What is the Difference Between a Sight Test and an Eye Exam by Your Optometrist?
- A sight test (or vision test, vision exam, etc.) refers to a procedure which is called a refraction (a measurement of the focusing error of the eye). This procedure is being done by some opticians in B.C. as a single procedure by itself. As an optometrist we do a refraction as an integral part of an eye exam which is much more extensive and comprises many different procedures and tests based on a proper and thorough patient case history. As optometrists we have significant concerns with a sight test because it does not really take into account any of the other possible causes for any symptoms the patient may be having such as blurry vision, eyestrain, focusing difficulties, tired eyes, burning, grittiness, headaches, etc..
- One of the most common symptoms for which a patient seeks an eye exam is having blurry or poor vision. Although certainly the most common cause of blurry vision is the need for an updated spectacle prescription, there are many, many other possible causes of blurry vision. Many of these conditions can be very serious and are better managed with early detection.
- The detection of these ocular health conditions may also be "masked" by obtaining new spectacles which might correct pre-existing refractive errors but do not address the concurrent or underlying ocular health condition which may have initiated the visit in the first place. This is to say that in addition to the need for a change in glasses to correct your blurry vision you could quite conceivably be having other concurrent or underlying ocular health problems also contributing to your blurry vision symptoms which would be missed.
- In addition, having 20/20 vision is no reassurance that you do not have significant eye disease. A large percentage of eye problems we see are in patients who are correctable with glasses to 20/20 and have no other symptoms until their eye disease has progressed significantly. An good example of this is in open angle glaucoma which is typically has no symptoms until it has become advanced and irreversible. Glaucoma is one of the leading causes of blindness in developed nations. Regular eye exams are recommended even if you see 20/20 and have no symptoms.
- As optometrists, we feel that having sight tests may result in a loss of continuity of care for our patients. For our longstanding patients, we often use all aspects of our patients exam history including their refractive history and visual acuities to help manage their ocular health and vision. For example, in poorly controlled diabetes we often see unusual changes in spectacle prescriptions or some patients may have significant myopic shifts with 20/20 vision that is due to significant cataract changes.
- Our clinical experience has found that patients who have had these sight tests quite often have reasonably accurate spectacle prescriptions but in a significant number of patients they are over or inaccurately corrected. This overcorrection is usually due a lack of understanding or control for what is called instrument myopia or pseudomyopia. In addition, many of our patients require a cycloplegic refraction (done after instillation of eyedrops) in order to obtain an accurate refraction especially in hyperopic (farsighted) patients.
- Although sight testing is often explained as being possible due to advances in technology, in actual fact at present the systems being used are usually a conglomeration or automation of longstanding technologies that have been used in optometrists office for many years if not decades. At this time, researchers are always trying to improve our ability to check refractive errors quicker and more accurately but have yet to replace traditional methods such as a careful manual refraction which still remains the gold standard.
- It has also been our experience clinically that almost all our patients who have had a sight test in the past thought that they actually had a full eye exam. We have also noticed that perhaps because of the concerns surrounding these sight tests that they are now starting to be referred to as vision tests, vision exams, vision examinations, or similar names further confusing patients.
- As optometrists we follow and value the principles of informed consent and freedom of choice. However, these principles in a health care setting are based on advising patients about what tests and procedures are recommended to be done to protect the patient's well being based on accepted standards of care. Having a sight test in isolation unfortunately does not meet the current prudent standard of eye care recommended in North America.
Some of the Many Organizations and Groups on Record as Opposing or Concerned About Sight Testing:
- Canadian National Institute for the Blind
- Canadian Diabetes Association
- College of Physicians & Surgeons of B.C.
- Canadian Ophthalmological Society
- B.C. Society of Eye Physicians and Surgeons
- Dr. Robert Schertzer, Ophthalmologist & Glaucoma Specialist
- University of Waterloo School of Optometry
- B.C. Association of Optometrists
- Canadian Association of Optometrists