Results Of Corneal Lenticule Extraction For Advanced Refractive Correction (Clear) In Patients With Thin Corneas.

To asses CLEAR safety and efficacy for myopia correction in patients with thin corneas.

Centre for Research in Refractive Surgery (Poggibonsi, Italy).
Siena Eye Laser Refractive and Cataract Surgery Clinic (Poggibonsi, Italy).

retrospective study of CLEAR procedures performed at Siena Eye Laser (Poggibonsi, Italy) with Ziemer FEMTO LDV femtosecond laser in patients with myopia and corneas ≤500 μm.Inclusion criteria were corrected distance visual acuity (CDVA) ≥ than 0.2 logMAR, age ≥18 years or older, corneal thicknes ≤500 μm, and suitable for CLEAR. Patients were evaluated at baseline, post-operative day 1 (POD1) ,6 and 18 months.

we included 280 eyes of 213 patients.Mean corneal thickness was 484.6 ± 7.2 μm,with a mean myopic error of -5.75±2.2 D,a mean cylinder of 1.0±0.7 D, and a mean spherical equivalent refractive error (SER) of -6.8±2.2 D.CDVA was 0.0 logMAR in all eyes.Expected residual stroma thickness (RST) calculated by Ziemer platform was 248.0±14.8 μm. At POD1 uncorrected distance visual acuity (UDVA) was 0.13±0.12ogMAR with a mean SER of -0.1±0.9 D.RST significantly increased to 259.3±11.4 microns (p<0.001).At 6 months follow-up, mean UDVA was 0.0±0.1 logMAR (p<0.001),RST was 260±11.2 microns (p>0.05) and mean SER was -0.15±0.7D (p>0.05) compared to POD1.At 18 months FU,all data remained stable with no differences compared to 6 months FU (all p>0.05). 

In patients with thin corneas, CLEAR showed good results in terms of refractive error correction. At follow-up, observed residual stromal thickness was signfiicantly higher than the expected value calculated by the software pre-operatively, allowing clinicians to safely perform the surgery in patients with corneas ≤500 μm.