• Invest. Ophthalmol. Vis. Sci. · Jul 2004

    Comparative Study

    Tear secretion induced by selective stimulation of corneal and conjunctival sensory nerve fibers.

    • M Carmen Acosta, Assumpta Peral, Carolina Luna, Jesús Pintor, Carlos Belmonte, and Juana Gallar.
    • Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Campus de San Juan, San Juan de Alicante, Spain. mcarmen.acosta@umh.es
    • Invest. Ophthalmol. Vis. Sci. 2004 Jul 1; 45 (7): 2333-6.

    PurposeTo measure the increase in tear secretion evoked by selective stimulation of the different populations of sensory receptors of the cornea and conjunctiva by using moderate and intense mechanical, chemical, and cold stimuli.MethodsSix healthy subjects participated in the study. Tear secretion was measured in both eyes by the Schirmer's test conducted under control conditions and after stimulation of the center of the cornea and the temporal conjunctiva with a gas esthesiometer. Mechanical stimulation consisted in three pulses of 3 seconds' duration of warmed air (at 34 degrees C on the eye surface) applied at moderate (170 mL/min) and high (260 mL/min) flow rates. Cold thermal stimulation was made with cooled air that produced a corneal temperature drop of -1 degrees C or -4.5 degrees C. Chemical (acidic) stimulation was performed with a jet of gas containing a mixture of 80% CO(2) in air.ResultsThe basal volume of tear secretion increased significantly (P < 0.05, paired t-test) after stimulation of the cornea with high-flow mechanical stimuli (260 mL/min), intense cooling pulses (-4.5 degrees C), and chemical stimulation (80% CO(2)). The same stimuli were ineffective when applied to the conjunctiva. Moderate mechanical (170 mL/min) and cold (-1 degrees C) stimulation of the cornea or the conjunctiva did not change significantly the volume of tear secretion.ConclusionsReflex tear secretion caused by corneal stimulation seems to be chiefly due to activation of corneal polymodal nociceptors, whereas selective excitation of corneal mechanonociceptors or cold receptors appears to be less effective in evoking an augmented lacrimal secretion. Conjunctival receptors stimulated at equivalent levels do not evoke an increased tear secretion.

      Pubmed     Copy Citation     Plaintext  

      Add institutional full text...

    Notes

     
    Knowledge, pearl, summary or comment to share?
    300 characters remaining
    help        
    You can also include formatting, links, images and footnotes in your notes
    • Simple formatting can be added to notes, such as *italics*, _underline_ or **bold**.
    • Superscript can be denoted by <sup>text</sup> and subscript <sub>text</sub>.
    • Numbered or bulleted lists can be created using either numbered lines 1. 2. 3., hyphens - or asterisks *.
    • Links can be included with: [my link to pubmed](http://pubmed.com)
    • Images can be included with: ![alt text](https://bestmedicaljournal.com/study_graph.jpg "Image Title Text")
    • For footnotes use [^1](This is a footnote.) inline.
    • Or use an inline reference [^1] to refer to a longer footnote elseweher in the document [^1]: This is a long footnote..

    hide…