Unlike other mucous membranes of the body, the conjunctiva has a limited normal bacterial flora, the only two constant inhabitants being Corynebacterium xerosis and Staphylococcus epidermidis albus, both of which are saprophytes. The mechanical cleansing action of the tears as well as their lysozyme content acts to eliminate accidental contaminants, usually bacteria from the air, as well as to inhibit the normal conjunctival flora. In the presence of acute or subacute conjunctivitis the saprophytes are often crowded out by the invading micro-organisms to such an extent that in films of secretions or scrapings of epithelium the exciting agent is found in pure or almost pure culture. This feature renders the diagnosis of conjunctivitis, by a study of films, practical and often simple.
IMPORTANCE OF AN ETIOLOGIC DIAGNOSIS
The determination of the etiology, when possible, is a fundamental principle of scientific medicine. The importance of knowing the active microbic agent
THYGESON P. ETIOLOGIC DIAGNOSIS OF CONJUNCTIVITIS. Arch Ophthalmol. 1934;12(5):676–688. doi:10.1001/archopht.1934.00830180052003
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