HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (10) Citing Articles via Google Scholar Google Scholar Articles by Acosta, M. C. Articles by Gallar, J. Search for Related Content PubMed PubMed Citation Articles by Acosta, M. C. Articles by Gallar, J.

Tear Secretion Induced by Selective Stimulation of Corneal and Conjunctival Sensory Nerve Fibers

¹From the Instituto de Neurociencias de Alicante, Universidad Miguel Hernández-CSIC, Campus de San Juan, San Juan de Alicante, Spain.; and the ²Departmentos de Óptica and de ³Bioquímica, Escuela Universitaria de Óptica, Universidad Complutense de Madrid, Madrid, Spain.

PURPOSE. To 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.

METHODS. Six 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°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°C or –4.5°C. Chemical (acidic) stimulation was performed with a jet of gas containing a mixture of 80% CO₂ in air.

RESULTS. The 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°C), and chemical stimulation (80% CO₂). The same stimuli were ineffective when applied to the conjunctiva. Moderate mechanical (170 mL/min) and cold (–1°C) stimulation of the cornea or the conjunctiva did not change significantly the volume of tear secretion.

CONCLUSIONS. Reflex 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.

This article has been cited by other articles:

				J. Varikooty and T. L. Simpson The Interblink Interval I: The Relationship between Sensation Intensity and Tear Film Disruption Invest. Ophthalmol. Vis. Sci., March 1, 2009; 50(3): 1087 - 1092. [Abstract] [Full Text] [PDF]

				J. Lilja, H. Lindegren, and A. Forsby Surfactant-Induced TRPV1 Activity A Novel Mechanism for Eye Irritation? Toxicol. Sci., September 1, 2007; 99(1): 174 - 180. [Abstract] [Full Text] [PDF]

				A. Peral, G. Carracedo, M. C. Acosta, J. Gallar, and J. Pintor Increased levels of diadenosine polyphosphates in dry eye. Invest. Ophthalmol. Vis. Sci., September 1, 2006; 47(9): 4053 - 4058. [Abstract] [Full Text] [PDF]