Customized aspheric treatment zone ablation to treat irregular corneas after corneal refractive surgery

To describe the retreatment of highly aberrated corneas due to previous keratorefractive surgery using topography-guided aspheric treatments.

Eight eyes (five patients) with reduced mesopic visual quality due to previous keratomileusis, excimer laser surgery, or radial keratotomy underwent retreatment with the customized aspheric treatment zone (CATz) algorithm with the CXIII excimer laser (NIDEK Co Ltd) to correct corneal wavefront aberrations. Before CATz treatments, all patients were satisfied with their preoperative photopic vision (all 20/30 or better uncorrected) yet were dissatisfied with their vision at night. All eyes had >20 microm (range: 20 to 33 microm) of corneal irregularity before CATz retreatment. All eyes had a flap cut or flap lift procedure for CATz retreatment.

One year after treatment with CATz, no eyes lost best spectacle-corrected visual acuity (BSCVA); all eyes had BSCVA of 20/30 or better. Mean modulation transfer function increased by 13% by the end of the first postoperative year. A 0.45-microm decrease was noted in coma 1 year postoperatively.

The CATz algorithm is effective in the treatment of severe corneal irregularities due to previous corneal surgery.