A number of optical stores offer what are called “sight tests,” using automated machinery. But make no mistake – a sight test is not a proper eye exam, which only optometrists and ophthalmologists are trained and licensed to perform…
Sight Tests and Eye Exams: Understanding the Difference
A number of optical stores offer what are called “sight tests,” using automated machinery. But make no mistake – a sight test is not a proper eye exam, which only optometrists and ophthalmologists are trained and licensed to perform. The eye health care of our community depends on consumers knowing the difference.
What is a sight test?
A sight test, more accurately described as a type of refraction, determines a lens power by relying on a combination of computerized tests using automated equipment.
The comprehensiveness and accuracy of these automated sight tests is limited. Eye muscle coordination is completely ignored, and the test results can be influenced by eye fixation and alignment, pupil size, corneal or lens irregularities, and something called instrument myopia. This last problem is created by the eye’s tendency to over-focus when looking through a machine such as this. This can lead to an inaccurate measurement of refraction.
Furthermore, these tests will completely overlook many serious problems and diseases that do not blur a person’s vision at all or until the disease is more advanced. Some of these include: glaucoma, diabetes, brain tumors, eye cancer, high blood pressure and retinal detachment. Early detection of any of these conditions is important to be able to protect not only the health of the eyes and the clearness of vision, but also the patient’s overall health and maybe even their life. Having a refraction (a “sight test”) done without an eye health examination presents a serious risk.
The College of Physicians and Surgeons of British Columbia has condemned signing a prescription for visual correction without a complete ocular health examination as “unacceptable medical practice.”
What is an eye exam?
The eye exam performed by an optometrist or ophthalmologist looks at the entire eye and vision system and is an important part of preventative health care. An eye exam includes, but is not limited to:
- A summary of past and present vision and medical problems, including those that may be inherited
- An analysis of the patient’s vision needs
- Measurement of visual acuity
- Binocular vision assessment (ability to see from both eyes), as it relates to eye coordination,
- Depth perception
- Colour vision
- Eye pressure measurement
- Assessment of the health of the eye both inside and outside, including a neurological review of the pupils and other muscle reflexes and functions, and an assessment of peripheral vision.
- Prescription determination
- The final analysis of the eye exam includes optometrists’ professional knowledge, experience and judgment. Recommendations for future eye care can be made based on the history of eye health and the results of the examination.
In summary, a sight test is not an eye exam, and the practice of sight testing puts the public at risk of late diagnosis of eye disease, as well as potentially inaccurate eyeglass prescriptions. Most jurisdictions in North America forbid this practice, but it is approved in British Columbia. Be eye care aware!