Topical Anti-fungal Eye Drops In Ophthalmology

Fungi do not invade the cornea easily and seems to require trauma, contact lens wear or immunological compromise for infection. In the rural areas, trauma with vegetative material is a common cause while contact lens wear is a common cause in the urban areas. 
The fungi can be broadly divided into two types namely yeasts (candida species) and filamentous (Fusarium, Aspergillus, Curvularia and cephalosporium) fungi.

 There is no single broad spectrum antifungal drug which could be used effectively to treat all the fungal infections and hence treatment is usually initiated empirically till the offending organism is confirmed. An ideal ocular antifungal drug must be long-acting, possess good intraocular penetration and should be highly effective.

Examples of ophthalmic antifungal drugs include the following;

FLUCONAZOLE: Among the azole group of antifungal drugs, fluconazole has the least activity towards cytochrome P450 enzymes and hence does not produce drug interactions. It is available for both systemic and topical use. Topically, it is available as 0.3% ophthalmic solutions indicated in the treatment of fungal keratitis with deep abscess and corneal ulcers because of its deep cornea penetration. The patient is advised to instill one drop in the lower conjunctival sac every four hours (which is tapered slowly; one drop four times daily) for fourteen to twenty one days until corneal ulcer resolves.

MICONAZOLE: It is available only for topical use(1.0% ophthalmic solution and applicaps) and is effective against yeast and filamentous fungi. The initial dosage in fungal keratitis is one drop of miconazole at hourly interval, which may be gradually reduced with the response.

ECONAZOLE: Because of its poor intraocular penetration, it is effective only in superficial fungal infections of the eye. It is available only for topical use and is more effective against filamentous fungi than yeasts. Econazole is available as 1.0% ointment and 1.0% ophthalmic solution. Patient is advised to instill one four to six times daily.

CLOTRMAZOLE: It is available only for topical use and is used in the treatment of superficial fungal infections like tinea infections and corneal ulcers. It is poorly soluble in water and cannot be given parenterally. Clotrimazole is available as 1.0% topical solution and the patient is advised to instill one drop every hour until ulcer heals and then three to four times daily over several weeks.

AMPHOTERICIN B: It is the most effective topical antifungal for candida keratitis but penetration through intact cornea is poor as compared to natamycin. For treatment of keratomycosis, it can be given by topical, subconjunctival, intracameral, intravenous or intravitreal routes. For treatment of fungal keratitis, instill one drop of 0.75-0.3% at hourly interval and gradually taper it over several weeks. In severe fugal endophthalmitis, intravitreal injections are required.

NYSTATIN: It is effective against candida infections and is available in topical ointments or creams that contain 100000units/g. Patients are advised to apply four to five times a day till the ulcer heals. It is also used orally in treatment of oropharyngeal and intestinal candidiasis and topically for treatment of vaginal candidiasis.