Weighing the Options in Cataract and Corneal Endothelial Disease

Increased demand for triple-DMEK necessitates new surgeon strategy. Dermot McGrath reports from Milan

Several viable options exist for the surgical treatment of patients with concomitant cataract and corneal endothelial disease, but no “one size fits all” approach exists to consistently deliver optimal outcomes for these complex cases, according to Björn Bachmann MD, PhD, FEBO, FEBO-CR.

Dr Bachmann noted the increasing demand in recent years for so-called triple Descemet membrane endothelial keratoplasty (DMEK) surgery, which combines phacoemulsification, IOL implantation, and DMEK in one procedure.

“There is a significant and growing population of patients with cataract and corneal endothelial diseases, and we need to have a strategy to be able to deal with them in the future,” he said, adding that the key question is whether combined (triple-DMEK) or sequential cataract surgery and endothelial keratoplasty is the best approach for these patients.

PROS AND CONS “All surgical approaches have their advantages and disadvantages,” he said. “The advantages of triple-DMEK are that phacoemulsification and lens implantation does not affect the graft while the downside is inaccurate IOL calculation and variable pupil size during DMEK with this approach.”

Before DMEK in patients with marked FECD, elevation maps show depression of the posterior surface. After DMEK, the posterior surface curvature may transform into excess elevation leading to an altered postoperative posterior to anterior corneal curvature radii ratio (as demonstrated by Diener et al. Graefes Arch Clin Exp Ophthalmol 2020).

Before deciding the optimal approach, it is important to establish both cataract surgery and endothelial keratoplasty are indeed required. The LOCS III classification for cataract is not always well correlated with visual impairment, and phakic patients after DMEK need cataract surgery within two years in 40% of cases, Dr Bachmann said. Likewise for endothelial keratoplasty surgery, the Krachmer system or more advanced grading systems are not always well correlated with visual impairment. And, there are limited predictive parameters for endothelial decompensation by cataract surgery.

There are two options for sequential surgery, said Dr Bachmann: cataract surgery and then DMEK surgery, or DMEK surgery followed by cataract surgery.

“The advantage of the first approach is that DMEK may be avoided if the patient is satisfied and comfortable after cataract surgery alone. The disadvantage is the possibility of further endothelial decompensation and corneal opacification while waiting for DMEK. And there is also the risk of a hyperopic shift if the patient does proceed to have DMEK surgery.”

If inversed, with DMEK performed first, he said the main advantage is improved predictability of IOL calculation, while the downside is the cataract surgery will decrease the endothelial cell density of the DMEK graft.

“DMEK first is a suitable approach for younger patients with corneal oedema, corneal opacification, and a clear lens. It is also appropriate for patients with massive corneal opacification as the improved visualisation after corneal clearing increases safety during cataract surgery,” he said.

Based on the available evidence and his own clinical experience, Dr Bachmann said triple-DMEK is a viable option in patients with pronounced corneal oedema and cataract with both causing significantly reduced visual acuity.

“These patients will benefit in quality-of-life gain through rapid success with combined surgery, although it is important to take into account the presumed postoperative posterior to anterior corneal curvature radii ratio to ensure optimal outcomes,” he said.

Patients with mild corneal oedema and mild cataract might be bothered by postoperative refractive error, he said.

“Consider DMEK first in extremely demanding patients and again take into account the true posterior to anterior corneal curvature radii ratio for the IOL calculation.”

For patients without corneal oedema and with cataract, Dr Bachmann advised cataract surgery first to see whether the problem sufficiently resolved and transplant surgery might be avoided.

Björn Bachmann MD, PhD, FEBO, FEBOS-CR is a Consultant Ophthalmologist at the Department of Ophthalmology, University of Cologne, Germany. bjorn.bachmann@uk-koeln.de