To the Editor.
—A relative afferent pupillary defect usually indicates a disorder in the anterior visual pathway anterior to the optic chiasm. Its detection is helpful in the diagnosis of optic nerve diseases. It has generally been evaluated using Kestenbaum's number1 or the swinging flashlight test and neutral-density filters that were calibrated in logarithmic units of light attenuation and percentage of light transmittance.2We measured the relative afferent pupillary defect employing the infrared video camera of the OCTOPUS perimeter 201 (Interzeag AG, Switzerland). The study included 10 healthy subjects (mean ± SD age, 41.6 ± 16.7 years; refractive error, +0.27 ± 1.81 diopters [spherical equivalent]) and 17 patients suffering from primary open angle glaucoma (mean age, 53.0 ± 11.9 years; refractive error, −0.15 ± 2.22 diopters). The mean difference in refractive error between the two eyes of the same individual was 0.01 diopter. Since in the control group
Jonas JB, Zäch F, Naumann GOH. Quantitative Pupillometry of Relative Afferent Defects in Glaucoma. Arch Ophthalmol. 1990;108(4):479–480. doi:10.1001/archopht.1990.01070060025009
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