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A slit lamp examination is a type of eye exam. It looks at the front part of the eye, primarily, although it can also be used to look closely at the back section. A slit lamp is a low powered microscope. It has a bright light source that shines a layer of light upon the eye. A biomicroscope is used at the same time to conduct the exam.
The slit light examination is capable of providing the optometrist with a three dimensional look at the various sections of the eye. The cornea or clear outer covering of the eye will be visible during the exam, as will the iris, the lens, and the vitreous gel, which is the fluid that takes up a fair amount of space in the middle section of the eye. In some cases, the eye doctor may decide to place a special lens between the cornea and the lamp, or place it directly on top of the cornea. The purpose of this is to allow for a deeper view into the eye to look at the retina, the optic nerve and the drainage angle.
To perform the test, the patient will be seated in a chair and the slit lamp will be directly in front of him. He will rest his forehead and chin on the support in front of him on the instrument. Orange eyedrops, with a dye known as fluorescein, may be administered in order for problems such as injuries or infections to be easier to uncover.
Once the slit lamp examination is performed for the front section of the eye, drops are then carefully placed in both eyes to allow for pupil dilation. Once the eyes have dilated, the slit lamp examination is done again. This time it is performed on the back section of the eyes.
A slit lamp examination is most often performed as part of a routine eye exam alongside other tests, including vision testing and tonometry. It is also used to detect any disorders that exist in the front section of the eye, such as cataracts, iritis, conjunctivitis, an injury to the cornea, or the start of any infection. A slit eye examination is very beneficial in terms of discovering macular degeneration and glaucoma. It can also help to carefully monitor these health conditions in those who have already been diagnosed with them.