The slit lamp allows you to examine the eye with a beam or a slit of light (instead of diffuse light) whose height and width can be adjusted. The light slit, when directed at an angle, accentuates the anatomical structures of the eye, allowing for a close inspection. A slit lamp is a microscope with a bright light that is used during an eye exam. It allows the ophthalmologist to take a closer look at the different structures in the front and inside of the eye.
It is a key tool for determining eye health and detecting eye diseases. The doctor will examine the eyes, especially the eyelids, cornea, conjunctiva, sclera, and iris. Often, a yellow dye (fluorescein) is used to help examine the cornea and tear layer. The dye is added in the form of eye drops.
Or, the provider may touch the white part of the eye with a thin strip of paper stained with the dye. The dye washes away from the eye with tears when it blinks. A slit lamp is an instrument that consists of a high-intensity light source that can be focused to make a thin layer of light shine on the eye. It is used together with a biomicroscope.
The lamp makes it easy to examine the front and back segments of the human eye, including the eyelid, the sclera, the conjunctiva, the iris, the natural lens and the cornea. The binocular examination with a slit lamp provides an enlarged stereoscopic view of the eye structures in detail, allowing anatomical diagnoses to be made for a variety of eye conditions. A second portable lens is used to examine the retina. The first slit lamp concept dates back to 1911, attributed to Allvar Gullstrand and his large glare-free ophthalmoscope.
One sign that can be seen on the exam with a slit lamp is a flash, which is when you see the slit lamp beam in the front chamber. The person will sit with their head resting on the microscope with a slit lamp and the doctor will place a special contact lens directly on the eyeball. A slit lamp exam is generally very safe, although medications that dilate the pupils carry some risks. The person will sit in a chair in front of the slit lamp with the chin and forehead resting on a support.
At this time, the great importance of color temperature and luminance of the light source for examinations with slit lamps was recognized and the basis for examinations with non-red light were created. It wasn't until 1919 that several improvements were made to the Gullstrand slit lamp manufactured by Vogt Henker. It will then turn on the slit lamp and focus a narrow, high-intensity beam of light toward the eye.