Investigation into the Influence of Secondary Suction within FLACS on the Postoperative Ocular Surface and Associated Mechanisms

Purpose: To explore secondary suction’s impact on postoperative ocular surface, tear factors, and dry eye risk factors in femtosecond laser-assisted cataract surgery (FLACS). Setting: Xiamen Eye Center, Xiamen University. Design: Prospective cohort study; patients grouped by intraoperative secondary suction (no randomization/masking). Methods: Age-related cataract patients undergoing FLACS (Dec 2023–May 2024) were included (inclusion: FLACS consent, no prior eye surgery/trauma, pupil dilation >7 mm; exclusion: ≥3 suction attempts, lens dislocation, pregnancy, psychiatric issues, poor compliance). Preoperative parameters (corneal diameter, corneal K value) and intraoperative eye movement were recorded. Ocular Surface Disease Index (OSDI), Tear Meniscus Height (TMH), and tear cytokines were assessed preoperatively and at 1 day, 1 week, and 1 month post-surgery. Results: 41 patients (21 secondary suction, 20 conventional) were analyzed. The secondary suction group had higher 1-week OSDI (6.43±7.96 vs 1.90±5.85; P=0.045), higher 1-week (0.04±0.09 vs 0.01±0.07 mm; P=0.020) and 1-month TMH (0.07±0.17 vs 0.03±0.07 mm; P=0.023), and greater tear Interleukin-6 (IL-6) log increases at 1 day (0.44±0.68 vs -0.04±0.78; P=0.042) and 1 week (0.01±0.64 vs -0.49±0.89; P=0.045). Risk factors: smaller corneal diameter (P=0.025) and obvious eye movement (P<0.001). Conclusion: Secondary suction in FLACS may worsen early-stage postoperative dry eye, but it recovers in 1 month. Key risk factors for secondary suction include smaller corneal diameter and significant ocular movement, which inform targeted prevention strategies to reduce secondary suction incidence.