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Ziyuan Liu, Pei Zhang, Cong Liu, Wei Zhang, Jing Hong, Wei Wang; Descemet’s membrane-schisis in fungal keratitis: a pathological analysis of 23 corneal buttons. Invest. Ophthalmol. Vis. Sci. 2014;55(13):6268.
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We have discovered that Descemet’s membrane (DM) could split into two layers in severe fungal keratitis. We named it “Descemet’s membrane-schisis” (DM-schisis). This phenomenon seems to be fungi-related because it has not yet been found in other infectious keratitis. It may add new knowledge about fungal keratitis pathogenesis and provide evidence for the existence of pre-Descemet’s layer. Our research was designed to investigate the morphological characteristics of DM-schisis and the collagen distributions.
The medical, microbiologic and histopathologic records of 23 patients who were surgically managed with pathology-proven diagnosis of fungal keratitis were collected. All 23 patients had microbiologic evaluation of the corneal scrapings when they presented to the eye clinic. The corneal buttons obtained from the surgeries were cut into two halves and sent for fungi culture and pathologic analysis respectively. The pathologic analysis included Periodic acid Schiff staining and immunofluorescence staining. The morphological characteristics of DM-schisis and the distribution of fungi elements and inflammatory cells were recorded. The stromal inflammation was graded. The collagen I and IV distributions within DM-schisis were also studied.
The microbiologic and pathologic evaluation of all 23 patients proven the diagnosis of fungal keratitis. Pathologic analysis revealed four types of DM-schisis. Type I, thin cleft, showed a narrow and long cleft within the DM. Type II, lamellar defect, showed a partial lamellar DM missing. Type III, total separation, showed the DM separated into two distinct strands. Type IV, local attenuation showed a local gradual thinning of DM. Instead of fungi involvement, it was the inflammation degree of the stroma that influenced DM status. Severe inflammatory infiltrates in posterior stroma, which always had inverse relationship with fungi distributions, caused DM-schisis. Immunofluorescence staining confirmed that both strands of DM-schisis contained type I and type IV collagens but with different distributions and proportions.
DM could spontaneously separate into two layers in severe fungal keratitis. The posterior stroma inflammation seemed to be closely related to the separation.It could be attributed to collagen degeneration in the two layers in the presence of inflammation suggesting different defending capacity of them.
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