A Novel Method of Visual Field Assessment for Patients with Unilateral Severely Limited Central Vision: A Pilot Study

PURPOSE: Reliable visual field testing requires the tested eye to be fixated on a central target. This poses a major obstacle for eyes with severe central vision loss. This pilot study assesses whether it may be feasible to examine such patients with a modified method. METHODS: A green filter was placed over the fellow eye. A FASTPAC algorithm was used with a red stimulus. The green filter prevented transmission of the red stimuli but allowed visualization of the yellow fixation light. Subjects were tested by both the conventional and the novel method, performed in a randomized order. We compared the reliability indices and also the precision of the two methods. RESULTS: We present results from six patients. The novel method was associated with an 85% reduction in fixation losses (P=0.028) and a 58% reduction in eye motion on gaze tracking (P=0.007). Further, specialized testing in one of the volunteers demonstrated that the novel technique could more precisely define a small zone of preserved peripheral vision (P=0.008). CONCLUSION: The results of this pilot study suggest that the novel method described may be a feasible strategy for visual field testing in patients with unilateral severe central vision loss.