Pathogenesis and Clinical Features of Fungal Keratitis (Review)

Abstract

In this review we presented the information about pathogenesis of mycotic keratitis and the most characteristic clinical signs that can help ophthalmologists to suspect mycotic etiology. In conditions of poor accessibility and informativeness of laboratory and instrumental diagnostic tests, the analysis of the anamnesis and the clinical signs remain the only information that can be used by a physician while making a diagnosis and choosing treating strategies. This review contains the results of a number of studies. In the review we show the progression phases of cornea mycotic infection, among them adherence, invasion, morphogenesis and toxigenicity. We also reveal that the most characteristic clinical signs of mycotic keratitis are scalloped rough edge of stromal defect, prominent dry crumby or caseous structured view of infiltrates and necrotic masses, satellite infiltrates, certain changes of color of the defected area. Heaviness of mycotic keratitis ulcer defect has a correlation with an unfavourable prognosis for disease. Mycotic keratitis during contagion can be complicated by mycotic glaucoma with a malignant disease course and endophthalmitis. There can be cases with mixed infection. While Almost No clinical sign is pathognomonic for keratomycoses, summing up all the signs can verify the diagnosis. Ophthalmologists need training in the recognition the clinical signs of infectious keratitis. Also new methods of fast diagnostics of infectious keratitis etiology and implementation on a large scale are needed.

Modern Technologies in Diagnosis of Fungal Keratitis (Review)

“…In some studies, the incidence of the Fusarium genus reached 61.9% [ 15 ], Candida — 72.22% [ 16 ]. The complaints of patients are similar: sensation of the foreign body, lacrimation, photophobia, eye reddening, blurred and reduced vision [ 17 ]. None of the symptoms is pathognomic for fungal keratitis, and it is often impossible to differentiate it from the infections of other etiology due to the similar clinical picture [ 18 ].…”

“…Probably, it is the ability of fungi to suppress the immune response that explains why in some observations the amount of inflammatory cells in the cornea is in reverse proportion to the fungal content, and in the process of fungus growth, the inflammatory process weakens [ 17 , 53 ]. Together with these significant specific features of pathogenesis, application of local corticosteroids results in the protracted course and addition of secondary infection in case of surgical treatment [ 35 ].…”

“…For example, one of the studies [ 84 ] reported negative results of inoculation and unestablished laboratory diagnoses in 37% of patients with fungal keratitis explaining the reason by antibiotic therapy administered before the admission to the hospital. It is worth mentioning that in case of positive culture detection, identification of a causative agent is successful only in 40–60% of cases [ 17 ].…”