DED is a multifactorial disease with various symptoms and signs, which has gained increasing attention, and various treatment options have emerged.1, 5, 7 In the light of new data, the pathophysiology of DED involves a combination of tear film instability, hyperosmolarity, neurosensory abnormalities and ocular surface inflammation and damage.1, 3 The common conservative options, including artificial tear supplement, warm compresses, lid hygiene, steroidal anti-inflammatory agents, hormone therapy, rarely focus on the meibomian gland MG, lacrimal and corneal nerve function, which could be a fundamental solution to the problem.7 To the best of our knowledge, our study is the first worldwide to adopt TEAS therapy in the treatment of DED.
Its potential effects make TEAS a candidate for the off-label treatment of DED. To better understand its utilization patterns, we assessed off-label use of different current intensities. In this study, TMH, TBUT and almost all symptoms showed significant improvement after treatment in 5mA group, and the symptoms except pain, watering and increased secretions were also significantly improved in 3mA Group. However, in the control group, only the symptoms of dryness, asthenopia and blurred vision were significantly different after treatment.
These results indicated that all group could improve the symptoms of dryness, asthenopia and blurred vision, which was likely due to its effect, as an eye shield, of reducing ocular exposure time, stimulating contraction of the orbicularis oculi muscle and squeezing the meibomian glands (MGs). Consequently, the tear film became stable, and the muscles around the eyes were relaxed, which brought the relief of dryness, asthenopia and blurred vision. However, it is a pity that we didn’t assess MGs expressibility and secretion quality after each treatment, which could be included in our long-term observation of treatment in the future. 3mA and 5mA group both showed remarkable relief in symptoms of burning and photophobia, probably because TEAS could stimulate the trigeminal nerve to act on the photophobia pathway (trigeminal–thalamic–cortical pathways), which similar to those of previous studies. 11–13 All the four acupuncture points (Cuanzhu, Chengqi, Tongziliao and Sibai) have been proved the effect of alleviating eye pain asthenopia.14, 15 However, the pain relief, and TMH, TBUT significant improvement only in 5mA group, which might indicate that 5mA is the better parameter for DED treatment, and this parameter could act on analgesic pathway. Eellan et al. noticed that TENS, whose difference is that not acting on specific acupoints compared with TEAS, significantly reduced the pain intensity and photophobia in both eyes five min after treatment.12 In long-term sequential treatment at least three months of these patients, pain intensity decreased by approximately 27.4% and no adverse events associated with TENS were reported.11 Emilio et al. manifested transcutaneous periorbital electrical stimulation could improve OSDI, TBUT and Schirmer I after 6-months and 12-months.13 And Xie et al. found that the eye symptom score, BUT, TMH and visual analogue scale (VAS) score were improved after 1-month Electroacupuncture (EA) treatment.15 In addition, Cheng et al. discovered that 1-month eye acupuncture combined with conventional acupuncture could relief subjective symptom scores, TBUT, TMH, corneal staining for DED patients, compared with control group, which proved that eye acupuncture might increase the secretion of tears, prolong the break up time of tear film, and restore the integrity of corneal epithelium.14 There are reasons to believe that our TEAS, which combined the TENS and eye acupuncture, could relief the signs and symptoms for DED. However, the long-term effect remains to be further observed in our ongoing research. During the process of treatment and examinations, we hadn’t found any adverse events.
In the comparisons for variation between each two groups, 5mA Group showed greater improvement in the signs than other two groups, in the dryness, asthenopia, blurred vision, and photophobia symptom scores than 0mA Group, and in the dryness, pain, and blurred vision symptom scores than 3mA Group. However, 3mA Group had greater improvement than 0mA Group in the symptoms of asthenopia and blurred vision.
Again we explained 5mA could be a better parameter, which might be applied to long-term research. In the comparison of 5mA and 3 mA, we might speculate the greater the energy is, the better promote for lacrimal glands, MGs and nerves, which contribute more tear production, better secretions of MGs and less ocular pain. And more stable tear film brought the relief of dryness and blurred vision, and more activation of analgesic pathways brought the relief of pain. Maybe we could include higher energy in our future observation. However, the comparison of 0mA and 3 mA might expose low-energy acupoint stimulation could also better improve asthenopia. We suspect that its squeezing for MG as a patch might work.
The strength of our study is that it provided new therapeutic option for DED treatment, as well as reasonable guidance and recommendations for parameter adjustment. There are also limitations to our study. First, the following-up duration was rather short, only half an hour after treatment was assessed. Our ongoing study will be further improved. Second, parameter optimization could not be performed, and we will try higher energy and include comparative assessment below safe premise. The frequency dependent should also be explored. Third, we did not evaluate the MGs expressibility and secretion quality, corneal staining, corneal sensitivity and so on. Further long-term studies should include a larger sample size, optimized parameters and additional examinations, including eyelid margins for conditions such as telangiectasia, irregularity, and neovascularity, corneal nerve layer detection, for further confirmation of our conjecture. The therapeutic mechanisms for TEAS will be further aided by vitro studies of molecular biology. Animal studies may involve its effect on lacrimal glands, MGs and nerves.
In summary, we found that TEAS were effective in the treatment of DED. However, 5mA provided greater signs and symptoms relief. TEAS can be a new therapeutic option for the treatment of DED.