Endothelial keratoplasty on the rise in northwestern Italy

Endothelial keratoplasty has become increasingly common in northwestern Italy, paralleling a rise in the demand for corneal surgery, researchers said.

The procedure offers advantages over penetrating keratoplasty, which it appears to be replacing, wrote Ugo de Sanctis, MD, PhD, Eye Clinic, University of Turin, Turin, Italy, and colleagues in the International Journal of Ophthalmology.

Eye banks need accurate knowledge of the changes in indications and surgical techniques in order to plan for the future. Such information can also allow comparisons among surgeons in different countries.

Researchers retrospectively reviewed indications and corneal tissue use for penetrating and lamellar surgery between 2002 and 2011 using tissues supplied by the Eye Bank of Piedmont in Italy.

The bank received reports from eight surgical centres that performed more than 90% of the corneal grafts in northwestern Italy during the study period.

For analytical purposes, the Dr. de Sanctis and his colleagues divided the study period into two 5-year periods: from January 1, 2002 to December 31, 2006; and from January 1, 2007 to December 31, 2011. They chose this subdivision because the majority of new surgical procedures were introduced in the early years of 2000.

They found the eye bank supplied 3,615 tissues for corneal grafting during the study period: 1,567 during 2002-2006, and 2,048 during 2007-2011.

Of the 3,617 surgical reports, 94.8% were complete enough to meet the researchers’ inclusion criteria. They found 58.1% of the patients were female and the mean age at the time of intervention was 67.2 years. In 49.7%, the surgery was performed in the right eye.

A shift detected

Keratoconus was the most common indication for corneal graft, accounting for 30.8% of cases.  It was followed by ABK/PBK (19.5%), graft failure (18.0%), Fuchs endothelial dystrophy (15.1%), herpetic keratitis (4.3%), microbial keratitis (4.1%), trauma (2.1%), stromal dystrophies (1.8%), and non-infectious keratitis (1%). Miscellaneous corneal disorders made up the remaining 3.4%.

However, the researchers detected a shift between the two 5-year periods. The proportion of corneal grafts for ABK/PBK, graft failure, and Fuchs endothelial dystrophy was significantly higher (P<0.05), and that for keratoconus significantly lower (P<0.05) in 2007-2011 than in 2002-2006.

Penetrating keratoplasty was the most widely used procedure over the 10-year period, accounting for 2,466 surgeries, compared with only 606 for endothelial keratoplasty and 534 for deep anterior lamellar keratoplasty (DALK).

Comparing the two 5-year periods, researchers found the proportion of penetrating keratoplasty decreased from 92% to 57.2%, while endothelial keratoplasty (P<0.001) increased from 0.4% to 30.2%, and DALK increased from 7.2% to 12.6%. The changes were statistically significant (P<0.001).

In a year-by-year comparison, an even more striking shift emerged with the popularity of the endothelial approach overtaking penetrating keratoplasty by 2011. The frequency of DALK procedures rose from 2003 to 2005, but did not change significantly after that.

The change in procedures and indications paralleled each other, as the proportion of endothelial keratoplasty increased significantly (P<0.001) as a treatment for ABK/PBK, graft failure and Fuchs endothelial dystrophy.

Looking at indications, the researchers found that the proportion of DALK increased significantly (P<0.001) for the treatment of keratoconus and microbial and herpetic keratitis.

The aging of the population in northwestern Italy and the introduction of endothelial keratoplasty could account for the 30.7% increase in corneal grafting between the two study periods, the researchers hypothesised.

ABK/PBK and Fuchs endothelial dystrophy affect older people.

Comparing procedures

Endothelial keratoplasty provides faster visual recovery, more predictable refractive results, and easier postoperative management than penetrating keratoplasty, Dr. de Sanctis and colleagues wrote.

These advantages “have probably increased patients’ and surgeons’ propensity for surgery,” they wrote. “Surgeons may also consider surgery earlier, since EK [endothelial keratoplasty] procedures must be performed before corneal scarring occurs.”

DALK also offers advantages over penetrating keratoplasty: it reduces post-operative endothelial cell loss, eliminates the risk of endothelial rejection, and typically requires a shorter topical steroid treatment.

However, DALK is a technically demanding procedure and takes longer. This might account for its slower adoption, Dr. de Sanctis and his colleagues hypothesised.

Advances in contact lens technology and new therapeutic options, such as riboflavin/ultraviolet-A-induced collagen cross-linking, may have increased the threshold for surgery to treat keratoconus, the researchers noted. However the demand for corneal surgery for this indication remained constant over the two 5-year periods.

How did they meet the domand?

The researchers noted the Eye Bank of Piedmont was able to meet the increased demand because of an increased number of donors coupled with modern procedures allowing a single donor cornea to supply sufficient tissue for endothelial keratoplasty and DALK in two patients.

In addition, corneal tissues whose sub-optimal endothelial condition made it unsuitable for penetrating keratoplasty can be used for anterior lamellar graft.

The findings largely parallel a report in the United States that the odds of undergoing a corneal graft increased for patients with endothelial diseases as endothelial keratoplasty procedures have been widely adopted, the researchers wrote.

In other European countries, endothelial keratoplasty has not caught on as quickly, the researchers noted. They hypothesised that this difference could be attributed to a “lower proportion of interventions for endothelial diseases in those countries.”

They noted that their study could not address whether the trends they reported affect the visual acuity of patients, because this information was not included in surgical reports. “Further studies are required to clarify this point,” they wrote.