Pre-testing is a detailed process that gathers all necessary information for the optometrist prior to the doctor-administered eye examination. This process involves completing a detailed patient history, as well as a series of standard tests. Pre-testing is an essential part of the comprehensive eye exam process, providing valuable information and visuals for both the optometrist and patient.
Information gained by asking specific questions, either of the patient or of their caregivers, with the aim of obtaining information useful in formulating a diagnosis and providing medical care to the patient. The medically relevant complaints reported by the patient are referred to as symptoms, in contrast with clinical signs, which are ascertained by direct examination. The medical history, together with the physical examination, enables the optometrist to form a diagnosis and treatment plan.
An autorefractor is a computer-controlled machine used during an eye examination to provide an objective measurement of a person's refractive error and prescription for glasses or contact lenses. This is achieved by measuring how light is changed as it enters a person's eye. Auto-refraction is used to provide the starting point for the optometrist in subjective refraction tests.
Keratometry is the measurement of the corneal curvature; corneal curvature determines the power of the cornea. Differences in power across the cornea results in astigmatism, so keratometry measures astigmatism. A keratometer, also known as a ophthalmometer, is a diagnostic instrument for measuring the curvature of the anterior surface of the cornea, particularly for assessing the extent and axis of astigmatism.
Corneal pachymetry is the process of measuring the thickness of the cornea. A pachymeter is a medical device used to measure the thickness of the eye's cornea. It is used to perform corneal pachymetry prior to refractive surgery, for Keratoconus screening, laser eye surgery and is useful in screening for patients suspected of developing glaucoma, among other uses.
A tonometry test measures the intraocular pressure (IOP), or pressure inside your eye. This test is used to check for glaucoma, an eye disease that can cause blindness by damaging the optic nerve in the back of the eye. Tonometry measures IOP by evaluating the resistance of your cornea to pressure. A non-contact tonometry test uses a puff of air to create pressure against your cornea.
A visual field test is used to detect dysfunction in central and peripheral vision, which may be caused by various medical conditions such as glaucoma, stroke, brain tumours, or other neurological deficits. FDT stands for the Frequency Doubling Technology deployed during the test. During the test, flickering targets are randomly presented to the patient. Patients are asked to click a button each time they see a target.
If a patient currently wears eyeglasses and the prescription of the lenses is not known by the patient nor the doctor, then lensometry will be performed. A lensometer will be used to determine the sphere, cylinder, axis, and prism present in each lens. It can also be used to determine the focal power in multi-vision lenses (e.g., bifocals).
A colour blind test is performed to determine if you have a colour vision deficiency, or colour blindness. The most widely used screening test for colour blindness is the Ishihara Colour Vision Test, named after Japanese ophthalmologist Shinobu Ishihara. The Ishihara Colour Vision Test consists of a series of coloured plates comprising many dots of various colours, brightness, and sizes. The seemingly random composition of dots are arranged so that a person with normal colour vision will see a single-digit or two-digit number, but a colour blind person will not.
Stereoscopic vision and depth perception testing is important for identifying diseases, such as amblyopia, strabismus, suppression, and stereopsis. Stereoscopic vision refers to how each eye may see an object from different angles, but combines these angles to provide a three-dimensional image. Stereoscopic vision tests consist of asking the patient to identify the "raised" letter, shape, or animal to measure depth perception and to evaluate if the patients eyes are working together to identify the intended image.
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eye-deology Vision Care differentiates itself from other clinics by having the most advanced modern diagnostic specialty testing equipment available. Specialty equipment, such as a retinal scanner, OCT, Humphrey Visual Field Analyzer and corneal topographer, ensures that patients receive the best comprehensive eye care. In some cases, this diagnostic equipment can be used to perform both screening and detailed comprehensive tests. Screening tests are typically performed before seeing the optometrist, while detailed comprehensive tests are commonly performed following initially seeing the doctor. However, returning patients who are contact lens wearers, or that have known conditions (e.g., diabetes, cataracts, glaucoma) may have specialty tests scheduled to supplement their regular exam.
Wide-angle retinal imaging is a unique technology that can capture more than 80% of the retina in one panoramic image, while traditional imaging methods typically only allow for 15% the retina to be viewed at one time. These images enable optometrists to both comprehensively view the retina and to visually point out any concerns to patients. Getting a retinal image is fast, painless, and comfortable. Nothing touches the eye at any time. To receive a scan, one simply looks into the device and follows the prompts.
Optical Coherence Tomography uses low intensity infra-red light to provide a 3D image of the back of the eye. It shows not only the surface but also the depth of the structures. It is similar to using ultrasound and creates an image similar to that of a MRI or CT scan. The scan takes only seconds to acquire an image, and it is totally painless. All you need to do is look at a light, keep your eyes still, and not blink for two seconds.
This specialty test is frequently necessary to provide a comprehensive evaluation of a patient's visual field. For example, if a patient has glaucoma, or receives poor results during the FDT screening test, they will likely undergo Humphrey Visual Field Analysis. For this test, the patient is instructed to maintain focus on a central target and is given a button to press each time they see a light stimulus. It is not possible to see every light and some lights may appear brighter/duller and slower/faster than others. The eye not being tested is often covered and room lights are often dimmed prior to initialization of the test.
Since the cornea is responsible for approximately 70% of the eye's refractive power, an assessment of its topography, or surface curvature, is essential for determining the quality of vision and ocular health. Corneal topography is a non-invasive medical imaging technique used for mapping the surface curvature of the cornea. The three-dimensional map generated by the scan is a valuable aid for optometrists that can assist in the diagnosis and treatment of a number of conditions, planning cataract surgery, planning refractive surgery (i.e., LASIK) and evaluating its results, and in assessing the fit of contact lenses.
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eye-deology Vision Care provides eye care services eyewear products to the Edmonton region. Established in 2017 by Dr. Jennifer Ash OD, eye-deology Vision Care blends expertise, advanced technologies, patient education and exceptional service to provide patients with the best eye care experience in the Edmonton, St. Albert, Morinville, Sherwood Park and Fort Saskatchewan areas.
The optometrist will discuss any concerns identified by the patient during pre-testing. The medically relevant concerns, or symptoms, reported by the patient, along with their medical history will assist the optometrist in determining if additional specialty tests are required, formulating a diagnosis, and providing a treatment plan.
Among the first tests performed in a comprehensive eye exam are visual acuity tests that measure the sharpness of your vision. These usually are performed using a projected eye chart to measure your distance visual acuity and a small, hand-held acuity chart to measure your near vision.
A cover test or cover-uncover test is an objective determination of the presence and amount of ocular deviation. The test involves having the patient focusing on a near object. A cover is placed over an eye for a short moment then removed while observing both eyes for movement. A misaligned eye will deviate inwards or outwards. The process is repeated on both eyes and then with the patient focusing on a distant object.
An eye alignment test is an essential examination for investigating strabismus. Optometrists use a variety of tests to evaluate eye alignment. For information on the techniques used to assess eye alignment and identify strabismus, please speak with your optometrist.
Like the cover test, the equipment required to perform pupil testing is minimal. All that is needed is a pupillary gauge and a transilluminator, or pen light. During pupillar testing an optometrist will evaluate four elements: 1) pupil shape, location and size; 2) pupillary reaction to light; 3) pupillary reaction to the swinging flashlight test; and 4) pupillary reaction to a nearby stimulus.
Extraocular muscle function testing examines the function of the eye muscles. Patients are asked to sit or stand with their head up and looking straight ahead. The optometrist will hold a pen or other object approximately 40 centimetres (16 inches) in front of their face and move it in several directions. Patients are asked to follow the object with your eyes, without moving their head.
The refraction test is an eye exam that measures a person's prescription for eyeglasses or contact lenses. For the test, patients sit in a chair with a special device (called a phoroptor or refractor) attached to it. The patient is asked to look through the device and focus on an eye chart approximately six metres (20 feet) away. The eye doctor performing the test will ask if the chart appears more or less clear when different lenses are in place. The test is performed one eye at a time.
A slit lamp is a binocular microscope (or "biomicroscope") that your eye doctor uses to examine the structures of your eye under high magnification. 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. A variety of eye conditions and diseases can be detected with the slit lamp exam, including cataracts, macular degeneration, corneal ulcers, and diabetic retinopathy, etc.
A variety of tests are available to assess the presence and severity of dry eye syndrome. The advanced, modern diagnostic technologies at eye-deology Vision Care use a combination of white and infrared light to non-invasively assess tear film quality. eye-deology Vision Care's high-resolution colour camera makes even the finest structures of the eye visible. Moreover, in addition to measuring tear break-up time and meniscus tear, these technologies provide an assessment of the lipid layer and tear film dynamics. All of these measurements are essential to properly diagnosing and treating dry eye symptoms.
The view to the back of the eye is limited when the pupil is not dilated. When your pupil is small, an optometrist can see your optic nerve and macula but the view is limited. To see the entire retina, the pupil must be dilated. This is achieved through the use of eye drops. They typically take about 15-30 minutes to fully dilate the pupils, depending the person’s response to the medication, and typically take 4-6 hours to wear off.
A Binocular Indirect Ophthalmoscope, or BIO, is an instrument used for examining the interior structures of the eye, especially the retina. It is primarily used to evaluat the periphery of the eye that cannot be seen or scanned with other instruments. Individuals with no medical history or symptoms typically require BIO evaluations once every 3-5 years.
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If the optometrist determines you require corrective lenses, or that your prescription has changed and needs updating to improve your vision, then one of our highly trained opticians or optical dispensers would be pleased to help you select a new frame and lenses and customize their fit to your unique attributes. Our opticians are happy to provide you with information about the latest frame and lens technologies available so you can make informed decisions to get you seeing, and looking, your best. We have a wide variety of frames and lenses to fit any budget.
Following their exam, patients requiring prescriptive eyewear will be greeted by an eye-deology Vision Care optician to discuss their eyewear, lifestyle and budgetary preferences. Equipped with this information, the optician will assist the patient in picking eyewear that address their medical needs and lifestyle preferences.
For most individuals, the most important factor when choosing eyeglass frames is how they look on their face. Certainly, one could try on every pair of frames in the store, but narrowing down the choices in advance can save a lot of time, stress and aggravation. To accomplish this, eye-deology Vision Care opticians will subjectively evaluate your face shape and tone, and present eyeglass frame styles and colors that would look best on you.
Several measurements are necessary to ensure that eyeglass frames properly fit and that lens optics are properly aligned to the eyes of the patient. Pupillary distance (PD), or the distance between the centers of the pupils of each eye, is measured at the time of eyewear purchase and is one of the most important. If an individual has been prescribed multifocal lenses, then several other measurements are necessary. Some of these include pupil height, segment height and pantoscopic tilt. These measurements are especially important for higher prescriptions and multifocal lenses, and should only be acquired by experienced professionals.
Before patients leave with their new eyeglasses opticians may perform several final adjustments so that they fit perfectly to the individual. Temple arm bowing, temple arm balancing, earpiece bending and nosepiece/nose pad adjustments are commonly made to customize and personalize fit to the patient.