3. What is the difference between an eye examination and a sight test?

An eye exam performed by an optometrist looks at the whole eye and vision system.
It includes an assessment of:

• the ocular health and function of the eyes,
• the central and peripheral sensory function of the eyes,
• the integrity of the visual pathway,
• the refractive status of each eye,
• oculomotor and binocular function,
• visual processing of information, and
• incidental signs and symptoms.

In examining the total vision system, the optometrist can identify eye conditions such as glaucoma, cataracts, retinal and macular degeneration, and systemic conditions such as diabetes, high blood pressure and brain tumors, often before symptoms of these conditions manifest themselves.

On the other hand, a sight test, or refraction, is just one part of a complete eye exam. A simple sight test fails to consider all other aspects needed to ensure good vision and ocular health. Testing vision and prescribing lenses without determining the cause of vision impairment ignores the health reasons for vision deficiencies.

Having 20/20 vision, naturally, or with use of corrective lenses, simply means that a person can see, from 20 feet, what most other people can see at 20 feet. It does not indicate good ocular health. Eye diseases are often without symptoms and usually do not manifest pain or vision disturbance until irreparable damage has been done. Conditions unlikely to be noted during a sight test include: glaucoma, diabetes, high blood pressure, brain tumors, cataracts, pending retinal detachment.