## 2 Materials and Methods  
This retrospective observational case series was approved by the Institutional Review Board of Asan Medical Center and the University of Ulsan College of Medicine, Seoul, Republic of Korea (Approval No. : 2020-0148). This study adhered to the tenets of the Declaration of Helsinki and followed clinical practice guidelines. A retrospective chart review was conducted on patients who underwent FLACS, performed by one surgeon (H.T.) at Asan Medical Center, between September 2019 and February 2020. Patients who met the following inclusion criteria were included: 50 years or older with age-related cataract. Patients with a history of other ocular diseases, such as glaucoma or retinal diseases, a history of prior ocular surgery, active ocular inflammation, or those taking either systemic or topical corticosteroids or topical cyclosporine were excluded from the study. The following parameters were recorded from the clinical record: demographic and clinical information including sex, age, and medical and surgical history. Ocular surface disorder assessments were performed within 1 week preoperatively (baseline) for tear osmolarity, MMP-9, and OSDI questionnaire score results. After FLACS, tear osmolarity and MMP-9 were re-assessed 1 day, 1 week, and 1 month after surgery (D1, W1, M1, respectively), and the OSDI questionnaire was re-assessed 30 days postoperatively. At the time of evaluation, tear osmolarity was assessed first, followed 10 min later by an assessment of MMP-9, and he OSDI questionnaire was completed last. Tear osmolarity was measured using the i-Pen (i-Med Pharma, Dollard-des-Ormeaux, QC, Canada). The i-Pen determines tear osmolarity by placing the device tip on the conjunctiva of the lower lid and measuring the electrical impedance. This diagnostic tool has been shown to provide reliable and reproducible tear osmolarity results in both in vitro and in vivo conditions [18,19]. Previous studies have reported a recommended cutoff osmolarity range of 304 to 316 mOsm/L for the diagnosis of dry eye disease [20, 21, 22, 23, 24, 25, 26]. In this study, an osmolarity value of \(\geq\) 310 mOsm/L in the testing eye was defined as an abnormal osmolarity as suggested by the user manual [27]. Patients were eligible to have osmolarity testing if they had not used eye drops within two hours prior to testing. Tear osmolarity was performed beforehand, as the manual recommends not to perform the test after invasive ocular diagnostic testing. The presence of increased MMP-9 levels on the ocular surface was measured using InflammaDry (Rapid Pathogen Screening, Inc., Sarasota, FL, USA). Testing was conducted in accordance with the user manual provided. In brief, the sampling strip was dabbed in multiple locations of palpebral conjunctiva until saturated. The appearance of a red indicator line next to the blue control line indicates a positive or abnormal result which reflects a concentration of MMP-9 higher than 40 ng/mL. The result is read and interpreted at least 10 min after completion of the sample collection. Abnormal results were also semiquantitatively interpreted using the color intensity of the result line. The results were recorded as negative (grade 0), trace-positive (grade 1), weak-positive (grade 2), positive (grade 3), and strong-positive (grade 4) using a grading index provided by the manufacturer. Grading the intensity of the InflammaDry results has been shown to correlate well with the symptoms and signs of dry eye disease patients [28]. The OSDI questionnaire is a validated questionnaire used to assess ocular surface symptoms. It has 3 subscales: ocular symptoms, vision-related function, and environmental triggers [12,29]. The total OSDI score is calculated by multiplying the summated answered scores by 25 and dividing by the number of questions answered. Scores of 0 to 12 are considered normal and those above 12 are considered abnormal. The subscale scores are computed similarly, with only the questions from each subscale used to generate its own score.