All study subjects were recruited consecutively from the glaucoma service at the Massachusetts Eye and Ear Infirmary (MEEI) between April 2009 to July 2009. Each patient had a complete ophthalmologic examination, including history, visual acuity (VA) testing, refractive error exam, Goldmann applanation tonometry, slit-lamp biomicroscopy, gonioscopy, central corneal thickness by ultrasonic pachymetry, dilated ophthalmoscopy of the posterior segment, visual field (VF) testing [Swedish Interactive Threshold Algorithm (SITA) 24-2 test of the Humphrey visual field analyzer 750i, Carl Zeiss Meditec, Dublin, CA], and peri-papillary RNFL thickness measurements using the Spectralis OCT (Spectralis software version 4.0). Inclusion criteria included patients with a spherical equivalent between −5.0 diopters and +5.0 diopters and with best corrected VA of 20/40 or better. The study included only patients with reliable VF testing with acceptable fixation losses as defined by the Ocular Hypertension Treatment Study (OHTS) of less than 33% fixation losses.28 (link) Patients also had to have had less than 20% false positives and 20% false negatives. Exclusion criteria included patients with 1) any anterior segment dysgenesis, 2) corneal scarring or opacities, 3) proliferative or non-proliferative diabetic retinopathy, 4) field loss attributable to a non-glaucoma condition, 5) a dilated pupil diameter of less than 2 mm.
Participants included normal subjects and glaucoma patients. Normal subjects were those without significant ocular disease (except for mild cataract) and with normal VF test results that were defined as a pattern standard deviation (PSD) > 5% and glaucoma hemifield test (GHT) within normal limits.28 (link) Glaucoma patients included those with any form of chronic glaucoma except for traumatic glaucoma and were defined as having characteristic glaucomatous disc abnormality with corresponding VF loss. The VF was considered abnormal if three or more contiguous test locations in the pattern deviation plot were depressed significantly at the P < 5% level with at least 1 at the P < 1% level on the same side of the horizontal meridian, or was classified as outside normal limits by the GHT.29 (link) If both eyes of one subject fit inclusion and exclusion criteria, one eye was selected randomly by using a random number generator statistical table.