Decreased corneal sensitivity and tear production in fibromyalgia.
Invest Ophthalmol Vis Sci. 2009 Mar 25.
Gallar J, Morales C, Freire V, Acosta MC, Belmonte C, Duran JA. Instituto de Neurociencias, Universidad Miguel Hernandez-CSIC, San Juan de Alicante, Spain.
Purpose: To investigate corneal sensitivity to selective mechanical, chemical, heat and cold stimulation in fibromyalgia (FM) patients.
Methods: Twenty FM patients (18 female, 2 male; 51,9+/-2,3 years old) and 18 control subjects (16 female, 2 male; 51,7+/-2,4 years) participated voluntarily in the study. Subjective symptoms of ocular dryness were explored and Schirmer's 1 test was performed. The response to selective stimulation of the central cornea with the Belmonte gas esthesiometer was measured.
Results: The majority (18 out of 20) of FM patients reported dry eye symptoms, being the ocular dryness score significantly higher than in healthy subjects (2,3+/-0,1 vs. 0,05+/-0,02; p<0,001). Schirmer'stest values were significantly reduced in FM patients compared to those of the control group (10,5+/-,2 mm and 30,6+/-1,6 mm, respectively; p<0,001). Mean corneal threshold sensitivity to chemical stimulation (31,16+/-2,04 %CO2 FM; 15,72+/-0,67 %CO2 control) to heating (1,87+/-0,11 degrees C FM; 0,99+/-0,05 degrees C control) and to cooling (-2,53+/-0,11 degrees C FM; -0,76+/-0,05 degrees C control) were increased in FM patients while threshold to mechanical stimulation did not vary significantly (123,0+/-8,0 ml/min FM; 107,8+/-4,4 ml/min control).
Conclusions: The reduced corneal sensitivity of patients with fibromyalgia is attributable to a moderate decrease of corneal polymodal and cold nociceptor sensitivity, that may be the
consequence or the cause of the chronic reduction in tear secretion also observed in these patients.