Mycotic keratitis is a fungal infection of the cornea, which constitute an important eye problem in outdoor workers. This infection is difficult to treat, and it can lead to severe visual impairment or blindness. Trauma is the major predisposing factor, followed by ocular and systemic defects, prior application of corticosteroids and prolonged use of antibiotic eye-drops. We report this case because of the rarity of endogenous Aspergillosis presenting as blindness in tropical India and review of the relevant literature.
Keywords: Aspergillus, fungal, keratitis, mycotic
Fungal infections of the cornea are frequently caused by species of Fusarium, Aspergillus, Curvularia, and Candida. Trauma is the most important predisposing cause; ocular and systemic defects and prior application of corticosteroids are also important risk factors. Culture remains the cornerstone of diagnosis; direct microscopic detection of fungal structures in corneal scrapes or biopsies permits a rapid presumptive diagnosis. A variety of anti-fungals have been evaluated in therapy of this condition. Medical therapy may fail, necessitating surgical intervention.
Fungal infections of the cornea (mycotic or fungal keratitis, keratomycosis) present as suppurative, usually ulcerative lesions. Such a corneal infection poses a challenge to the ophthalmologist because of its tendency to mimic other types of stromal inflammation and because its management is restricted by the availability of effective anti-fungal agents and the extent to which they can penetrate into corneal tissue.
Absence of a significant systemic history compounded the diagnostic dilemma in our patient. Definitive differentiation of this rare entity from a foreign body, amelanotic melanoma, and other inflammatory conditions such as sarcoidosis and tuberculosis, may be possible only on microbiological and histo-pathological evaluation. We report this case because of the rarity of endogenous Aspergillosis presenting as blindness in tropical India and review of the relevant literature.
A 62-year-old man presented with complaints of pain, redness, watering, photophobia, and decreased vision in the right eye of a week’s duration. Slit-lamp bio-microscopic examination revealed a cream-colored, irregular elevated inferior iris mass, extending on to the anterior lens surface. [Figure 1] An excisional biopsy of the mass was performed through a superior clear corneal incision. Polymerase chain reaction analysis of the aqueous humor showed a positive pan fungal genome. Histopathology of the biopsied mass showed a giant cell granuloma with surrounding numerous branching, septate hyphae [Figure 2]. Culture growth revealed Aspergillus fumigatus. Finally, a penetrating keratoplasty was performed with intracameral amphotericin-B (7.5 mg). Phacoemulsification and lens implantation were carried out 2 months after the graft. Twelve months after keratoplasty, the graft remained clear with 6/18 vision.
Mycotic keratitis has been reported from many different parts of the world, particularly tropical areas, where it may account for more than 50% of all ocular mycoses.  Two basic forms have been recognized: That due to filamentous fungi (especially, Fusarium and Aspergillus), which commonly occurs in tropical and subtropical zones, and keratitis due to yeast-like and related fungi (particularly Candida). 
Keratitis due to filamentous fungi is believed to usually occur following trauma, the key predisposing factor, in healthy young males engaged in agricultural or in other outdoor work. Traumatizing agents of plant or animal origin (even dust particles) either directly implant fungal conidia in the corneal stroma or abrade the epithelium, permitting invasion by exogenous fungi. Environmental factors (humidity, rainfall, wind) greatly influence the occurrence of filamentous fungal keratitis and may also determine seasonal variations in frequency of isolation and types of fungi isolated. ,
Less frequent predisposing factors include immunological incompetence, prior administration of corticosteroids or anti-bacterial agents, ‘allergic conjunctivitis,’ and the use of hydrophilic contact lenses.  Gopinathan et al recently reviewed the epidemiological features of 1352 patients, with culture-proven mycotic keratitis seen over a period of 10 years, at a tertiary care eye hospital in southern India and showed that males were significantly more frequently affected than females (a ratio of 2.5:1), and 64% of patients were in the age group 16-49 years.
Fungal infections of the cornea need to be promptly recognized to facilitate a complete recovery. Symptoms are usually non-specific, although possibly more prolonged in duration (5-10 days) than in bacterial corneal ulcers.  Pre-existing ocular or systemic disease needs to be identified for correction. Microbiological investigations should always be performed when fungal infections of the cornea are suspected.  Material for microscopy and culture is obtained by scraping the base and edges of the ulcer with a sterile blade or spatula several times. Sometimes, it may not be possible to obtain corneal scrapes because of the occurrence of a very small or non-existent epithelial defect. In such situations, corneal material may be obtained by performing a corneal biopsy.  Corneal material may also be obtained at the time of performing a penetrating keratoplasty. 
Several techniques for direct microscopic examination of corneal scrapings permit a rapid presumptive diagnosis of mycotic keratitis.  A suggested set of smears for direct microscopic detection of fungal structures in corneal material would be: A wet preparation (potassium hydroxide 10% (KOH), or lactophenol cotton blue); a smear stained by the Gram or Giemsa method; a smear stained by a special fungal stain (periodic acid Schiff (PAS) and Gomori methenamine silver (GMS).  Culture of corneal biopsies may sometimes yield better results than those of corneal scrapings, especially if there is active proliferation of fungi in the depth of the corneal stroma with only a small epithelial defect. 
Several authors have advocated different therapeutic regimens for Aspergillus fumigatus. Kaushik et al treated their cases with hourly natamycin and clotrimazole eye drop, and oral fluconazole 200 mg twice-daily, whereas Fahad et al have reported that therapeutic keratoplasty with intracameral amphotericin eliminates 90-100% of fungal infections. A penetrating keratoplasty with intracameral amphotericin-B (7.5 mg) followed by phaco-emulsification and lens implantation was performed in our case as part of the medical treatment .
Fungal infections of the cornea continue to be an important cause of ocular morbidity, particularly in the agricultural communities of the developing world. A proper understanding of agent and host factors involved in these infections will improve the outcome of this condition. Rapid diagnosis and early institution of anti-fungal therapy is necessary to prevent ocular morbidity and blindness. Although culture helps in definite diagnosis and identification, direct microscopic detection of fungal structures in corneal scrapes or biopsies permits a rapid presumptive diagnosis.
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2]