Bagolini Filter Bar

The Bagolini Filter Bar is used to investigate the depth of suppression in patients with amblyopia up to the age of 7 years. This instrument consists of a series of red filters of increasing density from very pale to very dark. This decreases the illumination in front of the fixating eye to induce fixation with the deviating eye and therefore diplopia. The patient looks at a spot light about 30 cm away in the primary position and the Bagolini bar is introduced before the fixating eye starting with the palest filter. The filter strength is increased until the patient sees one red and one white light as a result of diplopia. The strength of the filter at which this occurs indicates the density of suppression.