by What is Electroretinography?
Electroretinography (ERG) is a diagnostic test that measures the electrical activity generated by the retina of the eye in response to a light stimulus. When light enters the eye, it is detected by the photoreceptor cells (rods and cones) in the retina. These cells generate an electrical signal that is transmitted via the optic nerve to the brain, allowing us to see. The ERG uses surface electrodes on the skin around the eye to detect this retinal response, recording it as waveforms on an oscilloscope or other display device.
Recording and Interpreting ERG Signals
During an Global Electroretinogram test, eye drops are used to dilate the pupil and numb the eye. Small surface electrodes are gently placed on the skin near the lower and upper eyelids to pick up the retinal response. A ground electrode is placed on the forehead or earlobe. Brief flashes of light are then shone into each eye while the retinal response is recorded. Different intensities and wavelengths of light may be used to activate either just the rod photoreceptors or both rods and cones. The resulting ERG waveforms can be compared to norms to identify any delayed, reduced or distorted responses that may indicate possible retinal abnormalities. Both scotopic (dark-adapted) and photopic (light-adapted) responses are evaluated.
Applications in Diagnosing Eye Disease
ERG testing is useful for diagnosing and monitoring many inherited and acquired retinal diseases. It can detect disorders affecting photoreceptors or post-receptoral inner retinal cells. Some common conditions where ERG aids diagnosis include retinitis pigmentosa, cone-rod dystrophy, Leber’s congenital amaurosis, diabetes, toxoplasmosis, cancer retinal toxicity and many others. Serial ERGs also help in monitoring disease progression or response to treatment in conditions like retinitis pigmentosa. Besides a clinical diagnosis, genetic testing may further help characterize the cause of certain retinal diseases detected initially by an abnormal ERG.
Role in Neurological and Metabolic Disorder Evaluation
Abnormal ERGs may also be indicative of neurological or metabolic disorders primarily affecting the retina. For example, ERG changes have been seen in disorders like Refsum disease (phytanic acid storage disease), Tay-Sachs disease, Sandhoff disease and other ganglioside storage disorders. ERGs aid in distinguishing retinal problems from other potential neurological causes of vision loss. They are valuable for workup of unexplained visual symptoms to identify if retinal dysfunction may be contributing to visual impairment. Multifocal ERG testing allows mapping retinal responses across different regions and can help localize retinal lesions.
Going Global With Tele-ERG Technology
Conventional ERG requires specialized equipment, skilled technicians and an examination facility – limiting widespread applications globally especially in underserved rural areas. However, recent tele-ERG technology allows ERG testing to be performed remotely using portable devices. Refined cloud-based software transmits retinal responses to expert interpreters elsewhere. Pilot programs demonstrate tele-ERGs can provide accurate diagnostic-quality tests from distant, primary care locations when in-person ERG is not feasible. This holds promise to expand diagnostic ERG access on a larger global scale. Ongoing research aims to refine hardware, Internet connectivity and artificial intelligence techniques to optimize diagnostic performance of remote tele-ERG examinations worldwide.
Impact on Global Eye Health and Research
Increasing global utilization of Global Electroretinogram diagnostics benefits retinal disease patients internationally. It facilitates earlier detection and improved management of hereditary retinal disorders plus vision-threatening conditions like diabetes retinopathy across diverse populations. Population-based ERG screening trials help define disease prevalence and genetic factors varying between ethnic groups. International ERG databases advance comparative studies of retinal disease phenotypes and natural histories. Multinational collaborative networks leverage pooled ERG and genetic datasets to accelerate research into novel therapeutic targets. Well-established diagnostic ERG standards now enable large multicenter retinal clinical trials globally. Overall, continuing ERG technology innovations worldwide hold promise to transform retinal disease outcomes on a global scale.
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1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.
