Slit Lamp Exam

A slit lamp is a binocular microscope (or "biomicroscope") that your eye doctor uses to examine the structures of your eye under high magnification. It looks somewhat like a large, upright version of a microscope used in a science lab.

During the slit lamp exam, you will be asked to place your forehead and chin securely against the rests on the front of the instrument and your doctor will begin by examining the structures of the front of your eyes — including your eyelids, cornea, conjunctiva, iris, and lens.

With the help of a hand-held lens, your doctor may also use the slit lamp to examine structures located farther back in the eye, such as the retina and optic nerve.

A wide range of eye conditions and diseases can be detected with the slit lamp exam, including cataracts, macular degeneration, corneal ulcers and diabetic retinopathy, etc.

Stereopsis (Depth Perception) Test

Stereopsis is the term used to describe eye teaming that enables normal depth perception and appreciation of the 3-dimensional nature of objects.

In one commonly used stereopsis test, you wear a pair of "3D" glasses and look at a booklet of test patterns. Each pattern has four small circles, and your task is to point out which circle in each pattern looks closer to you than the other three circles. If you can correctly identify the "closer" circle in each pattern, you likely have excellent eye teaming skills that should enable you to experience normal depth perception.

Retinoscopy

Your eye doctor may perform this test early in the eye exam to obtain an approximation of your eyeglass prescription.

In retinoscopy, the room lights will be dimmed and you will be asked to focus on a large target (usually the big "E" on the eye chart). As you stare at the "E," your eye doctor will shine a light at your eye and flip lenses in a machine in front of your eyes. This test estimates which lens powers will best correct your distance vision.

Optometrists and ophthalmologists use a wide variety of tests and procedures to examine your eyes. These tests range from simple ones, like having you read an eye chart, to complex tests, such as using a high-powered lens to visualize the tiny structures inside of your eyes.

A comprehensive eye exam can take an hour or more, depending on the doctor and the number and complexity of tests required to fully evaluate your vision and the health of your eyes.

Here are eye and vision tests that you are likely to encounter during a comprehensive eye exam:

Visual Acuity Tests

Among the first tests performed in a comprehensive eye exam are visual acuity tests that measure the sharpness of your vision. 

Halloween is a popular time for people to use colored contact lenses to enhance their costumes. From blood-drenched vampire eyes to glow-in-the-dark lizard lenses, costume contacts can certainly add a spooky, eye-popping touch. But colored contact lenses are popular year-round, not just at Halloween.

But few know the risks associated with these lenses. "Most people believe that decorative lenses do not require the same level of care or consideration as a standard contact lens because they can be purchased over-the-counter or on the Internet," says Dr. Samina Khan Lead Optometrist at Sight N' Steps Optometrists Pickering Town Centre. "This is far from the truth."