Ophthalmic perimeter what is it, application, review of models

Ophthalmic perimeter

The human eyeball has certain fields of vision.
This is the perimeter around a person, which he is able to perceive with the help of his visual organs.

There are diseases in which the fields of vision are narrowed. The reason may be ophthalmological or neurological defects.

Using this parameter, a person can perceive many objects of the surrounding reality. If the field of view is significantly reduced, a person's quality of life decreases.

Boundaries of the field of view

Light rays from all objects enter the pupils and are projected on the retina. A person can perceive all objects of the surrounding reality. The eyes work together to produce binocular vision. Using it, it is possible to determine many areas of the perimeter around a person.

The boundaries of the visual field may narrow, which is formed as a result of many diseases in the following areas:

• optic nerve;
• oculomotor muscles;
• cortex;
• internal structure of the eyeballs.

A person sees a certain field of vision using the retina, which is located on the back of the eyeball. It contains nerve receptors that perceive the light signal and transmit information along the optic nerve to the center of the brain.

Border of vision

The perimeter of a person’s vision is not unlimited; this is due to the anatomical structures located on the face. The indicator is limited to the following areas of the face:

• upper eyelid;
• brow ridge;
• the inside of the nose.

In people, these formations have different sizes, so the field of vision is individual for each person. The perimeter of vision is indicated in degrees. There are average parameters that have been determined by experts:

• limiting the perimeter from above to 55 degrees;
• limiting the perimeter of the interior to 90 degrees.

For each person, these parameters are different and can fluctuate by a large number of degrees. Therefore, special devices have been invented that can measure this value.

Blind spot

The retina does not have nerve receptors in all areas. In the place where the optic nerve comes into contact with it, a physiological scotoma or blind spot is formed. It is normal for all people.

But if it pathologically expands, this is a sign of a disease that leads to a narrowing of the field of vision.

There may be more than one blind spot; if diseases form, they can form in multiple numbers.

To determine them, there are ophthalmological devices that measure the perimeter of vision. To fully assess the condition of the spot, scotoma meters are used.

Preparing for a visual field examination

To carry out the technique for measuring the patient’s visual field, no specific preparation is required.

A person’s eyes should be in their natural state, that is, there is no need to dilate the pupil or instill medications.

The person must not have infectious or inflammatory eye diseases, as this may complicate the procedure. He may develop photophobia to exposure to bright rays.

The patient must have no diseases that lead to a recumbent state, since the study is carried out in a sitting position.

How is the examination carried out?

The research takes place in several stages. First, a person’s eyes are affected by a white glow, then a colored one.

The action using white light is carried out in several stages:

1. The study is performed in turn for each eye. Therefore, first one organ of vision is closed by a shutter, then the other.
2. The eye being tested with the device must be fixed on a white dot inside the device.
3. The patient is given 1-2 minutes to allow his eyes to adjust.
4. A person must fix his gaze on a stationary object. When a moving object occurs, he should tell the doctor about it.
5. The ophthalmologist sequentially moves the points in the direction from the periphery to the center of vision. In this case, the patient speaks when he begins to detect the point.
6. During all operations, the device rotates alternately 45 and 135 degrees.

Such actions are carried out for each eye separately. After completing the identification of the visual function, the doctor produces a schematic image that shows the person’s visual fields. After completing the white glow test, color codes are used. This study is carried out in several stages:

1. The patient sits in front of the device, closing each eye in turn. The working organ of vision is fixed on a fixed point.
2. When the point begins to move, a person must not only catch this action, but also recognize the color of the object. If a person makes a mistake in choosing a color, the dot continues to move until it is recognized.

Since the human vision function is limited to 4 shades, red, yellow, blue, green are used. During the procedure, the device is also rotated at a certain angle.

A new drug for vision treatment was presented at the Skolkovo Innovation Center. The medicine is not commercial and will not be advertised... Read more

It is possible to use not a manual device, but an automatic one, which is based on the operation of a computer. The research is carried out in several stages:

1. The patient places his chin in the notch in front of the automatic device. One eye is covered, the other remains working.
2. When the patient catches a moving object, he must press a button. The computer independently records the results; no medical intervention is needed.

Computer perimetry is performed automatically and lasts a short amount of time, no more than 10 minutes.

How the perimeter works

The principle of operation of the device is based on the fact that a person can detect a moving object only within a certain perimeter of his vision. They are detected by nerve receptors located on the retina. If a person has a blind spot in any area of ​​the retina, he will not be able to perceive an object moving at a certain angle.

This is detected by an ophthalmologist or a computer program.

If the ophthalmologist or device detects the presence of a blind spot on the retina, the doctor will be able to identify the area in which it appears. Additional diagnostic tests are prescribed. This may indicate the presence of the following retinal pathologies:

• detachment;
• mechanical damage;
• hemorrhage;
• thinning;
• disruption of blood flow through the vessels in the retinal area, which causes hypoxia and atrophy.

It is important to identify the affected area in a timely manner; the sooner treatment is performed, the greater the chance of completely eliminating the pathology.

Model overview

Ophthalmic perimeters differ according to the type of device:

• manual – the doctor independently directs moving dots to the eye area, records the visual field, and draws a map of the identified data;
• computer - the device includes a computer program that starts moving points, records data from the patient (pressing a button while detecting a point) and produces a graph of the visual perimeter.

Handheld analyzers are much cheaper than computer analyzers. Therefore, most municipal institutions are equipped with them.

There are fully automated devices for measuring the perimeter, in which there is no need for the participation of a doctor. The only thing the patient does is press a button when he sees a moving object. Therefore, the risk of medical error or distortion of results due to incorrect data from the patient is reduced.

Manual perimeter PNR-03

Determines the field of view and defects in this area. The device is manufactured in Russia, manufactured specifically for medical institutions (municipal and private clinics).

The main advantage of the device is its simplicity and convenience for medical staff. It is quick and easy to learn how to analyze the function of vision. Based on the data received from the device, the doctor independently takes measurements, recording them by hand. Approximate cost: 60,000 rubles.

Semi-automatic perimeter Periscan

A modern device on the basis of which sensitivity to light and fields of vision in various lighting conditions (day, twilight, complete darkness) are determined. To fully reveal the visual field, the doctor can activate the light stimulus function in a chaotic manner.

Despite the fact that the device is connected to a computer, all measurements are carried out by a doctor. Mostly the models are a user-friendly interface, generating a diagram on a computer, warning about system errors. The doctor does not need to draw diagrams; they are printed from a computer on a printer. Approximate cost – 70,000 rubles.

Projection analyzer APPZ-01

The device affects the human eye not only by moving the point, but also by light of various ranges. The maximum boundaries of the visual fields differ. Defects are detected at early stages.

The device is highly functional and allows you to determine not only the area of ​​the visual field, but also their defects. Approximate cost: 120,000 rubles.

Computer perimeter Peritest-300

Determines the boundaries of the field of view, identifying sensitivity to light in daylight and nighttime. Using the device, you can set the time period for the appearance of luminous points.

The program can occur in fast, partial or full mode. The data is printed on a research form for the doctor, and also stored in the computer memory and used as needed. Using the device, you can determine the central and peripheral field of vision, macula, glaucoma, blind spots. The approximate cost of the device is 320,000 rubles.

Spherical perimeter of Pericombe

The device reveals such clear parameters that it can identify the initial stage of glaucoma formation or retinal pathology. All results are displayed on the display, so they can be viewed by a doctor.

They can be printed as a color graph or in standard black and white form. Data received from patients is stored in the database. The approximate cost of the device is 320,000 rubles.

Perigraph Pericombe

A device that detects visual field impairment with high accuracy. It can detect increased intraocular pressure and retinal pathology in the early stages.

It is easy to use and has more than 9 programs. The computer database saves all received data into the computer.

The device can detect scotoma, blind spot, eye artery damage, venous thrombosis, retinal or corneal malnutrition.

Determination of the visual perimeter is an important diagnostic test that is necessary to identify data about the fields being viewed using the eyeballs. If the angle of vision is impaired, the patient’s quality of life is significantly reduced. Therefore, it is recommended not to wait for the later stages, but to consult a doctor in a timely manner.

Poor vision significantly worsens the quality of life and makes it impossible to see the world as it is.

Not to mention the progression of pathologies and complete blindness.

MNTK "Eye Microsurgery" published an article on non-surgical restoration of vision up to 90%, this became possible thanks to...

Read more Was this article helpful?

Source: //proglazki.ru/diagnostika/perimetr-oftalmologicheskij/

Limits of vision

The size of the field of view is an individual parameter. Its value is determined by the anatomical features of the face and in particular the size of the following areas - the upper eyelid, brow ridges, and the inside of the nose.

The perimeter of vision is the angular area of ​​space visible to the eye when the head is stationary. Field of view is measured in degrees. The range of average values ​​is limited to 55 degrees at the top and 90 degrees at the inside.

To determine the individual visual field indicator, special instruments and devices have been developed.

Preparing for a visual field examination

Examination through the ophthalmological perimeter is convenient in that it can be carried out without specific preparation of the patient. There is no need to dilate the pupil with medications as the eye apparatus should be in its natural state.

The main requirement for the patient is that he does not have any diseases that would make the procedure difficult:

• infectious diseases and inflammatory conditions,
• increased reaction to bright light rays,
• conditions requiring a lying position.

Survey process

The patient examination consists of two parts. First, the eye apparatus is exposed to white light, and then to colored light. The patient must sit in front of the machine.

The white glow procedure is carried out separately for each eye and consists of the following operations:

1. The eye not participating in the test is covered with a shutter.
2. Within 1-2 minutes the patient's eyes adapt.
3. The eye being tested fixes its gaze on a fixed white point inside the device. If a moving object appears, the patient should notify the doctor.
4. The ophthalmologist gradually moves points from the periphery of the visual field to the center, recording the positions in which the patient discovered the object.
5. The device is periodically rotated first by 45 degrees and then by 135 degrees.

After the procedure is completed, the same steps are repeated for the other eye.

As a result of the examination, a graphic picture is created that displays the patient’s vision boundaries. Then they move on to the second stage of the examination using color marks. Also, for each eye in turn, perform the following steps:

1. One eye is closed and the other is fixed on a fixed point.
2. The patient should see the movement of the point and determine its color. In case of color perception error, the dot will move until it is correctly recognized.

The marks are painted only in primary colors - red, blue, green and yellow. During the examination, the device is rotated at the desired angle, similar to the first stage.

An automatic ophthalmic perimeter is considered a more effective and convenient device. You do not need a medical professional to use it. Computer perimetry is similar to the operation of a hand-held device, but the movement of points and recording of results is carried out automatically. The advantages of this automatic device are the shorter duration of the procedure and convenience for the patient.

Before perimetry begins, the patient is positioned in front of the device so that one eye is closed and the chin is fixed in a special notch.

How the device works

The action of the ophthalmological perimeter is based on the fact that human vision has certain boundaries and they can be determined by the moment when the nerve receptors of the retina catch the reflection of light rays from an appearing object. If a person is unable to notice a moving object, then this indicates the presence of blind spots in the retinal area. To identify the size of blind spots, the angle of movement of the object is important.

Having received such information during a manual or automatic perimeter examination, the ophthalmologist can conduct additional studies. As a rule, the presence of blind spots indicates the formation of retinal pathologies. Most likely, further diagnostics will detect the following problems:

• Retinal detachment;
• Hemorrhage;
• Mechanical damage;
• Thinning of the retina;
• Insufficient blood supply to the retina;
• Atrophy of blood vessels.

Hardware research using the perimeter helps to identify violations in a timely manner and take measures to eliminate the pathology.

Projection analyzer APP3-01

An effective device allows you to accurately determine the boundaries of the visual fields and defects in the eye area at the initial stage. The research is carried out not only by moving the marks, but also by changing the light range. The price of the device is about 120,000 rubles.

Content:

• 1 Clinical assessment of the boundaries of the absolute field of vision 1.1 CHECK QUESTIONS

Description

Purpose of the lesson.

Understand the design features of perimeters that are supplied to eye offices and hospitals, as well as their advantages and disadvantages. Practically master the techniques of working on these devices. To study methods of individual clinical assessment of the results of an absolute visual field study.

Lesson methodology.

In preparation for the lesson, students independently study the factory instructions for portable, tabletop, ball (GDR) perimeters and for PRP-60, and also become familiar with the contents of this section of the Instruction. In practical classes - during exercises - the skills of working on these perimeters are developed: first on each other, and then on patients of different ages. Average and individualized norm criteria (in relation to the absolute visual field) are first discussed with the teacher, and then, when working with each other and with patients, their relative clinical significance is clarified.

Contents of the lesson.

Brief recommendations for working with the perimeters of other systems.

Although the basic principles of measuring the boundaries of the absolute field of view remain the same when working with any perimeter, there are still some features in their design that should be taken into account in the work.

Portable perimeter (Fig. 29)

simple in design and easily transportable.

However, it has an arc of reduced radius, as a result of which the angular error of the boundary of the field of view in degrees increases (with an equal linear inaccuracy in installing the test object on the arc). Consequently, when using this device, greater accuracy and a lower speed of movement of the mark are required than on the PRP. This is not difficult to achieve, since the mark moves by hand. The device is indispensable for perimetry of bedridden patients. Moreover, in this version of its assembly (manual perimeter) there is no support for the chin - it is replaced by a facial support on the lower edge of the orbit on the side of the study. Since this stop has rather sharp edges and its position is not very reliable, damage to the eye may occur when the metal slides off the bone. Therefore, we recommend that you ensure that the patient holds the device not with one, but with both hands, and further limiting as much as possible the possibility of their accidental movements by resting the elbow of the right hand on the body, and the left hand on the chin (Fig. 30).

At the same time, this perimeter in the manual version is very convenient for determining the absolute field of view. When working with it, you can not only turn the patient’s head in the desired direction, but, if necessary, deflect the entire perimeter around the place where it rests on the subject’s face in opposite directions (if, for example, the mobility of the head is limited). It goes without saying that the upper eyelid should not be forgotten in both cases. A black pointer with a white mark measuring 5x5 mm is guided along the inner surface of a rather narrow perimeter arc from the periphery to the center.

The boundary of the field of view is read for each meridian directly from a scale marked on the outer surface of the perimeter arc according to the position of the handle of the test object, since the doctor does not see the mark itself. Therefore, it is necessary to guide the test object so that its handle does not deviate noticeably from a right angle with respect to the edge of the perimeter arc, regardless of the position of the arc. This requires a certain skill.

Using a portable (manual) perimeter,

you need to illuminate its arc from the patient’s side quite well, seating the person being examined with his back to the window or placing two lamps behind the patient (on either side of him). If we are talking about a bedridden patient, a portable lamp should be placed on the floor at the head of the bed, or the lamp should be placed in a protective cap near the pillow. In no case should you use the general overhead lighting of the room, which does not help, but interferes with the examination, leaving the arc shaded and blinding the patient.

Marking of boundaries as they are identified can be carried out on a standard form from the PRP. But it is more convenient to write out the primary information in numbers on a multi-ray figure, which is drawn by hand on any sheet of paper (Fig. 31).

As can be seen from this figure, in the simplest version (scheme “a”) we can limit ourselves to four directions; the field of view is usually measured along eight semi-meridians (diagram “b”); in more than 12 directions (scheme “c”), it is not advisable to examine the field of view on a portable perimeter. It also makes no sense to try to determine numbers with an accuracy greater than 5°. This will exceed the accuracy of the research methodology itself.

Currently, it is generally accepted among ophthalmologists to write as if the field of view of your eye of the same name is projected onto paper. This picture is exactly the opposite of what we observe when examining an anterior radiograph of the skull. Just in case, it will be useful to indicate on the diagram the nasal and temporal sides of the visual field even before perimetry.

Exercise No. 8. Studying the boundaries of the absolute field of vision in a bedridden patient using a manual perimeter.

Assemble the perimeter manually.

Alternately playing the roles of a doctor and a bedridden patient, conduct an absolute visual field study on each other according to the recommended rules. Pay attention to the prevention of interference created by an incorrectly applied bandage, the upper eyelid, facial protrusions - the brow ridge and the nose (less often - the cheek). In this case, repeat each study 2 times: the first time, using turns of the head relative to the perimeter held straight, and the second time, freeing the boundaries of the field of vision by moving the entire perimeter (and the patient’s gaze) in the desired directions - with the head lying motionless on the pillow. In conclusion, compare the results of these studies with those obtained earlier during exercises on the PRP: there should not be any particular differences in the extent and configuration of the absolute field of vision for each of the subjects.

Table perimeter (Fig. 32).
This perimeter is also simple in design but more durable than the portable one. Until now, a number of domestic neuro-ophthalmologists give preference to it over the projection perimeter, although this point of view is not shared by everyone. The presence of a vertically moving chinrest in a block with a fixed face rest makes it somewhat difficult to study the boundaries of the absolute field of view. It is still possible to turn the patient's head towards the nose, although the chin almost moves away from the chin plate. But it is not possible to tilt the forehead back correctly enough: the chin does not move forward, because the cheek rests against the facial support, and if this is not done, the eye being examined will move far back from the center of the perimeter, which will lead to errors in measurement. For this type of perimeter, we recommend using this technique when studying the absolute field of view.

A 5x5 mm square is cut out of the adhesive plaster and attached to the inside of the perimeter arc - along its midline - exactly on the projection of the 30° mark (Fig. 33). This sticker will serve as a new object of fixation of the patient’s gaze—instead of a mark at the midpoint of the perimeter arc—when examining the internal border (diagram I), upper border (diagram II) and lower border (diagram III) of the absolute field of vision. The required position of the sticker mark is ensured by rotating the perimeter arc around the axis so that the new fixation point is on that 1/2 of the arc that is opposite to the half-meridian under study (including in “oblique” directions). With such a system of transferring gaze fixation, to the figures obtained from perimetry, you need to add the amount of displacement of the fixation point from the center of the arc in degrees. In our example (Fig. 33, diagram I), the test object is seen by the patient on the 40° line. This means that the internal border of his field of vision is located 70° from the point of fixation (40 + 30 = 70).

The usual central mark when working with the table perimeter should be used only when checking the temporal border, where the shading effect of the facial protrusions is not pronounced. To ensure that the pasted label does not interfere with the study, it can be removed.

Exercise No. 9. Study of the boundaries of the absolute field of view on a simple perimeter using the method of transferring a fixation mark.

Learn to cut a mark of the desired size and shape from the adhesive plaster with scissors: this is easier to do if you hold the strip of plaster taut with the sticky surface facing up. Glue a mark at the desired point of the perimeter arc and, as recommended, study the absolute field of vision in 8 semi-meridians with a friend in the study group.

When moving the test object along an arc, maintain a uniform pace (about 5° per 1 sec) and, most importantly, do not cause distracting (or, rather, attracting) noise by rubbing the handle of the holder along the arc. The pointer with the mark must be moved in front of the perimeter arc - 0.5-1.0 cm from its inner surface.

Considering the high illumination of the room when working with a table perimeter, do not stand directly behind the device, especially if you are wearing a white coat, and do not make unnecessary movements with your hands within the patient’s field of vision. Also make sure that no moving shadows fall on the perimeter arc from the inside. Learn to properly instruct the “patient”. His answers should be extremely brief so that you can immediately stop the pointer as soon as the “patient” notices the mark. You need to accustom him to laconic remarks like “there is” or “I see.” . Otherwise, until a real patient says, “It seems to me, doctor, there’s a light ball flashing from above, or maybe I’m mistaken?” - your hand with the object will reach the fixation point. It will be even more reliable if you teach the patient to mark the moment a mark appears in his field of vision by tapping a pencil on the table surface.

Compare the obtained boundaries of the absolute field of view (taking into account the correction for the shift of the fixation mark!) with the results of previous studies of your partner on the PRP: the results should coincide or diverge by no more than 5° (i.e., by the amount of the method error).

Finally, practice tabletop perimeter skills on several patients with normal or altered—this should be initially unknown to you—absolute visual field.

Projection perimeter PRP-60 (Fig. 34)

. This modern device, mass-produced by our industry, basically replicates the PRP device in design. However, there are also significant differences.

1. The device is equipped not only with a step-down transformer, but also with a device for stabilizing the current, which makes it possible to conduct the most delicate studies.

2. An additional disk with light filters has been introduced, which significantly increases the range of selection of brightness of the test object.

3. On the outer surface of the arc there is a measuring degree scale, which allows you to work with a hand pointer or with a light bulb on the handle, as well as hang a fixation luminous mark on the arc in the right place, also included in the kit.

4. The device has its own system of dosed arc illumination; therefore, research on PRP-60 can be carried out in a completely darkened room.

5. The front installation retains all degrees of freedom as on the PRP, but the movements of its units are carried out much faster and easier - with the help of ratchet bars and screws.

6. The device is equipped with a curtain that isolates the lower half of the patient’s field of vision from visual interference.

7. The PRP-60 has an arc position lock every 30°. It standardizes the examination, but often interferes, since turning the arc without pulling back the latch handle leads to its breakage, and both hands of the doctor can be occupied, for example, during a combined examination with cattle of a complex configuration.

8. Finally, the kit includes a removable mirror attachment for dark perimetry, that is, for studying the field of view when the optical media of the eye are opaque. It should be borne in mind that in this attachment the mirror may be positioned with a slight distortion and may not cast the bunny directly onto the eye of the person being examined. In such a case, you need to very carefully bend the connection of the mirror with the attachment bracket until the bunny from the mirror begins to be reflected in the center of the perimeter.

Let us remember that this center corresponds to the point of alignment of the light rings on any screen that fits in the face mount.

Did you know that with simple, accessible eye exercises you can improve your vision?

The method of working on this device, with the exception of the additional capabilities discussed above, does not differ from the previously described method of working on the PRP. The presence of a hinged fixation object and a convenient mechanical system of tilting, shifting and rotating the facial unit together with the patient’s head make this device especially suitable for studying the absolute field of view. At the same time, a wide range of light characteristics of both the test object itself and the background illumination of the arc makes it possible to perform so-called quantitative perimetry on the PRP-60 in its dynamic (conventional) or static versions.

Ball perimeter (Fig. 35).

The device from K. Zeiss Jena, GDR, is available in many medical institutions. Its advantages include, first of all, the presence of test objects smaller than 1 mm2 (0.25 and 0.0625 mm2), a hemispherical projection screen that eliminates external interference to the study, and a larger registration form. All this is important when conducting quantitative perimetry. As for the main practical task - studying the absolute field of view - here this device is clearly inferior to the PRP-60. In it, the facial position moves only up, down and to the sides; turns are not provided for by its design. The hemisphere itself covers the patient's head from direct observation by the doctor. True, in the hemisphere there is a hole with a sighting tube, which allows you to control the position of the eye being examined from time to time, but it is impossible to conduct constant observation. In addition, the bulkiness of the device makes it impossible for the doctor's left hand to participate in freeing the upper boundaries of the visual field from the shading effect of the upper eyelid, and an alternative technique - lifting the eyelid using a strip of adhesive plaster - quickly leads to drying out of the cornea, causing anxiety to the patient. It should also be said that the adjustment of the registration block of this perimeter is more difficult, since its mechanical rods are hidden by decorative overlays.

Ball perimeter

It is very convenient for working with children precisely due to the presence of a hemisphere, which makes children less distracted by external stimuli. In general, to conduct perimetry in children, all types of perimeters can be used, but it is necessary to take into account the characteristics of the child’s nervous system, his reduced attention, and the inability to fix his gaze on one object for a long time. The process of studying the visual field must be given the character of a game, especially in younger children aged three to four years. At this age, it is still more advisable to check the boundaries of the visual field using the approximate method, but instead of fingers, it is better to show the child toys of different colors. Research using instruments becomes quite reliable from about the age of 5 years, although even here it is necessary to take into account the individual characterological characteristics of the child.

When conducting perimetry in children, especially preschoolers, it is necessary to take a break for a short rest in the middle of the study due to the easy fatigue of young patients.

The complete dependence of the perimetry results on the test subject's testimony is undoubtedly one of the general disadvantages of the technique. Therefore, in cases of potential dissimulation and aggravation of visual field pathology, devices in which the moment of the appearance of a test object in the subject’s field of vision would be recorded regardless of his will may be extremely promising. A relatively accurate signal that the light stimulus has reached the central parts of the visual analyzer is the constriction of the pupil. Based on this, a number of authors created and tested “objective perimeters”, in which the dynamics of the pupil are observed or recorded on film either with conventional illumination, or “illumination” with infrared rays is used, which makes it possible to record pupil movements through an electron-optical converter in full darkness (V.G. Shilyaev et al., etc.). It is too early to talk about introducing such devices into practice.

Ophthalmic perimeter – what is it, application, review of models – About the eyes

medical equipment

• USD = 64.21 rub.
• EUR = 70.68 rub.

• Cashless payments;
• Cash;
• Payment by bank card.

• Products
• Ophthalmology
• Visual field analyzers (Ophthalmic perimeter)

A device called an ophthalmic perimeter is indispensable for diagnosing the state of vision, identifying pathologies, and determining the field of vision of a person’s eyes.

It is used in medical institutions specializing in ophthalmology.

Using this device, you can perform kinetic, color, and statistical perimetry and determine the threshold sensitivity of the retina.

The ophthalmic perimeter allows you to conduct the most subtle studies and detect deviations from the norm at the earliest stages. This greatly facilitates patient treatment and improves outcomes. Doctors when using

the ophthalmic perimeter makes it possible to study both the central and peripheral vision of a person in several modes. Fast – 30%, reduced 50%, full – 100%. In this case, the device allows you to diagnose a person’s full field of vision (90 degrees).

Tests carried out with its help make it possible to identify such serious ophthalmological diseases as pathologies of the retina and optic nerve, and glaucoma at a very early stage.

The ophthalmological perimeter makes it possible to automatically save data obtained during research on the hard drive of a PC, which allows for statistical analysis and comparison of results with information obtained previously. Printing test results is very easy.

The device, depending on the model, is equipped with a set of test programs. Special screening programs make it possible to conduct a primary analysis of a person’s vision condition.

The data obtained make it possible to effectively identify pathological conditions at a very early stage. To determine the degree of sensitivity of the retina, the ophthalmic perimeter is equipped with threshold programs.

Such devices can be used for daily patient intake and daily testing. The device can be purchased in any configuration using our company’s catalog posted on the website.

The order will be delivered as soon as possible to any address specified by the client.

Source:

Ophthalmic perimeter

An ophthalmic perimeter is a device that is used by doctors to study the properties of a patient’s visual field. The term “field of view” refers to clinical ophthalmology, and refers to the area of ​​​​space that the human eye perceives when the gaze is motionless. Visual field refers to the functional properties of the peripheral retina.

The state of the visual field significantly affects a person’s ability to navigate the surrounding space. Why might this parameter change? Its condition is affected by diseases of the visual analyzer system, for example, the retina, optic pathway or optic nerve, central nervous system.

Field of view, field boundaries, blind spot: what do these categories mean?

In medicine, the visual field is the totality of all points in space that can be simultaneously perceived by a stationary eye that has fixed one central point.

This point is projected onto the retina in the area where the corpus luteum is located. All other points of the field are located in the peripheral parts of the retina.

At the point where the optic nerve exits the eye, where there are no light-receiving elements of the retina, there is a physiological scotoma, the so-called blind spot.

How can the field of view change? His functional perception abilities may narrow, and in certain cases some areas of the field “fall out”. So, if a patient has bilateral blindness in half of the visual field, this condition is called hemianopia. The lesion can develop against the background of diseases of the optic nerve, cerebral cortex, and visual pathways.

Field narrowing is measured in degrees. The size of the blind spot or spots is determined through the use of special grids, and is expressed in linear quantities or degrees.

To obtain more accurate and specific digital data on the size of the visual field, the presence of its defects, and the boundaries of blind spots, ophthalmologists use special devices, including perimeter. Identification and study of the central spot is carried out with a special scotoma meter.

The peripheral boundaries of the visual field normally depend on the anatomical features of the structure of the eyelids, bones and eyeball, since from above they are determined by the upper eyelid and brow ridges, from below - by the side of the nose. The normal field of view, on average, is limited above to 55 degrees from the point of fixation, below and along the inside - up to 90 degrees.

It should be noted that such data are averaged, standard, and cannot be accepted as the only normal ones.

When assessing the boundaries of the field, the doctor takes into account the fact that the full visual acuity of the eye is observed only in the center, and the closer to the periphery of the retina, the less the acuity becomes.

Visual field examination: how and why it happens

Clinical practice of treating patients with visual impairments cannot do without visual field examination, since based on its results, the doctor can identify and clarify a number of general and eye diseases.

In the process of topical diagnosis of lesions of the central nervous system, if it is necessary to clarify the localization of basal tumors, hemorrhages and foci of inflammatory processes, doctors use the results of examining the patient’s visual field.

If the lesion is localized in the area of ​​the sella turcica, a person experiences loss of temporal fragments of the visual field of both eyes. If pathological processes are vascular in nature in the same area, loss of the inner halves of the visual field may be observed in both eyes.

If a patient loses two left or two right halves of the fields at the same time, this indicates the location of the pathology behind the sella turcica.

The preserved central portion of the visual field in the left and right eyes signals the formation of a lesion in the occipital part of the cerebral cortex, or in the zone of visual radiance.

If the patient loses half and the center of the field, this makes it possible to detect a focus of pathology in the tractus area. A narrowing of the size of the visual field of a concentric nature, combined with the appearance of a central blind spot, indicates the presence of retrobulbar neuritis.

There are also cases when pronounced disturbances in field size are accompanied by the formation of inflammation in the retina, for example, if the patient has retinitis, exudates, and retinal hemorrhages. Characteristic changes in the visual field are also observed with glaucoma, retinal pigmentary degeneration, even with hysteria.

Thus, visual field studies are of significant value for clarifying complex and hidden pathologies localized in the brain and cranium.

Among all methods of field survey, the simplest is control - it is carried out without the use of special instruments.

The doctor sits opposite the patient at a distance of 1 meter. The subject fixes the gaze of his right eye in the area of ​​the doctor's left eye, and vice versa. The second eye needs to be closed.

The doctor slowly moves his right hand in all directions from the central fixed point of view, so that the hand is always at the same distance from the person being examined and the doctor himself. It is necessary to note the moment when the hand simultaneously disappears from view for both.

Provided that both the physician and the patient have a normal field of vision, they will no longer see the hand at the same time; otherwise, we can talk about a narrowing of the patient’s field of vision.

This technique cannot be the basis for making a diagnosis, but provides only indicative information.

Other ways to measure this category:

• kinetic perimetry;
• static;
• approximate definition of hemianopsia;
• determination of central scotomas and metamorphopsias.

Kinetic perimetry

Carried out using tabletop or projection perimeters. A tabletop device requires daylight, while a projection device requires reduced artificial lighting.

During diagnosis, an object with a diameter of 1 to 5 millimeters is slowly moved along the length of the perimeter arc in the direction from the periphery to the center. If a white object is selected, the subject must determine the moment when the marker appears in the field of view.

Chromatic (colored) objects are identified by color.

Norm for an adult:

• outer boundaries: 90 degrees;
• internal: 55 degrees;
• top: 55 degrees;
• lower: 60 degrees.

Permissible deviation is no more than 10 degrees in both directions.

In preschoolers, the peripheral boundaries of the visual field can be determined, on average, 10 degrees narrower than in adults.

Static perimetry

The method was first proposed in 1939. It allows you to identify the light sensitivity thresholds of the retina in decibels, at those study points that suffer from glaucoma. This measurement is carried out by special computer perimeters.

Approximate definition of hemianopsia

Does not require medical equipment. The patient is asked to split any oblong object used in the process into two parts with his index finger. A pencil, ruler or pen will work for this purpose.

If a person has a limitation in his field of vision, one of the sides of the object seems to be visually cut in length, not completely falling into his field of vision.

If in this case you ask him to place his finger exactly in the center of the object, in reality it will be shifted either to the left or to the right.

Determination of central scotomas and metamorphopsias

It is produced with the Amsler test - a special grid of squares intersecting with horizontal and vertical lines. The table contains a cross, which the patient must fixate with his gaze during the examination. By the way he perceives this mark - clearly or with distortion - one can judge whether he has metamorphopsia.

Ophthalmic perimeter: what it is and how it works

A device called “ophthalmological perimeter” is an analyzer that allows the ophthalmologist to examine the patient’s visual field, disturbances in it, and shifts in its boundaries. Based on such data, the attending physician can diagnose eye diseases, the state of visual acuity, and the presence of functional pathologies.

• The operating principle of the device is based on stimulation of vision analyzers by light exposure, resulting in specific reactions that reflect the state of the visual organs.
• Thanks to the operation of the device, doctors were able to diagnose pathological changes at the very beginning of their appearance, and often the changes detected by the ophthalmological perimeter are the only symptoms and manifestations of some diseases, on the basis of which a patient can be diagnosed.
• For the purpose of determining and clarifying the diagnosis, two types of perimeters are used:

• for kinetic examination;
• for static perimetry.

Source: //4hospital.ru/veki/perimetr-oftalmologicheskij-chto-eto-primenenie-obzor-modelej.html

Affordable price for ophthalmic perimeter

The price we set for an ophthalmic perimeter is one of the most objective, since our company is a direct manufacturer. We do not use the services of intermediaries or third parties, including for warranty and service maintenance of branded equipment.

Therefore, cooperation with is invariably characterized by economic feasibility and efficiency.

Order a high-precision computer ophthalmological perimeter by contact numbers or directly on the website - our managers will tell you in detail about the advantages of the chosen model and the advantages of branded VIDA equipment.

Ophthalmic perimeter

An ophthalmic perimeter is a device that is used by doctors to study the properties of a patient’s visual field. The term “field of view” refers to clinical ophthalmology, and refers to the area of ​​​​space that the human eye perceives when the gaze is motionless. Visual field refers to the functional properties of the peripheral retina.

The state of the visual field significantly affects a person’s ability to navigate the surrounding space. Why might this parameter change? Its condition is affected by diseases of the visual analyzer system, for example, the retina, optic pathway or optic nerve, central nervous system.