The general method is: insert the fixed focus bar into the fixed focus bar jack and turn on the lighting power supply. Operate the handle on the sliding table to see if it can move back and forth, left and right flexibly. Open a big slit, rotate the aperture plate, and observe the aperture shape, whether the color filter is good and whether the aperture rotation is flexible. Then open the aperture and adjust the crack to see whether the crack image is evenly opened and closed and whether the two sides are parallel. At the same time, it is necessary to focus the microscope: the microscope is adjusted according to normal eyes. If the doctor has ametropia, he should wear appropriate glasses or adjust the visibility of the eyepiece. At this time, he should close his left eye, turn the visible ring of the right eyepiece until he sees the clearest crack image on the focusing rod, and then correct the focal length of the left eyepiece in the same way. After use, reply to 0 digits for others to use. The pupil spacing of binocular stereo microscope can be adjusted artificially. At the same time, eyepieces and conversion objective lenses with different magnifications can also be used to convert the magnifications. Check whether the * * * focal axis is in good condition. Finally, take off the fixed focus rod and check the work.
When in use, the patient's head is fixed on the chin rest and forehead rest, the height of the table top is adjusted, and the adjusting screw of the chin rest is rotated, so that the eye to be examined is roughly aligned with the optical axis of the microscope, that is, the outer corner of the patient's eye is as high as the scribed line on the column (there is a circle of scribed line on the headrest column, indicating the approximate height position of the optical axis). Adjust the height of microscope and slit lamp with joystick (or handwheel) to make the position of slit image moderate, and adjust the left and right and front and rear positions of slide table to ensure the observed image is clear. When the position is appropriate and the focus is correct, the inspection can be carried out.
According to the optical principle, slit lamp microscope can be divided into the following types:
1. Oblique projection method is the most commonly used method, in which the fracture system is located at 45 and observed by microscope. Most lesions in front of eyes can be observed by oblique photography, such as conjunctival papilla hyperplasia, conjunctival follicles, trachoma scar, corneal foreign body, corneal cloud, pigment in anterior lens capsule, lens opacity and so on. This method mainly judges the lesions by examining the color and morphological changes of the eyes.
2. Reflection method When the slit lamp shines on people's eyes and encounters smooth interfaces such as the front and back of the cornea and the front and back of the lens, reflection will occur. At this time, if you rotate the microscope bracket to make the reflected light enter the microscope, you will see a bright reflection when you observe it with the microscope. Moving the microscope back and forth can clearly see the subtle changes of the reflecting surface. If the irradiation position is changed by rotating the angle between the slit lamp and the microscope without moving the microscope, the purpose of reflecting light can also be achieved (note: the microscope must focus on the reflecting surface). This method can be used to check the "small swelling" of corneal surface, corneal epithelial exfoliation, scar of corneal ulcer healing, wrinkles of anterior lens capsule, light reflection or color reflection of posterior lens capsule, etc.
3. The back illumination method is basically the same as the oblique illumination method, but at this time, the observer does not see the illuminated place clearly, but turns his eyes to the other side of the field of vision. For example, the slit lamp shines on the human body from the right side, the microscope focuses on the cornea, and the slit lamp passes through the cornea to reach the iris, forming a fuzzy crack point. Turn your eyes to the cornea in front of the iris spot, and you can see corneal lesions on a bright background. When the cornea has opaque tissues such as neovascularization or post-deposition, opaque dots or lines will be displayed on a bright background. This method is suitable for the examination of posterior corneal deposition, deep corneal foreign bodies, deep corneal blood vessels and pannus.
4. Adjust the purpose of the diaphragm. Poke the slit and turn the handle to the left or right. The slit can be turned from a straight position to a horizontal position. When using transverse slit as optical slice, the position of slit lamp should be placed in the middle position, so that the included angle between slit lamp arm and microscope is 0. When the aperture is adjusted, we can get slit images with different lengths. Long slit images are usually used to scan the eyes and make a comprehensive observation of eye lesions. When inspecting the crystal, the length of the crack image can be shortened appropriately to reduce glare. When examining the fundus or posterior vitreous with anterior lens or contact lens, the length of fissure image should also be shortened appropriately.
Blue filter is often used for fluorescence observation, and green filter is used for observing blood vessels.
Operating steps and methods
Before operation
Environmental preparation: a relatively dark room
Instrument preparation: base zeroing, including: adjusting the length of the laser scalpel to 8 or 9 and the width to 0, adjusting the focal length of the eyepiece to 0, loosening the lock wheel, and adjusting the magnification to low magnification.
Inspector preparation: wear a white coat or overalls and wash your hands.
Candidate preparation: to understand the medical history, you can do a general eye examination first.
operation sequence/order
1. Adjust the height and position of the chair according to the patient's body shape, so that the examiner and the examinee are in a comfortable position. The examinee takes off the frame glasses, instructs the examinee to put the forehead and mandible on the forehead support and the mandible support respectively, and adjusts the height so that the canthus height of the examinee is level with the line of sight.
2. Explain to the patient properly before the examination, and ask him to look at the indicator light or look directly at the microscope during the examination.
3. Ask the client to close his eyes, turn on the lighting system, and adjust all parts, so that the slit lamp and the microscope are 30 ~ 50 degrees, and the light enters from the temporal side. Take the eyelashes or the bridge of the nose of the examinee as the focusing target, adjust the focal length, and then adjust the binocular microscope to make its distance consistent with the pupil distance of the examinee.
4. According to the situation of the inspected, different lighting methods are used for inspection. For standard operation, it is necessary to check the eye condition of the subject from front to back. First, adjust the width of the laser knife to the widest, observe the eyelashes, let the patient open his eyes and look straight ahead, and check the general situation of cornea and conjunctiva; Then adjust the width of the laser knife to observe the cornea, iris, anterior chamber, lens and anterior 1/3 lens.
After surgery
Clean things up, turn off the power in time and put them back. Inspectors need to wash their hands with disinfectant or hand sanitizer; If there is any problem with the inspection instrument, it should be adjusted and maintained in time to ensure the accuracy of the inspection results of slit lamp microscope.
Matters needing attention
1) Don't apply eye ointment before inspection. 2) Glare is not allowed during inspection. 3) 1 The observation time should not be too long. 4) If the examinee's eye irritation symptoms are obvious, a small amount of topical anesthetic can be dropped. 5) Ask the client if there is any discomfort during the examination, and handle it in time if there is any discomfort. Answer customer's questions patiently.
Common inspection methods
1) Diffuse illumination method: it is a common inspection method for slit lamps. The illumination light source projects obliquely, and the observation angle is 45 (30 ~ 50). The light source cover has a frosted filter, and the slit is fully open, so that the eye surface is in a diffuse illumination state. Observe with a high brightness and low magnification microscope.
This is the most commonly used examination method, which is often used for rapid preliminary examination of the anterior segment of the eye, including eyelid, conjunctiva, tear film, cornea, sclera, anterior chamber, iris, pupil and lens. The best way is to check the gross edema of the cornea, and aim a wide beam at the periphery of the cornea so that the edema surface of the cornea appears gray in the center of the cornea.
If lesions are found, switch to other methods for examination. At the same time, it can also be used for fitting evaluation of soft contact lenses and hard contact lenses. This method mainly judges the lesions by examining the color and morphological changes of the eyes. 2) Direct irradiation method: This method is the basis of slit lamp microscopy. Its basic feature is that the focal points of slit lamp and microscope coincide. The light source is projected on the corneal tissue at 40 ~ 65 degrees from the left or right side, and the slit is adjusted to a very thin width to form a "light knife", and the focus of the microscope is projected on the examined tissue to observe the tissue carefully. Observe with medium and high power microscope. After the focus of light touches the eyes, its optical effect depends on the transparency of the tissue through which the light passes. If the focus of light falls on opaque tissues, such as sclera and iris, most of the light is reflected, and some of it is dispersed and absorbed, and a bright and tidy irradiation area is obtained. However, if the focused light passes through transparent and scattered substrates, such as cornea and lens, an opalescent optical parallelepiped is formed. This is because the cornea or lens is transparent under diffused light, but it is composed of complex cells and still belongs to heterogeneous media. When light passes through, due to the internal structure of the tissue, it will reflect, bend and scatter, and finally form an opalescent optical parallelepiped on the cornea or lens.
Wide-angle irradiation: If the crack widens to 1mm (that is, half the width), it is called wide-angle irradiation, so as to check the lesions seen by low-power lens irradiated with diffused light before, or find lesions that have never been seen before. It can comprehensively observe corneal curvature and thickness, corneal infiltration, corneal ulcer, corneal foreign body, corneal post-deposition, pupil, iris and other aspects, shapes and lesions.
Narrow light irradiation: if the crack narrows, the front and back of the optical parallelepiped will narrow at the same time, but the thickness of the front and back remains unchanged, which is narrow light irradiation. When the crack is reduced to less than 0.5 mm, the optical cross section can be formed. This method is convenient to determine the location of the lesion, distinguish whether the corneal wound is penetrating, and observe other detailed lesions. Because of the weak light, in order to achieve better inspection effect, the inspector's eyes need to be in a good dark adaptation state. Conical light: This method uses a small round hole instead of the usual crack to make the small round hole emit conical light. When the sub-cone light enters the anterior chamber, the lightest turbidity of aqueous humor can also be detected, and floating particles can be seen in aqueous humor. When using this method, the darkroom should be extremely dark, and the inspector should be in a good dark adaptation state, otherwise it is not appropriate to see this detail change. When operating, adjust the slit lamp to the minimum length, widest width, high brightness and medium-high magnification for observation. When observing, focus on the iris and observe the situation of aqueous humor.
3) Back reflection illumination method: The transparent, translucent, normal and pathological tissues are examined by the light reflected from the back. During inspection, the focus of the slit lamp shines on the opaque tissue behind the target or on the reflective surface, while the focus of the microscope is adjusted to the observed tissue, and the corresponding anterior tissue is observed through the reflected light projected on the iris, lens or retina. For example, when observing the front of the lens, the focus of light should shine on the posterior capsule of the lens, or use the light reflected from the fundus. Direct back reflection illumination method, that is, the examined tissue is just in the path of reflected light. Clinically, it is often used to observe the deposits on the posterior wall of cornea, corneal epithelial or corneal endothelial edema, deep corneal foreign bodies, corneal neovascularization, corneal fibrous scar and so on. For example, the light focus of slit lamp shines on the posterior capsule of lens, which is used to reflect light.
Tiny vacuoles, iris atrophy and cataracts in the lens can also be observed. Indirect back reflection irradiation method, that is, the tissue to be examined is located on one side of the reflected light path and observed under the background of no light area. It can be used to check corneal infiltration, corneal folds and so on. And can also be used for detecting contact lens deposits, such as protein deposits.
When the back reflection irradiation method is used, the lesions show different colors with different reflection colors of the background. For example, the lens capsule is blue-gray when the posterior lens capsule is used as the reflection screen, and yellow-red when the fundus is used as the background.
4) Specular reflection irradiation method: the surface reflection area formed by irradiation light on the surface of cornea or lens coincides with the optical parallelepiped of direct focusing irradiation method, and the tissues in this area are examined through the enhancement of luminosity in this area. At this time, the reflective belt is dazzling, just like a mirror, so it is called specular reflection lighting. Using this method, we can find the exfoliated cells on the tear film on the corneal surface, the mosaic morphology of corneal endothelial cells, and the patterns on the anterior capsule and posterior capsule of lens and adult nucleus. It should be noted that this method requires monocular observation. 5) Corneal edge light irradiation method: also called corneal edge scattering illumination method. This method takes advantage of the transparency of cornea. First, the slit light source is directly projected on the corneal limbus, and the light is totally reflected in the corneal tissue, forming an annular halo on the corneal scleral limbus. Then, the microscope focuses on the cornea, which can clearly show the transparency of corneal tissue, especially on the opposite limbus. Under normal circumstances, the cornea itself is invisible except for halo and annular shadow (caused by scleral process) at the edge of the cornea. However, if the cornea is turbid somewhere, there is obvious gray-white shadow. Corneal edge illumination method is suitable for detecting subtle changes of cornea, which is often used to detect corneal deposits, corneal infiltration, corneal blisters, corneal blood vessels, corneal edema and corneal scars, and can also be used to detect corneal contact lens deposits.
6) Indirect irradiation method: This method irradiates a part of the tissue with light, and distinguishes the shading objects near the irradiation place through the dispersion, refraction and reflection of light in the tissue. At this time, the focus of the microscope and the focus of the light emitted by the illumination mirror are not together, and the focus of the light is on the hood. This method can also be said to be the combined application of corneoscleral edge light illumination and back reflection illumination. The angle between the incident light and the observation line is large, and moving the light slowly is helpful for observation. This method can be used to check the internal bleeding of the iris, iris blood vessels, cornea and blisters in blood vessels. The pupil sphincter can also be observed by illuminating the iris close to the pupil.