For this longitudinal study, we enrolled patients with PPG (43 eyes). All of the participants had visited the Glaucoma Clinic of Seoul National University Hospital from August 2014 through May 2015 and been enrolled in the Macular Ganglion Cell Imaging Study, an ongoing prospective study designed in 2011. The study protocol, approved by the institutional review board of Seoul National University Hospital, adhered to the tenets of the Declaration of Helsinki.
Each patient underwent a comprehensive ophthalmic examination, including a medical history review, slit-lamp biomicroscopy, IOP measurement using Goldmann applanation tonometry, gonioscopy, disc examination using a 90-diopter (D) lens, color fundus, and disc photography as well as red-free fundus photography (VX-10; Kowa Optimed, Tokyo, Japan), SAP 24-2 testing (Humphrey Field Analyzer; Carl Zeiss Meditec, Dublin, CA, USA), and SS-OCT (DRI-OCT-1 Atlantis, Topcon, Tokyo, Japan).
The PPG diagnosis was made based on the presence of one or more localized RNFL defects corresponding to characteristic glaucoma optic disc changes defined on stereo disc photography as an inter-eye cup-to-disc (C/D) ratio difference >0.2, increased cupping (>0.7 vertical C/D ratio), neuroretinal rim thinning, notching, or excavation.
20–22 All of the disc and RNFL photography images were evaluated by two glaucoma specialists (YKK, JWJ) in a masked fashion. Discrepancies between the observers were resolved by consensus or adjudication by a third glaucoma specialist (KHP). Patients were required to have an SAP result not meeting the conventional criteria of glaucomatous VF at the initial examination. Eyes with glaucomatous VF defects were defined as those with a cluster of three points with probabilities of <5% on the pattern deviation map in at least one hemifield, including at least one point with a probability of <1%, or those with a cluster of two points with a probability of <1%, and a glaucoma hemifield test (GHT) result outside 99% of age-specific normal limits or a pattern standard deviation (PSD) outside 95% of normal limits. All VF defects were confirmed on two consecutive reliable tests.
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The inclusion criteria were as follows: (1) PPG in one or both eyes at the first clinic visit, (2) no history of IOP-lowering treatment use, (3) follow-up examination attendance every 6 months for at least 2 years, and (4) no treatment or treatment with only topical medications during the follow-up period. Additionally, patients to be included in the study had to have a best-corrected visual acuity of 20/40 or better, spherical equivalent refractive errors between +6.0 and −6.0 D, cylinder correction <3.0 D, and an open anterior chamber angle. All of the SS-OCT images referenced had an image quality score of 50 or better. For cases in which both eyes met all of the eligibility criteria, one eye was randomly chosen as the study eye.