Laughter as medicine? New trial finds laughter exercise as effective as artificial tears in relieving dry eye symptoms, offering a fun alternative for patients.

Study: Effect of laughter exercise versus 0.1% sodium hyaluronic acid on ocular surface discomfort in dry eye disease: non-inferiority randomised controlled trial. Image Credit: Gatot Adri/Shutterstock.com

In a recent study published in the British Medical Journal, researchers conducted a randomized controlled trial to compare the safety and efficacy of laughter exercise with that of artificial tears containing 0.1% sodium hyaluronate in patients with symptomatic dry eye disease (DED).

They found that laughter exercise was non-inferior to artificial tears in reducing dry eye symptoms and improved tear film stability, with no significant differences in other outcomes.

Background

DED is a common condition characterized by chronic discomfort, tear film instability, and visual disturbances, now affecting an estimated 360 million people worldwide. While not life-threatening, DED significantly reduces the quality of life and imposes a substantial economic burden.

Its prevalence has surged due to aging populations, increased screen time, and rising air pollution. In addition to physical symptoms, a growing body of evidence suggests a strong link between DED and mental health conditions like depression and anxiety, with emotional factors often exacerbating the symptoms.

Laughter therapy, an intervention designed to promote positive emotions, has long been recognized for its ability to alleviate depression, anxiety, and chronic pain, while boosting immune function. Despite its success in improving mental health, its impact on DED— a condition closely tied to both mental health and lifestyle— remains unclear.

Pilot studies have shown that laughter may immediately improve tear film stability and reduce dry eye symptoms. Building on this evidence, researchers in the present study compared the effectiveness of laughter exercise to artificial tears for treating DED, hypothesizing non-inferiority in the two approaches.

About the study

In the present two-arm, non-inferiority randomized controlled trial, 299 participants were included from clinics and surrounding areas through advertisements and social media.

Eligible participants were aged between 18 and 45 years, had symptomatic DED, an ocular surface disease index (OSDI) score of 18–80, and a fluorescein tear break-up time (TBUT) of eight seconds or less.

Participants with severe corneal staining, history of dry eye treatments, contact lenses, eye surgery, trauma, eye infection, allergy, severe ocular surface scarring, glaucoma, and neurological disorders were excluded.

The included participants were randomly assigned (1:1) to either the laughter exercise group (n = 149) or the control group using 0.1% sodium hyaluronic acid eye drops (n = 150), both administered four times daily for eight weeks.

Laughter exercise, adapted from existing laughter therapy methods, involved repeating specific vocalizations while engaging facial muscles, tracked through a custom face recognition app. The app ensured adherence to treatment by sending reminders and tracking sessions to patients.

Control group participants also logged their eye drop use in the app. The primary outcome was the change in OSDI score from baseline to eight weeks. Secondary outcomes included non-invasive TBUT, corneal fluorescein staining, and additional measures of quality of life, mental health, and subjective happiness.

Follow-up visits up to 12 weeks and adverse events were tracked. Statistical analysis involved the use of the Shapiro-Wilk test, Student’s t-test, multiple imputations, generalized estimated equation models, and Benjamini-Hochberg adjustment.

Results and discussion

According to the study, the mean change in the OSDI score at eight weeks showed a significant reduction in both groups (−10.5 for laughter exercise and −8.83 for control), indicating that laughter exercise was not inferior to artificial tears.

At 12 weeks, the laughter exercise group demonstrated a greater decrease in OSDI scores compared to the control group (−4.08 points, P=0.024).

Secondary outcomes revealed similar proportions of participants achieving a 10-point decrease in OSDI scores (49.3% for laughter exercise vs. 47.3% for control) and a significant improvement in noninvasive TBUT for the laughter exercise group (mean difference 2.30 seconds, P

The laughter exercise group also showed improvements in mental health subscale scores but no significant differences in anxiety or depression scores compared to controls. Notably, there were no reported adverse events in either group, supporting the safety and potential efficacy of laughter therapy as an intervention for symptomatic DED.

The trial’s strengths include a randomized controlled design, rigorous compliance monitoring and support, high compliance and follow-up rates, and the standardization of the laughter exercise intervention through instructional videos.

The limitations of the study include the impracticality of a double-blinded design due to the absence of a validated sham laughter exercise and the greater time investment required for laughter exercise compared to eye drop use.

Future studies could potentially explore the optimal frequency and duration of laughter exercise, investigate its biological mechanisms, and evaluate its efficacy for other ocular conditions.

Conclusion

In conclusion, the present study demonstrates that laughter exercise performed four times daily is non-inferior to 0.1% sodium hyaluronic acid eye drops in alleviating DED symptoms.

Given its safety, environmental friendliness, and low cost, laughter exercise may serve as a first-line, home-based treatment for individuals with symptomatic DED and minimal corneal staining.