What are these words and what do they mean?

While our opticians perform pre-examinations, our doctors perform your comprehensive eye exams. Some of the words and terms you may hear are listed below.

Cover Test

During a cover test, the eye doctor has you focus on a small letter or object at distance and will then alternately cover each of your eyes as you stare at it. The doctor is then able to observe how much each eye has to move when uncovered to pick up the fixation letter or object. This test is then repeated as you focus on a near object.

Cover tests are very useful in detecting even very subtle misalignments that can interfere with your eyes as they try to work together (binocular vision) and cause "lazy eye" or amblyopic.

Slit Lamp

The slit lamp (biomicroscope) is an instrument an eye doctor uses to examine your eye health. It gives the doctor highly magnified views of the interior structures of the eye, such as the lens behind the pupil and the retina. This test is important to thoroughly examine you inner eye for infection and disease.


A test called a refraction is used to determine the exact prescription for your eyes. The doctor places an instrument called a phoropter in front of your eyes and you then see a series of lens choices, your eye doctor will then ask you, "which looks better, 1 or 2," as you decide which lens makes the letters on the wall chart look clearer.

Your vision problems, whether nearsightedness, farsightedness, and/or astigmatism will then be corrected with the required eyeglasses or contacts.

Tonometry (eye pressure test)

Tests performed to determine the pressure inside the eye is called tonometry. Increased eye pressure can cause a number of problems including glaucoma, which is damage to the optic nerve in the back if the eye causing vision loss.

A tonometer is usually attached to a slit lamp. During this quick test, a numbing drop is placed in your eye, followed by a small amount of yellow dye. The doctor will then have you stare straight ahead in the slit lamp as they rest the brighter blue probe of the tonometer on the front of each of your eyes to manually measure the intraocular pressure. This test is painless and takes only a few seconds. It is important for ensuring the health of your eyes.

Pupil Dilation

This examination includes the use of drops to enlarge your pupil so that the doctor can get a better view of the inside of your eye. It usually takes about 20minutes to dilate your eyes. After this exam, you will be sensitive to light, because more light gets into your eye. These effects can last up to several hours depending on the strength of the drops used. You will need to wear sunglasses following the exam. Disposable sunglasses will be provided for you.