An analysis of step-like field defects in Gilles de la Tourette syndrome

Abstract

Step-like visual field defects have been found in 37 individuals exhibiting Gilles de la Tourette syndrome (TS). The authors present an analysis of these step-like field defects. There is a near equal distribution of nasal and temporal steps in this group of individuals. The majority (76%) of steps face upwards. These results are independent of age and sex. However, drugs used in management of TS have a quantitative effect on visual fields. Drug therapy reduces the number of steps detected and also reduces areas of sensitivity difference at the horizontal meridian. Analysis also suggests that plotting at least two isopters will result in detection of a step-like field defect in all individuals exhibiting TS and in 91% of the eyes of such individuals.

It is difficult to determine the underlying pathophysiology for these types of visual field defects. It is suggested that dopamine, a neurotransmitter of the retina might be involved in some manner in the pathogenesis of the visual field defects.

Key Words:

• visual fields
• nasal and temporal steps
• Goldmann perimetry
• Gilles de la Tourette syndrome
• neurotransmitters
• dopamine