Comment on: A novel device to visualize Descemet membrane during donor preparation for Descemet membrane endothelial keratoplasty.

Dear Editor,

We read the article by Fogla R, which described the use of a novel device with a capacity to retroilluminate the Descemet’s membrane (DM) for peeling donor grafts for Descement membrane endothelial keratoplasty (DMEK).[1] Our intention is to highlight the advantages of transillumination, which in addition to the benefits of retroillumination, also allows the visualization of donor corneal endothelial cells.

Routinely, an inverted light or confocal microscope is used by the eye banks to investigate the health and density of corneal endothelium, whereas a dissecting or stereomicroscope is used for peeling a DMEK tissue.[2] The light from a stereomicroscope is focused (built-in LED or external fiber optic) on the surface of corneal endothelium, which does not allow imaging the endothelial morphology or positive trypan blue stains especially those that are scattered. Fogla R also highlighted that analysis of endothelial cell counts could have been useful in validating the safety of the novel device. This feature can be added using transillumination. Transillumination using stereomicroscope [Fig. 1a] can be useful when the light is emitted from the base while placing the donor corneal endothelium facing the air. In addition to the advantages of retroillumination such as improved success rates, smoothening of learning curve, and avoiding complications,[1] transillumination further helps to (a) reduce corneal drying time during DMEK graft preparation (observed while using external fiber optic lights), (b) evaluate global health of corneal endothelium [Fig. 1b] after each manipulation step [Fig. 1c] accurately, and (c) provide better visibility of the tissue with or without staining, thus guiding the surgeon to avoid area with scars, tight adherences, or tears.

Figure 1

(a) Stereomicroscope used for transillumination of human donor cornea. (b) Global picture of corneal endothelial cell health observed using transillumination without staining. Deep iatrogenic folds (black arrow) observed clearly along with corneal endothelial cell morphology. (c) Trypan blue positive area showing mortality at folds (black arrow) and scattered (black arrow-dotted). Area without DM after DMEK peeling showing bare stromal region (black asterisk)

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