What is the slit lamp exam?
The slit lamp examination is a standard diagnostic procedure, also known as biomicroscopy. A slit lamp combines a microscope with very bright light. The slit lamp exam is usually part of a comprehensive eye exam. The individual will sit in a chair in front of the slit lamp with the chin and forehead supported by a support.
The doctor can use this instrument to observe the eyes in detail and determine if there are any abnormalities. They will be able to discuss the results with the person right away.
Uses of slit lamp examination
Doctors use the slit lamp as part of a comprehensive eye exam to better look at the structures within a person’s eyes. These include the following:
- Conjunctiva: The conjunctiva is a thin, transparent membrane that covers the white of the eye. It also includes the membranous surface of the inner lids.
- Cornea: The cornea is the transparent cover of the iris and pupil. It protects the eye and also helps send light through the pupil to the retina at the back of the eye.
- Eyelids: The eyelids help protect the eyeball from debris or injury. Blinking helps lubricate the eye and prevent it from drying out.
- Iris: the iris is the coloured portion of the eye. It controls the quantity of light that arrives in the eye by contracting and dilating the pupil.
- Pupil: The pupil is the black spot in the middle of the eye. It occupancies light to enter the eye and travel to the retina.
- Lens: The lens is placed behind the iris and focuses light on the retina.
- Sclera: The sclera is the white portion of the eye. It consists of relatively strong fibrous tissue that helps provide structure and protection to the rest of the eye.
- Retina: The retina is the tissue in the eye that contains cells that detect light. These cells join nerves that eventually join to form the optic nerve.
Process undergoing slit lamp examination
After the first look into your eyes, your doctor may apply a special dye called fluorescein to make the exam easier. It will be given as an eye drop or on a small, thin strip of paper that touches the white of the eye. The doctor will then manage a series of eye drops that will dilate the pupils. Enlargement will make it easier for the doctor to see the other structures in the eye. The drops take about 20 minutes to work.
Once the person has dilated pupils, the doctor will repeat the eye exam. This period they will grip a particular lens close to the eye.
The procedure does not hurt, although there may be a brief sting during the application of the eye drops. Dilated pupils develop very large, which can make the eyes sensitive to light. This can make driving or outlay time outside painful. However, the eye drops should garb off within a combine of hours, and wearing sunglasses should help during this period.
Slit lamp exam preparation
There is no special preparation for this test. If the doctor plans to dilate the pupils, the person may want to wear sunglasses and arrange a trip home after the test.
Risk factors in the slit lamp exam
A slit lamp exam is generally very safe, although medications that dilate the pupils carry some risks. They can increase eye pressure, causing nausea and eye pain. Anyone experiencing these symptoms should inform a doctor immediately.
Types of slit lamp exam
Other common eye exams include:
Wood’s lamp examination
Wood’s lamp projects ultraviolet light into the eye to reveal any abrasions or scratches on the cornea. Doctors can use this if a slit lamp is not available.
During a fundus exam, the doctor will use an ophthalmoscope to look inside the eye. Some will use a direct ophthalmoscope, which is a small hand-held instrument with a light on. However, most doctors will use an indirect ophthalmoscope, as they can wear it on the head and it gives them a wider field of view for the exam. The patient will be asked to look into the distance while using the device to examine the internal structures of the eye.
For this process, the doctor will first administer numbing eye drops. The person will sit with their head supported by the slit lamp microscope, and the doctor will place a special contact lens directly over the eyeball. Happens during a slit lamp exam.
You do not need to prepare in advance for a slit lamp exam. Once you are in the exam chair, the doctor will place an instrument in front of you to support your chin and forehead. This helps stabilize the head for the exam. Your ophthalmologist may put drops in your eyes to make any abnormalities on the corneal surface more visible. The drops contain a yellow dye called fluorescein, which washes away tears. Additional drops may also be put in your eyes to allow your pupils to dilate or enlarge.
The doctor will use a low-power microscope, along with a slit lamp, which is a high-intensity light. They will look you in the eye closely. The slit lamp has different strainers to get different views of the eyes. Some doctor’s offices may have devices that detention digital images to track variations in the eyes over time.
Throughout the test, the doctor will examine all areas of your eye, including:
- Optic nerve
Diagnosis in the test
A slit lamp exam can help diagnose the following circumstances:
- Macular degeneration, a chronic condition that affects the part of the eye responsible for central vision.
- Detached retina, a condition in which the retina, which is a main layer of tissue at the back of the eye, is shed from its base.
- Cataracts, a clouding of the lens that damagingly affects the ability to see images visibly.
- Corneal injury, an injury to one of the tissues that cover the surface of the eye.
- Retinal vessel obstructions, obstructions in the blood vessels of the eye that can cause a sudden or gradual loss of vision.
Ask your doctor what you are looking for during the exam and what eye conditions you may be at risk for. This test usually has no major side effects. Your eyes may be sensitive to light for a time afterwards, especially if your pupils were dilated. If you start to feel nauseous or have pain in your eyes, return to your doctor’s office as soon as possible. These may be symptoms of increased fluid pressure in the eye, which can be a medical emergency. While the risk of this is small, eye drops used to dilate the eye can rarely cause this to occur.
Abnormal results mean
If the results of your slit lamp exam are abnormal, there can be a variety of conditions, including:
- Increased pressure in the eye
- Degeneration of the arteries or veins of the eye
For example, if macular degeneration is occurring, the doctor may find drusen, which are yellow deposits that can form in the macula at the beginning of age-related macular degeneration. If your doctor suspects a particular cause of vision problems, she may recommend more tests to get a more definitive diagnosis.