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Biomicroscopy is usually performed in an ophthalmology office using a slit lamp. This allows the doctor to microscopically examine the eyes for any abnormalities or problems.
Eye conditions can be difficult to diagnose during a general physical examination. A doctor who specializes in treating eye problems, called an ophthalmologist, is better able to investigate and diagnose these conditions because the tools they have are eye-specific. When a patient undergoes an eye examination, they will most likely have a biomicroscopy.
Biomicroscopy of the eye uses an instrument that provides an enlarged three-dimensional view of parts of the camera. During the examination, the doctor may look at the anterior parts of the eye. These parts include the outer covering (cornea), the lens, and the colored part (iris). The doctor can also see the front of the vitreous, which fills the large space in the middle of the eye.
Special lenses can be placed between the slit lamp and the cornea to help the doctor see deeper structures in the eye. These structures include the optic nerve, the retina, and the area where fluid drains from the eye (anterior chamber angle). A camera can be attached to the slit lamp to take pictures of different parts of the eye. Fluorescein dye can be used during eye biomicroscopy. The dye makes it easier to see a foreign object, such as a metal fragment, an infected or damaged area on the cornea.
What happens during eye biomicroscopy?
There is no need to prepare in advance for eye biomicroscopy. As soon as the patient is in the exam chair, the doctor will place an instrument in front of him on which he will need to put his chin and forehead. This helps to strengthen the head for exploration. The ophthalmologist may place drops in the eye to make any abnormalities on the surface of the cornea more visible. The drops contain a yellow dye called fluorescein, which washes away tears. Additional drops may also be placed in the eyes to make the pupils dilate, or enlarge.
The doctor will use a low power microscope along with a slit lamp, which is a high intensity light source. With their help, it will be possible to carefully look at the eyes. The slit lamp has various filters. Some devices may have features that capture digital images to track changes in the eyes over time.
slit lamp
The slit lamp is a binocular microscope that provides the examiner with a stereoscopic (three-dimensional) image of the eye. It has changed little since it was developed by Goldman in 1937. However, there are alternative methods of examining the eye using portable digital cameras and imaging devices. These new methods may offer some advantages, but may not offer slit lamp compatible stereoscopic imaging or magnification. The slit lamp allows the eye to be examined with a beam or “slit” of light (versus ambient light) whose height and width can be adjusted. An angled slit of light highlights the anatomical structures of the eye, allowing for a thorough examination. The slit lamp provides greater magnification (10x to 25x) and illumination than most handheld devices (such as the Woods lamp), which is essential for diagnosing a range of traumatic and non-traumatic disorders.
Non-ophthalmic slit lamp indications include any acute condition that requires magnification to view the anterior segment of the eye (eg, eyelids, eyelashes, conjunctiva, cornea, anterior chamber, iris, and lens) or to facilitate removal of a foreign body from the eye. Thus, it is well suited for diagnosing conditions such as corneal epithelial defects, keratoconjunctivitis, hypopyon, lens dislocation, herpes infections, iritis, or for evaluating red eyes.
The slit lamp is less useful in diagnosing posterior segment (i.e., vitreous, fundus, optic disc) conditions in the primary care or emergency department. Such conditions include vitreous hemorrhage and retinal detachment. Diagnosis of such conditions with the slit lamp is only possible with special devices, and the examiner is trained and experienced in their use.
Slit lamps can be divided into two broad groups: those with illumination above the viewing system and those with illumination below the viewing system.
Procedure algorithm
Proper adjustment of the biomicroscope is essential. Lighting and observation systems should be connected and be the focus of the observer, the patient should be seated comfortably, the chin firmly on the headrest, and eye level should be in the center of the vertical stroke of the instrument. Steps required to achieve this goal:
- Instrument Focusing – The use of a focusing rod in the slit lamp ensures that the narrow slit beam is clearly in focus through each eyepiece individually and then binocularly through the interpupillary distance adjustment.
- The position of the patient. It is necessary to explain the nature of the examination to the patient and make sure that he is sitting comfortably. If the patient is uncomfortable, the study becomes much more difficult. Similarly, if eye level is not present in the middle of the vertical stroke of the instrument, the examiner will have difficulty viewing the lower and upper parts of the eyes. Most slit lamps have a notch on the headrest to ensure the patient’s head is in the optimal position.
- Focus check. With the eyelids closed, the examiner should focus the light on the lids and check its focus by rotating the lighting system from side to side. As it rotates, the light should remain stationary on the lid. If it shows relative motion, the tool is out of focus.
- Examination of patients. Now the examination can begin, the slit beam should never remain shining on the eye when the doctor is doing the examination. If the practitioner is looking away from the eyepieces, the beam should be turned off or directed away from the eyes.
Coloration
The cornea should be examined after fluorescein application. Sodium fluorescein is a vital dye that stains damaged epithelial tissues. This is the best way to assess the cornea and the integrity of the conjunctiva.
Fluorescent substances absorb light at certain wavelengths and radiate the absorbed energy at longer wavelengths. The fluorescein dye absorbs blue light in the region from 460 to 490 nm.
The appearance of fluorescein in the eye can be enhanced by placing a yellow protective filter over the eyepiece. This filters the blue light to make the fluorescent green appear clearer. Evaluation of corneal staining with fluorescein is essential and should be performed at every appointment.
Purpose of the study
Biomicroscopy of the eye can help diagnose the following conditions:
- macular degeneration, a chronic condition that affects the part of the eye that is responsible for central vision;
- retinal detachment, a condition where the retina, which is an important layer of tissue at the back of the eye, separates from its base;
- cataracts, clouding of the lens, which adversely affect the ability to see images clearly;
- damage to the cornea, damage to one of the tissues covering the surface of the eye;
- blockages in the blood vessels of the retina, obstructions in the blood vessels of the eyes, which can cause sudden or gradual loss of vision.
During the examination, the doctor will examine all areas of the eye, including:
- eyelids;
- conjunctiva;
- iris;
- lens;
- sclera;
- cornea;
- retina;
- optic nerve.
The doctor will first examine the anterior regions of the eye, and then examine again with a different lens to look at the back of the eye.
Indications for research
Usually biomicroscopy is performed to find eye problems early and determine treatment if eye problems occur.
Biomicroscopy can be performed:
- As part of a routine eye examination. It may be used in conjunction with other procedures that evaluate the eye, such as ophthalmoscopy, vision testing, and tonometry (to measure pressure in the eye).
- To look at structures at the back of the eye such as the optic nerve and retina.
- To help find problems in structures in front of the eye. For example, it can help find problems such as cataracts, conjunctivitis, iritis, infection, or damage to the cornea.
- To help find and monitor glaucoma or macular degeneration.
- Check for a foreign body, such as a metal fragment, on or in the eye.
- Look for eye problems that may be caused by other conditions such as diabetes or rheumatoid arthritis.
- Watch for problems such as bleeding after an eye injury.
- Continue to check for problems such as cataracts that form due to chemotherapy, or radiation therapy, or after a bone marrow transplant.
How to prepare?
If the patient wears glasses or contact lenses, they must be removed before the examination.
Eye drops may also be used to dilate the pupils and numb the surface of the eyes. Before the examination, it is imperative to inform the doctor if the patient has glaucoma, or is allergic to eye drops that can be used during this diagnostic method.
If dilator drops are used, the eyes may be sensitive to light. You will have trouble focusing your eyes for several hours. You will also need to wear sunglasses when going outside or into a brightly lit room.
It is very important to talk to your doctor if you have any concerns about whether the test should be done, the risks involved, how it will be done, or what results will matter.
What happens during research?
The doctor may place one or more types of drops in the eye. Drops can be used to enlarge the hole (pupil) in the center of the eye. This makes it easier for the doctor to see the structures of the eye. Pain drops may also be used if a foreign object needs to be removed or eye pressure (tonometry) needs to be checked. In some cases, a fluorescein dye is used.
The patient should sit on a chair and rest their chin and forehead on the grate on the slit lamp. The light in the room will be dimmed.
The slit lamp will be placed in front of the patient’s eyes according to the doctor’s eyes. You need to focus your eyes in the direction that the doctor says and try to keep your eyes still without blinking.
A narrow beam of bright light from a slit lamp is directed into the eyes, and the doctor looks through a microscope. In some cases, a camera can be attached to the slit lamp to capture different parts of the eye.
Fluorescein staining can be performed along with biomicroscopy.
During this test, the doctor applies a dye called fluorescein. The dye is injected into the eyeball or as a paper strip that gently touches the inside of the lower eyelid. The dye dissolves into tears, coats the cornea, and picks up any scratches or other abnormal areas within a short time. The rest of the paint is washed off with tears. Fluorescein dye appears under light. This helps the doctor see scratches, sores, burns, or areas of irritation from infection or dryness.
Biomicroscopy takes 5 to 10 minutes.
Complications after using drops
Usually this study is not painful.
Expanding droplets can cause a medicinal taste in the mouth. There will be trouble focusing the eyes for 12 hours. Distance vision usually does not affect near vision. But the eyes can be very sensitive to light. It is not recommended to move for several hours after the eyes have been dilated. Wearing sunglasses can make this period more comfortable until the droplet effect wears off.
In some people, the drops used during the study may cause: nausea, vomiting, dry mouth, short-term dizziness; allergic reaction; a sharp increase in pressure inside the eyeball (closed angle glaucoma).
One should immediately consult a doctor if there is severe and sudden pain in the eyes, vision problems such as halos that appear around the world, or loss of vision after the examination.
The results
For examination, an instrument is used that provides an enlarged three-dimensional view of parts of the eye. Normal: Eyelashes, eyelids, and the lining of the eyelids (conjunctiva) appear normal; all structures within the eye appear normal. Pathology: a cataract is seen, changes in the cornea are found, such as a corneal scratch, ulcer, and infection, a foreign object is found, such as a metal fragment, an infection is found, such as iritis or conjunctivitis, bleeding occurs between the iris and cornea from a sudden rupture in a blood vessel, or as a result of an eye injury, signs of glaucoma are visible.
The inability of the patient to remain in the right place during the biomicroscopy of the eye may complicate the study.
Alternative Methods
Other eye examinations may be performed in conjunction with eye biomicroscopy. These investigations include ophthalmoscopy, vision testing, and tonometry for glaucoma. A test called a gonioscopy may be done during a biomicroscopy to check for certain types of glaucoma. A special contact lens is placed on the eye. A narrow beam of bright light is pointed into the eyes. The doctor then views the slit lamp at a drainage angle in the eye.