In the JournalsPerspective

Pre-Descemet’s corneal layer discovered

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.

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.

    Perspective

    Harminder Dua’s description of the new layer between Descemet’s membrane and the stroma helps explain the observations of big bubbles popping when they reach about 8 mm in diameter as well as the differences in bubbles which form in the periphery of the cornea compared to those in the center. 

    It will be interesting to see when Dua’s layer develops and if it is part of Descemet’s or the stroma.  More importantly, separating it along with Descemet’s membrane during preparation of DMEK donor grafts could allow for both thicker corneas and the ability to use tissue from younger donors.

    Massimo Busin’s technique for harvesting DMEK grafts with a big bubble instead of stripping Descemet’s membrane will need to be re-examined to see if donor tissue can be harvested without bubble ruptures from bubbles forming in the periphery.

    • Francis W. Price Jr., MD
    • OSN Cornea/External Disease Board Member

    Disclosures: Price has no relevant financial disclosures.