Sensitivity and Specificity of the NOVA-VEP (FP) Fixed Protocol for Glaucoma Diagnosis

This study is utilizing electrophysiology, called Visual Evoked Potental (VEP) and pattern Electroretinography (ERG) to measure the electrical activity of the visual pathway. VEP measures the electrical activity of the entire vision system. When light enters the eye, it is converted into electrical energy at the retina and travels through the optic nerve to the visual cortex of the brain which processes this information. The NOVA-VEP measures the strength and speed of the signal from your retina all the way to your visual cortex. Pattern Electroretinography (PERG) measure the function of the retina, the light-sensitive layer at the back of the eye. When light enters the eye, it is converted into electrical energy by specialized cells in the retina. The NOVE-ERG records how well the cells of the retina are conveying the electoral impulses within the eye. The purpose of this study is to evaluate the ability of the NOVA-VEP (FP) and PERG to discriminate between healthy eyes and the eyes with early to advanced glaucomatous visual field loss. The aim of this study is to obtain VEP and PERG measured outcomes from patients without glaucoma, with glaucoma, and risk factors for glaucoma to measure the health of their visual pathway.

Inclusion Criteria:

Healthy subjects:

- Intraocular Pressure <22 mmHg

- Normal appearing optic discs and RNFL

- Normal OCT (RNFL thickness) 

- Normal SAP results in both eyes

Glaucoma suspect subjects:

At least one of the following:

- A cup to disc ratio > 0.6

- Inter-eye cup to disc ratio asymmetry > 0.2 

- Retinal nerve fiber layer defects

- Neuroretinal rim notching

- Disc hemorrhage.

Glaucoma subjects:

- Repeatable abnormal SAP results (pattern standard deviation with p ≤5% and/or Glaucoma Hemifield Test outside normal limits)

- Glaucomatous optic disc appearance (those with cup to disc area ratio, rim thinning or RNFL defects indicative of glaucoma) 

- And/or repeatable intraocular pressure ≥23 mmHg, in at least one eye.

Obstructive Sleep Apnea Subjects:

- Diagnosis of obstructive sleep apnea as determined by Sleep Medicine Associates physician

Diabetic Retinopathy subjects:

- Diagnosis of mild to moderate proliferative diabetic retinopathy

Ocular hypertensive subjects:

- Diagnosis with ocular hypertension without glaucoma

- Currently not using pressure lowering eye drops and at least 4 weeks prior

- Refractive error of ± 6 diopters and ± 3 diopters of astigmatism

- Corneal thickness < 510 µm or ≥ 510 µm (without glaucoma)

- No other ocular pathologies such as corneal edema

- No refractive laser surgery

Exclusion Criteria:

Glaucoma Suspect Subjects:

- Absence of any other retinal or neurophthalmic abnormality 

- Abnormal nerve fiber layer by OCT with normal SAP results

Glaucoma Subjects:

- SAP test using the Glaucoma Staying System (GSS) of -3dB.

Obstructive Sleep Apnea Subjects:

- No known diagnosis of glaucoma

Ocular hypertensive subjects:

- No diagnosis of glaucoma or other ocular pathologies

- Not using pressure lowering eye drops and/or 4 weeks prior

- No refractive error more than ± 6 diopters and ± 3 diopters of astigmatism

- No refractive laser surgery, incisional ocular surgery except for cataract surgery

Conditions:
• Glaucoma