Dr. Jaehyun Jung will present a lecture on “Multiplexing prism glasses for field expansion in bitemporal hemianopia, acquired monocular vision, and normally sighted.”
Patients with acquired monocular vision (AMV) are missing the temporal crescent on the affected side, while patients with bitemporal hemianopia (BH) due to lesions at the optic chiasm are missing the crescents on both sides. Previous visual field expansion devices for AMV or BH required scanning into the device and created a blind area (apical scotoma) of equal magnitude to the shifted view. A multiplexing prism (MxP) can expand the visual field in both cases avoiding these limitations. The MxP prevents apical scotomas by superimposing both see-through and shifted views. MxP (base-in) is placed over the nose bridge to expand the nasal visual field unilaterally for AMV/bilaterally for BH. The MxP optimal configuration for wide visual field expansion was determined by considering the effective prism powers. Rotating the prism nasal edge towards the eye can increase the effective prism power due to the increased angle of incidence. For the case of BH, the deflected ray at the nasal edge of one prism has to stay forward of the fellow eye’s prism, constraining the amount of rotation. MxP also can be used for field expansion of far periphery in normally sighted such as bicycle and bike riders. The prism rotation angle, power, and size are best fitted individually due to variations in facial biometry.