The visual testing protocol was approved by the University of Iowa Institutional Review Board. Sixty ocularly normal subjects and 120 patients with glaucoma were tested at baseline and again at a separate sitting within 1 to 8 weeks. They all gave informed consent to participate in the study. The tenets of the Declaration of Helsinki were followed. The normals were recruits, paid in accordance with the Institutional Review Board, who answered advertisements inviting them to participate in research. The patients with glaucoma were invited from the glaucoma clinic at the University of Iowa Department of Ophthalmology and Visual Sciences if they met the entry criteria. They were enrolled if they had glaucomatous optic disc changes with abnormal standard automated perimetry (glaucomatous visual field defects i.e., three or more adjacent abnormal test locations in a clinically suspicious area at the P < 0.05 level or two adjacent locations abnormal with at least one at the P < 0.01 level. In addition, mean deviation was in the range of 0 to −20 dB on SAP). We included patients with primary, secondary, or normal-tension glaucoma. The patients did not have another disease affecting vision and were capable of performing SAP and returning for follow-up visits. Patients were excluded if they had cataract causing visual acuity worse than 20/30, pupil size less than 2.5 mm, age less than 19 years, or pregnancy. The first 120 consecutive patients who agreed to enter the study constituted the glaucoma cohort. If both eyes qualified for the study, one eye was chosen at random as the study eye. The average age (SD) of the normal subjects was 57.2 ± 7.9 year, with a range of 41 to 78 years. Thirty-eight of the participants were women and 22 were men. The average age of the patients with glaucoma was 64.9 years (SD, 9.5; range, 38–81); their mean deviation was −6.7 dB (SD, 4.4). Patients with glaucoma were free of other diseases that cause visual loss; if a cataract was present, the patient had a visual acuity of 20/30 or better.
Normal participants were included if they had no history of eye disease, refractive error within ±5 D sphere and ±2 D astigmatism, no history of diabetes mellitus or systemic arterial hypertension, and a normal ophthalmic examination including 20/25 or better Snellen acuity. The subjects either had undergone a complete eye examination within 12 months before this study or were examined by an ophthalmologist on the day, of testing to ensure normal ocular health. One eye of each participant was randomly chosen as the study eye.