Selective Keratoplasty: Current Status and Future Directions

Specialists shared the various ways they treat corneal disease by just transplanting what they need and not disturbing healthy tissue, on the second day of the ESCRS 2022 Winter Meeting. 

Penetrating Keratoplasty vs Lamellar Keratoplasty

The first speaker, Dr. Paulo Guerra from Portugal, talked about the evolution of anterior and posterior lamellar keratoplasty and noted that in recent years, there has been an impressive development in corneal transplants. Penetrating keratoplasty (PK) has been progressively abandoned and replaced by lamellar transplantation, which offers huge advantages — and it addresses several disadvantages associated with PK, including high irregular astigmatism and poor refractive outcomes, graft rejection and suture-related problems, among others. 

He explained that keratoplasty can be divided into anterior lamellar keratoplasty (ALK), which selectively replaces diseased corneal stroma while preserving the endothelium; and posterior lamellar/endothelial keratoplasty (EK), which is targeted to replace damaged endothelium in endothelial disorders. ALK procedures include superficial anterior lamellar keratoplasty (SALK), deep anterior lamellar keratoplasty (DALK) and Bowman layer transplantation (BLT). Meanwhile, EK includes Descemet stripping endothelial keratoplasty (DSEK) and Descemet membrane endothelial keratoplasty (DMEK).  

“Although DALK is more technically challenging, it has several clear advantages over PK. Meanwhile, EK has revolutionized the treatment of corneal endothelial dysfunction, setting a high standard for safety and efficacy. The shortage of human donor corneas has prompted an investigation into the injection of cultured human corneal endothelial cells (hCEC) with initial favorable results. Although lamellar keratoplasty is here to stay, PK will remain for a ‘cloudy day’,” he said. 

As for Prof. Dr. Berthold Seitz from Germany, he shared that PK still has a role to play due to “timeless indications,” such as in eyes with macular dystrophy, high irregular astigmatism with stromal thinning and acanthamoeba ulcer. He added that excimer lasers have been used in PK for over 32 years to improve visual acuity. 

DALK 

Speaking on DALK, Dr. James Myerscough from the United Kingdom said that ectasia recurrence post-keratoplasty is manifested as the loss of best-corrected visual acuity (BCVA) in clear PK caused by late keratoconus recurrence in recipient cornea. “In these eyes, we have progressive peripheral thinning with wound elongation, which causes anterior chamber deepening, and progressive high myopia and astigmatism with eventually worsening of the BCVA. The ideal solution should be able to reshape the anterior curvature of the cornea, retain healthy endothelium and add tissue volume to address thin periphery,” he said, giving examples of procedures that were performed to address this problem, such as the Melles technique, the small-bubble deep anterior lamellar keratoplasty and stromal peeling.

DSAEK

Meanwhile, Dr. Mor M. Dickman from the Netherlands reported on a randomized controlled clinical trial he and colleagues did on the role of ultrathin Descemet’s stripping automated endothelial keratoplasty (DSAEK).¹ In this trial, 54 pseudophakic eyes of 54 patients with corneal endothelial dysfunction resulting from Fuchs’ endothelial corneal dystrophy were enrolled in six corneal centers in the Netherlands. Participants were allocated to DMEK (n = 29) or UT-DSAEK (n = 25) using minimization randomization based on preoperative best spectacle-corrected visual acuity (BSCVA), recipient central corneal thickness, gender, age and institution. Donor corneas were prestripped and precut for DMEK and UT-DSAEK, respectively.

“The UT-DSAEK versus DMEK randomized clinical trial found no significant difference in mean BCVA at one year, but a higher percentage of DMEK reached a VA of above 0.8. Endothelial cell loss was comparable in both techniques, stabilizing after three months. A similar mild hyperopic shift was found after both techniques (<0.5), while more complications were seen following DMEK (24% versus 4% of rebubbling). DMEK provides faster recovery of contrast sensitivity and straylight, with ultrathin DSAEK catching up after three months. Before surgery, VA is poor in both groups. After surgery, VA improves significantly and there’s no significant differences in generic vision-related quality of life in both groups,” he said. 

DMEK

According to said Prof. Marc Muraine from France, the advent of DMEK has completely changed the management of endothelial pathologies. The procedure offers impressive results from the first postoperative weeks itself. “There is a low complication rate, a 1% rejection rate, and a significant number of patients were able to reach 20/20 vision,” he said. 

While the Melles peeling technique remains the most popular, other surgeons have proposed their own methods with similar results. “For example, we are the first to describe the DMEK technique using hydrodissection and injection with the endothelium inward,” he said. Other methods include Hemi-DMEK and Quarter-DMEK, and they provide equivalent results. 

“Today, preloaded DMEK grafts are available, making the procedure safer and faster. Studies showed that the results of using preloaded DMEK grafts are identical to surgeon-prepared grafts.² These improvements explain the significant increase in the number of DMEK done worldwide in just a few years,” he noted. 

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