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近日，来自斯坦福大学的研究人员通过研究开发了一种新型设备，该设备可以利用电子来刺激眼泪产生，该研究或为后期开发治疗干眼症的患者提供希望，干眼症是常见的一种眼部疾病，相关研究发表于国际杂志the Journal of Neural Engineering上。
这种设备有16mm长，3-4mm宽，1-2mm厚，其可以植入到兔子眼部的下泪腺皮下组织中，并且利用无线电激活来增加将近57%的眼泪的产生。研究者Daniel Palanker教授说道，我们研究电子神经界面已经将近10年了，但产生刺激泪腺产生眼泪的想法却是在我进行博士后工作时提出来的。
干眼症，即角膜表面缺失泪液膜，主要会引发角膜和结膜产生炎性表现；干眼症作为常见的一种眼部疾病，其影响着5%至6%的人口健康，在美国影响着将近500万65岁以上个体的生活，当前并没有有效的疗法来对干眼症进行治疗。研究人员发现，传入的神经通路，即从感觉神经元向大脑传输的神经通路可以刺激反射流泪，而这就提供了一种增强眼泪产生的途径。
研究者指出，起初我们仅仅计划刺激泪腺，而让我们最不可思议的是，当我们对传入的神经通路进行刺激时，就发现这可以提供一种潜在的且持久性的眼泪产生效应。下一步我们计划通过更为深入的研究来评估研究对象眼泪产生的质量，其中容量、蛋白质和脂质的内容比较重要，而当前开发的设备目前正在FDA批准的临床试验。
最后研究者Palanker总结道，我希望该设备可以在明年推向市场，与此同时我们还将继续进行研究来阐明眼泪反应的机制，而神经刺激将会增强眼泪的产生，本文研究对于后期开发更多治疗干眼症的新型疗法提供了新的思路和希望。
doi:10.1088/1741-2560/13/1/016006
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Electronic enhancement of tear secretion
Mark Brinton1, Jae Lim Chung2, Andrea Kossler3, Koung Hoon Kook4, Jim Loudin5, Manfred Franke5 and Daniel Palanker3,6
To study electrical stimulation of the lacrimal gland and afferent nerves for enhanced tear secretion, as a potential treatment for dry eye disease. We investigate the response pathways and electrical parameters to safely maximize tear secretion. Approach. We evaluated the tear response to electrical stimulation of the lacrimal gland and afferent nerves in isofluorane-anesthetized rabbits. In acute studies, electrical stimulation was performed using bipolar platinum foil electrodes, implanted beneath the inferior lacrimal gland, and a monopolar electrode placed near the afferent ethmoid nerve. Wireless microstimulators with bipolar electrodes were implanted beneath the lacrimal gland for chronic studies. To identify the response pathways, we applied various pharmacological inhibitors. To optimize the stimulus, we measured tear secretion rate (Schirmer test) as a function of pulse amplitude (1.5–12 mA), duration (0.1–1 ms) and repetition rate (10–100 Hz). Main results. Stimulation of the lacrimal gland increased tear secretion by engaging efferent parasympathetic nerves. Tearing increased with stimulation amplitude, pulse duration and repetition rate, up to 70 Hz. Stimulation with 3 mA, 500 μs pulses at 70 Hz provided a 4.5 mm (125%) increase in Schirmer score. Modulating duty cycle further increased tearing up to 57%, compared to continuous stimulation in chronically implanted animals (36%). Ethmoid (afferent) nerve stimulation increased tearing similar to gland stimulation (3.6 mm) via a reflex pathway. In animals with chronically implanted stimulators, a nearly 6 mm increase (57%) was achieved with 12-fold less charge density per pulse (0.06–0.3 μC mm−2 with 170–680 μs pulses) than the damage threshold (3.5 μC mm−2 with 1 ms pulses). Significance. Electrical stimulation of the lacrimal gland or afferent nerves may be used as a treatment for dry eye disease. Clinical trials should validate this approach in patients with aqueous tear deficiency, and further optimize electrical parameters for maximum clinical efficacy..