Slit Lamp lighting Types
Slit Lamp lighting Types
1. Diffuse:
Spread illumination or wide beam illumination deserves a short part discussion from the other types of illuminations. The term diffuse has been carried over from earlier writings when slit lamps had either diffusing filters or free racking microscopes. This permitted each to be independently focus on different structures. Most of todays slit lamp microscopes have their light sources and microscope coincident to one an additional and are focused on the same structure at the same time. Diffusing filters are still found in some slit lamps and are used in photographing the frontal segment of the eye. Wide beam illumination is the only type that has the light source set wide open. Its main function is to illuminate as much of the eye and its adnexa at once for general observation.
2. Direct Focal
a. Optic Section: Optic section is used primarily to shaping the depth or elevation of a defect of the cornea, conjunctiva or locating the depth of a cloudiness within the lens of the eye. The optic section as mentioned above, it is likely to detect changes in corneal and conjunctival thicknesses, to assess depths of foreign bodies, scars and cloudiness, to approximation the frontal chamber depth and to identify the anatomical location of cataracts within the crystalline lenation source at about 45 degrees and S.
The slit lamp microscope should be straight in front of the patients eye, the illuminthe illumination mirror in click position. The slit width is almost closed, about 0.25 mm wide and 7 to 9 mm high. First place the enlargement on low to medium 7 - 10 X and focused on the patients closed lid. The thickness of the eyelid is about 1 mm thick, which means focusing on the cornea is accomplished by only to some extent moving the joystick ahead.
b. Conical Beam: Examination of the frontal chamber for cells or flare must be performed earlier than dilation . Magnification 16 - 20x and illumination high or what the patient will tolerate. Dilation frequently results in add to in the number of cells causes an enlarge in flare . This type of illumination is used to notice floating aqueous cells and flare by the, Tyndall effect, much like seeing dust floating in the air of a sun filled window.
C. Parallelepiped: A parallelepiped is one of the majority common types of illumination used. It is used in blend with a number of different types of illuminations. The slit lamp microscope should be directly in front of the patients eye, the illumination starting place at about 45 degrees and the illumination mirror in click, position. A parallelepiped is basically an optic section, except the slit width is greater 2.0 - 4.0 mm and the height may vary, providing a more three dimensional view of the cornea or crystalline lens.
The three-dimensional view permits observation of obvious details within the crystalline lenses zones of discontinuity. As with the optic section, the angle between the illumination source and slit lamp microscope may be varied to expose more corneal epithelium, and endothelium.
3. Retro-Illumination:
typically uses a parallelepiped that bounces unfocused light off one structure while observing the back lighting of another. The arrangement and angular separation of the slit lamp microscope to the illumination source will vary. The light source beam is reflected off another structure like the iris, crystalline lens or retina while the slit lamp microscope is focused on a more anterior structure.
4. Sclerotic Scatter:
for this illumination uses a parallelepiped at the limbus to spread out light internally throughout the cornea. Use low 6 - 10x magnification. In the case of innermost corneal clouding CCC the slit lamp microscope is not used. The pupil is observed with the naked eye from an angle directly opposite from the light starting place.
5. Indirect-Lateral-Proximal:
Place the slit lamp microscope directly in front of the patients eye and the illumination light source at about 45 degrees. Make certain the illumination mirror is in click position. Use a parallelepiped beam sharply focused on a given structure like the cornea. The light passes through the cornea and falls out of focus on the iris. The dark area just sideways or proximal to the parallelepiped is the indirect or proximal zone of illumination. This is the area of the cornea which one surveys through the slit lamp microscope.
6. Specular Refection:
Once more a parallelepiped is used. This is the only means by which one is capable to view the endothelial cells of the cornea or the epithelial cells on the backside of lens. The cells are seen only by one eye and they come out in the ocular opposite from the direction of the illumination light source.
