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About eye biomicroscopy in detail

Examination of the internal structures of the eye is necessary when there is a suspicion of any disease or anomaly of the anterior or posterior part of the eyeball. The use of a special microscope combined with a powerful lighting device for this purpose is called biomicroscopy. This study helps to identify and study in detail the many abnormalities within the visual organ.

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Biomicroscopy: basic concepts

Biomicroscopy is the study of the internal state of the eyeball with a medical device called a slit lamp. It includes a wide range of complex methods of visualization of pathologies of various origins, texture, color, transparency, size and depth.

Slit lamp

Slit lamp allows you to do a detailed microscopic examination of the eye

A slit lamp is a tool consisting of a high-intensity light source that can be focused to direct a thin strip of light into the eye through various filters providing the location and size of the slit. It is used in combination with a biomicroscope, which, together with the illuminator, is mounted on the same coordinate table. The lamp facilitates inspection of the anterior and posterior segments of the human eye, which include:

  • eyelid;
  • sclera;
  • conjunctiva;
  • iris;
  • natural lens (lens);
  • cornea;
  • vitreous body;
  • retina and optic nerve.

The slit lamp is equipped with a diaphragm, which forms a slit with dimensions up to 14 mm in width and height. A binocular microscope includes two eyepieces and a lens (magnifying lens), the optical power of which can be adjusted using a disc that changes the magnification ratio. The range of gradual increase - from 10 to 25 times. With an additional eyepiece - up to 50-70 times.

Binocular examination with a slit lamp provides a stereoscopic magnified image of the eye structures in detail, allowing anatomical diagnoses to be made in various eye conditions. A second hand lens is used to study the retina.

For a full biomicroscope examination, there are various methods of illumination of slit lamps. There are six types of basic lighting options:

  1. Diffuse lighting - study through a wide aperture using glass or a diffuser as a filter. It is used for general examination in order to detect the localization of pathological changes.
  2. Direct focal illumination is the most frequently used method, which consists in observing with the help of an optical slit or direct focal hit of rays. The slit of thin or medium width is directed and focused on the cornea. This type of lighting is effective for determining the spatial depth of eye structures.
  3. Specular reflection or reflected light is a phenomenon similar to the image visible on the sunny surface of the lake. Used to assess the endothelial contour of the cornea (its inner surface). In order to achieve a mirror effect, the tester directs a narrow beam of light to the eye from the side of the temple with a floor angle of about 25–30 degrees to the cornea. A bright area of ​​mirror reflection will be visible on the corneal epithelium (outer surface).
  4. Translucence (transillumination), or research in reflected (transmitted) light. In some cases, illumination with an optical slit does not provide sufficient information or is simply impossible. Transillumination is used to inspect transparent or translucent structures - the lens, the cornea - in the reflection of rays from deeper tissues. To do this, illuminate the background of the object.
  5. Indirect illumination - the light beam, passing through the translucent fabrics, is scattered, simultaneously highlighting certain places. Used to identify pathologies of the iris.
  6. Scleral scattering - with this type of illumination, a wide light beam is directed at the limbal region of the cornea (the edge of the cornea, the place of articulation with the sclera) at an angle of 90 degrees to it to create a scattering effect. In this case, under the cornea, a certain halo appears, which illuminates its anomalies from the inside.

The slit lamp provides the opportunity to study the structural parts of the cornea:

  • epithelium;
  • endothelium;
  • back edge plate;
  • stroma.

And also to determine the thickness of the transparent outer shell, its blood supply, the presence of inflammation and swelling, other changes caused by trauma or dystrophy. The study allows a detailed study of the state of scars, if they exist: their size, adhesions with surrounding tissues. Biomicroscopy reveals the smallest solid precipitation on the back of the cornea.

If you suspect corneal pathology, the doctor additionally prescribes confocal microscopy - a method for assessing the morphological changes of this organ using a special microscope with a magnification of 500 times. It allows to investigate in detail the layered structure of the corneal epithelium.

In lens biomicroscopy, a doctor examines an optical section for possible clouding of his substance. It determines the place of localization of the pathological process, which often begins exactly at the periphery, the state of the nucleus and the capsule. When viewing the lens, you can use almost any kind of lighting. But the first two are the most common: diffuse and direct focal illumination. In this order they are, as a rule, carried out. The first type of lighting allows you to evaluate the overall appearance of the capsule, to see the lesions of the pathology, if any. But for a clearer understanding of exactly where the “breakdown” occurred, it is necessary to resort to direct focal lighting.

Inspection of the vitreous body with a slit lamp is not an easy task that not every newcomer in ophthalmology can handle. The vitreous body has a jelly-like consistency and lies quite deep. Therefore, it reflects light rays weakly.

Vitreous humor

Vitreous biomicroscopy requires established skill

In addition, the study prevents the narrow pupil. An important condition for high-quality biomicroscopy of the vitreous body is preliminary medical mydriasis (pupil dilation). The room where the inspection is carried out should be as dark as possible, and the area under study, on the contrary, should be rather brightly lit. This will provide the necessary contrast, since the vitreous body is a weakly refractive optical medium that slightly reflects the light. The doctor uses mostly direct focal illumination. On examination of the posterior sections of the vitreous body, research in reflected light is possible, where the fundus of the eye plays the role of a reflecting screen.

The concentration of light on the fundus allows you to explore in the optical section of the retina and the optic nerve head. Early detection of neuritis or edema of the nerve (congestive papilla), retinal breaks helps in the diagnosis of glaucoma, prevents atrophy of the optic nerve and reduced vision.

Slit lamp will also help to determine the depth of the anterior chamber of the eye, to identify turbid changes in moisture and possible impurities of pus or blood.
A wide choice of types of lighting thanks to special filters allows you to study vessels well, to detect areas of atrophy and tissue breaks. The biomicroscopy of translucent and opaque tissues of the eyeball (for example, conjunctiva, iris) is less informative.

Slit Lamp Device: Video

Indications and Contraindications

Biomicroscopy is used to diagnose:

  • glaucoma;
  • cataracts;
  • macular degeneration;
  • retinal detachment;
  • corneal damage;
  • retinal vascular obstruction;
  • inflammatory diseases;
  • neoplasms, etc.

And it is also possible to detect injury to the eyes, foreign bodies in it, which are not able to show an x-ray.

There are no absolute contraindications for a slit lamp examination. Nevertheless, it is worth paying attention to some important nuances associated with eye injuries:

  1. Patients with possible penetrating wounds of the eyeball should be examined with extreme caution. The physician should avoid pressure on the eye until this injury is excluded.
    Eye biomicroscopy

    A patient with a penetrating eye injury should be examined very carefully.

  2. The eye after exposure to caustic (caustic) substances should be thoroughly washed, and the normal acid-base balance of the conjunctival fluid should be restored before the examination.
  3. During the removal of a foreign body, the physician must take care to avoid injury from a sudden change in the position of the patient’s head or an awkward movement of the instrument (needle) used to remove the foreign body.

Observation of the fundus is known as ophthalmoscopy using a fundus lens. But with a slit lamp, direct observation of the bottom is impossible because of the refractive power of the eye media, as a result of which the microscope does not provide focusing. Rescues the use of auxiliary optics. With the help of the Goldman diagnostic three-mirror lens, in the light of a slit lamp, it is possible to investigate those peripheral areas of the retina that cannot be examined with an ophthalmoscopy.

Advantages and disadvantages of the method

Biomicroscopy has a number of significant advantages over other methods of ophthalmologic examination:

  • Ability to accurately localize anomalies. Due to the fact that a beam of light from a slit lamp with biomicroscopy can penetrate into the structures of the eye from different angles, it is quite possible to determine the depth of pathological changes.
  • Increased diagnostic capabilities. The device provides lighting in vertical and horizontal planes at different angles.
  • Convenience in a detailed survey of a particular site. A narrow beam of light directed into the eye provides a contrast between the illuminated and dark areas, forming the so-called optical cut.
  • The possibility of biomicroophthalmoscopy. The latter is successfully used for examination of the fundus.

The method is considered highly informative, devoid of significant shortcomings and contraindications. But in some cases it is advisable to prefer a handheld device to a stationary, although a manual slit lamp has limited capabilities. For example, it is used:

  • for biomicroscopy of the eyes of babies who are still in the supine position;
  • when examining anxious children who cannot sit at the prescribed time in a conventional slit lamp;
  • for examination of patients in the postoperative period, during strict bed rest, it is an alternative to the stationary version of the device.

In these cases, the hand lamp has advantages over diffused (diffuse) illumination; it makes it possible to examine in detail the surgical incision and the anterior chamber with intraocular fluid, the pupil, and the iris.

Manual Slit Lamp

Manual slit lamp has modest capabilities, but sometimes it is indispensable

Carrying out the procedure

The survey is carried out in a darkened room. The patient sits in a chair, puts his chin and forehead on a support to fix his head. She must be motionless. Blink preferably as little as possible. Using a slit lamp, the ophthalmologist examines the patient's eyes. To aid inspection, a thin strip of paper with fluorescein (a luminous dye) is sometimes used, pressing it to the edge of the eye. This stains the tear film on the surface of the eye. The paint is later washed away with tears.

Then, at the discretion of the physician, drops may be needed to expand the pupils. You must wait 15 to 20 minutes for the medicine to work, and then the inspection is repeated, which allows you to check the back of the eye.

Eye with dilated pupil

Sometimes before biomicroscopy you need to dilate the pupil with medication.

First, the ophthalmologist tests the front structures of the eye again, and then, with the help of another lens, examines the back of the organ of vision.

As a rule, such a test does not cause significant side effects. Sometimes the patient experiences a slight photosensitivity for several hours after the procedure, and dilating drops can increase eye pressure, which leads to nausea with a headache. Those who feel a serious discomfort are advised to immediately consult a doctor.

Adults do not need special preparation for the test. However, it may be necessary for children in the form of atropinization (pupil dilation), depending on age, previous experience and level of trust in the doctor. The whole procedure takes about 5 minutes.

The result of the study

During the examination, the ophthalmologist visually assesses the quality and condition of the structures of the eye to detect possible problems. In some models of slit lamps there is a photo and video module, which fix the process of the survey. If the doctor finds out that the results do not correspond to the norm, it can speak about such diagnoses:

  • inflammation;
  • infection;
  • increased pressure in the eye;
  • pathological changes in the ocular arteries or veins.

For example, during macular degeneration, the doctor will find drusen (calcification of the optic nerve head), which are yellow deposits and can form in the macula - areas on the retina - at an early stage of the disease. If the doctor suspects a certain vision problem, he will recommend further detailed examination for a definitive diagnosis.

Biomicroscopy is a modern and highly informative method of examination in ophthalmology, which allows a detailed examination of the anterior and posterior ocular structures with different illumination and magnification. Especially to prepare for this study, as a rule, is not necessary. Thus, the five-minute procedure makes it possible to effectively monitor the health of the eye and prevent possible deviations in time.

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