Abstract
Purpose: :
Fibromyalgia syndrome (FM) is a systemic disease characterized by chronic widespread pain and tenderness in specific body points on digital palpation. FM patients often present sensations of ocular dryness and discomfort. However the status of corneal sensitivity in this disorder has not been explored. The aim of this work is to analyze tear production and corneal sensitivity to selective mechanical, chemical, heat and cold stimulation in 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. Ocular discomfort and ocular surface dryness were quantified with a questionnaire validated for Spanish-speaking people. Stimulation of the central cornea with mechanical (air at 0 to 300ml/min flow), chemical (0 to 80% CO2 in air), heat (changing corneal temperature between 0 and +2.5ºC) and cold (changing corneal temperature between 0 and -3.5ºC) stimuli was performed with the Belmonte gas esthesiometer and responses measured using a visual-analog scale.
Results: :
90% of FM patients reported dry eye symptoms and showed ocular dryness scores significantly higher than control subjects (2,3±0,1 vs. 0,05±0,02, respectively; p<0,001). Schirmer’s test values were significantly reduced in FM patients compared to the control group (10,5±2,2 mm vs. 30,6±1,6 mm; p<0,001). Mean corneal sensitivity threshold to chemical, heat and cold stimuli were significantly increased in FM patients (Chemical: 31,16±2,04 %CO2 vs. 15,72±0,67 %CO2, p<0,001. Heat = 1,87±0,11 ºC vs. 0,99±0,05 ºC, p<0,001. Cooling = -2,53±0,11 vs. -0,76±0,05 ºC, p<0,001) while threshold to mechanical stimulation was not significantly altered (123,0±8,0 ml/min vs. 107,8±4,4 ml/min, p=0.279). The changes in chemical and thermal threshold seen in FM patients were independent of age.
Conclusions: :
Patients with FM exhibit a moderate reduction of corneal cold and polymodal nociceptor sensitivity that is probably secondary to the presence of chronic ocular dryness and appears early in the development of the disease.