The investigators performed the current study to compare: 1) the pain scores by Visual Analogue Scale; 2) the cytokines concentrations in aqueous humor by human cytokine antibody array; 3) the prostaglandin E2 (PGE2) concentrations by enzyme linked immunosorbent assay (ELISA); 4) the pupil behaviors by Image J between first-eye and second-eye in bilateral cataract patients undergoing sequential femtosecond laser-assisted cataract surgery (FLACS). To our knowledge, this is the first intraindividual study investigating contralateral effect in FLACS. The findings from the current study may broaden our understanding on the mechanism of sympathetic reaction, help to improve clinical performances, and provide strong clinical guidance for cataract surgeons.

Inclusion Criteria:

• Consecutive cataract patients aged 40-80 years, regardless of gender, with bilateral similar grades of lens opacity, and scheduled for sequential FLACS were enrolled in this study.

Exclusion Criteria:

• history of ocular or systematic inflammatory diseases like uveitis, rheumatism or other autoimmune diseases;
• previous ocular surgery or trauma;
• preoperative glaucoma, zonular weakness, lens dislocation, or poor pupil dilation (measured pupil diameter <5.0 mm) or synechiae;
• use of systemic or topical steroids, non-steroidal anti-inflammatory drugs (NSAIDs), alpha-adrenergic antagonist, or pain relief medications within 1 month prior to surgery;
• patients with baseline eye pain, having anxiety, muscle spasm around the eye or involuntary eye movement disorders which may influence the pain score;
• eyes needing for any other type of anesthesia, failed to obtain > 100 μl aqueous humor (AH) or encountered intra-operative complications like posterior capsule rupture