FLASHING LIGHTS IN THYROID EYE DISEASE - A NEW SYMPTOM DESCRIBED AND (POSSIBLY) EXPLAINED

Backgroundlaims-Some patients with restrictive thyroid ophthahmopathy, referred for consideration of extraocular muscle surgery, complained of flashing lights in the superior visual field on upgaze. The frequen cy was assessed and the pathogenesis of this previously unreported sym ptom explored. Methods-30 patients were recruited, all of whom had tig ht inferior recti and were in the burnt out phase of thyroid eye disea se. They were directly questioned regarding any symptoms of photopsia and their records were examined with respect to disease status and tre atment, ocular motility, intraocular pressure, retinal status, and sur gical intervention. Magnetic resonance imaging (MRI) and cine MRI scan s were reviewed for evidence of globe compression. The frequency of sy mptoms was compared with an age and sex matched control group. Results -Three patients spontaneously complained of flashing lights. A further nine patients had this symptom when directly questioned. 18 patients had no symptoms. None of the 33 control patients had symptoms on direc t questioning. Sagittal MRI and cine MRI failed to demonstrate globe c ompression by the inferior rectus muscle even in cases that showed an intraocular pressure rise in upgaze. Conclusion-A new symptom of flash ing lights in upgaze has been identified in thyroid eye disease patien ts with tight inferior recti. It is suggested that the Lights are like ly to be phosphenes as a result of either compression of the globe by a tight inferior rectus or traction on the insertion of the inferior r ectus. The small amount of globe compression required to produce phosp henes seems to be beyond the resolution limit of MRI.