Ultra-Short-Term Corneal Changes to Nd:YAG Laser Capsulotomy: Energy-Dependent Changes Assessed by Specular Microscopy and Topographic Analysis

<b>Background:</b> This prospective observational study was conducted to systematically assess immediate changes occurring (within one hour) in corneal endothelial cell morphology and anterior segment parameters following Nd:YAG laser posterior capsulotomy in pseudophakic patients and to analyze the correlation between these changes and laser energy parameters. <b>Methods:</b> A single-arm, within-subject pre-post design was employed to evaluate corneal endothelial morphology (cell density, count, area, coefficient of variation and hexagonal percentage) and anterior chamber parameters (depth, angle, volume) before and one hour after the procedure using specular microscopy and Pentacam analysis. Patient demographics (age), clinical parameters (best corrected visual acuity and intraocular pressure), postoperative-YAG laser interval, and laser energy parameters (energy per shot, pulse count, and total applied energy) were also documented. <b>Results:</b> Thirty-two pseudophakic patients (mean age 56.3 ± 19.2 years) underwent Nd:YAG laser posterior capsulotomy with mean energy per shot of 3.15 ± 1.07 mJ and pulse count of 34.3 ± 20.4. Specular microscopy revealed significant post-procedural decreases in endothelial cell density (2184.05 to 2057.2 cells/mm²; <i>p</i> = 0.006) and increases in average cell area (529.25 ± 242.72 to 587.75 ± 281.09 µm²; <i>p</i> = 0.004) and minimum cell area (199.3 ± 170.62 to 248.35 ± 202.7 µm²; <i>p</i> = 0.035). Corneal topography also decreased significantly in the anterior chamber angle (40.07 ± 10.34 to 35.42 ± 6.78 degrees; <i>p</i> = 0.048), with positive correlations between energy per shot and endothelial cell density (r = 0.557; <i>p</i> = 0.011) and average cell area (r = 0.544; <i>p</i> = 0.013). <b>Conclusions:</b> This study demonstrates that Nd:YAG laser capsulotomy causes immediate, energy-dependent alterations in corneal endothelial density and anterior chamber parameters within one hour post-procedurally. The identification of energy per shot as a key determinant represents a preliminary observation for optimizing laser parameters and reducing potential complications in pseudophakic patients.