Preferably the causative organism is identified before determining treatment of ocular infection, but in most cases, empiric treatment—guided by knowledge of local patterns of microbial resistance—is used in the first instance. In the treatment of conjunctivitis and for prophylaxis against ocular infection, it is preferable to use a drug that is not given systemically. Although fluoroquinolones are advocated for the treatment of conjunctivitis, they are better reserved for treatment of bacterial keratitis and other serious infections. There is no clinical evidence indicating the superiority of any topical antibiotic agent for common bacterial conjunctivitis. Of the available local antibiotics, sodium sulfacetamide is effective and inexpensive. It is available in ointment or solution form. Combined bacitracin-polymyxin ointment is often used prophylactically after corneal foreign body removal for the protection it affords against both gram-positive and gram-negative organisms.
In addition to the fluoroquinolones, the most effective broad-spectrum antibiotics for severe ocular infections are aminoglycosides and cephalosporins. If a proprietary ophthalmic preparation is not available, a suitable preparation may be available from a compounding pharmacy. Intraocular and unusual corneal infections require specially formulated preparations, made either from proprietary parenteral preparations or de novo.
METHOD OF ADMINISTRATION
Most ocular anti-infective drugs are administered topically. Ointments have greater therapeutic effectiveness than solutions, since contact can be maintained longer. However, they cause blurring of vision; if this must be avoided, solutions should be used. Intravitreal injections, prepared from parenteral formulations, are used for severe intraocular infection.
Systemic administration is required for some intraocular infections, orbital cellulitis, dacryocystitis, gonococcal keratoconjunctivitis, inclusion conjunctivitis, and severe external infection that does not respond to local treatment.