Optimizing acupuncture treatment for dry eye syndrome: a systematic review

Dry eye syndrome is a multifactorial condition affecting the tears and ocular surface, causing discomfort and visual problems. With population aging and increased use of electronic devices, its prevalence has grown significantly. This systematic review investigated the efficacy of acupuncture in treating this condition, analyzing 19 randomized controlled studies with 1,126 participants. The researchers sought not only to confirm the effectiveness of acupuncture but, primarily, to optimize treatment protocols through detailed subgroup analyses.

The methodology included a search of 10 international databases, with rigorous inclusion criteria focused on trials comparing acupuncture with artificial tears. Primary results were evaluated through the Schirmer test (which measures tear production) and tear film break-up time. The meta-analysis demonstrated significant superiority of acupuncture over artificial tears in both primary outcomes. On the Schirmer test, acupuncture showed a mean improvement of 2.14 mm (95% CI: 0.93-3.34), while break-up time improved by 0.98 seconds (95% CI: 0.79-1.18).

Subgroup analyses revealed important insights for clinical optimization. Treatments lasting more than 1 month were more effective than shorter protocols, suggesting the need for adequate time to consolidate therapeutic effects. Counterintuitively, a lower session frequency (less than 3 times per week) was superior to intensive treatments, indicating that recovery periods between sessions may be beneficial. The specific analysis of acupuncture points showed that regimens including BL-2 (Zanzhu) and ST-1 (Chengqi) were less effective than protocols that avoided these points.

This finding suggests important positional specificity, possibly related to the proximity of these points to nerve blocks that could reduce conjunctival sensitivity and consequent tear production. The combination of acupuncture with artificial tears showed a synergistic effect on tear production but not on tear film stabilization, suggesting complementary mechanisms of action. Despite the positive results, the review identified high heterogeneity among studies (I²=62-96%), not reduced by subgroup analyses, indicating significant variability in protocols and populations studied. The methodological quality of the included studies was variable, with only some presenting adequate randomization, allocation concealment, and assessor blinding.

The clinical implications are substantial. Acupuncture emerges as a valid therapeutic alternative for dry eye syndrome, especially considering the limitations of artificial tears regarding duration of effect and need for frequent application. The suggested optimized protocol includes treatment for more than 1 month, frequency of 2-3 sessions per week, focusing on periorbital points except BL-2 and ST-1. Limitations include high unexplained heterogeneity, variable methodological quality of primary studies, and the need for more research on electroacupuncture and other modalities.

Future studies should focus on protocol standardization, long-term follow-up, and investigation of the underlying neurophysiological mechanisms.