A randomized controlled trial found that a laughter exercise regimen was noninferior to 0.1% sodium hyaluronic acid eyedrops in alleviating symptoms of dry eye disease over 8 weeks.
The study, published in The BMJ, also reported improvements in tear film stability and meibomian gland function with laughter exercise.
Researchers conducted a noninferiority trial involving 299 participants aged 18 to 45 years (mean age = 28.9 years; 74% female) with symptomatic dry eye disease. Participants were randomized 1:1 to perform a structured laughter exercise or use 0.1% sodium hyaluronic acid eyedrops 4 times daily for 8 weeks. The laughter exercise involved vocalizing phrases like "Hee hee hee, hah hah hah" while exaggerating facial expressions for 5 minutes at a time, 4 times daily. Participants used a mobile app to standardize the exercise and track compliance.
The primary outcome of the trial was change in Ocular Surface Disease Index (OSDI) score from baseline to 8 weeks; inclusion criteria for the study included an OSDI score of 18 of 80 and a tear film break-up time of ≤ 8 seconds.
Key Findings
After 4 weeks of follow-up, the laughter exercise group showed a mean OSDI score decrease of 10.5 points (95% confidence interval [CI] = -13.1 to -7.82) compared to 8.83 points (95% CI = -11.7 to -6.02) in the eyedrop group. The between-group difference of -1.45 points (95% CI = -5.08 to 2.19) was within the prespecified noninferiority margin of 6 points.
Secondary outcomes revealed the laughter group had greater improvement in noninvasive tear break-up time compared to controls (mean difference = 2.30 seconds; 95% CI = 1.30–3.30; P<0.001). Exploratory analyses showed improvements in meibomian gland function only in the laughter group.
No adverse events were reported among participants in either group.
Additional Data
Baseline characteristics of participants included:
- 95% (283/299) had >12 years of education
- Baseline OSDI scores: Laughter group = 35.9 (standard deviation [SD] = 13.6), control group = 36.8 (SD = 14.4)
- Baseline noninvasive tear break-up time: Laughter group = 7.95 seconds (SD = 3.65), control group = 7.91 seconds (SD = 3.69).
Compliance and follow-up:
- Median cumulative compliance over 8 weeks: Laughter group = 85% (interquartile range [IQR] = 65%-96%), control group = 81% (IQR = 68%-90%)
- 12-week follow-up completion: Laughter group = 92% (137/149), Control group = 98% (146/150).
Secondary outcomes at 8 weeks:
- Proportion of participants with an OSDI decrease of ≥10 points: Laughter group = 49.3% (95% CI = 41.0%-57.5%), control group = 47.3% (95% CI = 39.3%-55.3%)
- Change in tear meniscus height (μm): Laughter group = 0.02 (95% CI = 0.01-0.03), control group = 0.005 (95% CI = -0.002-0.010)
- Change in corneal fluorescein staining score: Laughter group = -0.19 (95% CI = -0.42-0.04), control group = -0.06 (95% CI, -0.27-0.15).
Psychological outcomes at 8 weeks:
- Self-rating anxiety scale change: Laughter group = -3.05 (95% CI = -4.39 to -1.71), control group = -1.98 (95% CI = -3.14 to -0.82)
- Self-rating depression scale change: Laughter group = -2.95 (95% CI = -4.40 to -1.50), control group = -1.68 (95% CI = -2.95 to -0.41)
- SF-36 mental health subscale change: Laughter group = 3.28 (95% CI = 0.80-5.75), control group = 0.89 (95% CI = -1.06-2.85).
Exploratory outcomes at 8 weeks:
- Fluorescein tear break-up time change (in seconds): Laughter group = 1.82 (95% CI = 1.60-2.03), control group = 0.32 (95% CI = 0.16-0.48)
- Meibomian gland secretory capacity change: Laughter group = -0.24 (95% CI = -0.33 to -0.14), control group = 0.01 (95% CI = -0.07-0.10)
- Meibomian gland secretion property score change: Laughter group = -3.78 (95% CI = -4.45 to -3.12), control group = 1.13 (95% CI = 0.54-1.71).
Long-term effects at 12 weeks:
- OSDI score change from baseline: Laughter group = -14.6 (95% CI = -17.2 to -11.9), control group = -10.1 (95% CI = -13.0 to -7.30)
- Between-group difference in OSDI change: -4.08 (95% CI, -7.62 to -0.55; P=0.02).
The authors noted limitations for the study, including the inability to blind participants and the greater time investment required for laughter exercise compared to eyedrops.
The study authors concluded, "As a safe, environmentally friendly, and low-cost intervention, laughter exercise could serve as a first-line, home-based treatment for people with symptomatic dry eye disease and limited corneal staining."
All authors reported no financial relationships with any organizations that might have an interest in the submitted work. The study was supported by the National Natural Science Foundation of China, and the High-level Hospital Construction Project, which did not influence the study design, data analysis, or manuscript preparation.