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Eye Health Library / Eye Exam & Diagnoses
In some provinces, a number of optical stores offer sight tests, or vision tests, which use automated machinery. However, a sight test is not a proper comprehensive eye exam and may not be performed by a trained and licensed professional. A doctor of optometry, on the other hand, can examine, diagnose, treat, manage and help prevent diseases and disorders affecting the visual system, the eye and related structures, as well as check an individual’s prescription and prescribe eyewear. Depending on the province, doctors of optometry can also prescribe medications to treat certain eye conditions, such as infections, inflammations, allergies and injuries.
A sight test prescribes a refraction to determine the lens power required for correction of vision 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 unaccounted for, and eye fixation and alignment, pupil size, corneal or lens irregularities, patient movement and attention, and something called instrument myopia can influence the test results. 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 completely overlook many serious eye or health problems and diseases, as the eye itself is not examined during a sight test. Many serious conditions do not blur a person’s vision, or only do so once the disease is more advanced. Some of the eye and health conditions that cannot be detected through a sight test include:
An eye exam performed by a doctor of optometry looks at the entire eye health and visual system, as well as your prescription, and is an important part of preventative health care. Think of an eye exam as a physical for your eyes. Eye exams can detect eye diseases and disorders such as glaucoma, cataracts, retinal detachments and macular degeneration, and other health problems such as diabetes, high blood pressure and brain tumors.
A doctor of optometry may use automated computerized instruments to provide an estimate of the prescription prior to providing a more detailed refraction; however, they use their extensive training and experience, together with professional judgment, to direct the testing and interpret the results. Only on this basis can an accurate prescription be determined and customized to the patient’s visual needs. An eye exam includes: