Illumination perception in photophobic patients suffering from panic disorder with agoraphobia.

Ten (6.9%) of a sample of 144 patients with panic disorder and agoraphobia developed photophobic behaviour in the course of their anxiety disorder. Their illumination ratings were characterized before and after cognitive behaviour therapy and compared to 10 age- and sex-matched normal control subjects. The illumination of a sheet of printed paper by a continuously adjustable reading lamp was rated by the subjects as 'too dark', 'comfortable' or 'too bright'. The ratings for comfortable luminance were significantly lower in the photophobic patients than in the controls, and renormalized after cognitive behavioural therapy. No differences were observed in the ratings for 'too dark' and 'too bright'. Photophobia in a subsample of patients with panic disorder is a state-dependent phenomenon that can be influenced by cognitive behavioural therapy. The role of neurotransmitters, conditioning processes and a concomitant neurasthenic syndrome requires further characterization.