Digital Retinal Photography
Digital retinal photography is a non-invasive, diagnostic tool that produces digital high resolution, colored images of your retina, optic nerve, and blood vessels in the back of your eye. This image can be used to screen for eye diseases or photo document baseline conditions and can be used to compare to images taken in future examinations. If a retina condition or disease is found, the we will repeat the test with even higher resolution or enhanced imaging tests, such as Fundus Fluorescein Angiography, Ocular Coherence Tomography (OCT), and B-Scan Ultrasonography. Digital retina photography can be useful for monitoring disease progression.
Fluorescein Angiography (FA)
Fluorescein angiography is a diagnostic test routinely administered in the office to detect and better understand a variety of retinal disorders. A small amount of orange colored dye is injected into a vein in the patient’s arm. The dye travels throughout the blood vessels in the body including those in the eyes. A special camera and light flashes are used to image the dye as it passes through the eyes in order to detect changes involving the retinal blood vessels and the pigmented layer behind the retina. No radiation is used. The dye is in no way similar to contrast dye used in radiological testing.
Side effects of the dye include yellowing of the skin which lasts for several hours. The urine will also become more yellowish for a short time. Fewer than 5% of patients experience nausea which resolves within minutes. Skin itching and dizziness occur rarely. Serious reactions involving the heart or breathing difficulty are extremely rare. Your doctor will discuss the possibility of these reactions with you.
Digital Indocyanine Green Angiography (ICG)
Indocyanine Green Angiography, known as ICG, is a test which can provide further information about problems at the back of the eye. Indocyanine green dye shows up under infrared light after injection into a vein and is a procedure which images a layer of the posterior part of the eye- called the choroid-which is deeper than the retina and normally obscured by pigmentation. The choroid contains a unique network of blood vessels. These blood vessels flow very fast and probably help to control the temperature of the eyeball in addition to carrying nutrients to the photoreceptors that convert light into vision. Unfortunately, these large, fast flowing vessels can be affected by disease and change as we age.
Optical Coherence Tomography (OCT)
Optical Coherence Tomography (OCT) is a sensitive, noninvasive test used to create high-resolution images of the central retina-the Macula. OCT uses light-not X-ray-that is shone onto and reflected by the different layers of the retina to measure thickness and to detect the extent of various conditions which affect the macula. Macular edema causes the retina to be abnormally thickened. Active Wet Macular Degeneration is characterized by the presence of fluid under and within the central retina while Macular Puckering causes distortion on the surface of the retina. OCT also clearly shows the size and extent of Macular Holes. OCT images are quite useful for monitoring disease progression and response to therapy.
B-Scan Ultrasonography is a noninvasive test for diagnosing problems and conditions of the posterior portion or back of the eye. Conditions such as retinal detachment, ocular trauma, eye tumors such as choroidal melanoma and retinoblastoma and vitreous degeneration can be accurately evaluated with this testing even when direct visualization of the intraocular structures is difficult or impossible. Situations that prevent normal examination might include lid problems, dense cataracts, corneal scars and vitreous opacities or hemorrhages. In such cases, diagnostic B-scan ultrasound can accurately image intraocular structures and give valuable information on the internal structures of the eye.
Fundus Autofluoresence Imaging
Fundus Autofluorescence (FAF) imaging is used to record fluorescence that may occur naturally in ocular structures or as a byproduct of a disease process not yet visible by other imaging methods and tests. This technique allows us to map the health and distribution of pigmented cells and pigment byproducts that could be markers for various retinal diseases. FAF provides unique information to complement that obtained through other imaging modalities.
An Electroretinogram measures the electrical response of the light-sensitive cells in your eyes including the photoreceptors, inner retinal cells, and the ganglion cells. Electrodes are placed on the surface of the cornea or on the skin beneath the eye to measure retinal responses. While you are in a sitting position, we place numbing drops into your eyes, so you will not have any discomfort during the test. Your eyes are held open with a small device called a speculum and an electrical sensor (electrode) is placed on each eye. The electrode measures the electrical activity of the retina in response to light. A light flashes, and the electrical response travels from the electrode to a TV-like screen, where it can be viewed and recorded. No special preparation is necessary for this test. The probes that rest on your eye may feel a little scratchy and the test takes about 1 hour to perform. This test is done to detect disorders of the retina as well as being useful for determining if retinal surgery is recommended in certain instances.
Visual Evoked Potential (VEP)
A Visual Evoked Potential (VEP) is a test that measures the integrity of the optical pathway from your eyes to the visual cortex or occipital lobe of your brain. It is used to determine if there is any damage to this pathway that may be causing certain visual symptoms. The Visual Evoked Potential measures the time it takes for the brain to respond to light sensory stimulation and can help diagnose multiple sclerosis (MS) and other conditions that can cause a person's reactions to slow.