Two surgical techniques for corneal transplant (replacing the clear part of the eye with donor tissue)

Citation: Stuart AJ, Romano V, Virgili G, Shortt AJ. Descemet's membrane endothelial keratoplasty (DMEK) versus Descemet's stripping automated endothelial keratoplasty (DSAEK) for corneal endothelial failure. Cochrane Database of Systematic Reviews 2018, Issue 6. Art. No.: CD012097. DOI: 10.1002/14651858.CD012097.pub2

What is the aim of this review?
The aim of this Cochrane Review was to compare two different ways of doing corneal transplant surgery: Descemet’s membrane endothelial keratoplasty (DMEK) and Descemet’s stripping automated endothelial keratoplasty (DSAEK). Cochrane Review authors collected and analysed all relevant studies to answer this question and found four studies.

Key messages
DMEK may result in better vision compared with DSAEK. DMEK may be associated with more complications but these complications do not occur often and can be managed without further surgery.

What was studied in the review?
The cornea is the clear (transparent) front part of the eye. In some conditions, for example, Fuch's endothelial dystrophy, the cells that line the inside of the cornea (endothelium) stop working so well. This can lead to cloudy vision. Doctors can restore vision by doing a corneal transplant which means replacing the corneal tissue with donor tissue. When the endothelium only is replaced this is known as 'Descemet’s membrane endothelial keratoplasty' or DMEK. An alternative corneal transplant is to replace the endothelium and the next layer of tissue in the cornea as well. This is known as 'Descemet’s stripping automated endothelial keratoplasty' or DSAEK.

Cochrane Review authors aimed to find out whether vision is better after DMEK or DSAEK, and how the techniques compare with respect to surgical complications.

What are the main results of the review?
The Cochrane Review authors found four studies. These studies included people who had DSAEK in their first eye to receive a corneal transplant followed by DMEK in their second eye to have a transplant. The studies were from Canada, Germany, India and the USA. None of the studies were supported by sponsors with a commercial interest.

The Cochrane Review authors judged the evidence to be low- or very low-certainty because there may be differences between the first eye and second eye surgeries (other than DMEK or DSAEK) and, in some cases, the data were limited or inconsistent.

The results were:

• DMEK may result in better vision compared with DSAEK (low-certainty evidence). This difference is equivalent to reading one or two lines more on a vision chart.
• None of the people taking part in these studies had severe vision loss after surgery. Severe vision loss was defined as vision worse than 6/60 or 20/200. There were not enough people enrolled in these studies to measure reliably this infrequent outcome (very low-certainty evidence).
• The studies measured how many cells there were in the endothelium after surgery but found inconsistent results (very low-certainty evidence).
• Almost everyone taking part in the studies had good graft survival, with very few graft rejections and no graft failures. There were not enough people enrolled in these studies to measure reliably these infrequent outcomes (very low-certainty evidence).
• DMEK may be associated with more early surgical complications. Graft dislocation may happen in one or two out of 100 people with DSAEK and about five times more often with DMEK. This difference was not measured reliably and could be smaller or much larger (very low-certainty evidence). Graft dislocation occurs within days or weeks after surgery and is usually treated with an injection of air into the eye ('re-bubbling').

How up-to-date is this review?
Cochrane Review authors searched for studies that had been published up to August 2017.