All participants received a complete ophthalmologic examination, including best-corrected visual acuity, a slit lamp examination, IOP measurement (Tonoref II; Nidek Co., Ltd., Gamagori, Japan), fundus examination, and standard automated perimetry with the Humphrey Visual Field Analyzer Swedish Interactive Threshold Algorithm–Standard 24-2 program (HFA 24-2; Carl Zeiss Meditec, Dublin, CA, USA). Primary open angle glaucoma was diagnosed if at least two reliable visual field examinations confirmed the presence of glaucomatous visual field defects consistent with glaucomatous optic disc changes with open angle observed with gonioscopy or slit lamp biomicroscopy. Patients were excluded if they had significant media opacity or other intraocular or neurological diseases affecting the visual field. Eyes with unreliable visual field results (fixation loss > 33%, false-positive > 15%, or false-negative > 20%) were also excluded. Consequently, patients with primary open angle glaucoma were enrolled. The FP receptor agonists used were 0.005% latanoprost for 954, 0.0015% tafluprost for 82, 0.004% travoprost for 30, and 0.03% bimatoprost for 43 patients.
Binocular near add power was measured at a distance of 30 cm using a Bankoku near-acuity chart (Handaya Inc., Tokyo, Japan). After determining the patient's distance refractive correction, the minimal additional power required to achieve near acuity above 20/25 at 30 cm was measured in 0.25 D increments and was recorded as near add power. The prevalence of symptomatic presbyopia (near add power ≥ 1.50 D) was calculated. Ocular surface examinations consisted of tear break-up time (BUT) and a corneal staining test. BUT was defined as the time taken for the first black spot to appear on the stained ocular surface after the last complete blink observed using the cobalt-blue filter of the slit lamp. Three consecutive measurements were acquired, and the mean value calculated and recorded. A BUT measurement below or equal to five seconds was determined as a short BUT. Corneal staining was used to detect corneal epitheliopathy by grading the stain intensity (0–2) one minute after administering fluorescein dye in the eye using the slit lamp's cobalt blue illumination and a yellow barrier filter.
Optical coherence tomography (OCT; RS-3000; Nidek, Tokyo, Japan) was used to measure macular RNFL, ganglion cell layer (GCL) + inner plexiform layer (IPL) (GCL/IPL), and macular RNFL + GCL + IPL (GCC) of the maps based on macular cube scans of a 6 × 6 mm2 area centered on the fovea. For peripapillary RNFL imaging, raster scanning over a 6 × 6 mm2 area centered on the optic disc center was conducted at a scan density of 512 A-scans (horizontal) × 128 B-scans (vertical). Peripapillary RNFL measurements were performed along a 3.45-mm diameter circle automatically positioned around the optic disc.