Purpose

To evaluate the role of transient receptor potential melastatin 8 (TRPM8) activity in menthol-induced cold sensitivity and its qualitative perception in patients with dry eye (DE).

Methods

This prospective, cross-sectional, comparative study included 52 eyes of 52 subjects (mean age: 66.8 ± 9.2 years; range: 44–86) with a tear break-up time (TBUT) of ≤5 s. The participants were classified into three groups: 17 patients with DE symptoms and keratoconjunctival (KC) staining scores of ≥3 points (positive KC-DE group), 18 patients with DE symptoms and KC staining scores of <3 points (negative KC-DE group), and 17 individuals with KC staining scores of <3 points and no symptoms (non-DE control group). The menthol-induced cool sensation (M-cool) and TBUT were measured after administration of 2 μl of 1.0 mM menthol eye drops. Furthermore, participants answered a questionnaire regarding their stimulus perception (pleasant, unpleasant, or neither).

Results

M-cool values were similar in the three groups. TBUT significantly increased in the negative KC-DE and control groups (P < 0.05) and remained unchanged in the positive KC-DE group (P > 0.05) after menthol administration. DE patients reported the sensation as pleasant or unpleasant, whereas most control participants were indifferent (P < 0.05).

Conclusions

While M-cold sensitivity was similar in DE and control groups, its qualitative perception differed between these groups. Thus, TRPM8 activation at the peripheral level alone may not be sufficient to account for the manifestation of discomfort symptoms associated with DE.

中文翻译：

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瞬态受体电位褪黑素8活性在薄荷醇诱导的冷敏性及其干眼定性感知中的作用

目的

若要评估瞬态受体电位褪黑素8（TRPM8）活性在薄荷醇引起的冷感及其对干眼症（DE）患者的定性感知中的作用。

方法

这项前瞻性，横断面的比较研究包括52位受试者的52眼（平均年龄：66.8±9.2岁；范围：44-86），泪液破裂时间（TBUT）≤5 s。参与者分为三组：17例DE症状和角膜结膜（KC）染色评分≥3分的患者（阳性KC-DE组），18例DE症状和KC染色评分＜3分的患者（阴性KC-DE的患者）组），以及17名KC染色得分<3分且无症状的患者（非DE对照组）。服用2μl的1.0 mM薄荷醇滴眼液后，测量了薄荷醇引起的冷感（M-cool）和TBUT。此外，参与者回答了有关他们的刺激感知（令人愉快，不愉快或没有）的问卷。

结果

三组的M-cool值相似。 薄荷醇给药后，阴性KC-DE组和对照组的TBUT显着增加（P  <0.05），而阳性KC-DE组则保持不变（P > 0.05）。DE患者报告感觉为愉悦或不愉快，而大多数对照者则无动于衷（P  <0.05）。

结论

尽管DE和对照组中的M感冒敏感性相似，但这些组之间的定性感知却有所不同。因此，仅在外周水平的TRPM8激活可能不足以解释与DE相关的不适症状的表现。