June 12, 2013
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Pre-Descemet’s corneal layer discovered

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A strong, acellular corneal layer exists between the stroma and Descemet’s membrane, according to a study.

The discovery may significantly alter posterior corneal surgery and affect treatment of conditions such as acute hydrops, descemetocele and pre-Descemet’s dystrophies, the study authors said.

They examined 31 human donor sclerocorneal discs, including six controls. Mean donor age was 77.7 years.

Air was injected into the corneal stroma, and three types of big bubbles were produced. Type 1 was a central, dome-shaped elevation that started in the center of the cornea and enlarged toward the periphery; type 2 was a large, thin-walled bubble that started at the periphery and enlarged centrally; and type 3 had characteristics of type 1 and type 2.

Descemet’s membrane could be peeled away without deflating type 1 bubbles, showing that Descemet’s membrane was not needed for the bubble and that another layer existed to maintain the bubble.

Histological analysis confirmed a cleavage occurred along the last row of keratocytes, revealing the pre-Descemet’s layer, called Dua’s layer, was 10.15 ± 3.6 µm thick and made of five to eight lamellae of collagen bundles arranged in longitudinal, transverse and oblique directions.

Type 2 bubbles deflated as Descemet’s membrane was stripped. The manner in which type 2 bubbles form suggests Dua’s layer ends before the end of Descemet’s membrane, the authors said.