DMEK borrows tricks from retina surgery for better results

An air pump, a light pump and vitrectomy may help DMEK surgeons.

Issue: September 25, 2018

ByJack S. Parker, MD, PhD

ByKristen Peterson, MD

The innovations are piling up in Descemet’s membrane endothelial keratoplasty surgery. Perhaps as a consequence, the operation has been leaping in popularity, especially in the United States. A few tricks recently borrowed from retina surgeons promise to make the operation even faster and more enjoyable.

1. Air pump assist: It is often best to perform the descemetorhexis under air because air provides the best contrast and because this minimizes the chances of leaving Descemet’s membrane remnants behind. The problem with stripping under air is that — with just an air fill — the anterior chamber tends toward instability, particularly in eyes with significant posterior pressure.

An air pump solves this problem. With an anterior chamber maintainer connected to a vitrectomy machine and air infusion set to 30 mm Hg, the eye is nearly immune to collapse during all scoring and stripping maneuvers (Figure 1). This dramatically reduces the operating time and the number of surgical manipulations, improves the chances of removing the whole host Descemet’s membrane en masse, and avoids overhydrating the posterior stroma as may occur if fluid is used for anterior chamber maintenance instead (a tactical misstep that may predispose to graft detachments).

2. Light pipe assist: Even when using air for contrast, Descemet’s membrane remnants can hide — for example, as dangling strips or dehisced sheets spread out across the iris. These lingering shreds may degrade the optical quality of the eye after surgery or even complicate the operation itself by interfering with graft unfolding.

Figure 1. Descemetorhexis with air pump assist.

Figure 2. Light pipe illumination of hidden posterior corneal irregularities.

Figure 3. Vitrector-created peripheral iridotomy (green arrow).

A light pipe spotlights these sneaky pieces: It functions like a search beam, providing directed (rather than diffuse) illumination, further boosting the contrast between disparate tissues (Figure 2).

3. Vitrectomy assist: Many DMEK surgeons fashion peripheral iridotomies to discourage postoperative pupillary block, and the vitrector is ideal for this purpose. It behaves as though it were custom-designed for the task: With a one-handed operation, it effortlessly munches small, perfectly circular openings in the far peripheral iris, with far more precision and less trauma (and bleeding) than either intraocular scissors or needle “scratch-down” maneuvers (Figure 3).

As a bonus, it is not uncommon to encounter vitreous when doing DMEK in a pseudophakic eye with an open posterior capsule; with the vitrector already in hand, this otherwise unpleasant discovery is reduced to a non-issue.

Since deciding to use the vitrectomy machine for all of our routine DMEK surgeries, our operating times have plummeted. Moreover, the surgeries are more fun. Try it — we bet you will like it.

References:
Chamberlain W, et al. J Clin Exp Ophthalmol. 2016;doi:10.4172/2155-9570.1000608.
Gabbay IE, et al. Graefes Arch Clin Exp Ophthalmol. 2017;doi:10.1007/s00417-017-3675-0.
Gonzalez A, et al. Cornea. 2016;doi:10.1097/ICO.0000000000001015.
Güell JL, et al. Cornea. 2013;doi:10.1097/ICO.0b013e3182933aee.
Jacob S, et al. Cornea. 2017;doi:10.1097/ICO.0000000000001225.
Jacob S, et al. J Cataract Refract Surg. 2014;doi:10.1016/j.jcrs.2014.06.019.
Kobayashi A, et al. Clin Ophthalmol. 2015;doi:10.2147/OPTH.S74981.

For more information:
Jack S. Parker, MD, PhD, can be reached at Parker Cornea, 700 18th St. South, Suite 503, Birmingham, AL 35233; email: jack.parker@gmail.com.

Disclosure: Jack Parker reports he is a consultant for DORC International/Dutch Ophthalmic USA and Ziemer Ophthalmic Systems.