Blue versus white stimuli in ocular hypertension with the Friedmann Mark 1 Visual Field Analyser

Fifty eyes of fifty patients with ocular hypertension had their visual fields tested on a Friedmann Mark 1 field analyser whilst wearing a Wratten 47B blue filter in a spectacle frame. All had normal visual fields to a white stimulus. Use of a scoring system with the blue field identified 11 patients (22%) with ocular hypertension as abnormal. The scores from this subgroup were indistinguishable from a group of subjects with early glaucomatous field loss, whilst the remaining scores were similar to normal subjects. These two subgroups of ocular hypertensive patients were similar in age and intraocular pressure. The use of a blue filter in front of the eye may offer a simple test to identify a subgroup of patients with ocular hypertension who are at increased risk of developing field loss.