A young man aged 30 years, presents with difficulty in vision in the left eye for the last 10 days. He is immunocompetent, a farmer by occupation, comes from a rural community and gives history of trauma to his left eye with vegetative matter 10-15 days back. On examination, there is an ulcerative lesion in the cornea, whose base has raised soft creamy infiltrate. Ulcer margin is feathery and hyphate. There are a few satellite lesions also. The most probable etiological agent is:
C i.e. Fusarium The points in our of fungal (Fusarium) corneal ulcer include history of trauma to eye with vegetative matter, mild symptoms with greater signs, feathery /fluffy margins, hyphate ulcer, satellite lesions, yellow line/ring of Wesseley and thick, immobile, big pseudohypopyon. It is more common in rural /agricultural areas of developing tropical countries. Keratomycosis/ Fungal (Mycotic) Corneal Ulcer Etiology Filamentous septate hyphae (tubular projections) producing multicellular fungi, most notably, Fusarium and Aspergillus (fumigatus) are the most common causative organism in tropics (or hot climate) and around the word - Unicellular budding yeast eg Candida is most common cause of fungal keratitis in temprate (cold) regions. Predisposing Factors - Injury by vegetative materials or animal tail are common modes of infectionQ. - Antibiotics disturb the symbiosis between bacteria & fungi; and the steroids make fungi facultative pathogens by decreasing local immunity. Therefore excessive use of these drugs result in fungal infections. Corneal trauma often tril, involving plant matter or gardening / agricultural tool (in tropics); corneal disease, local immunosuppression, long term use of topical steroid, prior corneal transplantation, contact lens wear, systemic immune suppression and diabetes (in temperate zones). Clinical Features - Symptoms are much tnilder than the clinical signs would suggestQ -.There is marked ciliary, & conjunctival congestion but symptoms of pain, watering and photophobia are dispropoionately less (as compared to those with bacterial corneal ulcer) - Presents with a gradual onset of pain, grittiness, photo phobia, blurred vision and watery or mucopurulent discharge. - The ulcer is dry-lookingQ, grayish white with elevated rolled out margins and feathery finger like extensionsQ into surrounding stroma under intact epithelium. - A sterile immune ring (yellow line of Wesseley)Q present where fungal antigen and host antibody meet. - Multiple small satellite lesions Q may be present around ulcer (feathery /fluffy margins with satellite lesions) - A big hypopyon is present even if the ulcer is very small. Unlike bacterial ulcer the hypopym may not be sterile (pseudohypopyon) Q as fungi can penetrate into anterior chamber without perforation. Hypopyon is thick and immobile d/t direct invasion and enmeshing of fungal hyphae. Perforation is rare & corneal vascularization is conspicuously absent. Q Diagnosis Examination of wet KOH Q calcofluor white, for fungal hyphae and culture on Sabouraud's agent. Treatment - Topical antifungal eg. natamycin, Amphotericin B drops. - Oral agents are used in severe ulcer and there is suspicion of endopthalmitis.
Acanthamoeba
Corynebacterium diphtheriae
Fusarium
Streptococcus pneumoniae