Considering keratoconus-like changes after DMEK in Fuchs' dystrophy

This article was reviewed by Jeffrey Tapley, MD

In patients with endothelial dysfunction, performing Descemet membrane endothelial keratoplasty (DMEK) rapidly deturgesces an edematous cornea. In some cases that deturgescence reveals posterior corneal steepening similar to keratoconus, but the authors note recent studies have shown there is no genetic overlap between Fuchs’ dystrophy and keratoconus.

A retrospective review was performed to describe changes in corneal thickness, and identify the incidence of posterior corneal changes characteristic of keratoconus, following DMEK surgery.

Study

The study was a retrospective chart review that included 50 eyes that received cataract surgery and 50 eyes that received DMEK for Fuchs’ Dystrophy. Scheimpflug images (done with an Oculus Pentacam) for each eye were reviewed. For the DMEK group, follow up Pentacam images from 6 months and 1 year were used. The central corneal thickness (CCT) of the preoperative cataract surgery eyes served as normal controls and was compared to the CCT of the postoperative DMEK eyes.

The 6 month and 1 year postoperative Pentacam images in the DMEK group were also reviewed for posterior elevation changes and localized steepening, characteristics that resemble keratoconus. Mean age, gender, preoperative CCT, and postoperative peripheral corneal thickness (PCT) were recorded. Statistical significance comparing CCT, PCT, and CCT:PCT was determined using the Student’s T-test.

The study found:

• Normal CCT from the 50 control eyes was 543 µm ± 35 µm. The 6-month postoperative CCT in the DMEK group was 534 µm±35 µm (P=0.23) and the 1-year CCT was 536 µm ± 35 µm (P=0.33).
• 19 out of 50 DMEK eyes (38%) had posterior steepening resembling keratoconus at the 6 month visit.
• A subgroup analysis of the preoperative CCT from those 19 eyes vs 31 eyes without keratoconus-like changes was not statistically different (611 µm ± 51 µm vs 615 µm ± 56 µm, P = 0.80).
• All 19 of those eyes had the same posterior corneal changes at the 1 year visit.

Conclusion

The authors concluded that CCT after DMEK was not statistically different compared to normal corneas at 6 months and 1 year postoperative. Localized posterior corneal steepening characteristic of keratoconus was seen in 38% of DMEK corneas at 6 months following surgery. The localized steepening persists out to 1 year postoperative, suggesting that there may be structural loss in the stroma. The steepening was not a function of preoperative CCT or postoperative PCT, and the authors believe it is likely a consequence of stromal keratocyte apoptosis due to chronic edema.

Limitations of the study include its retrospective nature and the small sample size, and it is noted that future studies should be performed focusing on identifying predictive factors for these corneal changes.

Jeffrey Tapley, MD

jltapley1@gmail.com

This article is based on Tapley’s presentation at the ARVO 2021 virtual annual meeting. Tapley has no financial disclosures.