Corneal graft survival better after ALK than PK

By Sarah Guy

Patients treated with anterior lamellar keratoplasty (ALK) for tectonic indications have better physiologic graft survival outcomes than their counterparts treated with penetrating keratoplasty (PK), despite the former procedure raising the risk for anatomic failure, report researchers.

While ALK patients were more likely to need a repeat corneal graft within 3 months, if the graft did survive that time, 10-year graft survival was higher in ALK than PK patients, at 66.8% versus 44.2%.

Furthermore, almost all patients (95%) had tectonic (anatomic) success after corneal grafting (where anatomic failure is defined as recurrence of corneal thinning/melting), but those with severe lid disease had a sixfold increased risk for failure compared with those without the disease.

"Tectonic grafts are vital in restoring globe integrity in patients with descemetoceles and corneal perforation," say Donald Tan (Singapore National Eye Centre) and colleagues in Ophthalmology.

"Our study results strengthen the benefits of tectonic ALK over that of PK," they add.

The most frequent reasons for the 362 patients (362 eyes) in the study undergoing either ALK (n=127) or PK (n=142) during the 18-year data period were active infection (37.3%) followed by trauma (21.8%).

A total of 18 eyes (5%) needed secondary surgery within 3 months of their initial procedure, and 10 of these eyes had been treated with ALK.

After accounting for confounders including age, gender, race, and donor size, the risk for anatomic failure was significantly higher in patients with severe lid disease (n=30, odds ratio [OR] 6.1), patients who had undergone ALK (OR=7.5), and those who had received peripheral (rather than central) grafts (OR=5.7).

However, eyes that underwent ALK had better physiologic survival probabilities in Kaplan-Meier survival analysis than PK-treated eyes, say Tan et al, with 1-, 3-, and 5-year survival rates of 83.0%, 70.3%, and 66.8% versus 75.1%, 63.2%, and 56.2%, respectively, although these differences were not significant.

The research team analyzed visual acuity (VA) outcomes, despite their secondary importance in corneal graft cases, and found significantly greater improvement in best spectacle-corrected VA among ALK-treated eyes compared with PK-treated eyes at 3 years, at 1.5 points versus 0.9 points on the Snellen VA chart.

"Longer-term studies are required to confirm the trend that tectonic ALK provides better visual rehabilitation compared with PK," remark the authors.

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