In our office, we utilize advanced technology to detect potential retinal problems. Your doctor can discuss the process and benefits of the following tests.
Anterior High Resolution Ultrasound (UBM)
Although ultrasound is more commonly used to evaluate the retina and optic nerve it can also be used at higher frequencies to help evaluate some parts of the anterior or front part of the eye. Anterior high resolution ultrasound can therefore be used to evaluate any abnormalities of the front of the eye, including the cornea, angle of the eye, iris, ciliary body, and lens.
Dark adaptometry is a test to see how well you see in the dark. It is a useful test for evaluating certain hereditary or genetic retinal diseases since night vision problems are a common complaint in many of these diseases.
In dark adaptometry a patient sits in a dark room for two minutes and is then exposed to a bright light for several minutes. The bright light is then turned off and the patient is in total darkness once again. At this time different intensities of dim light are introduced to the patient over a period of time and the patient lets the technician know when they can see the light. The technician records the information as a curve on a graph and can compare it to a normal dark adaptation curve. Patients who have diseases that cause poor night vision (such as retinitis pigmentosa) are unable to see better in the dark over time.
Dark adaptometry can be a useful adjunct to an electroretinogram/electrooculogram in the evaluation of inherited retinal diseases.
ERG (Electroretinography) and EOG (Electrooculography)
ERG (electroretinography) and EOG (electrooculography) measure the electrical response of the different layers and components of the retina to light and dark stimuli. These tests are usually very useful in the diagnosis of hereditary conditions affecting the retina such as retinitis pigmentosa or Stargardt’s disease.
Fluorescein Angiography (FA)
Fluorescein Angiography is a photographic study of the blood supply to the retina. Fluorescein dye is injected into the vein of an arm and this yellow dye passes through the blood vessels in your retina. A specialized camera is then used to take digital photographs of the blood vessels. This procedure is used to diagnose many different disorders affecting the retina and is generally very safe. The dye can be used in people who are allergic to shellfish or iodine and can also be used in patients who previously had reactions to contrast dye during radiologic procedures. However, in some rare instances, the dye may cause an allergic reaction and this will be closely monitored during the procedure. Patients who undergo fluorescein angiography may also notice the urine is yellow or green on the day of the procedure. This is normal and should stop within a day or two.
Fundus Autofluorescence utilizes a blue-green wavelength light to visualize conditions that affect the pigment layer of the retina (retinal pigment epithelium). This simple non-invasive technique has greatly expanded our understanding and management of many different diseases affecting the macula, including dry age-related macular degeneration. Fundus autofluorescence takes only a few minutes and has no known adverse effects.
High Resolution Anterior Segment OCT
Although OCT is more commonly used to evaluate the retina and optic nerve it can also be used to visualize parts of the anterior or front part of the eye. High resolution anterior segment OCT can therefore be used to evaluate any structures in the front of the eye including the cornea, angle of the eye, iris, ciliary body, and lens.
Humphrey and Goldmann Visual Field Test
Certain eye diseases, such as glaucoma and retinitis pigmentosa may cause loss of peripheral vision over time. This loss of peripheral vision can be documented and followed using visual field testing. Depending on the patient’s vision and the degree of the visual field loss, your doctor may recommend a Humphrey or a Goldmann visual field test.
During an automated Humphrey visual field test, a patient is asked to look at a target straight ahead and then press a button if and when they see a light that shows up in their peripheral visual field. A Goldmann visual field is less commonly performed. It is generally used in patients who have very poor vision or advanced visual field loss. In a Goldmann visual field test, an examiner manually moves a light target of differing sizes and intensities while the patient looks straight ahead. The patient lets the technician know as soon as they see the target in their visual field. In a Humphrey test the computer automatically generates and prints out a copy of the patient’s visual field test. In a Goldmann test the examiner draws or maps out the visual field as they are performing the test.
Indocyanine Green Angiography
Indocyanine Green Angiography (ICG) is a photographic study of the blood supply to part of the retina. Indocyanine green dye is injected into the vein of an arm and a specialized camera is used to take digital photographs of the blood vessels under the retina. This procedure can allow your doctor to study parts of the eye that are difficult to visualize with the more commonly preferred procedure of fluorescein angiography. It is especially useful in evaluating cases of central serous chorioretinopathy, certain forms of macular degeneration, and some inflammatory disorders. ICG is generally safe but has a slightly higher incidence of allergic reactions than fluorescein angiography. Furthermore, patients who are allergic to shellfish or iodine should not undergo ICG testing.
Microperimetry allows us to measure the visual function of a specific part of the retina. Usually the test is used to measure macular function. Before the test begins the patient stays in a dimly lit room for a few minutes. After this, the patient is asked to fixate on a target and is presented lights of varying intensity. The patient presses a button every time they see a light stimulus. The computer generates a map of the specific part of the retina that was tested, measuring the visual function of the areas tested. The microperimeter can be correlated with optical coherence tomography and is used to objectively measure the visual function of a particular area of the retina over time.
Ocular & Orbital Ultrasound
Ocular ultrasound is an extremely important tool to evaluate the eye in circumstances where there is poor visibility into the eye during a dilated exam. Not being able to evaluate the eye with conventional methods is frequently due to eyelid swelling, poor pupil dilation, corneal scarring, an advanced cataract, or a hemorrhage in the eye. Ultrasound can also be useful after a traumatic injury to the eye to evaluate a foreign body or retinal detachment. Some optic nerve findings, such as optic nerve drusen, can also be confirmed using ultrasound. Finally, ultrasound is indicated in the evaluation and treatment of tumors in the retina and choroid.
After anesthetic eye drops are placed, an ultrasound probe is gently positioned over the eye. The probe is used to transmit sound waves that travel through the eye. As these sound waves hit different parts of the eye, they are reflected back to the probe. The reflected sound waves are then transmitted into an electrical signal that is then turned into an image on a computer monitor. The examiner can then study and even measure these images from the ultrasound.
Ultrasound is a very safe, non-invasive test that has no adverse effects and is available at all RCH offices.
Retinal photography (as well as ultra-widefield photography) utilizes a camera to take pictures of the retina in the back of the eye. The eye generally needs to be dilated to enable quality retinal photography. Retinal photography may be used in a variety of conditions to document findings and follow them over time. It is non-invasive and there are no reported adverse effects.
Spectral Domain Optical Coherence Tomography (SD-OCT) Imaging
OCT is an imaging technique that utilizes light wave interferometry to produce high resolution cross-sectional images, similar to a computed tomography (CT) scan of the retina. The images measure the thickness of the retina and are very useful in the diagnosis and follow-up of many diseases affecting the macula. The scan takes only a few minutes and is non-invasive with no adverse effects. High resolution Spectral Domain OCT testing is available at all of our offices.
Spectralis Multi-Color Imaging
Multi-Color Imaging is a new technology that enables your doctor to obtain higher-quality photographs of the retina. This new system uses three separate laser colors, each scanning a different layer of the retina. The combined information from each laser provides a sharper and clearer image than previously possible. An advantage of using this technique is that quality photographs can be obtained even in difficult to image patients such as those with advanced cataracts or eye movement disorders.
Ultra-Widefield Photography and Fluorescein Angiography
Classic retinal photography and angiography usually covers only about 45 degrees, or roughly 20% of the retina at one time. Many abnormalities of the peripheral retina are difficult to image during fluorescein angiography and therefore we are unable to evaluate it thoroughly. However, with ultra-widefield photography we are able to view a much larger portion of the retina in one image.
Ultra-widefield imaging enables us to view almost 200 degrees or 80% of the retina at one time. Fluorescein angiography can also be done using ultra-widefield photography and it provides superior visibility of the peripheral retina. Many abnormalities in the peripheral retina that were previously unable to be viewed on traditional angiography are demonstrated clearly on wide-field imaging. However it is important to note that ultra-widefield photography, or any photography for that matter, does not take the place of a good, dilated eye exam by your doctor.
Most of our offices are equipped with instruments that allow ultra-widefield photography and fluorescein angiography.