FAQs-OCT and OCT Angiography Test
What are OCT and OCTA?
The word OCT is an abbreviation of Optical Coherence Tomography and similarly, OCTA means Optical Coherence Tomography Angiography. These are two latest investigating tools, used in the diagnosis of certain eye diseases. The OCT and OCTA machine provides three-dimensional (3D) imaging of the anterior segment, retina, and optic nerve head (similar to a C T Scan of the eye) allowing early diagnosis and timely management of eye disorders.
What is Angiography?
Angiography is an examination or study of blood or lymph vessels that is performed via using a dye.
What do you mean by Fundus and funduscopy of the eye?
The fundus is a term used by eye specialist for back part of the eye, that is Retina. Examination of the retina using different instruments is known as Funduscopy.
What is FFA (Fundus Fluorescein Angiography) and ICG Angiography?
When it comes to examining the blood vessels in the eye fluorescein angiography (FA) and indocyanine green angiography (ICG) was once the only options available to doctors. Both of these imaging techniques required the use of intravenous dye injections. Common (FA) and (ICG) angiogram side effects included nausea, vomiting, headache, fainting and low blood pressure due to the invasive properties of the dyes. The limitations associated with (FA) and (ICG) angiography led doctors to perform these tests only to determine the critical diagnosis of sight-threatening complications due to diabetic retinopathy (DR), age-related macular degeneration (AMD) and other retinal vascular diseases. It was not used during routine screenings or for early diagnosis. OCTA is the latest tool used for this purpose.
What is the role of OCT in retinal diagnosis?
Optical coherence tomography (OCT) is a non-invasive imaging test. OCT uses light waves to take cross-section pictures of your retina. With OCT, your ophthalmologist can see each of the retina’s distinctive layers. This allows your ophthalmologist to map and measure their thickness. These measurements help with diagnosis. They also provide treatment guidance for glaucoma and diseases of the retina. These retinal diseases include age-related macular degeneration (AMD) and diabetic eye disease.
How is this test performed?
There is no special preparation for this test. The testing time is very short. You will be seated for the test. Your face will be stabilized with a positioning device during the test. Your doctor will use a special camera to take pictures of your inner eye. The images are transmitted to a computer for your doctor to view.
Can something happen to my eyes after OCT?
To prepare you for an OCT exam, your ophthalmologist may put dilating eye drops in your eyes. These drops widen your pupil and make it easier to examine the retina. 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. If your eyes were dilated, they may be sensitive to light for several hours after the exam.
What conditions can OCT help to diagnose?
OCT is useful in diagnosing many eye conditions, including:
macular hole
macular pucker
macular oedema
age-related macular degeneration
glaucoma
central serous retinopathy
diabetic retinopathy
vitreous traction.
OCT is often used to evaluate disorders of the optic nerve as well. The OCT exam helps your ophthalmologist see changes to the fibres of the optic nerve. For example, it can detect changes caused by glaucoma.
OCT relies on light waves. It cannot be used with conditions that interfere with light passing through the eye. These conditions include dense cataracts or significant bleeding in the vitreous.
What are the advantages of OCTA over FFA?
Advantages of OCTA over FFA are:• A high-speed device- produces images in 10-15 seconds; FFA takes over 10-15 minutes
• Noninvasive; FFA needs injections
• No dye injected, instead uses motion contrast. Hence no leakage, staining and other side effects such as nausea and severe allergic reactions (anaphylaxis)
• Can acquire different scan sizes in the macula and the optic disc in about 3 seconds
• Can scan the other eye in the same sitting, unlike FFA, which is one eye per sitting
• Provides accurate size and localization. FFA results are highly variable and often obscured by subjective interpretation by doctors
• Visualizes both the retinal and choroidal vasculature
• Can be used for routine screening examinations for early diagnosis of vascular abnormalities, and for routine
What are the limitations of OCT and OCTA?
As a light source established tool, some barriers get up for OCTA technology. Media opacities can cause signal attenuation and shadowing. Projection artefact is inevitable. Moreover, the imaging the peripheral retina is obligatory in many instances, for both diagnosis and remedy. As such, the confined location of visualization (3mm to 12mm) is a limitation in case of OCTA.
