Abstract
Purpose :
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).
Methods :
This prospective, non-randomized study enrolled patients with progressive keratoconus who were candidates for CXL. Preoperatively, epithelial thickness (ET) and high-order aberrations (HOA) were measured using OCT and corneal topography,. In the tPRK group, the ablation profile was calculated including the correction of HOAs, where the stromal ablation did not exceed 50 µm in the cone. In the tPTK group, the depth of ablation was determined as the measured ET 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.
Results :
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. All secondary measures 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, but not I-S value, decreased statistically significantly (all P<0.05). Direct comparison of 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, whereas the mean differences was not statistically significant (P=0.143).
Conclusions :
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.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.