Single, Double, or Triple? Surgery for Patients with Fuchs’ Dystrophy and Cataract

Choosing cataract surgery over a triple procedure depends on shared decision making. Cheryl Guttman Krader reports

Should a patient with cataract and Fuchs’ endothelial corneal dystrophy undergo cataract surgery alone or with endothelial keratoplasty (EK)? In the absence of data to support evidence-based practice, patients should be fully informed of the pros and cons of both approaches and the decision should be tailored to meet patient expectations, advised Mor Dickman MD, PhD.

“Significant costs can be avoided, and scarce donor corneas spared if the patient’s vision can improve with cataract surgery alone, but endothelial cell loss after cataract surgery complicates the decision to perform only cataract surgery,” Dr Dickman said.

Staged or simultaneous corneal transplantation exposes patients to risks of graft dislocation, graft failure, and indefinite immune suppression. However, the threshold for a triple procedure is lowered by choosing Descemet Membrane Endothelial Keratoplasty (DMEK), which has a better risk-benefit ratio than Descemet Stripping Automated Endothelial Keratoplasty (DSAEK) or penetrating keratoplasty, he noted.

ASSESSING THE SITUATION Determining whether Fuchs’ or cataract is the primary cause for the patient’s visual complaints is hampered by the fact that the two conditions have overlapping symptoms. There are also limitations for considering Fuchs’ severity based on morphological staging criteria, central corneal thickness (CCT), or endothelial cell density.

However, a revised Fuchs’ severity classification proposed in 2018 by Sun et al can be helpful in guiding surgical decisions for eyes that do not have clinically evident oedema. The topographic classification considers irregularity of the isopatches, displacement of the thinnest point of the cornea, and posterior surface depression towards the anterior chamber. The risk of Fuchs’ progression and need for intervention, including after uncomplicated cataract surgery, increases according to the number of parameters present, Dr Dickman explained.

He also noted surgeons should not underestimate the effect of corneal guttata on straylight because it can result in disturbing symptoms despite good subjective high contrast visual acuity.

“We found that DMEK improves straylight and vision-related quality of life to age-normal levels,” Dr Dickman said.

CATARACT SURGERY TECHNIQUE Evidence supports using the soft-shell technique to protect the endothelium when performing cataract surgery in eyes with Fuchs’. According to the findings of a randomised controlled study conducted by Dr Dickman and colleagues, torsional phacoemulsification reduces surgical time and ultrasound energy when compared to longitudinal phacoemulsification. There are no benefits with torsional phacoemulsification, however, for reducing the risk of corneal decompensation.

Only preoperative CCT predicted the need for DSAEK postoperatively. For each 10-micron increase in CCT above 620 microns, the probability of corneal decompensation increased with an odds ratio of 1.7, he reported.

Results from two seminal randomised clinical trials show no endothelial safety benefit from choosing femtosecond laserassisted cataract surgery over conventional phacoemulsification.

ADDRESSING BOTH CONDITIONS If the surgeon decides to perform both cataract surgery and DMEK, there are pros and cons to consider for a sequential approach—starting with the cataract procedure and for simultaneous surgery. A sequential approach has the advantage of a more stable iris lens diaphragm. With a triple procedure, patients benefit from having both procedures done in a single session.

EK is associated with short-term risks of graft detachment and primary graft failure. In the long term, graft rejection is less frequent when choosing DMEK. Using topical steroids for immune suppression after EK results in ocular hypertension in one-fourth of patients. Because the endothelial cell count deteriorates over time, a repeat transplant may be needed, especially if the patient was young at the time of the primary surgery.

When choosing a triple procedure, surgeons should make a smaller capsulorhexis to prevent IOL prolapse. Meticulous viscoelastic removal is essential to prevent graft detachment.

Whether the two surgeries are staged or done in the same session, there should be consideration for the risk of a hyperopic shift when choosing an IOL, Dr Dickman stressed.

Data from pseudophakic patients in a randomised controlled trial conducted by Dr Dickman and colleagues show the shift is about 0.25 to 0.5 D with DMEK and about 0.5 to 0.75 D with ultra-thin DSAEK. These numbers correspond to a 0.35 D hyperopic shift found in a recent real-world registry study of DMEK in the Netherlands, Dr Dickman said. Looking at the Q value can also be helpful for avoiding a refractive surprise.

“Oedematous corneas are oblate, have a positive Q value, and are at increased risk for a profound hyperopic shift after surgery,” Dr Dickman explained.

When combining cataract surgery and DMEK, results from several studies did not show differences in refractive outcomes comparing triple and sequential procedures. One retrospective study suggested the triple procedure carries a higher risk of early graft detachment, but the data are controversial. The authors of another study concluded that pseudophakia, not cataract surgery, increases the risk of graft detachment. The same authors also reported that using 20% SF6 gas instead of air tamponade decreased the risk of detachment.

“We also reported in a recently published study that a triple procedure was not a risk factor for rebubbling and primary graft failure,” Dr Dickman reported.

This presentation was made at the 12th EuCornea Congress. Mor M Dickman MD, PhD, is Professor of Ophthalmology, Maastricht University Medical Centre, the Netherlands. mor.dickman@mumc.nl