Components of a Slit Lamp

The slit lamp is a medical instrument used to perform eye examinations. It provides three-dimensional, magnified views of various parts of the eye, including the cornea, iris and lens. A health care provider may use a slit lamp during a routine eye exam, to look for cataracts or diagnose conjunctivitis, or to monitor glaucoma. Each component of the slit lamp performs a function that allows for a safe and thorough eye examination.

Illumination Arm

• The illumination arm component of the slit lamp allows the eye examiner to swing the arm up to 180 degrees. This component swings side to side on pivoting bases, and it allows the eye doctor to beam light anywhere in the areas between the temporal aspect and nasal aspect of the eye examination. The swinging ability of the arm allows the examiner to accommodate the lamp for use in small children as well as larger adults.

Patient Positioning Frame

• The patient positioning frame of a slit lamp consists of two metal rods in an upright position. The rods are attached to a forehead strap as well as a chin rest. This allows the patient to press his forehead against the forehead strap, while resting his chin on the chin rest. For patient comfort, and for optimal examination positioning, the chin rest height can be moved up or down with the knob located below it. The forehead strap and chin rest can be cleaned with a mild antiseptic or other cleanser after each use, to ensure hygienic clinical compliance.

The Joystick

• The joystick component of the slit lamp is responsible for focusing, and does so by being shifted forward, backward, diagonally or laterally. The joystick can be rotated to elevate or lower the light beam as well.

The Viewing Arm

• The viewing arm houses binocular eyepieces which provide stereoscopic vision. They can be manipulated or adjusted to accommodate the inter-pupillary distance, which differs in each individual. In addition, the focusing ring component of the viewing arm can be adjusted to accommodate the refractive error of the examiner. The final component of the viewing arm is the magnification element, which is adjusted via the side dial.

The On Switch

• The "On" switch is located below the table on which the slit lamp is held. It allows the slit lamp to be turned on and off and provides high or low light intensity options. This switch is located on the lower left side of the table for easy access by the health care provider.