Electrophysiological vision exams play a very important role in the diagnosis of diseases of the retina, optic nerve and visual pathways. There are four tests performed in this field, the Electroretinogram (ERG), the Electrooculogram (EOG), the Occipital Potential Evoked (POE) and the Pattern Electroretinogram. This set of combined tests helps to determine, at any given time at what level between the retina and the brain (occipital cortex) is the damage or pathology of the visual system.
Electroretinogram and Electrooculogram
The electroretinogram (ERG) and Electrooculogram (EOG) are useful tests for diagnosing retinal dystrophies (Distance of cones, Retinitis Pigmentosa, Stargardt Disease, Dist. Vitelliforme), (choroidal atrophy) ( artrofia gyrate , Coroidermia ), degenerations vitreous-retinal ( Retinoschisis Juvenile, Stickler Disease), inflammatory conditions, circulatory deficiencies (occlusion of artery and Central retinal Vein, Diabetes), toxic retinopathies (for drugs such as chloroquine, Phenothiazines , or substances such as methanol, etc. ) and to detect the first signs of Siderosis in cases of intraocular metallic foreign bodies.
Occipital Potentials Evoked
They reflect the electrical brain activity corresponding to the individual’s central visual field. Its clinical application includes: inflammatory disorders (such as Optic Neuritis, Papillitis), demyelination (Multiple Sclerosis), circulatory (such as Ischemic Optic Neuropathy) and post-traumatic visual pathways, as well as the determination of amblyopia. In combination with the ERG they can predict visual potential in children and in patients with opacities of transparent media (Cataract, Vitreous Hemorrhage, etc.), in addition to helping the detection of simulator patients. In the case of young children and patients unable to collaborate with the exam, glasses are available that have intermittent light stimuli, like Light Emitting Diodes (LED), which allow the light stimulation of the retina even with the eyelids closed.