The autorefractor-keratometer is used during the comprehensive eye examination and at follow-up visits after cataract surgery. No preparation is needed. The ophthalmic technician will ask you to sit in an exam chair and to place your chin on the chin rest and forehead against the forehead bar. You will be asked to look at an image in the computerized machine. The computer will analyze how light rays are bent as then enter the eye (autorefraction) and the relationship between the size of an image shone on the surface of the eye and its reflected image. (keratometer).

At Vista eye center, we use the Nidek ARK1s Auto refractor/keratometer, which provides precise refraction measurements and also allows the technician to detect the patient’s quality of vision with a low contrast chart (manifest refraction). This information can help determine if a glasses prescription would improve the patient’s vision.

The measures the curve of your cornea to determine if you have astigmatism. Your eye doctor may also use corneal topography to evaluate astigmatism. Corneal topography provides more information about the shape of the surface of the cornea.

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A visual field test can help to map out blind spots (scotomas) in your vision. The location, size and shape of the blind spot can help to explain why your vision is blurred and if this is due glaucoma, optic nerve problems, retina problems or compression of the optic nerve in the brain (pituitary gland disorders or tumors) or other brain disorders (stroke). If you have glaucoma, the visual field test helps to make the diagnosis by mapping out peripheral vision loss, which can be tracked over time. If you have a central retina problem, the visual field test can help to diagnose and monitor the condition.

At Vista Eye Centre, we use an automated visual field machine for visual field testing, called the Humphrey® Field Analyzer 3 (HFA3). This is the gold standard in visual field testing. The HFA 3 reduces testing time with new algorithms (SITA™ Faster) and also provides progression analysis using mixed guided progression analysis (intermixing of SITA Standard, SITA Fast and SITA Faster). Central visual field testing is more accurately evaluated using new SITA Faster 24-2C, which adds additional test points in the central field.

No preparation is necessary for the test. This test is non-invasive. During the test, you will be asked to look into the center of a bowl-shaped instrument with one eye and the other eye will be covered with a patch. The eye being tested will have your lens prescription in front of it. It is important to keep your head still and to continue looking at the center target throughout the test. You will be asked to press a button when you see small brighter as well as dimmer lights in various sizes and in different places throughout the bowl. It is important to keep looking at the fixation light or center target throughout the test (even when you are seeing lights on the side) and to press the button when you see the light on the side. You can continue to blink normally throughout the test. The machine tracks which light you see and which ones you don’t see. The machine also monitors reliability of the test based on gaze, head tracking, and blind spot monitoring.

This test usually takes from 5-10 minutes to do but can take longer in some cases. If you are having problems doing the test, please let the ophthalmic technician know during the test or when you are finished.

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The OCT is used as baseline testing during many comprehensive eye exams, and to fully evaluate patients with diabetic eye disease (diabetic retinopathy), macular degeneration (dry or wet), uveitis, central retinal (macular) abnormalities, narrow angles and glaucoma. The OCT is also used before and after cataract surgery in order to evaluate macular health.

No preparation is required for this test. This is a non-invasive test which takes 2-5 minutes to do. The ophthalmic technician will ask you to sit in a chair and to place your chin on the chin rest and forehead against the forehead bar. You will be asked to look at an image in the computerized machine. The OCT will shine a light in the eye and will create a series of images from the reflected light (from different structures in the eye) which are then analyzed using interferometry techniques. The ophthalmologist uses these two-and three-dimensional images (micrometer resolution) to diagnose and monitor eye conditions.

At Vista Eye centre, we use one of the newest models of OCT machines, the CIRRUS HD-OCT 5000, with improved resolution visualization capabilities and ability to evaluate and measure not only the retina but also the deeper layers including the retinal pigment epithelial and choroid. En Face views allow for layer by layer retinal analysis including the Vitreoretinal interface, mid-retina and photoreceptor (IS-OS or ellipsoid) views, which helps to diagnose epiretinal membranes, cystoid macular edema and hydrochloroquine toxicity, for example.

OCT is also used for optic nerve evaluation (in glaucoma or other optic nerve conditions), by measuring the retinal nerve fibers (retinal ganglion cell axons) as they approach the optic nerve (peripapillary region). Measurements used to evaluate glaucoma include disc and rim area, cup to disc ratio, cup volume. The enhanced Cirrhus 5000 HD-OCT also measures the retinal ganglion cells in the macula (center of the eye) as part of the glaucoma evaluation. The macula has the highest concentration of retinal ganglion cells in the retina and therefore glaucomatous loss may be detected in the macula before it is evident in the peripapillary region. By reviewing these various measurements, the ophthalmologist can determine the extent of structural damage in glaucoma.

The Cirrus 5000 HD-OCT also includes a module which allows for full anterior chamber imaging and measurements, used for narrow angle and corneal thickness (pachymetry) measurements.

Anterior chamber measurements include a 15.5 mm wide view of the entire anterior chamber which includes tools for measuring anterior segment ocular structures , including the cornea thickness and irregularities in various locations (pachymetry map), anterior chamber angle (OCT goniometry, a non-contact method to help identify patients at risk of angle closure glaucoma) and detailed iridocorneal measurements to quantify and track degree of angle closure .

The new FastTrac™ retinal tracking included in all testing by the Cirrus 5000 HD-OCT reduces eye motion artifacts using high speed 20 Hz LSO camera, and single-pass alignment scanning. This feature enables the highest resolution images to be captured in identical locations from visit to visit providing precise assessment of change of any identified abnormalities.

Wide Angle-to-Angle scan and HD Angle Scan

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