[An Unusual Cause of Increased Light Sensitivity].

Photophobia is in many cases linked to pathologies of the anterior segment of the eye, e.g. cataract or iritis. We report an unusual case of increased light sensitivity due to a compressing lesion of the chiasm. Pituitary adenomas are among the most frequent intracranial tumours and can affect the chiasm - the site where all the visual afferences meet. A lesion of the chiasm is therefore particularly dangerous. Fortunately, in two-thirds of all cases, pituitary adenomas lead to hormonal dysfunction, so that magnetic resonance imaging of the brain is conducted. However, in the remainder of the cases, the ophthalmologist may be the first physician to see the patient because of visual problems. Usually patients report reduced vision or show typical visual field defects, such as bitemporal hemianopsia. However, the only pathological symptom may be increased light sensitivity. In rare cases of photophobia which cannot be explained by pathologies of the anterior segment, a compressing lesion of the chiasm should be considered.