Usually biomicroscopy is performed in an ophthalmologic office using a slit lamp. This allows the physician to microscopically examine the eyes for any abnormalities or problems.
Eye disease 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 that they have are eye-specific. When the patient undergoes an eye examination, he will most likely be subjected to biomicroscopy.
In eye biomicroscopy, an instrument is used that provides an enlarged three-dimensional view of camera parts. During the examination, the doctor may look at the front of the eye. These parts include the outer covering (cornea), lens and color part (iris). The doctor can also see the front of the vitreous body, which fills a 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 the deeper structures of the eye. These structures include the optic nerve, the retina and the area where fluid flows from the eyes (anterior chamber angle). A camera can be attached to the slit lamp to shoot different parts of the eye. Fluorescein dye can be used during eye biomicroscopy. The dye facilitates the visibility of a foreign object, such as a metal fragment, of an infected or damaged area on the cornea.
What happens during eye biomicroscopy?
No need to prepare in advance for eye biomicroscopy. As soon as the patient is in the examination chair, the doctor will place a tool in front of him on which he will need to put his chin and forehead. It helps to strengthen the head for research. The ophthalmologist may drip eye drops to make any anomalies on the surface of the cornea more visible. The drops contain a yellow dye, called fluorescein, which washes away tears. Additional drops can also be dripped into the eyes so that the pupils expand or grow.
The doctor will use a low-power microscope together with a slit lamp, which is a source of high-intensity light. With their help, you can carefully look at the eyes. Slit lamp has different filters. In some devices, there may be features that capture digital images to track changes in the eyes over time.
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 its development by Goldman in 1937. Nevertheless, there are alternative methods of eye research using portable digital cameras and image visualization devices. These new methods may offer some advantages, but cannot offer a stereoscopic image or magnification compatible with a slit lamp. A slit lamp allows you to explore the eye with a beam or a “slit” of light (compared to diffused light), the height and width of which can be adjusted. A slit of light directed at an angle emphasizes the anatomical structures of the eye, which allows for a thorough examination. The slit lamp provides greater magnification (10 to 25 times) and luminosity than most handheld devices (for example, Wood's lamp), which is necessary to diagnose a number of traumatic and non-traumatic disorders.
Indications for using a slit lamp in non-ophthalmological conditions include any acute condition that requires magnification to inspect the anterior segment of the eye (eg, eyelids, eyelashes, conjunctiva, cornea, anterior chamber, iris and lens) or to facilitate removal of the 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 red-eye assessment.
Slit lamp is less useful in diagnosing the state of the posterior segment (i.e. vitreous body, bottom, optical disk) in the primary health care department or in the emergency room. Such conditions include vitreous hemorrhage and retinal detachment. Diagnostics of such conditions using a slit lamp is possible only with special devices, and the examiner has training and experience in using them.
Slit lamps can be divided into two broad groups: with the lighting system above the viewing system and those with lighting below the viewing system.
Proper biomicroscope setup is required. Lighting and observation systems must be connected and be the center of attention of the observer, the patient must sit comfortably, his chin firmly adhere to the head restraint and eye level must be at the center of the vertical stroke of the instrument. Stages required to achieve this goal:
- Tool focusing - using a focusing rod in a slit lamp ensures that a narrow slit beam is clearly in focus through each eyepiece individually, and then binocularly, through the adjustment of the interpupillary distance.
- The position of the patient. You need to explain to the patient the nature of the examination and make sure that he is sitting comfortably. If the patient is uncomfortable, the study becomes much more difficult. Similarly, if the eye level is not in the middle of the vertical stroke of the instrument, the examiner will have difficulty viewing the lower and higher parts of the eyes. Most slit lamps have a notch on the head restraint to ensure the patient's head is in the optimal position.
- Focus check. With closed eyelids, the examiner should focus the light on the covers and check its focus by rotating the lighting system from side to side. When it rotates, the light must remain fixed on the lid. If it shows relative motion, the instrument is not in focus.
- Examination of patients. Now the examination can begin, the slit ray should never remain shining on the eye when the doctor performs the examination. If the practitioner looks away from the eyepieces, the beam should be turned off or directed away from the eyes.
The cornea should be examined after fluorescein has been applied. Fluorescein sodium is a vital dye that stains damaged epithelial tissue. This is the best way to evaluate the cornea and conjunctival integrity.
Fluorescent substances absorb light at specific wavelengths and emit absorbed energy at longer wavelengths. 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 on top of the eyepiece. It filters blue light to make fluorescent green more clear. Evaluation of corneal fluorescein staining is important and should be performed at every appointment.
Purpose of the study
Eye biomicroscopy can help diagnose the following conditions:
- macular degeneration, a chronic condition affecting 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 in the back of the eye, separates from its base;
- cataracts, clouding of the lens, which adversely affect the ability to clearly see images;
- damage to the cornea, damage to one of the tissues covering the surface of the eye;
- retinal vascular obstruction, obstruction in the blood vessels of the eye, which can cause a sudden or gradual loss of vision.
During the study, the doctor will examine all areas of the eye, including:
- optic nerve.
The doctor will first examine the front areas of the eye, and then again conduct a study with another lens to examine the back of the eye.
Indications for study
Usually biomicroscopy is performed to find problems with the eyes at an early stage and to determine the treatment if there are problems with the eyes.
Biomicroscopy can be performed:
- As part of a routine eye exam. It can be used in conjunction with other procedures that evaluate the eye, such as ophthalmoscopy, eye exam and tonometry (for measuring pressure in the eye).
- To look at the structures in 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 the eye or in the eye.
- Find eye problems that may be caused by other diseases 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 are formed due to chemotherapy, or radiation therapy, or after bone marrow transplantation.
How to prepare?
If a patient wears glasses or contact lenses, they need to remove them before testing.
Eye drops can also be used to dilate the pupils and numb the surface of the eyes. Before the examination, it is necessary to inform the doctor if the patient has glaucoma, or is allergic to eye drops, which can be used during this diagnostic method.
If dilated drops are used, the eyes may be sensitive to light. There will be problems focusing the eyes for several hours. You will also need to wear sunglasses when going outside or in a brightly lit room.
It is very important to talk with your doctor if there are any problems with the need for a test, its risks, how it will be done or what results will matter.
What happens during the study?
A doctor may drop one or more types of drops into the eyes. 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. Anesthetic drops can also be used if it is necessary to remove a foreign object or to check eye pressure (tonometry). In some cases, a fluorescein dye is used.
The patient needs to sit on a chair and put his chin and forehead on the grate on the slit lamp. The light in the room will be dimmed.
A slit lamp will be placed in front of the patient’s eyes in accordance with the doctor’s eyes. You need to focus your eyes in the direction that the doctor is talking about and try to keep your eyes motionless, without blinking.
A narrow beam of bright light from a slit lamp is sent to the eyes, and the doctor looks through a microscope. In some cases, the camera may be attached to a slit lamp for shooting different parts of the eye.
Fluorescein staining can be performed along with biomicroscopy.
During this study, the doctor uses a dye called fluorescein. The ink is inserted into the eyeball or in the form of a paper strip, which gently touches the inside of the lower eyelid. The paint dissolves in tears, covers the cornea and collects for a short time any scratches or other abnormal areas. The rest of the paint is washed off with tears. Fluorescein dye appears under the light. It helps the doctor see scratches, ulcers, burns, or areas of irritation from infection or dryness.
Biomicroscopy takes from 5 to 10 minutes.
Complications after using drops
Usually this study is not painful.
Dilating drops can cause medicinal taste in the mouth. There will be problems with focusing eyes for 12 hours. Distant vision usually does not affect close vision. But eyes can be very sensitive to light. It is not recommended to move within a few hours after the eyes have been dilated. Wearing sunglasses can make this period more comfortable until the effect of the drops disappears.
In some people, drops that are used during the study may cause: nausea, vomiting, dry mouth, short-term dizziness for a short time; allergic reaction; a sharp increase in pressure inside the eyeball (closed angle glaucoma).
You 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.
For the study used a tool that provides an enlarged three-dimensional view of the parts of the eye. Normally, the eyelashes, eyelids and lining of the eyelids (conjunctiva) look normal, all the structures inside the eye look normal. Pathology: a cataract is visible, changes in the cornea are found, such as scratching the cornea, ulcer and infection, a foreign object is detected, such as a metal fragment, an infection such as iritis or conjunctivitis is detected, bleeding is observed between the iris and the cornea from a sudden rupture of a blood vessel or as a result of an eye injury, signs of glaucoma are visible.
Difficult to study may be the inability of the patient to stay in the right place during eye biomicroscopy.
Other eye examinations may be performed with eye biomicroscopy. These studies include ophthalmoscopy, eye exam and tonometry for glaucoma. A test called gonioscopy can be performed during biomicroscopy to check for certain types of glaucoma. A special contact lens is placed on the eye. A narrow beam of bright light is sharpened in the eyes. The doctor then scans the slit lamp at an angle of drainage in the eye.