Comparison Of Laser-Assisted Epithelium Removal With And Without Corneal Wavefront-Guided Photorefractive Keratectomy Combined With Corneal Cross-Linking In Progressive Keratoconus

To evaluate the improvement of best corrected spectacle visual acuity (BCVA) and corneal tomography parameters after corneal wavefront-guided transepithelial photorefractive keratectomy (tPRK group) compared to transepithelial phototherapeutic keratectomy (tPTK group) combined with corneal cross-linking (CXL) in progressive keratoconus.

Prospective and non-randomized study performed at the Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Germany

In the tPRK group, the ablation profile was calculated including the correction of high order aberrations (HOA), where the stromal ablation did not exceed 50 µm in the thinnest area of the cornea. In the tPTK group, the depth of ablation was determined as the measured epithelium thickness plus 5 µm. The primary outcome measure was the change in BCVA (logMar) after 12 months. Secondary outcomes were the change in maximum keratometry (Kmax), thinnest corneal thickness (TCT), inferior-superior value (I-S), index of vertical asymmetry (IVA), root mean square of HOA of the total cornea (RMS-HOA-total), and total coma (RMS-coma-total). Statistical analysis was performed using a t-test. A P value < 0.05 was considered as statistical significant.

This study included 20 eyes in each group with no significant differences in demographics (P>0.05). BCVA improved significantly from 0.15±0.12 to 0.11±0.11 (P=0.041) in the tPRK group at 12 months after treatment. Kmax, TCT, I-S value, IVA, RMS-HOA-total, and RMS-coma-total decreased significantly indicating a more regular but thinner cornea (all P<0.05). In the tPTK group, BCVA did not change significantly (P=0.655), whereas Kmax, TCT, IVA, RMS-HOA-total, and RMS-coma-total decreased statistically significantly (all P<0.05). The mean differences between the two groups showed a statistically stronger effect of the reduction in these parameters (P<0.05) in the tPRK group, which explains the improvement in BCVA compared to the tPRK group.

Correction of HOA in progressive keratoconus in combination with CXL resulted in a more significant improvement in visual acuity compared to tPTK ablation alone. These results are supported by a more regular cornea based on topographic and tomographic indices. Corneal wavefront-guided photorefractive keratectomy combined with CXL is an effective method to stabilize the cornea and improve visual acuity in progressive keratoconus.