Q-value customized versus wavefront-optimized ablation in femtosecond laser-assisted LASIK for myopia and myopic astigmatism: a prospective contralateral comparative study

• Published in: Eye and vision (Novato, Calif.) Vol. 9; no. 1; pp. 1 - 43
• Main Authors: Mostafa, Magdi Mohammad, Abdelmotaal, Hazem, Abdelazeem, Khaled, Goda, Islam, Abdel-Radi, Mahmoud
• Format: Journal Article
• Language: English
• Published: London BioMed Central Ltd 02.11.2022; BioMed Central; BMC
• Subjects: Ablation; Ablation (Surgery); Astigmatism; Comparative analysis; Comparative studies; Cornea; Corneal asphericity; Custom Q; Eye; Lasers; Myopia; Patients; Q-value; Software; Surgery; Topography; Wavefront-optimized; United States > US
• ISSN: 2326-0254; 2326-0246; 2326-0254
• DOI: 10.1186/s40662-022-00312-3

Background Corneal refractive surgery for myopia results in an oblate shift with increased postoperative aberrations inversely affecting the quality of vision. Aspheric ablation profiles have been introduced to minimize such a problem. The aim of this study was to compare changes in corneal asphericity, central and mid-peripheral pachymetry between the Q-value customized and the wavefront-optimized (WFO) ablation profiles. Methods A prospective, comparative non-randomized fellow eye study was conducted. Eighty eyes of 40 eligible patients underwent femtosecond laser-assisted laser in situ keratomileusis for myopia and myopic astigmatism. In each patient, the more myopic eye was included in the custom-Q ablation experimental group and the other less myopic eye was included in the WFO control group. For the custom-Q group, the target asphericity was set to the preoperative Q-value. Corneal asphericity, central and mid-peripheral pachymetric changes and the root mean square of corneal higher-order aberrations (RMSh) were assessed 6 months following surgery. Visual and refractive outcomes were also evaluated in both platforms 6 months postoperatively. Results The mean preoperative refractive spherical equivalent was significantly more myopic in the custom-Q group than in the WFO group (P = 0.001). The mean Q-value changed from - 0.2 [+ or -] 0.1 to 0.6 [+ or -] 0.7 and from - 0.2 [+ or -] 0.1 to 0.4 [+ or -] 0.5 in the custom-Q and WFO groups, respectively. The oblate shift in corneal asphericity was not significantly different between both treatment groups (P = 0.094). The mean ablation depth at the pupillary center was significantly greater in the custom-Q group (P = 0.011), while there was no significant difference at the mid-peripheral pachymetry (P = 0.256). The RMSh significantly increased in both treatment profiles (P < 0.001) with no significant difference between the two groups (P = 0.06). The uncorrected distance visual acuity (UDVA) and the manifest refraction spherical equivalents (MRSE) significantly improved in both treatment groups (P < 0.001). Conclusions The custom-Q treatment profile with target asphericity set at the preoperative Q-value achieved comparable outcomes vs. the WFO profile in terms of postoperative corneal asphericity and mid-peripheral pachymetry despite the greater amount of ablation, the smaller optical zone, and the resulting increase in postoperative corneal flattening in the custom-Q group. Trial registration (Clinicaltrials.gov): NCT04738903, 4 February 2021- Retrospectively registered, Keywords: Custom Q, Wavefront-optimized, Corneal asphericity, Q-value