How endothelial cell loss in DSEK compares to PK

Reviewed by Marianne O. Price, PhD

Indianapolis-Endothelial keratoplasty (EK) has been steadily gaining in popularity over the past decade, and as of 2012, topped the charts, with more EK procedures performed in the United States compared with penetrating keratoplasty (PK).

Descemet stripping endothelial keratoplasty (DSEK) is the most popular of the EK procedures performed in the United States.

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An initial evaluation of the DSEK outcomes after 5 years suggested that endothelial cellular loss might be less over the long run than that observed with PK and suggested better midterm endothelial cell survival, Marianne O. Price, PhD, recounted from a 2011 study (Ophthalmology. 2011;118:725-729).

A more recent single-center, retrospective, longitudinal study, which is forthcoming in Ophthalmology, sought to model DSEK cell loss over 10 years postoperatively and identify factors associated with the cell loss; they compared the findings to cell loss at that same time point in patients who underwent PK in the Cornea Donor Study (Lass JH, et al. Arch Ophthalmol. 2011;129:1149-1154).

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Both procedures are indicated to treat patients with Fuchs’ endothelial corneal dystrophy and pseudophakic or aphakic corneal edema.

The investigators analyzed 752 eyes of 590 patients (age range, 21-96 years) who underwent DSEK, and the data on donor age, and baseline endothelial cell density (ECD) and recipient age, gender, graft indications, and postoperative ECD were studied at 6 ± 3 months, 12 months (-3 to +6 months), and annually from 2 to 10 years, each ± 6-months). All study patients had undergone one or more evaluations between 6 months and 10 years after the surgeries, which were performed by six surgeons. The main outcome measure was the central corneal ECD.

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The investigators used the four statistical models of cell loss that were used with the Cornea Donor Study PK data. All four models showed a similar linear decline in ECD from 6 months to 10 years after DSEK.

Median cell loss

However, the Bayesian Markov chain Monte Carlo model was preferred, because it accounted for missing data, correlations between fellow eyes and the longitudinal repeated measures, and selective dropout from graft failure, according to Dr. Price.

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Dr. Price reported that after DSEK the median perioperative cell loss was 32% (based on comparison of the 6-month postoperative ECD with the baseline donor ECD) and then the ECD stabilized with annual declines of about 110 cells/mm².

The most important finding was that the median cumulative ECD loss over the 10 years following DSEK was 71%, which was comparable to that after PK, i.e., 76%, in patients treated for similar diseases. This finding was despite the thesis that DSEK would result in less loss of ECD, based on the findings at 5 years.

Dr. Price and colleagues pointed out that the patterns of the ECD loss associated with the two procedures differed, which underscores the need for long-term follow-up of patients who undergo these procedures.

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With PK the decline was initially rapid, reached a median of 70% at 5 years postoperatively, and then slowed substantially. (Figure 1)

In patients who underwent DSEK, the 10-year median endothelial cell count was higher than that seen at 5 years after PK, so it still needs to be determined if the ECD after DSEK will ultimately stabilize at a low level of about 500 cells/mm² as occurred after PK.

“Longer follow-up will be needed to see if that happens between 10 and 15 years after DSEK,” said Dr. Price, who noted that the study is being extended.

Marianne O. Price, PhD

E: marianneprice@cornea.org

Dr. Price was joined in the study by Peter Calhoun, MD, Craig Kollman, PhD, Francis W. Price Jr., MD, and Jonathan Lass, MD. The authors have no proprietary interest in any aspect of this study.