Outcomes of low-level light therapy before and after cataract surgery for the prophylaxis of postoperative dry eye: a prospective randomised double-masked controlled clinical trial

BACKGROUND: Despite increasing evidence shows that optimising ocular surface before cataract surgery is fundamental in patients with pre-existing dry eye disease (DED) to achieve the desired postoperative outcomes, the prophylactic treatment of healthy patients undergoing surgery aiming at preventing iatrogenic DED is worth investigating. METHODS: This was a prospective, interventional, randomised, controlled, double-masked clinical trial. Patients were randomly assigned 1:1 to receive either low-level light therapy (LLLT) or sham treatment (LLLT with a power output <30%). Patients underwent two treatment sessions: 7±2 days before cataract surgery (T0) and 7±2 days after (T1). Outcome measures evaluated 30±4 days after surgery (T2) included Ocular Surface Disease Index (OSDI) questionnaire, non-invasive break-up time (NIBUT), tear meniscus height, meibomian gland loss (MGL) and redness score. RESULTS: Out of 153 patients randomised to receive LLLT (n=73) or sham treatment (n=80), 131 (70 men, 61 women, mean age 73.53±7.29 years) completed regularly the study. Patients treated with LLLT had significantly lower OSDI scores compared with controls at T1 and T2 (respectively, 7.2±8.8 vs 14.8±13.0 and 9.0±9.0 vs 18.2±17.9; both p<0.001), higher NIBUT values at T2 (12.5±6.6 vs 9.0±7.8; p=0.007) and lower MGL Meiboscore values at T1 (1.59±0.70 vs 1.26±0.69; p=0.008). Unlike controls, patients treated with LLLT had significantly lower OSDI scores and higher NIBUT values at T2 compared with T0 (respectively, 9.0±9.0 vs 21.2±16.1; p<0.001 and 12.5±6.6 vs 9.7±7.2; p=0.007). CONCLUSION: Two sessions of LLLT performed before and after cataract surgery were effective in ameliorating tear film stability and ocular discomfort symptoms. TRIAL REGISTRATION NUMBER: NCT05754437.