English

Abstract

INTRODUCTION : The eye is an important organ of sensory perception. The Cornea is a clear, circular, transparent structure and continuous with the sclera, the junction between the two is called the limbus. Microscopically the cornea consists of five layers, (a) The corneal epithelium with its basement membrane, (b) The Bowman‟s layer, (c) The stroma, (d) The Descemet‟s membrane, (e) The Endothelium. The cornea is usually kept free from microbial invasion due to the intact epithelium and cleansing effect of the tears. Corneal ulceration is defined as any disruption to the intact epithelium with underlying stromal infiltration and suppuration associated with signs of inflammation, the organism either being implanted from without or from conjuctival flora. Exception to the rule are Neisseria gonorrhea and Corynebacterium diphtheria which are able to invade an intact epithelium. The possible reasons for the corneal ulceration are, (a) Trauma, (b) Infection, which again may be organism or may be an extension of the disease process from other ocular tissue, (c) Allergic conjunctivitis, (d) Autoimmune disorders. Conditions like trauma, steroid therapy and immunosuppressive states like Diabetes mellitus render the cornea susceptible to bacterial, fungal, parasitic infections. Mostly the fungal pathogens are opportunistic, they show wide range of resistance to antifungal agents and not able to overcome the problem with currently available antifungal agents. So antimicrobial susceptibility tests are mandatory to monitor the efficiency of available antimicrobial agents and the emergence of drug resistance among the fungus causing corneal ulceration. Considering the importance of corneal ulceration and its impact on vision, the present study is conducted to identify the predisposing factors of fungal corneal ulcers and the aetiological agents and antifungal susceptibility pattern, in patients attending a tertiary care Ophthalmic Hospital in Chennai. AIMS AND OBJECTIVES : 1. To find out the spectrum of fungal pathogens causing corneal ulcers in the patients attending a tertiary care hospital in Chennai. 2. To try and establish the etiopathogenesis of these infections. 3. To identify the predisposing factors for fungal corneal ulcers. 4. To evaluate the efficacy of diagnostic methods for isolation of corneal pathogens. 5. To study the sensitivity pattern of fungal isolates to the commonly used antifungal drugs. MATERIALS AND METHODS : The study was conducted to know the spectrum and etiopathogenesis of fungal organism causing keratitis and to evaluate by culture techniques in isolation of fungus causing corneal ulcer. The study group comprised of 160 patients attending the cornea clinic at Govt. Regional Institute of Ophthalmic Hospital, Chennai during the period from June 2009 to May 2010. Inclusion Criteria: (a) Patients having proven corneal ulcer on clinical examination, attending cornea clinic. (b) Both outpatient and inpatient were included in the study. (c) Patients under treatment for corneal ulcer with follow up. (d) Postoperative patients of ocular surgery with suspicion of impending corneal ulcer. RESULTS : A total of 160 patients with infectious corneal ulcer were selected for the study. 97 cases were culture positive (60.6%). (Table 1) The cases were analyzed under the following parameters. The age and sex distribution of infectious corneal ulcer was analyzed. 95 males and 65 females among these patients were studied.(Table 2). P = 0.005 significant. 88.7% (142/160) cases were found to be in age group between 10-60 years and 31.25% (50/160) of cases were in the age group of 51-60 years. Extremes of the age group showed low prevalence of corneal ulceration. (Table 3). Considering the sex distribution 61(64.21%) males and 36 (55.38%) female patients showed positive culture. A high prevalence of fungal corneal ulcers was seen among males contributing to 64.21% of cases. (Table 2). CONCLUSION : The following are the conclusions derived from the present study on the aetiopathogenesis of corneal ulcers. • Corneal ulcers are more common during 5th decade of life with male preponderance with rural background. • A variety of fungal isolates can cause infectious corneal ulceration in which Aspergillus fumigatus was the most common fungal species isolated which was susceptible to Amphotericin B, Itraconazole, Voriconazole. • Among the various predisposing factors trauma in farm workers plays a major role in producing corneal ulceration with seasonal variation. • Microscopy and culture (gold standard) should be the dictum for every case of corneal ulcer investigation in the laboratory. • Precise identification of the causative organisms and timely institution of appropriate antifungal therapy based on the prevailing sensitivity pattern of the fungal isolates could save the eye from this preventable cause of blindness which was carried out by Media education and audio visual aids to create public awareness regarding “vision and vulnerability to infection”.