Ophthalmologists can perform a variety of Eye Diagnostics tests to protect you from harmful eye disorders. These examinations aid in the early detection and management of diseases that affect your eyes and overall health. Many of these tests look for glaucoma and retinal diseases, including macular degeneration.
At the offices of Dr. Khosla, we can conduct all of the following eye diagnostics tests in our center in Calgary:
Content from: American Academy of Ophthalmology
Your visual field is how wide of an area your eye can see when you focus on a central point. Visual field testing can detect blind spots and can be used for detection of eye or brain conditions. A scotoma’s size and shape can show how an eye disease or a brain disorder is affecting your vision.
For example, if you have glaucoma, this test helps to show any possible side (peripheral) vision loss from this disease.
Visual field testing is an important part of regular eye care for people who are at risk for vision loss from disease and other problems.
People with diabetes and high blood pressure have a greater risk of developing blocked blood vessels in the optic nerve and retina. They may need visual field testing to monitor any effects of these conditions on their vision.
To check for a suspected eye problem or monitor the progress of an eye disease, Dr. Khosla will rely on more specific tests to measure how you see objects in your field of vision. The automated static perimetry test is used for this purpose. It helps create a more detailed map of where you can and can’t see.
Amsler grid: A basic visual field test for central vision
People who have age-related macular degeneration (AMD) are familiar with one very basic type of visual field test: the Amsler grid. It is a pattern of straight lines that makes a grid of many equal squares.
The Amsler grid is commonly used at home by people with AMD. This test only measures the middle of the visual field, but is a simple yet helpful tool for monitoring vision changes.
The electroretinogram (ERG) is a diagnostic test that measures the electrical activity of the retina in response to a light stimulus. The ERG arises from currents generated directly by retinal neurons in combination with contributions from retinal glia (cells of the retina).
An ERG test provides reliable guidance to understand and assess functional changes that may impact a patient's vision by evaluating the retina's response to light. ERG’s are recorded using a thin sensor strip electrode that is placed under the eye. These electrodes permit the electrical activity generated by the retina to be recorded. The ERG test is performed by diffuse flashes or patterned stimuli.
The ERG a very selective measure of retinal function that can be recorded non-invasively, this test is usually administered to patients to provide further information concerning a variety of inherited and acquired retinal disorders, such as:
The ERG can be used to monitor disease progression and evaluate retinal toxicity due to various drugs or retained intraocular foreign bodies. An ERG may also help assess your need for retinal surgery or other types of eye surgery, such as the removal of cataracts.
Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina, when the distinctive retinal layers are visible and allows for the thicknesses to be measured. These measurements help with diagnosis and provide treatment guidance for glaucoma and retinal diseases such as age-related macular degeneration (AMD) and diabetic eye disease.
You will sit in front of the OCT machine and rest your head on a support to keep it motionless. The equipment will then scan your eye without touching it. Scanning takes about 5 - 10 minutes.
**Note: You may need to have your eyes dilated for this test - our receptionist will inform you of this when the test is booked.
If you have been diagnosed with any of the following conditions, an OCT test will be performed:
OCT is often used to evaluate disorders of the optic nerve, the exam helps see changes to the fibers of the optic nerve. For example, it can detect changes caused by glaucoma.
A B-scan Ultrasounds provides a detailed image of your eye and eye orbit, this image is made by using high frequency soundwaves that are transmitted from a probe/transducer into the eye. As these soundwaves strike the intraocular structures, an echo is reflected back to the probe and converted into an electrical signal. This signal is then reconstructed into a two-dimensional image on a monitor. The stronger the echo, the brighter the display. This process is repeated 1,000 times per second to produce a real-time display.
During a B-scan, you will be sitting with your eyes closed and the technician will put a gel on your eyelids. The technician will then tell you to keep your eyes closed while you move your eyeballs in many directions. The technician will place the probe against your eyelids. This procedure is non-invasive and painless.
Note: During this procedure anesthetic drops will be used to numb your eye and minimize discomfort. Your pupils will not be dilated but your vision may be temporarily blurred for up to 30 minutes.
This procedure can be helpful when identifying issues such as:
B-scan’s can be used to help diagnose and monitor:
Ultrasound biomicroscopy is a high-resolution ultrasound technique that allows non-invasive interior imaging of the structural details of the anterior (front third area of the eye) ocular segment by reflecting high energy sonic waves off of the inside of the eye.
During a UBM procedure, the technician will place a water filled pouch over the eye then the probe. The technician will instruct you to move your eye around in order to caption the correct angles and areas of the eye needed for imaging. This procedure is quick and does not require numbing or dilating drops.
A UBM can be ordered to be completed in order to detect many conditions, such as:
This imaging is used most commonly for patients with glaucoma and several from of glaucoma including:
This procedure uses a fundus camera to record color images of the condition of the interior surface of the eye, in order to record the presence of disorders and monitor any changes over time. A fundus camera or retinal camera is a specialized low power microscope with an attached camera designed to photograph the interior surface of the eye through the pupil.
The technician will instruct you to sit across from them and they will bring the camera up to your eye and fight the eyepiece cup over your eye. The technician will then focus the camera on the pupil and depending on how much of the fundus is required to capture, multiple photos may be taken. This procedure is very quick to complete.
Note: If a proper image of the fundus cannot be taken, your eyes may be dilated for this procedure. Your vision may be blurred for a few hours after the drops have been administered - it is best to schedule a driver after your appointment.
Fundus photography is used for detecting many eye conditions and diseases, and is one of the most commonly used procedures to detect changes in the eye.
These images are important for documenting conditions such as:
Gonioscopy is a painless exam used to check a part of your eye called the drainage angle. This area is at the front of your eye between the iris and the cornea. It is where fluid called aqueous humor naturally drains out of your eye. A gonioscopy will be performed to check to see if this drainage angle is functioning properly.
For a gonioscopy exam, you will rest your head in the chin holder of a slit-lamp microscope. At this point, your eyes will have been numbed with eye drops.
The technician will place a special contact lens with mirrors directly on your eye. They will shine a beam of light into the lens to highlight the drainage angle. The lens mirrors help to show this part of the eye that is essentially around a corner inside the eye and difficult to see.
You may feel the lens touch your eyelashes, but typically a gonioscopy is not painful in any way. This exam usually takes just a few minutes.
Early signs of vision changes and eye disease may begin around age 40. This is when all adults should get a baseline eye disease screening with an ophthalmologist.
Screening for signs of glaucoma, your ophthalmologist will perform a gonioscopy to check the appearance and function of your drainage angle. Some people are considered glaucoma suspects. They may or may not have higher than normal eye pressure, but their ophthalmologist may notice other signs that glaucoma could develop. In this case, the ophthalmologist will want to do a gonioscopy and other glaucoma screenings regularly to check for changes over time.
Microperimeters map the pattern of a patient’s retinal sensitivity onto an image of that individual’s fundus. They measure the patient’s response to light stimuli at various retinal points and superimpose that data on an image captured by scanning laser ophthalmoscopy (SLO) or fundus photography to precisely identify areas of impaired or preserved function.
Microperimetry employs eye-tracking technology to correct for eye movement, allowing accurate testing and retesting of the same retinal point. Patient will rest chin on chin rest and head against the headrest, the patient will cover one eye at a time and hold a clicker throughout the test. Flashes of light will be administered and the patient will click the button everytime they see a flash.
Most frequently used in patients with low vision due to retinal disease, microperimeters can reveal the correlation of residual vision and functional vision in a precise way that standard automated perimetry and optical coherence tomography (OCT) cannot. Microperimetry has several applications that are helpful in guiding rehabilitation efforts and teaching patients to locate and maximize use of their areas of best vision.
If you are a doctor or health care professional looking to refer patients to an eye specialist in Calgary, our offices accept new patients on a referral basis.
For urgent eye issues, we also offer a self-referral process for individuals. Contact us today to learn more about our eye diagnostics tests Center in Calgary. We also provide Dry Eye Diagnosis & Glaucoma Diagnosis.