Diopsys Visual Electrophysiology
New vision test helps doctors detect vision disorders including glaucoma, macular degeneration and other neuro-visual disorders
Device also Helps Track Disease Progression
Glaucoma is the second leading cause of blindness in the world, reports the World Health Organization. According to Prevent Blindness America, glaucoma is often called the “sneak thief of sight” because half of all patients who have it do not know it. Many optic nerve disorders are asymptomatic since central vision may not be affected until later stages of the disease. Also, diagnosis and management of optic nerve disorders are often based on structural or visual field tests which are limited in their ability to detect disease early.
The Diopsys® NOVA-VEP and NOVA-ERG vision tests allows clinicians to objectively assess vision disorders often earlier than traditional vision tests because they use electrophysiology and proprietary software to evaluate the entire vision system from the eye to the visual cortex. Eye care professionals may use VEP and ERG in addition to traditional testing methods to enhance diagnosis and treatment.
The Diopsys® NOVA-VEP records the electrical response of a patient’s entire vision system and provides easy-to-read reports that give the doctor a simple way to evaluate optic nerve function. The Diopsys® NOVA-ERG records the electrical response of the patient’s retina to help evaluate retinal function. Clinicians are able to compare tests over time to track disease progression.
Pattern Electroretinography (ERG)
The Diopsys® NOVA-ERG Vision Testing System has been developed for eye care professionals to provide objective measurements of macular and retinal ganglion cell function. The NOVA-ERG advanced protocols use steady-state pattern electroretinography (ERG), a measure of the electrophysiological activity at the retina, to provide data to the doctor to help detect cellular dysfunction that can precede evident structural defects, thereby contributing to earlier detection for more specific and timely management of diseases that impair macula and ganglion cells. The NOVA- ERG allows the clinician to choose one of two advanced testing protocols – Concentric Stimulus Fields or Contrast Sensitivity.
Contrast Sensitivity Protocol: Provides data to aid in the detection of diseases that affect the retina in a diffuse pattern like Chronic Open Angle Glaucoma (COAG) and Diabetic Retinopathy (DR). Since there is typically no specific topographic pattern of damage, the information collected using this protocol can help in detecting the depth of the macular
Concentric Stimulus Fields Protocol: Provides data to aid in the detection of diseases affecting the central or paracentral area of the macula in specific topographic patterns like Age Related Macular Degeneration (AMD), Diabetes Macular Edema (CME) and Toxic Maculopathies (e.g. Plaquenil Maculopathy).
Visual Evoked Potentials (VEPs) are electrical signals
that are measured from the electrophysiological activity (“brain waves”) at the visual cortex. A technician will generally place three sensors on the patient’s head to measure the VEP signal that travels from the retina to the visual cortex. VEPs occur when a patient observes a visual stimulus, such as a flash of light or a pattern on a monitor. VEP results are a representation of the functional integrity of all levels of the visual pathway including the retina, optic nerve, optic radiations, and visual cortex.
VEP waveforms are represented on graphs using amplitude and time (latency) measurements. In general terms, the amplitude, measured in microvolts (µv), indicates the integrity of the neural structures including axons conducting information along the visual pathway. Latency, measured in milliseconds (ms), indicates the time the electrical signal takes to travel from the retina to the visual cortex. The combination of amplitude and latency is helpful in determining the health of the visual pathway.
VEP recordings have been used for a variety of applications that involve neuro‐visual disorders such as glaucoma, amblyopia, multiple sclerosis, and diabetic retinopathy. Visual Evoked Potential tests provide the clinician with objective data on vision abnormalities that are often subtle and difficult to detect, as no response is required from the patient. This also allows clinicians to test preverbal children, infants, and patients with communication difficulties.
Diopsys® VEP Vision Testing Systems bring the science of visual evoked potential right into the practitioner’s office. The automated data collection, enhancement and display makes it easy and fast for the clinician to record, view and assess quality VEP signals in their office.
The Enfant® Pediatric VEP Vision Testing System produces a visual stimulus consisting of an equal number of horizontal black‐and‐white bars. By changing the width of the bars, the visual pathway’s response to stimuli requiring different visual acuities can be objectively assessed. The test is performed rapidly for each eye separately, and if a significant difference between the left and right eye is detected, the patient fails the test. The patient is then referred to an eye care specialist.
The Diopsys® NOVA‐VEP Vision Testing Systems also use black and white patterns to elicit a VEP response. The fixed protocol configuration with multi‐contrast stimulus uses a checkerboard pattern at both low contrast and high contrast to test the integrity of both the magnocellular (peripheral vision) and parvocellular (central vision) pathways. The user‐defined protocol enables the clinician to designate the pattern size and contrast level of checkerboard, horizontal, vertical, or sinusoidal patterns. Eye care specialists may use the Diopsys® NOVA‐VEP to improve their sensitivity in diagnosing vision disorders when used in conjunction with other tests. They may also use the device to track patients’ response to treatment and monitor disease progression.
To schedule your Diopsys test call (910) 484-2284 or (800) 829-2284