The electroretinography

The electroretinography is a record of the electrical potentials (biopotential) of the retina with the help of special devices - oscilloscopes. Electric potentials arise in the retina as a response to irritation of the eyes light.
The investigation of changes in the electroretinogram for various eye diseases often contributes to the establishment of a more precise diagnosis and the correct definition of the forecast of illness.

The electroretinography (pozdnee. retina - netted shell eyes, gr. grapho - write) - method to study the function of the organ of vision by registering and determine the nature and significance in the process of view of the electric potential of the retina, resulting from the effects of light on the eyes. How do these potentials and their graphic accounts are called electroretinogram. As clarify the physiological mechanisms of electroretinography expanding its use in medicine as an objective method of diagnosis, prognosis and monitoring of the pathological processes in the retina, especially in the clinic of eye diseases - clinical electroretinography. Electroretinogram man (Fig) registered with radioseriala instruments under standard conditions recording recommended by International society for clinical electroretinography: onto a contact lens and imposed on the eyes electrode pulsed light flash lamp significant intensity and short duration, mixed spectral composition, dark adaptation about 5-7 minutes Electroretinogram has a complex form, in which there are waves (a1, a2, x, b, and c. Consider that the basis of these waves there are several physiological processes (components)that takes place in different structures of the retina. Wave a1 and x arise in the cone system of the retina, a wave2 and b - rod system, and wave c - in layer of pigment epithelium, and wave a1 and a2 arise in the layer receptor cells, as wave b - the layer of bipolaron. Normal amplitude of wave (a1 OK. 35-50 me, waves b - from 200 to 400 mV; the latent period of a wave1 OK. 15 msec, waves b - approx 40 msec; the duration of wave (b OK. 120 msec, while the climax of its OK. 70 msec. When the detachment of retina, thrombosis of separate branches of the Central artery of a retina and other electroretinogram becomes subnormal, with the development of Salerosa or chalikosa retina and other damage - negative, i.e. in wave (b decreases, and wave a1 relative increases; when hereditary pigmentary retinal degeneration at early stages of disease development electroretinogram disappears, which is an important diagnostic feature; when atrophy of the optic nerve electroretinogram often supernormal, glaucoma it remains for a long time.

Schematic illustration of the comparative values that make up normal and pathological electroretinogram: 1 - normal, 2 - a subnormal; 3 - supernormal; the lower curve "missing" electroretinogram.