Ocular Electrophysiology What is ERG-VEP?
Ocular Electrophysiology What is ERG-VEP?
Ocular electrophysiology ERG and VEP tests are important tests for ophthalmology and neuroophthalmology. Ocular electrophysiology tests provide examination of the retina, optic nerve and visual pathways in the brain and provide important information about their functions. The VEP test measures the optic nerve, and the ERG test measures light-sensitive cells called photoreceptors. Electroretinography (ERG) and electrooculography (EOG) are tests used for the examination of retinal functions, and cortical response to visual stimuli (VER) for the evaluation of the optic nerve and visual pathways. ERG and VEP tests are non-invasive methods, no surgical procedure incisions are made in the tissues. Ocular electrophysiology tests are usually done in a dark environment and electrodes are attached to the cornea and skin. In the test performed by giving light to the eye with flash and pattern stimuli, the electrical response of many cells such as photoreceptors, pigment epithelium and nerve cells is recorded with the help of sensitive devices. The application of the test can take 1-2 hours and the people who perform the tests are knowledgeable and experienced. The results are reported in the waveform and the voltage and generation times of the waves are compared with values in the normal range.
For Which Situations Can It Be Applied?
- In visual disorders with visual loss but difficult to diagnose (post-traumatic visual disorders, night vision disorders, uncooperative patients, medico-legal conditions)
- In the differentiation of genetic and hereditary diseases (Retinitis Pigmentosa, Congenital night blindness)
- To distinguish whether the disease originates from the optic nerve or retina.
- In the evaluation of the functions of the retina and optic nerve in the formation of media opacity in the eye (in the formation of cornea, lens and vitreous opacity)
- For pediatric neuroophthalmologic patients (metabolic, hereditary and neurological diseases related to visual pathways, in monitoring visual development, in patients with binocular visual impairment and in patients with familial degenerative disease history)
- In the diagnosis of neuroophthalmological diseases in babies who do not make eye contact and babies with tremors in their eyes.
- In determining the degree of retinal vascular occlusion
- In the follow-up of patients using retinotoxic and neurotoxic drugs (Chloroquine Hydroxychloroquine, Ethambutol, Alcohol, Phenothiazine, Desferroxamine, Tamoxifen, toxicity, siderosis)
- In the follow-up of the progression of eye diseases (uveitis, thyrotoxicosis, evaluation of optic nerve functions before and after orbital and intracranial surgery, in the follow-up of retinal vascular diseases).
What are the Risks and Advantages?
Since ocular electrophysiology tests are non-invasive, there is no risk. It is very important to correctly evaluate the results obtained from the painless and painless tests. By evaluating the results obtained from ocular electrophysiology tests, the differential diagnosis of many important eye conditions can be made and the cause and degree of progression of eye diseases can be learned more clearly. It is important to examine the test results one by one and in detail and compare them with reference values. Devices that perform ERG-VEP tests are not available in every clinic. In cases where ocular electrophysiology tests are required, patients can be referred to special centers. ERG-VEP tests are evaluated together with other diagnostic tools and accordingly the results are interpreted more accurately.
