To the Editor.
—We have successfully evaluated an improved version of the negative-lens field expander recently described by Kozlowski et al1 in the Archives. The improvement consists of an aperture drilled in the center of the lens, enabling the patient to fixate through it (Figure).The original device is an oversized negative-powered spectacle lens held at a fixed distance in front of the eye. It was successfully used to orient patients with tunnel vision in unknown surroundings. When these patients used the field expander, maximum predetermined field expansion was obtained at the cost of a proportionate decrease in visual acuity. This outcome limited the field expander's use to patients with good central visual acuity. Once patients used the lens to locate objects of interest, they had difficulties discerning the details, as the device produced a minification effect. Without the lens, however, patients had difficulties in locating landmarks because of
Kozlowski JMD, Jalkh AE. An Improved Negative-Lens Field Expander for Patients With Concentric Field Constriction. Arch Ophthalmol. 1985;103(3):326. doi:10.1001/archopht.1985.01050030022009