gms | German Medical Science

Excimer laser ablation following corneal topography may allow individual corneal modeling and gives the possibility of improved visual acuity (contrast sensitivity, mesopic vision). We present the refractive, topographic and morphological results after topography-guided Re-LASIK and PTK.

We report about 15 eyes. 12 eyes got a myopic Re-LASIK in case of undercorrection (mean: -1.0 D spherical equivalent) or paracentral irregularity. In 3 eyes a topography-guided PTK was performed to correct surface scars after penetrating keratoplasty. Mean preoperative UCVA before refractive retreatment was 20/32, mean BCVA 20/20. Before PTK UCVA and BCVA were ≤20/400. Corneal wavefront was measured by the Keratron Scout system (Schwind). Regan charts were used to measure contrast sensitivity. Uneventful ablation was performed in all eyes with the Esiris Excimer laser (Schwind).

After a follow-up of minimal 6 months we observed an UCVA in the mean of 20/20 after retreatment and 20/100 after PTK. BCVA after PTK increased to 20/80. Higher order aberrations were reduced in the refractive candidates from 0.51 (coma) and 0.81 (spherical aberration) preoperatively to 0.19 and 0.45 postoperatively. After PTK these absolute values were reduced from 3.7 (coma) and 1.2 (spherical aberration) patients to 0.80 and 0.57. The Zernike coefficients up to 6^th order showed no significant change in vector direction. Contrast sensitivity was improved in all refractive patients.

Postoperatively all eyes showed a reduction of the aberrations lower and higher order. This was correlated with an improved UCVA. In 8 of 12 eyes after Re-LASIK the real optical zone could be enlarged. Topography-guided Laser ablation can be recommended in case of refractive retreatment and as a refinement in PTK.