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. 2015 Sep;16(9):881-6.
doi: 10.1016/j.jpain.2015.06.002. Epub 2015 Jun 15.

Topical Tetrodotoxin Attenuates Photophobia Induced by Corneal Injury in the Rat

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Topical Tetrodotoxin Attenuates Photophobia Induced by Corneal Injury in the Rat

Paul G Green et al. J Pain. 2015 Sep.

Abstract

Corneal injury can produce photophobia, an aversive sensitivity to light. Using topical application of lidocaine, a local anesthetic, and tetrodotoxin (TTX), a selective voltage-sensitive sodium channel blocker, we assessed whether enhanced aversiveness to light induced by corneal injury in rats was caused by enhanced activity in corneal afferents. Eye closure induced by 30 seconds of exposure to bright light (460-485 nm) was increased 24 hours after corneal injury induced by de-epithelialization. Although the topical application of lidocaine did not affect the baseline eye closure response to bright light in control rats, it eliminated the enhancement of the response to the light stimulus after corneal injury (photophobia). Similarly, topical application of TTX had no effect on the eye closure response to bright light in rats with intact corneas, but it markedly attenuated photophobia in rats with corneal injury. Given the well-established corneal toxicity of local anesthetics, we suggest TTX as a therapeutic option to treat photophobia and possibly other symptoms that occur in clinical diseases that involve corneal nociceptor sensitization. Perspective: We show that lidocaine and TTX attenuate photophobia induced by corneal injury. Although corneal toxicity limits use of local anesthetics, TTX may be a safer therapeutic option to reduce the symptom of photophobia associated with corneal injury.

Keywords: Eye pain; corneal nociceptor; lidocaine; photophobia; tetrodotoxin.

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Conflict of interest statement

The authors report no conflicts of interest.

Figures

Figure 1
Figure 1. Scale for quantification of eye closure response to bright light in the rat
Eye closure was scored according to its magnitude: no closure = 0, ~25% closure = 1, ~50% closure = 2, ~75% closure = 3, full closure = 4.
Figure 2
Figure 2. Lidocaine attenuates the increase in the eye closure response induced by corneal injury
Lidocaine (2%, 10 μl) did not significantly affect the magnitude of eye closure produced by exposure to bright light (~48 lumens, 465–480 nm) for 30 s in control eyes. However, the enhanced response, photophobia, following de-epithelialization injury was significantly attenuated by lidocaine (*P
Figure 3
Figure 3. TTX attenuates photophobia induced by corneal injury
The magnitude of eye closure response produced by bright light was not significantly affected by TTX (1 mM, 10 μl) applied to rats with uninjured corneas, but was significantly attenuated 1 and 2 h after application TTX to rats with injured corneas (*P

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References

    1. Belmonte C, Acosta MC, Gallar J. Neural basis of sensation in intact and injured corneas. Exp Eye Res. 2004;78:513–525. - PubMed
    1. Berson DM. Phototransduction in ganglion-cell photoreceptors. Pflugers Arch. 2007;454:849–855. - PubMed
    1. Bi RY, Kou XX, Meng Z, Wang XD, Ding Y, Gan YH. Involvement of trigeminal ganglionic Nav 1.7 in hyperalgesia of inflamed temporomandibular joint is dependent on ERK1/2 phosphorylation of glial cells in rats. Eur J Pain. 2013;17:983–994. - PubMed
    1. Binder PS. Optical problems following refractive surgery. Ophthalmology. 1986;93:739–745. - PubMed
    1. Bisla K, Tanelian DL. Concentration-dependent effects of lidocaine on corneal epithelial wound healing. Invest Ophthalmol Vis Sci. 1992;33:3029–3033. - PubMed

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