Glaucoma is the first cause of irreversible blindness worldwide with more than 60 millions people affected in 2010. It is defined as a neurodegenerative disease characterized by a progressive loss of retinal ganglion cells (RGC), visual field deterioration and optic nerve excavation. Intraocular pressure (IOP) is the most common risk factor. Despite its severity, its impact on quality of life and an existing treatment that can delay visual field damages, there is no recommended strategy to screen the disease. Clinical evaluation of optic nerve head excavation performed either by ophthalmologists or glaucoma specialists is highly inter-observer dependent and limits its accuracy to diagnose glaucoma. Additionally, up to 30 to 40% of nerve fiber layer may be lost before detecting first visual field defects, thus making this tool not accurate enough for screening purposes.

Spectral-Domain Optical coherence tomography (SD-OCT) imaging technology allows precise and reproducible measurements of optic nerve head structures and retinal layers mainly related to the speed of acquisition and an axial resolution of 5 microns. New SD-OCT parameters have been developed to improve its diagnostic accuracy for glaucoma disease. The investigators therefore investigate performances of SD-OCT to discriminate glaucoma patients and controls. All subjects will undergo SD-OCT imaging (Spectralis™ OCT, Version 6.3, Heidelberg Engineering, Germany) and other study procedures in one single visit. All examinations performed on the subjects are non-significant risk.

Inclusion Criteria: Normal Subjects

1. No history or evidence of retinal pathology or glaucoma
2. Normal Humphrey 24-2 Visual Field (VF) : A mean defect (MD), corrected pattern standard deviation (CPSD) within 95% limits of normal reference, and glaucoma hemifield test (GHT) within normal limits (97%).
3. Intraocular pressure < 21 mm Hg
4. Open angle (Shaffer's grading system)
5. Normal appearing Optic Nerve Hypoplasia (ONH) and Nerve Fiber Layer (NFL) : intact neuroretinal rim without peripapillary hemorrhages, notches, localized pallor, or NFL defect
6. Symmetric ONH between left and right eyes: Cup-to-Disc Ratio (CDR) difference < 0.2 in both vertical and horizontal dimensions

Inclusion Criteria: Perimetric Glaucoma

1. ONH or NFL defect visible on slit-lamp biomicroscopy defined as one of following:

   • diffuse or localized thinning of the rim
   • disc (splinter) hemorrhage
   • notch in the rim
   • vertical cup/disc ratio greater than the fellow eye by > 0.2

2. Consistent glaucomatous pattern on both qualifying Humphrey Swedish Interactive Threshold Algorithm (SITA) 24-2 VF meeting at least one of the following quantitative criteria for abnormality:

   • PSD outside normal limits (p < 0.05)
   • GHT outside normal limits (p < 0.01)

Inclusion Criteria: Pre-Perimetric Glaucoma (PPG)

PPG participants must have at least one eye meeting all of the following criteria:

1. ONH or NFL defect visible on slit-lamp biomicroscopy defined as one of following:

   • diffuse or localized thinning of the rim
   • disc (splinter) hemorrhage
   • notch in the rim
   • well-defined peripapillary NFL bundle defect.
   • inter-eye vertical CDR asymmetry > 0.2

2. Baseline VF not meeting the criteria for the PG group.

3. Risk factors for glaucoma, one of following:

   • Intraocular pressure > 21 mm Hg
   • Ethnics
   • Family history of glaucoma

Exclusion Criteria: All Groups

1. Age < 40

2. Refractive error of > +6.00 D or < -6.00 D (SE), +3,00 D for astigmatism

3. Diabetic retinopathy

4. Other diseases that may cause VF loss or optic disc abnormalities

5. Inability to clinically view or photograph the optic discs due to media opacity or poorly dilating pupil

6. Inability to perform reliably on automated VF testing

7. Insufficient quality of Spectralis OCT images (this is not determined until after Spectralis OCT examination, and is an unusual circumstance). Minimum requirements are:

   • Retina completely included in image frame,
   • Quality Score ≥ 15 in the stored mean images,

8. Refusal of informed consent