Surgical Treatment for Fuchs’ Dystrophy

While not a replacement for Descemet membrane endothelial keratoplasty (DMEK), Descemet stripping only (DSO) could be a useful surgical option for patients with Fuchs’ dystrophy.

Nino Hirnschall MD, PhD discussed patient selection, surgical factors affecting the corneal clearance rate, Rho-kinase inhibition as adjuvant medical therapy, and genetic screening at a recent conference.

“Size of the descemetorhexis matters a lot, and with use of a Rho-kinase inhibitor, corneal clearance can be achieved in about 80% of cases. Then, in the future, it may be possible to increase this rate by excluding unsuccessful cases through TCF4 screening,” he said.

POTENTIAL CANDIDATES Dr Hirnschall observed that DMEK is still the gold standard procedure when surgery is indicated for patients with Fuchs’ dystrophy. However, DSO might be something to consider in patients with severe glaucoma for whom there is a concern about any IOP spike or for patients who cannot lie flat on their back for any reason. In addition, DSO might be something to offer patients who decline DMEK because they reject the idea of having any transplant.

“And, if there is a shortage of corneal grafts, which could be the case in the future, DSO may be the way to go,” Dr Hirnschall said.

TECHNICAL ISSUES Early reports of outcomes after DSO showed low success rates. But in those series, the descemetorhexis size measured 6 to 8 mm. A subsequent series achieved a higher rate of corneal clearance with a 3- to 4-mm descemetorhexis for DSO.

Avoiding stromal contact during Descemet removal is also paramount to success because surgical trauma to the stromal tissue is believed to stimulate fibrosis that will serve as a barrier to the migration of endothelial cells from the periphery to the centre. In a video, Dr Hirnschall presented the preferred peeling technique for descemetorhexis instead of a scoring technique to avoid stromal trauma.

POSTOPERATIVE CARE Supplementary treatment with ripasudil 0.4% (Glanatec®, Kowa Pharma) or another topical Rho-kinase inhibitor has also been identified as important for increasing the corneal clearance rate after DSO and accelerating the time to clearance. Average time to corneal clearance is eight to 10 weeks without the medical treatment but reduces to about three weeks with use.

The Rho-kinase inhibitor drops must be continued for a period post-clearance to prevent relapse of corneal oedema and should not stop abruptly. Dr Hirnschall suggested using the medication for a minimum of six weeks or for four weeks after achieving corneal clearance. Then, the dosing regimen should be tapered slowly in the same fashion as would be done for a steroid after DMEK but should restart in case of relapse.

In following patients at the slit-lamp after DSO, surgeons should see an expanding clear zone between the descemetorhexis margin and a contracting area of epithelial oedema. Unique findings that emerge with topical Rho-kinase inhibitor use include a honeycomb appearance of the oedema and pseudoguttata.

“It is important to be aware that honeycomb oedema is a normal reaction to the Rho-kinase inhibitor that will disappear within one to two weeks. The pseudoguttata are also seen only during the first one or two weeks after DSO. They are part of the migration process and not a sign of recurrent Fuchs’,” Dr Hirnschall explained.

Even when topical Rho-kinase inhibitor treatment supplements DSO, 20% of patients will not achieve a clear cornea and will need to undergo DMEK, which is done by increasing the size of the descemetorhexis and then implanting the graft. Encouragingly, previous DSO does not seem to compromise the outcome after DMEK, assuming there is not a prolonged delay in performing the graft procedure.

“Waiting three months after DSO is not a problem. You should still have a good result with DMEK. However, if you wait longer to perform DMEK, perhaps one or two years, there will be a fibrotic process and poorer results,” Dr Hirnschall said.

REFINING PATIENT SELECTION In a recently published paper, Dr Hirnschall and colleagues reported on a pilot study investigating the possibility of using genetic screening as a tool to predict patients who are likely to fail DSO. The study found that having a very high allele repeat of TCF4 (≥80) alleles was associated with an 18-fold increased risk for incomplete corneal clearance after DSO.

“If we could identify patients who are most likely to benefit from DSO, it could be easier to introduce the technique,” he said.

This presentation was made at the ESCRS Virtual Winter Meeting 2022.

Nino Hirnschall MD, PhD is a clinician and researcher at the Kepler University Clinic, Linz, Austria. nino.hirnschall@kepleruniklinikum.at