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N.L. Herz, M.T. Yen; Modulation of Sensory Photophobia in Essential Blepharospasm With Chromatic Lenses . Invest. Ophthalmol. Vis. Sci. 2005;46(13):617.
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Purpose:Benign essential blepharospasm is a form of focal dystonia with involuntary contractions of the eyelid protractors. Current treatments have been directed towards symptomatic relief of the motor signs of eyelid spasm. Many patients also experience extreme photophobia in normal or even low light conditions; however, there has been no comprehensive analysis of the photophobia or evaluation of treatments for the photophobia associated with blepharospasm. The purpose of this study is to determine the effect of photochromatic modulation with tinted lenses on the sensory symptoms of photophobia in blepharospasm patients. Methods:Patients with the diagnosis of benign essential blepharospasm and normal subjects were enrolled in this study. Subjects were seated in front of a calibrated light source. Beginning at 0% intensity, the intensity of the light source was gradually increased until the patient reported symptomatic photophobia. The intensity of the light source was then measured with a light meter. This procedure was first performed with no chromatic lens and then with 7 different chromatic lenses, each blocking specific wavelengths of the visible spectrum. Statistical significance was calculated with ANOVA and t–test analysis. Results: Twenty–four patients with benign essential blepharospasm and ten normal subjects were tested. The intensity tolerated by the normal subjects compared to the blepharospasm group was similar with no lens, but grew to 3.5 times that tolerated by the blepharospasm group as more of the higher wavelengths of the visible spectrum were blocked (p=0.048). Lenses #4, #5, #6, and #7 allowed blepharospasm patients to tolerate a significantly higher intensity of light when compared to no lens (p=0.04, 0.007, 0.03, and 0.01 respectively). Although the highest intensity of light tolerated was measured with lens #6, most blepharospasm patients (72%) reported greatest relief of their photophobia with lens #7. Conclusions: Blepharospasm patients tolerate a lower intensity of light when compared to normal subjects, which becomes significantly more pronounced as the higher wavelengths of the visible spectrum are blocked. The symptoms of photophobia in blepharospasm patients can be significantly reduced with photochromatic modulation. Despite lens #6 allowing the patients to tolerate a higher intensity of light, the majority of patients preferred lens #7 for symptomatic relief of their photophobia. These findings suggest that sensory photophobia may be more related to the wavelength rather than the intensity of the light exposure.
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