To investigate corneal sensitivity to selective mechanical, chemical, heat, and cold stimulation in patients with fibromyalgia (FM).
Twenty patients with FM (18 women, 2 men; 51.9 +/- 2.3 years old) and 18 control subjects (16 women, 2 men; 51.7 +/- 2.4 years) participated voluntarily in the study. Subjective symptoms of ocular dryness were explored and a Schirmer I test was performed. The response to selective stimulation of the central cornea with the Belmonte gas esthesiometer was measured.
The majority (18/20) of patients with FM reported dry eye symptoms, with the ocular dryness score significantly higher in affected subjects than in healthy ones (2.3 +/- 0.1 vs. 0.05 +/- 0.02; P < 0.001). The Schirmer test results were significantly lower in patients with FM than in those in the control group (10.5 +/- 2.2 and 30.6 +/- 1.6 mm, respectively; P < 0.001). Mean corneal threshold sensitivity values to chemical stimulation (31.16% +/- 2.04% CO(2) FM; 15.72% +/- 0.67% CO(2) control), heat (1.87 +/- 0.11 degrees C FM; 0.99 +/- 0.05 degrees C control), and cold (-2.53 +/- 0.11 degrees C FM; -0.76 +/- 0.05 degrees C control) were increased in patients with FM, whereas threshold responses to mechanical stimulation did not vary significantly (123.0 +/- 8.0 mL/min FM; 107.8 +/- 4.4 mL/min control).
The reduced corneal sensitivity of patients with fibromyalgia is attributable to a moderate decrease in corneal polymodal and cold nociceptor sensitivity, which may be the consequence or the cause of the chronic reduction in tear secretion also observed in these patients.