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Biomicroscopy
Last reviewed: 23.04.2024
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Biomicroscopy is the intravital microscopy of the eye tissues, a method that allows one to examine the anterior and posterior parts of the eyeball under various illumination and image magnitudes. The study is carried out using a special device - a slotted lamp, which is a combination of a lighting system and a binocular microscope. Thanks to the use of a slit lamp, you can see the details of the structure of the tissues in the living eye. The lighting system includes a slit diaphragm, the width of which can be adjusted, and filters of different colors. Passing through the slit a beam of light forms a light section of the optical structures of the eyeball, which is viewed through a slit lamp microscope. Moving the light gap, the doctor examines all the structures of the anterior part of the eye.
The patient's head is placed on a special slit lamp stand with the chin and forehead emphasis. In this case, the illuminator and the microscope are moved to the eye level of the patient. The light gap is alternately focused on the tissue of the eyeball that is to be examined. Directed on translucent fabrics, the light beam is narrowed and increases the intensity of light to obtain a thin light cut. In the optical section of the cornea, it is possible to see foci of opacities, newly formed vessels, infiltrates, to estimate the depth of their occurrence, to reveal various minute deposits on its rear surface. When examining the marginal loopy vasculature and conjunctival vessels, one can observe the blood flow in them, the movement of blood elements.
With biomicroscopy, it is possible to clearly consider the different zones of the lens (the anterior and posterior poles, the cortical substance, the nucleus), and if there is a violation of its transparency, determine the localization of pathological changes. The lens of the vitreous body is visible behind the lens .
There are four ways of biomicroscopy, depending on the nature of the lighting:
- in direct focused light, when the light beam of the slit lamp is focused on the investigated area of the eyeball. At the same time, it is possible to estimate the degree of transparency of optical media and to reveal areas of turbidity;
- in reflected light. So you can consider the cornea in the rays reflected from the iris, when searching for foreign bodies or revealing puffiness zones;
- in indirect focused light, when the light beam is focused next to the area under study, which allows for a better view of the changes due to the contrast of the strongly and poorly illuminated zones;
- with indirect diaphanoscopic translucence, when reflective (mirror) zones form on the interface of optical media with different refractive indices of light, which makes it possible to examine the tissue sites near the exit point of the reflected light beam (investigation of the anterior chamber angle).
With these types of lighting, you can also use two methods:
- to carry out research in a sliding beam (when the slit-lamp handle moves the light strip along the surface to the left and to the right), which allows you to catch irregularities in the relief (corneal defects, newly formed vessels, infiltrates) and determine the depth of occurrence of these changes;
- To carry out research in a mirror field, which also helps to study the surface relief while still revealing irregularities and roughness.
The use of additional aspherical lenses (such as the Grubby lens) with biomicroscopy makes it possible to conduct eye ophthalmoscopy (against the background of medial mydriasis), revealing subtle changes in the vitreous, retina and vascular membrane.
The modern design and the devices of the slit lamps also make it possible to additionally determine the thickness of the cornea and its external parameters, evaluate its mirror and sphericity, and also measure the depth of the anterior chamber of the eyeball.
An important achievement of recent years is ultrasonic biomicroscopy, which allows to examine the ciliary body, the posterior surface and the iris section, the lateral sections of the lens, hidden under the usual light biomicroscopy behind the opaque iris.
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