Apr 19, 2010

Investigation of optical media in the eyes of the transmitted light

Inspection carried out to determine, primarily, transparency of the lens and vitreous. This desk lamp also need to install the left of the patient, but behind his head. The light from her doctor with ophthalmoscope take to send a pupil of the eye, seeking to glow red. This occurs when you capture the rays reflected from the choroid (the light reflex from the fundus). If the path of light rays will be fixed or floating cloud, then on a red glow, they will look dark structures of any shape. Location can be defined by the parallax, ie direction and amplitude of the displacement estimated shadow on a stable point, such as the center of the pupil. For this purpose it is necessary that the eye has made two movements - up and down or left and right. Then it turns out that cloud lying anterior to the plane of the pupil, are moving in the same direction as the eye. Opacity is located in this plane are displaced under the same conditions in the opposite direction.

When diffuse vitreous opacities with fundus reflex is attenuated more strongly, the closer these opacities.

Characteristics of the basic concepts

Exophthalmos - vystoyanie eyeball from the orbit at any distance greater than the limit value of the normal rate (18 mm).

Enophthalmos - acquisition of the eyeball in the orbit for any amount exceeding the limit value of the normal rate (13 mm).


The measurement can be performed with a special tool - proptometer or conventional millimeter ruler. In the latter case it is performed as follows. Line puts on the outer edge of the orbit of the patient, whose head is turned in profile, and determine what its division is at the top of the cornea. Normally vystoyanie eyeball varies from 13-18 mm, and the asymmetry in the position of fellow eyes did not exceed 1 mm.

Possible and only indicative version measuring exophthalmos, when the doctor is behind the seated patient and the index finger of the right and left hand raises his upper eyelids. We estimate (when you look down the test) the degree vystoyaniya tops of the corneas of both eyes in relation to the line, as if joining the nail phalanx of index fingers of the doctor
Investigation of the severity of central vision (vizometriya)

Determination of the visual possibilities in early childhood (from birth to 3-4 years)

The severity of central vision is a function that, like other visual functions, develops in the child gradually, with growth and development of his eyes and brain. On the visual possibilities of the newborn can be judged by the presence or absence of his motor reflexes to a visual stimulus. These include the following:

protective closing eyelids and upward deviation of the eyes.
the same thing with throwing the baby's head back (reflex Paper).
pupillary constriction (estimated direct and friendly reaction).
reflexive turn the baby's head and eyes to the source of light.
tracking eye moves slowly over the source of light.
Child 2-3 weeks of life can already show bright objects. If they get into his field of vision and perceived, then make eye tracking movements.

Baby 1-2 months, if view, which can not yet metrirovat, can have long-term fix with both eyes moving object (a bright toy).

Baby 2-5 months may already have the elements shaped view. In order to verify its presence is useful to use a bright red ball with a diameter of 4 cm he was hung on a thread, well lit and slightly shaking, show the child, noting the distance from which he begins to follow him.

A child 6-12 months and older by the method described above to show the ball is much smaller - 0.7 cm in diameter If, however, it turns out that he could not see, the study should continue with the object size. By the way, to quickly determine the outcome vizometrii advisable to use the table below ES Avetisova et al. (1987).

Determination of visual acuity in children aged 3-4 years and older and adults

Visual acuity - an indicator whose value is determined by the ability of the eye to the separate perception of the two light points at the smallest angle. The latter is formed by two rays emanating from the extreme points fixed by the object and intersecting at its nodal point. For convenience in the value of visual acuity expressed still not in the corner, but in relative terms with the help of special tables, first proposed Snellenom (Snellen G., 1862). They adopted as a physiological angle, equal to 1 '. This rule has remained common, and therefore all subsequent vizometricheskie table built so that each of the test sign visible from a fixed distance from the perspective of the 5 'and its distinctive details - in 1'. In accordance with the proposal of the same magnitude of Snellen visual acuity in many countries around the world expressed measure as a fraction: the numerator indicates the distance from which the study was carried out, - d (standard Snellen is 20 feet, that is 6 meters), and denominator - the distance from which a number of signs reading tables are visible in the norm at a given angle of view - D.

The study is fixed as follows:

Vis OD (OS) = 20/20 or 20/50, etc. Our country uses the metric table type Monuaye designed to show from 5 meters. They allow you to determine the visual acuity of the so-called decimal system - from 0,1 to 2,0. For the corresponding calculations used as already mentioned formula Snellen:

Vis = d / D.

Vizometriyu should be performed in 2 versions - to give (5 m) and near (33 cm), and separately for each eye. It is also useful to know and value of binocular visual acuity, because, as a rule, it is higher than monocular (≈ in 0,1-0,2).

In our country, the study of visual acuity to produce a given in the tables Sivceva (letters and Landolt rings) and Orlova (with children's pictures), placed in the apparatus Roth, a distance of 5 m. They should cover the filament in 40 Tues The lower edge of the table should be at eye level, sitting on a chair patient. Standards set for adults is 120 cm for the children she did not declare, but it is clear that in this case the apparatus Roth spreadsheet should hang lower (30-40 cm). Given the large age range of children who can vizometriya, preferably in the eye room to have two devices Roth and install them at various levels (eg, distance to the lower edge of the floor level at 80 and 100 cm).

Order vizometricheskogo study is as follows. First, determine the acuity of the right eye, then - the left. Neissleduemy eyes have an opaque cover flap. It is impossible to squint or tightly closed hand. Only the full visual acuity. The first six rows (Vis = 0,1-0,6) are read, if they learn all the signs. In the 7-10th rows (Vis = 0,7-1,0) allowable error in one sign.

For visual acuity less than 0.1 investigated to move toward the table until the moment when he sees one of her line. Subsequent vizometrichesky calculation based on a formula Snell (see above). The research process can be simplified if the doctor will show the patient with different distances fingers of his hand (corner of their value approximately corresponds to the details of tests from the first row table Sivceva). With this method of measuring 1 meter distance is equivalent to visual acuity of 0,02. Hence, for example, that if properly run your fingers on 1,5 m visual acuity equal to 0,03, at 2 m - 0,04, 2,5 m - 0,05, 3,5 m - 0,07 etc.

Determination of visual acuity for near vision is produced by a different (small) tables Sivceva. It is designed to show from 33 cm and strengthened in a special box with a handle. The test should take it in hand and holding at a given distance, to find and read separately by each eye, the text that he is free to regard it. The values of visual acuity in the table of this type are listed at the beginning of each text block. Abroad, now widely distributed small-format multi-purpose tables, which in addition to vizometrii (from a distance of 40 cm) make it possible to determine the patient position the nearest point of clear vision of each eye and the size of their pupils.

Evaluation of the functional state of the central sections of the retina in patients with clouding of optical media

Light banded sample Primrose (Primrose J., 1956)
Before investigational eye set cylinder axis Maddox, for example, horizontally. Healthy eye shield. Then use the ophthalmoscope through the said cylinder in the eye direct light beam. When a positive test subject sees a vertical light strip. The correctness of his answers can be easily controlled by changing the position of the axis of the cylinder. The test is easily perceived by children and adults.

Positive test Primrose suggests that successful treatment of patients may have visual acuity of at least 0,03 (Sosnowski VV, 1990).

The study is carried out in a darkened room. The patient is asked to close his eyes, and then to the upper eyelid interested eyes tip transillumination (light intensity from 60 to 110 cd/m2). Shifting the tip of the left and right 0,5 cm, the patient is asked to describe what he had with the saw. Normally in such a lit him a picture of "retinal vascular tree." Next tip transillumination to set a lower eyelid and to the corners of the palpebral fissure of the same eye. The result of the study is considered positive (is marked «+»), when analyzed vidit picture of the vascular "tree" when lit eyeballs with all the above points. The presence of defects in it being marked "-", which shall be placed in the appropriate box of the protocol form. The nature of the defect of the vascular "tree" is described verbally.

According VV Sosnowski (1990), a positive result autooftalmoskopii (EPA) indicates that the successful treatment of patients may have visual acuity of at least 0,2.

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