Optometrist Instruments

An optometrist is a medical doctor trained to diagnose and treat eye conditions, including disease and vision problems. While many optometrist tools are large machines mounted in a patient room, optometrists use several smaller tools on a daily basis. Treatment for conditions of the eye may include prescription medications or corrective lenses.

Eye Occluder

• An eye occluder is a piece of hard plastic used to cover one eye, blocking vision so the opposite eye can be tested or examined. The piece is shaped like a spoon with an indented cup used to cover the eye. The indentation prevents pressure on the eye, as the plastic never comes in contact with the eyelid. The typical eye occluder is made from dark plastic, but translucent varieties are available, allowing the optometrist to see the patient's eye while blocking vision.

Pupil Diameter Rule

• The pupil diameter (PD) rule measures the distance between pupils, also referred to as pupillary distance. Optometrists use this measurement when writing a prescription for glasses. Corrective lenses in glasses are curved with the center of the curve on each lens coordinating with the pupillary distance. For instance, a pupillary distance of 60 means the center of each pupil, and thus the center of each lens, must be 60 mm apart.

Screwdrivers

• Many varieties of corrective glasses are held together with tiny screws. A set of optical screwdrivers includes various screwdrivers to tighten and loosen screws in corrective glasses. Optical screwdrivers come in flat head and Phillips-head varieties. Flat head optical screwdrivers have a straight edge. Phillips screwdrivers have an end that looks like a plus sign.

Snellen Chart

• The Snellen eye chart displays a series of letters, numbers and shapes. The chart hangs on the wall in an optometrist's office. Patients are asked to read letters and numbers during vision screening. The Snellen chart is available in several varieties, some with common shapes and images. These are used for young children unable to read letters and numbers.

Penlight or Flashlight

• Doctors use penlights to test the eye's reaction to light. When a bright light is shined onto the surface of the eye, the pupil narrows, because less light is needed to see. When the light is removed from the eye, the pupil grows wider. Flashlights are too large to test pupil reaction, but they may come in handy when trying to test the vision of a young child. Doctors shine the light on the walls and ceiling of the patient room to capture the attention of young children.