Perimetry ( visual field study ) - Causes, Symptoms and Treatment .MF .
Perimetry - a method of research boundaries of visual fields with their projection on a spherical surface.Field of view - it's part of the space that the eye can see at a certain fixation of sight and a fixed head.If we fix the eyes of some object, something other than a clear distinction of the subject and other visible objects located at different distances from it and fall within the field of view of the person.Thus, the eye characteristic of peripheral vision, which is less clear than the central.
perimeter may be kinetic and static.In kinetic perimetry uses a moving subject, while noting the time of its appearance and disappearance, and varies with static illumination of the object in the same position.
With this study method you can judge the nature of change in the field of view, which can be seen on the localization of the pathological process.Changes in the field of vision will be different in patients with lesions of the retina, optic nerve, visual pathways and visual centers of the brain.In
static perimetry performed on modern automated perimeter.It allows you to evaluate the sensitivity of the retina.With this type of perimetry object is not moving and appears in different parts of the visual field, while changing its size and brightness.
indications for perimetry are:
2. Diseases of the optic nerve (optic neuritis, trauma, ischemia).
3. Pathology retina (degeneration, hemorrhage, radiation burns, detachment, tumor).
4. Hypertensive heart disease.
5. Brain tumors.
6. Head injuries.
7. Violations of the cerebral circulation.
8. Assessment of vision in preventive examinations.
Contraindications to perimetry:
1. Mental illness patient.
2. Alcohol or drug intoxication.
To perform kinetic perimetry requires a special instrument called a perimeter.Perimeters are desktop (arc), projection and computer.The study was conducted separately for each eye while the other eye cover with a bandage.During the study of the field of view on the perimeter of the patient sits in front of the unit so that is convenient to place the chin on a special stand, the study eye must be fixed by the exact opposite point of view, which is located in the Perimeter Center.The patient should not stopping to look at this point.But the doctor is on the side of the device and moves from one direction to the center obektovv meridians every 150. The patient should be noted that when looking fixedly at the fixation mark, see the appearance of a moving object, the doctor at this fixes the degrees at which the object was seenand marks them on a special scheme.Movement of the object needs to continue directly to the alignment marks to ensure the preservation of view throughout the meridian.Depending on the severity of objects of different diameters are used.So at a high visual acuity using object 3 mm in diameter, with a low visual acuity - 5-10 mm.Research is conducted mainly on 8 meridians, but the more accurate results can be obtained in the study on the 12 meridians.
At the very periphery retinal light perception not extreme periphery it takes only a white light, and as we move towards the center there is a sensation of blue, yellow, red and green.In the central part of the retina all different colors.Thus, the field of view of each eye at a white object is characterized by the following boundaries: outwards (to the temple) - 900, up outwards - 700 up - 50-550, upward medially - 600 inwards (towards the bow) - 550, down inwards - 500, down - 65-700, from top to bottom outwards - 900. There are slight variations in the range of 5-100.Investigation of other fields of color are made the same as for white, but color objects, and the patient should not be noted that when he noticed a moving object and a time when he can call his color.Very often it happens that the field of view changes to white there, with the other colors can reveal narrowing.
All results doctor brings in a special form, which are indicated in the field of view of the norm for each eye.All the "fallen" shade areas.
Driving normal boundaries of the field of vision obtained by perimetry left eye with white and colored test objects (black line indicates the boundaries of the field of view, the test white test object is painted gray blind spot).
During the computer perimetry patient also fixes his gaze on a particular label.At various points of the device in a chaotic manner with varying speed beginning to appear different brightness objects.Once the patient sees an object, it presses the dedicated button of the device.The device gives the survey results, on the basis of which the doctor puts an accurate diagnosis.
duration of the procedure depends on the device: 5 minutes on the computer perimeter and up to 20 minutes and arc projection perimeters.
must be remembered that much overhanging eyebrows, sunken eyeballs, drooping of the upper eyelid, a high nose bridge, hit a stimulus to the area of a large container near the optic disc, bad vision correction, too low vision, as well as interference from spectacle frames can simulate changesfield of view.
complications, this method does not survey.
Ophthalmologist Odnoochko EA