Get the ABCs of DSO

Descemet stripping only (DSO) is a relatively new treatment option that can be offered to select patients with Fuchs dystrophy.
It also is known as Descemetorhexis without endothelial keratoplasty (DWEK) or Descemetorhexis without grafting.

Speaking at the ASCRS-ASOA annual meeting, held May 3-7 at the Convention Center in San Diego, CA, Deepinder Dhaliwal, MD, LAc, discussed the rationale for the procedure and research that is providing guidance for choosing the best candidates and optimizing outcomes.

Dr. Dhaliwal, professor, of Ophthalmology, University of Pittsburgh School of Medicine, and director of Refractive Surgery and the Cornea Service, UPMC Eye Center, Pittsburgh, PA, explained that DSO is a technique that aims to provide corneal endothelial “rejuvenation.”

“The underlying concept for DSO is that guttae are barriers to endothelial cell migration,” she explained. “Therefore, the surgery involves simply removing the central 4 mm zone of Descemet membrane in patients with Fuchs dystrophy without placing any donor graft.”

Dr. Dhaliwal said that she decided to try DSO after reading an article about it published by Kathryn A. Colby, MD, PhD, and colleagues [Borkar DS, et al. Cornea. 2016;35(10):1267-73.].

Lessons learned

From her initial experiences, Dr. Dhaliwal said she learned some important lessons.

“First, surgeons and patients need to be prepared to see massive central corneal edema on the first postoperative day,” Dr. Dhaliwal said. “Amazingly, the cornea clears over four to 12 weeks, but because vision is markedly reduced immediately postop and can take three months to recover, patients need PATIENCE and good vision in the fellow eye.”

Preoperative counseling advises patients about the delayed return of visual function and also informs them that if the cornea does not clear, they are still a candidate for Descemet membrane endothelial keratoplasty (DMEK).

Publishing a retrospective study of their experience with DSO in patients with Fuchs dystrophy [Huang MJ, et al. Cornea. 2018;37(12):1479-1483], Dr. Dhaliwal and colleagues reported that the percentage of patients who ultimately achieved 20/40 visual acuity was not significantly different than in a comparative cohort of patients who had DMEK (93% vs. 100%).

However, the average time to reach 20/40 vision was 7.1 weeks in the DSO group but only 2.2 weeks after DMEK.

Patient selection

Early on, patient selection criteria for DSO required that the cornea be clear in the periphery and have only central involvement with Fuchs dystrophy.

“DSO is not a procedure for patients with pseudophakic bullous keratopathy,” Dr. Dhaliwal said.

Subsequently, Moloney et al. further delineated indications and contraindications [Moloney G, et al. Cornea. 2017;36(6):642-648].

According to Moloney et al. the indications for DSO require that patients be contemplating endothelial keratoplasty for Fuchs dystrophy AND have: central guttae deemed to be the chief cause of visual symptoms along with a clear peripheral cornea having an endothelial cell count >1000 cells/mm2. Advanced corneal stroma edema, presence of secondary corneal pathology, and history of herpes simplex virus or cytomegalovirus keratitis were identified as contraindications for DSO.

Improving outcomes

Moloney et al. also reported on the use of supplementation with the topical rho kinase inhibitor, ripasudil, as a salvage agent when the cornea was not clearing.
A recent prospective study from Marian Macsai, MD [Macsai M, Shiloach M. Cornea. 2019;38(5):529-534] showed that initiation of topical ripasudil 0.4% on the first postoperative day accelerated visual recovery.

In their study, that included 18 patients, Macsai and Shiloach reported that vision recovery occurred at an average of 4.6 weeks in patients assigned to use ripasudil 4 times a day for 2 months compared with at 6.5 weeks in patients who did not get the additional treatment.

The ripasudil group also had a higher average central endothelial cell density at 3, 6, and 12 months and experienced no change in the peripheral endothelial cell density whereas peripheral endothelial cell density decreased 10% in the control group.

“It is thought that the rho kinase inhibitor may be ‘awakening’ the endothelial stem cell niche, leading to some increase in the cell count and not just migration of the existing cells,” Dr. Dhaliwal said.

She suggested that the prospective study provides validation for using ripasudil for 2 months after DSO. Dr. Dhaliwal also emphasized that Descemet membrane stripping in the central 4 mm of the cornea should be done gently.

“The removal is a peeling, not a scraping like we do for DMEK. We want to ‘clean’ edges and do not want to roughen up the stromal fibers,” Dr. Dhaliwal said.

Disclosures:

Dr. Dhaliwal has no relevant financial interests to disclose.