophthalmitis requires penetration into the aqueous and vitreous humors. Pharmacodynamic models characterize the relationship between antimicrobial drug exposure and activity, expressed as the MIC, with efficacy or drug exposure with toxicity. The pharmacokinetics of intravitreal quinolones has been characterized for fleroxacin, ciprofloxacin, ofloxacin, and sparfloxacin. Lipophilic quinolones such as ofloxacin, levofloxacin, and sparfloxacin show good penetration into the vitreous humor following systemic drug administration even in the absence of inflammation.