High rate of progression after CXL in patients with advanced keratoconus

This retrospective study evaluated the effectiveness of corneal cross-linking (CXL) in eyes with advanced keratoconus.

Study design

The study included 61 eyes with preoperative maximum keratometry (Kmax) readings greater than 58 D. Study participants underwent standard Dresden epi-off CXL and were followed for 2 years with corneal topography and tomography. Progression was defined as an increase in Kmax of 1.0 D or more over a 1-year period.

Outcomes

After 1 year, progression was observed in 23% of eyes and 8.2% of eyes steepened by more than 2 D. After 2 years, progression occurred in 18% of eyes. Kmax flattening of 1 D or greater occurred in 47.5% of eyes. Overall mean Kmax (P=0.0029) and central corneal thickness (P=0.001) was reduced at 1 year. Change in Kmax did not correlate with preoperative Kmax values and no differences were noted in eyes that underwent a standard versus accelerated protocol.

Limitations

Due to high intersession variability of topographic measurements in advanced keratoconus, the definition of progression (increase in Kmax ³1 D) may be too strict. Many of the treated patients had cognitive impairment, so excessive rubbing or low postoperative treatment compliance may have contributed to progression. A single method of Scheimpflug-based imaging was used to measure progression.

Clinical significance

While a large proportion of patients experienced corneal flattening of Kmax, this retrospective study confirms the high rate of progression after CXL in patients who start with advanced keratoconus and a high preoperative Kmax. Lamellar and penetrating keratoplasty should be considered as an alternative first-line treatment in these specific cases.