Antifungal Eye Preparations

Most fungi causing orbital infections are ubiquitous aerobic organisms that are normal commensals of the respiratory, gastrointestinal and female genital tracts as well as in 25% of normal conjunctiva.¹ Fungal eye infections are rare.² Local trauma (especially in hot and humid climates), contact lens wear and topical antibiotic or steroid treatment can all predispose to fungal infection as does immunocompromise, non-ketotic diabetic ketoacidosis and contamination of distant indwelling devices (e.g. catheters and i.v. lines) via haematogenous spread.¹ Diagnosis is often difficult owing to the rarity of these infections and the fact that fungi may take weeks to culture and even longer to determine their sensitivity to antifungals.³

There are three main classes of ocular antifungals:^2,4

• Polyenes, particularly amphotericin B 0.15%, and natamycin 1% which have a broad spectrum of activity
• Azoles, as derivatives of imidazoles, which are useful in yeast infections e.g. clotrimazole 1%, econazole 1%, itraconazole 1%, miconazole 1%
• 5-fluorocytosine (flucytosine 1%), a synthetic fluorinated pyrimidine which is effective against yeasts

Treatment tends to be long (in the order of weeks or months) and may involve topical ± systemic therapy depending on the nature of the infection and its severity. They may also be delivered into the vitreous. Typical topical antifungals include econazole 1% and amphotericin B 0.15% or 0.3%.³ Azoles are the preferred group of antifungals when deep seated infection warrants systemic treatment.

Fungal infections of the eye which may include orbital cellulitis, dacryocystitis, conjunctivitis, keratitis and endophthalmitis.⁵ Thus they can work at a superficial level or penetrate deeply into the eye.⁶

Previous anaphylactic reaction to amphotericin.

• This is initiated by the ophthalmology team. The nature of fungal infections is such that many patients will already be under specialist care as symptoms will often have gone on for a length of time. A number patients will have been treated for a bacterial infection before a correct diagnosis is made.
• Samples such as corneal scrapes will have been obtained prior to initiation of therapy.
• Antifungal preparations for the eye are not generally available and have to be specifically made up for each patient.

This should be carried out by the ophthalmology team and in addition to monitoring the infection itself, care should be taken to monitor the full blood count, renal and hepatic functions, depending on which drug is being used (see 'Complications' below).

Complications from topical administration of these drugs are very rare but theoretically possible. The complications outlined below relate to systemic administration.

• Polyenes: anaphylactic reaction, renal tubular damage
• Azoles: transient liver function abnormalities
• 5-fluorocytosine: marrow aplasia

There are reports of in vitro anti-fungal resistant organisms due to the frequent use of azoles, polyenes and 5-fluorocytosines.⁵ Work is being done particularly on newer azoles, should the resistance manifest itself clinically. There is also research into improved delivery systems to potentiate the effect of existing drugs and allow their more effective use.⁶