The Comparison of Contrast Sensitivity After Keratorefractive Lenticule Extraction Between the VisuMax 800 and 500 Systems

Purpose: To compare the contrast sensitivity (CS) after keratorefractive lenticule extraction (KLEx) between the VisuMax 800 and VisuMax 500 systems (Carl Zeiss Meditec AG). Methods: Participants aged 18 to 46 years were recruited between November 2024 and April 2025. Visual and refractive outcomes were assessed and CS function (CSF) was measured using the quantitative CSF (qCSF) test at 1, 3, and 6 months postoperatively. The differential analysis and influencing factor analysis of qCSF parameters between the two systems were conducted. Results: In the VisuMax 800 group, qCSF parameters at 1 month postoperatively were better than those in the VisuMax 500 group ( P < .05). There were no statistically significant differences in qCSF parameters between the two groups at 3 and 6 months postoperatively ( P > .05). In the VisuMax 500 group, preoperative and postoperative cylindrical refraction were significantly correlated with CS (6 cycles per degree [cpd]) and CS (12 cpd) ( P < .05). In the VisuMax 800 group, preoperative and postoperative spherical refraction (SR) and postoperative SR was were significantly correlated with CS (6 cpd) and CS (12 cpd) ( P < .05). CS (12 cpd) in the VisuMax 500 group and CS (6 cpd) in the VisuMax 800 group were correlated with the optical zone ( P < .05). Conclusions: The VisuMax 800 system demonstrates a slight advantage in the early recovery of visual function following KLEx, particularly excelling in CS at medium and high spatial frequencies, and its outcomes converge with those of the VisuMax 500 system at postoperative 3 and 6 months.