Mar 29, 2018
Other parts of the eyeball( lens, vitreous, eye fundus) are visible when examined by an ophthalmoscope - a concave mirror with a small hole in the center. The study with the help of an ophthalmoscope is a very valuable method in the diagnosis of not only ocular, but also many diseases of the internal organs and the central nervous system, since with this examination one can see the bottom of the eye, the optic nerve disk, the retina and its vessels, the vascular membrane. The fact that the optic nerve is part of the peripheral brain explains why many diseases of the central nervous system, inflammatory and degenerative processes, tumors are reflected on the condition of the disc. Retinal vessels are a continuation of the brain. They react vividly to diseases of the body;especially often the vessels change with hypertension, blood, kidney, diabetes, infectious diseases and many other diseases.
To examine the optical media of the eyeball, the transmission light method is used. The patient is seated in a dark room, and the lamp is placed behind, to the left of it, at the level of the head. By sending light into the eye of the researcher with an ophthalmoscope, you can see the red glow of the pupil, resulting from the reflection of light rays from the bottom of the eye. If in the path of these rays there are opacities, then on the background of the red pupil spots, bands, etc. are visible. If these opacities are in front of the center of rotation of the eye( in the cornea or in the anterior parts of the lens), then when the eye moves to the sides they move toward the movement;when the opacities are localized behind the center of rotation of the eyeball( the posterior pole of the lens, the vitreous body), they move in the opposite direction from the movement of the eye.
When ophthalmoscopy, it is necessary to hold a magnifying glass in front of the patient's eye at 13.0 D at its focal length from the eye. The rays of light that hit the eye, reflected from the fundus, pass through the magnifying glass and gather in front of it in focus. In doing so, the examiner sees the opposite, enlarged and real image of the patient's fundus. In order for the doctor to see the patient's disc of the optic nerve, which lies inward from the posterior pole of the eye, the patient should look at the doctor's eponymous ear, ie.when examining the right eye on the doctor's right ear. If the patient looks directly into the ophthalmoscope, the area of the yellow spot becomes visible, which normally looks like a horizontal oval bordered by a shiny light strip. The same ophthalmoscope( and, even better, the electric one) can see the fundus in an even more enlarged and direct form. For this, the investigator approaches as close as possible to the eye of the patient and looks inside the eye through the pupil.
This same study is possible with a slit lamp and other sophisticated devices. When examining the fundus, attention is drawn to the color of the disc and its borders, the state of the tissue and vessels of the mesh and vascular membranes, the presence in them of any inflammatory or dystrophic foci, neoplasms, hemorrhages and other that can be observed in diseases of the kidneys,cardiovascular and central nervous systems, tuberculosis, syphilis, toxoplasmosis, diabetes and other diseases.