Ophthalmic Antibiotics: Clinical Overview
Role of Antibiotics in Eye Care
Antibiotics are central to managing bacterial conjunctivitis, keratitis, blepharitis, canaliculitis, and post surgical prophylaxis. Timely initiation limits corneal damage, reduces contagion, and lowers the risk of vision threatening complications. Selection should reflect likely pathogens, tissue penetration needs, and the urgency of obtaining therapeutic levels at the site of infection.
Key Drug Classes and Typical Coverage
Commonly used classes include fluoroquinolones, aminoglycosides, macrolides, and polymyxins. Each offers a different balance of gram positive and gram negative activity, corneal penetration, and resistance trends.
- Fluoroquinolones: Excellent corneal penetration and broad spectrum coverage, preferred for microbial keratitis and surgical prophylaxis.
- Aminoglycosides: Strong gram negative activity, useful for lid disease and as adjuncts in ulcer therapy.
- Macrolides: Good tolerability and dosing convenience for mild conjunctivitis, with activity against common gram positive organisms.
- Polymyxin combinations and cephalosporins: Helpful alternatives when resistance or allergy narrows choices.
Topical, Oral, and Fortified Preparations
Topical drops and ointments deliver high local concentrations with minimal systemic exposure, ideal for superficial infections. Oral agents are indicated for preseptal cellulitis, dacryocystitis, hordeola with cellulitis, and when adnexal involvement demands systemic levels. Severe corneal ulcers may require fortified drops prepared by compounding pharmacies to achieve bactericidal concentrations. Combine routes when tissue penetration or systemic involvement warrants it.
Antibiotic Stewardship and Culture Guidance
Empiric therapy should be guided by local resistance patterns and clinical presentation. Cultures are indicated for central, large, or unresponsive corneal ulcers, atypical presentations, or immunocompromised hosts. De escalate once sensitivities return, avoid unnecessary prolonged use, and switch to narrower agents to limit resistance and preserve future efficacy.
Patient Factors, Safety, and Monitoring
Consider age, pregnancy status, systemic allergies, renal or hepatic impairment for oral choices, and preservative sensitivity for frequent topical dosing. Watch for epithelial toxicity with aminoglycosides, delayed healing with frequent dosing, and hypersensitivity reactions. Educate patients on proper instillation, spacing with other drops, and the importance of completing the full course even when symptoms improve.
Follow Up, Documentation, and Escalation
Reassess within 24 to 48 hours for corneal ulcers and sooner if vision drops or pain worsens. Document size, location, and depth of ulcers to track response. Escalate to fortified therapy or refer for co management with corneal specialists when infiltration enlarges, thinning develops, or there is suspicion of atypical organisms such as fungi or Acanthamoeba.