Advanced Diagnostics in Modern Eye Exams
An eye exam is more than just reading letters from a chart; it is a comprehensive medical exam that evaluates the health of the eye and related structures from the front all the way through to the very back. As such, sometimes advanced diagnostic techniques are required for the Optometrist to fully isolate and identify underlying conditions. The following tests and tools are just some of these techniques our Optometrists might utilize during an exam.
OCT Scans
An OCT scan, also known as an Optical Coherence Tomography, is an imaging test that uses light to create a cross-section scan of the retina and the optic nerve, which are both located at the back of the eyes. The average retina is only about a quarter of a millimetre thick (a Canadian dime is just over a millimetre thick for reference!) but has many specialized layers that all play a role in transforming the light that enters the eye into visual signals that allow us to see the world around us.
An OCT scan can show these layers with a high level of detail and plays a very integral role in the diagnosis and treatment of conditions such as glaucoma and macular degeneration. It is a non-invasive test, and nothing physically touches the eye; at most the Optometrist may use dilation drops to widen the pupil and allow more light to reach the back of the eye.
Corneal Topography
Also known as Photokeratoscopy, Corneal Topography is used to create a topographical image of the surface of the front part of the eye, known as the cornea. The cornea is particularly important as it is responsible for approximately 70% of the eyes’ total focusing power. During the procedure, the patient sits facing a series of symmetrically arranged rings that reflect light off of the patient’s cornea to a camera located at the centre of the machine. The image taken is transformed into a topographical map of the surface of the cornea, showing the relevant high and low points. Corneal Topography is commonly used to determine the shape of the cornea and provide details essential for the accurate fitting of contact lenses, particularly for custom made contact lenses. Corneal Topography is also used to identify corneal deformities, astigmatism, abrasions, and other corneal conditions such as Keratoconus and PMD.
Meibography
A part of the eye responsible for maintaining a healthy tear layer is called the Meibomian Gland, located along the upper and lower lids along the lid margins of each eye. The glands produce a clear secretion that adds an extra layer to the tear film that helps to prevent evaporation. In cases where the glands do not produce enough of this lipid secretion, sometimes referred to as Meibomian Gland Dysfunction, the tears become susceptible to early evaporation, which can eventually lead to ocular surface conditions, one of the most common being Dry Eye Syndrome. A Meibography is a screening technique that illuminates the glands in a detailed manner in the optometrist’s slit lamp while the patient’s lid is everted. This way the doctor can directly examine the glands for signs of defective production. It takes a few minutes at most to perform, and the patient experiences minimal to no discomfort during the procedure.
Tear Osmolarity Testing using iPen
Dry Eye sounds like a simple condition on paper, but in actuality it can be tricky to pin down. Patients might not share the same symptoms or clinical signs, sometimes their description of symptoms does not match the clinical signs. Tests such as the Schirmer Tear Test or the Tear Break-Up Test have their place, but Optometrists find the objective method of testing tear osmolarity, the actual concentration of dissolved salts in the tears, much more effective in diagnosing Dry Eye.
The I-Pen is a new portable single-use diagnostic device specifically designed to test tear osmolarity levels in seconds. It requires only two seconds of contact with the eyelid tissues to return a clear osmolarity level with no additional calculations required. The test was created to screen suspected Dry Eye Syndrome patients as well as monitor current Dry Eye patients throughout the course of their therapies.
Perimetry & the Zeiss Humphrey
Also known as a visual field test, a perimetry test is a measure of a patient’s total range of vision, including the peripheral (side) vision. This is used to locate patterns of vision loss, which can be useful in the early detection of eye diseases such as glaucoma.
The Zeiss Humphrey Field Analyzer performs this test over the course of 5-12 minutes depending on the type of scan the Optometrist chooses to run. The patient sits with their head still while looking into an illuminated bowl, keeping their vision fixed on a point in the centre. A series of random white lights will flash at varying intensities all throughout the bowl, and the patient is to press a button each time they see the flash. The flashes correspond to a pattern map that the Optometrist will later examine for irregularities.
The newest Field Analyzer from Zeiss improves on the testing time and adds additional testing points to areas known to be susceptible to damage from glaucoma.
Retinal Imaging
Retinal imaging is an advanced type of screening that allows your optometrist to get a more detailed assessment of your ocular health as well as your health overall. Retinal imaging equipment captures a digital photograph of the back wall of the eye which encompasses not only the retina but also the blood vessels and the optic nerve. These images are highly effective in diagnosing and treating an array of medical issues such as glaucoma, diabetes, macular degeneration as well as hypertension. For this reason it is a strongly recommended component of your annual or bi-annual eye examination.
Oftentimes patients are concerned about immediate or long term effects of retinal imaging. Here’s the good news; there are none. Unlike x-ray technology this equipment operates in the same way as any camera, meaning it does no harm whatsoever to your eyesight or your health. It is entirely safe and ensures that you are receiving the best care possible. In most cases you will be shown these images which will allow you to have further insight into your own ocular health as well as the health of your body. These images will also be kept with your file which means that each time you have them done by your optometrist they will be able to review and compare any changes within your eyes and monitor any ongoing conditions you may have. It is a proactive way of ensuring premium patient care.
Retinal Imaging as a Preventative Method
This advancement in eye care essentially means that optometrists are more able than ever to offer cutting edge technology as part of routine eye exams. As our world changes so does the role of technology in the diagnosis and treatment of patients, which is always of the utmost importance. Now more than ever it is critical that eye care specialists utilize the most progressive types of equipment and screenings that surpass the workings of conventional eye care to ensure that your health and well-being comes first. Retinal imaging is preventive whereas conventional methods of medicine are often reactive in nature.
Many people are not aware that there is sometimes no discomfort or symptomology associated with certain ocular conditions and therefore it is possible to have a condition that will go undiagnosed until extensive damage has already been done. This is why regular screenings using retinal imaging can become so crucial in catching ocular or medical conditions early on which enables early treatment. For patients this means better chance of recovery, appropriate monitoring of newly discovered conditions, minimizing damage to vision as well as reducing the chance of requiring invasive procedures further down the line.
These advanced diagnostic techniques all play their part in ocular disease detection and management, but the most important part belongs to the routine eye exam that optometrists recommend at least once every one to two years. To book your comprehensive eye exam, dry eye assessment or other advanced diagnostic test today with one of our optometrists, please contact one of our locations closest to you: on Bloor St. East in Rosedale, or on Queen St. East in the Beaches neighbourhood.