What Is Slit Lamp?
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Slit Lamp - Procedure and Indications

Published on Mar 28, 2023   -  4 min read


A slit lamp, also known as biomicroscopy, is a test for evaluating any eye abnormalities or problems during an eye examination. Read about the topic in detail.


Getting an eye exam is essential for preserving good health. A routine eye exam includes a number of tests to evaluate overall vision and check for any issues that could be compromising the general health of the eyes. These can be both ophthalmologic disorders that damage the structures of the eyes, such as cataracts, as well as unrelated medical conditions like diabetes that manifest symptoms in the eye structures. During a routine physical examination, eye diseases might be challenging to identify. Ophthalmologists are medical professionals who treat eye issues and use equipment designed to inspect and diagnose eye conditions. For example, a slit lamp is a microscope with intense light during an eye exam. It allows your ophthalmologist to better look at the various structures inside and on the front of the eye. It is essential to assess eye health and identify eye diseases.

What Is the Slit Lamp Examination?

The slit lamp examination, known as biomicroscopy, is a standard diagnostic procedure. The slit lamp is a collection of equipment that functions as a single unit. It has a light source that can be adjusted, a binocular microscope with a movable base, and a frame for the patient's head to rest on while the examination is conducted. The doctor can use the light in several ways. For example, they can enlarge it, make it brighter, and apply a color filter. This allows the doctor to concentrate on specific areas of the eyes and face.

What Diseases Can Be Diagnosed?

By performing a slit lamp exam, a doctor will be able to identify a variety of diseases. A few examples of the abnormalities they might see include:

  • Detached Retina - A condition in which the retina, an essential layer of tissue in the back of the eye, separates from its base.

  • Macular Degeneration - Macular degeneration is one of the age-related eye disorders seen in elderly individuals above 50 years of age. It is also referred to as age-related maculopathy. This causes vision loss due to the macula's thinning or degeneration.

  • Cataract - Cataract is a condition in which blurring of the lens makes it difficult to perceive images. A cataract is caused by the breakdown of protein and fibers in the lens, which makes vision foggy or blurry.

  • Obstructions - Obstructions in the eye's blood arteries and blockages of the retinal vasculature, which may result in a sudden or progressive loss of vision.

  • Corneal Injuries - Injury to the cornea, the clear transparent tissue of the front layer of the eye is caused by foreign bodies, chemicals, ultraviolet rays, or infections.

How Slit Lamp Test Be Performed?

The slit lamp test requires no extra preparation.Bring sunglasses and plan transportation home if the doctor intends to dilate the patient's pupils. As soon as the patient is seated in the examination chair, they are instructed to rest their chin on the chin rest and their forehead against the forehead band. This maintains the patient's head steady during the exam. To make the exam more accessible, the doctor may give them a special dye called fluorescein. They will either use a tiny, thin paper strip that touches the white of the eye to apply this as an eye drop. The doctor will then apply several eye drops to dilate the pupils. The dilatation will make it simpler for the doctor to see the other eye structures.

The drops start working after around 20 minutes. The physician performs another eye examination after the patient has dilated pupils. A specific lens next to the eye is placed. The procedure is painless, although there may be a slight stinging sensation while applying the eye drops.The doctor examines every part of the eye during the test, including the following:

  • Sclera - The white portion of the eye is called the sclera. The strong, fibrous fibers that make up the sclera form the eye's outer layer of protection. A slit lamp examination can reveal sclera inflammation and discoloration.

  • Cornea - The transparent layer that protects the iris and pupil is called the cornea.The retina is located in the rear of the eye and helps send light through the pupil.

  • Conjunctiva -The thin, transparent membrane known as the conjunctiva covers the eye's white area. Additionally, it encompasses the inner eyelids' membrane surface.

  • Eyelids - The eyelids protect the eyeball from harm or foreign objects. The act of blinking lubricates the eye and keeps it from drying out.

  • Lens - The transparent portion of the eye that focuses light on the retina so the patient can see is located behind the pupil. During the examination, a cataract, or clouding of the lens of the eye, can be identified. This is a natural aspect of aging and l needs to be surgically treated whenever it affects daily life.

  • Retina - The retina is a layer of nerve cells that lines the back of the eye. For one to be able to see, it detects light and converts it into visual messages. A damaged or detached retina might be discovered via an examination to prevent vision loss. Inherited retinal illnesses, such as retinitis pigmentosa, can also be identified with a slit lamp examination, including age-related macular degeneration, which impairs the detailed, central vision.

  • Optic Nerve - A nerve that runs along the back of the eye that connects to the brain.

If glaucoma is not detected and treated early, it slowly destroys the optic nerve and results in vision loss.Therefore, an essential step in making the diagnosis is a slit lamp examination.


The doctors employ a slit lamp eye exam, a simple and painless treatment, to take a close look at a patient's eye's internal structures. A doctor will determine whether or not a patient needs the test. Although the medications used to dilate the pupils have some hazards, a slit lamp examination is typically relatively safe. However, they might raise ocular pressure, making people feel queasy, hurting their eyes. Anyone exhibiting these signs ought to consult a doctor right away. Eye specialists could suggest seeing a primary care physician if examination

Last reviewed at:
28 Mar 2023  -  4 min read




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