Dua’s Layer: its discovery, characteristics and applications

Definitive treatment for loss of corneal transparency or for corneal distortion is a corneal transplant. When the sight affecting pathology lies in the corneal stroma, deep anterior lamellar keratoplasty (DALK) allows retention of the healthy recipient endothelium and Descemet’s layer. The “Big Bubble” (BB) technique described by Mohamed Anwar is the most popular Descemet’s baring technique worldwide. It involves the injection of air into the corneal stroma, thus stripping the DM from the deep stroma and allowing excision of the affected tissue. Over nearly a decade of performing DALK by the BB technique, a number of clues pointed to a novelty in the surgical anatomy of the posterior cornea which, after characterisation, was termed the Dua’s layer. This report summarizes the events that suggested the existence, provided evidence, and finally led to the characterisation of the Dua’s layer, along to its clinical relevance and the applications of this discovery. J Emmetropia 2014; 5: 211-223 1Academic Ophthalmology, Division of Clinical Neuroscience, School of Medicine, University of Nottingham, England. Financial disclosure: The authors have no commercial or financial interests in the medical findings derived from this study. Copyright Authorization: All reproductions from the British Journal of Ophthalmology and from Ophthalmology are in accordance with the journal policies wherein authors are permitted to reproduce parts of their own publications for other publications such as book chapters with due acknowledgement to the source. Corresponding Author: Harminder S. Dua Room Division of Ophthalmology and Visual Sciences B floor, Eye ENT Centre, Queens Medical Centre, Derby Road Queen’s Medical Centre Nottingham NG7 2UH Email: [email protected] UPDATE/REVIEW Loss of corneal transparency or corneal distortion leading to visual impairment and blindness can occur for two main reasons – stromal disease with or without scarring and endothelial disease with consequent corneal hydration. The definitive treatment for these conditions is a corneal transplant. The first human corneal transplant was performed more than a hundred years ago1. The initial emphasis was on lamellar grafts wherein the anterior scarred layer of the cornea was replaced by a similar layer of clear tissue taken from a donor cornea. Full thickness corneal grafts or penetrating keratoplasty, to manage both stromal and endothelial disease, then became the norm and remained as the standard of care for most of the one hundred years, despite its many well recognised problems. Major problems include a prolonged visual recovery time, weaker structural integrity of the eye rendering it susceptible to rupture following trivial trauma, high astigmatism and graft rejection and failure. Inventions and innovations in eye banking, technology and instrumentation, particularly in the last decade have enabled refinements in corneal transplantation that address many of the problems mentioned above. When the endothelium is affected, specific replacement of the endothelial layer can be undertaken in the procedures termed Descemet’s stripping endothelial keratoplasty (DSEK) and Descemet’s membrane endothelial keratoplasty (DMEK)2,3. Endothelial transplantation allows for very rapid visual recovery, is astigmatically neutral, does not weaken the eye and also appears to have a reduced incidence of rejection. When the sight affecting pathology lies in the corneal stroma, it is no longer necessary to replace the entire cornea. Deep anterior lamellar keratoplasty (DALK) allows retention of the healthy recipient endothelium and Descemet’s layer while replacing the entire stroma and epithelium2-5. This virtually eliminates the risk of rejection related graft failure