Diagnostics & Treatments

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Retinal Diagnostic Testing and Treatments

Evaluation of the retina involves not just the examination of the retina, but also looking deeper into the retina. There are specific imaging modalities that we use that can evaluate the structure of the retina as well as the function of the retina. This is important to assess diseases like macular degeneration and diabetic retinopathy, among many others. Structural tests are usually tests such as color photographs or optical coherence tomography (OCT). The function of the retina can be assessed by angiography, where a special dye (fluorescein – vegetable dye) or indocyanine green (iodine-based contrast dye) is used.

Watch Our Video: Diagnostic Testing

Optical Coherence Tomography (OCT)

Since the early 2000s, the OCT has been a staple of diagnostic testing for retinal specialists and other eye care providers. It is a non-invasive scan of the retina. It is simple to do and takes only a few seconds. You simply put your head and chin in the device and look at a target. The scanner and photographer do the rest!

The OCT provides images of the retina in cross-section. It can show all the different cell layers of the retina and the structures underneath the retina. It is an important tool in the assessment of the structure of the retina. Specifically, it can tell the retina specialist whether there is fluid, blood, or other material within or underneath the retina or whether there are signs of swelling in the retina or signs of abnormal blood vessels growing under the retina. These types of changes are extremely important when assessing patients who have diabetic retinopathy or macular degeneration, among many other diseases.

In recent years, a modification of this specific scanning technique has been utilized to actually generate images of retinal blood vessels and capillaries in great detail, called OCT angiography. This is a sophisticated imaging tool that gives us a great deal of anatomic information about the changes that are going on at the capillary level within the central part of the retina. It is also easy to do, non-invasive, and is sometimes used in our practice.

Fluorescein and Indocyanine Green (ICG) angiography

Fluorescein angiography is an imaging technique where 2-5 ml (less than a teaspoon) of fluorescein (a harmless, vegetable-based dye) is injected intravenously by the technician or doctor. Within a few seconds of the injection, the dye shows up in the back of the eye and is imaged by a special camera that is able to take pictures as the dye transits through the blood vessels of the retina. This gives us tremendous information about diseases like diabetic retinopathy, macular degeneration, retinal vein occlusions, and many other rarer conditions.

The injection procedure itself and the pictures usually take about 10 to 15 minutes. It is very common to feel a little queasy with the injection, but this usually passes in a few seconds. Rarely, some patients can become fairly nauseous and can throw up. If we know this ahead of time, especially from past experience, we can pre-treat the patient with medication that can help reduce nausea. Rarely, severe allergic reactions such as hives or even more severe anaphylaxis can develop. In those situations, fluorescein angiography is not injected again.

If your doctor is ordering fluorescein angiography, it is to gain more information about the changes that are happening to your vision and the corresponding changes in the retina. After fluorescein angiography, your urine will likely be very bright yellow. This will go away within 24 hours. Fluorescein does not interact with or interfere with any medicines that you are taking. It can be used safely even in patients who have kidney problems or renal dysfunction because it is a small molecule that is harmlessly excreted in the urine and does not cause any damage to the kidneys.

Indocyanine Green Angiography

Indocyanine green angiography uses a special iodine-based contrast that is delivered intravenously, and the retina is imaged a few seconds after the injection, similar to fluorescein angiography. This imaging technique with indocyanine green is utilized to evaluate the retina and the choroid, which is the vascular layer under the retina, in more detail. It can be utilized in the evaluation of patients with macular degeneration or with uveitis, a severe ocular inflammatory disease.
Because this specific contrast is iodine-based, people who have shellfish allergies or iodine allergies should not be given this test. Similar to fluorescein angiography, transient queasiness or nausea is not uncommon. Rare allergic reactions to indocyanine green have been reported. These are extremely uncommon. Indocyanine green angiography is not usually performed in patients who have kidney damage or failure.

Fortunately, your physician and AVRUC are prepared to handle any side effects that may occur from these tests. However, these tests, especially fluorescein angiography, are very safe and very important imaging modalities. The benefits of its diagnostic use outweigh its risks.

B-Scan Ultrasonography

B-scan ultrasonography is utilized to evaluate structures of the back of the eye when they cannot easily be visualized by your doctor through the routine methods of dilating the pupil and looking with the lenses and lighted headset that is normally used. Ultrasonography is most commonly used in patients who have a very dense cataract, dense vitreous hemorrhage, suspected ocular or orbital tumors, and severe ocular inflammation in the back of the eye.

The procedure is quite simple. You will be reclined back in an exam chair. An ultrasound probe is gently placed on the surface of the anesthetized eye with the eyelids open or closed. Your doctor may obtain multiple images of the back of the eye with the probe oriented in different directions, along with the video. Your doctor will review the findings with you after the ultrasound. This is usually a very painless test and can add a great deal of detail in situations where the retina cannot easily be visualized.

Retinal Treatments

Pan Retinal Laser Photocoagulation

Pan retinal laser photocoagulation is utilized to treat areas of capillary loss because these areas of the retina are so damaged that they do not receive enough oxygen. As a result, the retina produces special chemicals that cause new blood vessels to grow out of the retina, sometimes as far away is on the iris.

When we see changes like this on our examination or signs of loss of capillaries on fluorescein angiography, pan retinal photocoagulation treatment is utilized. This treatment basically destroys all of the non-functional or poorly functional retina so that the diseased tissue cannot make any abnormal chemicals that can cause further damage to the eye. It is often used in proliferative diabetic retinopathy, retinal vein occlusions, ocular inflammatory diseases, or sickle cell retinopathy.

Pan retinal laser treatment is usually performed in the office as an outpatient under just topical anesthesia. It is usually performed in 5 to 15-minute sessions. The laser is often delivered using a special contact lens at the microscope, or the laser can be delivered using a headset (indirect ophthalmoscope), which allows us to treat much broader areas of peripheral retina more efficiently. Multiple sessions are often required in the affected eye. Usually, after laser treatment, there are very few restrictions, if any. Usually, no drops or patches are required.

Watch Our Video: Laser Treatmement Appointment

Focal Laser Photocoagulation

Focal or grid laser photocoagulation is utilized in the treatment of macular edema or swelling in the macula caused by retinal vein occlusions or by diabetic retinopathy. Sometimes we also use this type of laser treatment to treat abnormal blood vessels growing under the retina in certain selected cases of macular degeneration or ocular histoplasmosis.

These laser treatments are usually done in a slit lamp microscope with a special contact lens that is placed over the eye to keep the lids out of the way and to help focus the laser to where it needs to go. This type of treatment requires greater precision and accuracy. Often, images from the fluorescein angiogram will be utilized to determine exactly where to place the laser spots. These treatments take 10 to 15 minutes to do and are well tolerated by the patient. No drops or patches are required after treatment, and there are no activity restrictions.

Indirect Laser Treatment of Tears and Localized Retinal Detachment

The laser is often utilized to treat retinal tears or localized retinal detachments on an urgent basis in the office. These types of treatments are usually done with the laser on a headset (indirect ophthalmoscope). Usually, you are lying down for this treatment. The doctor will tell you where to look, and you may see bright flashes of light and feel a mild achiness around the eye that could feel like an ice cream headache. These types of treatments are relatively brief and last less than 10 minutes. There is usually no need for any eye patch or eye drops after such treatment. There may be specific restrictions after such laser treatment, and close follow-up may be required.

Cryoretinopexy (Cryotherapy)

Sometimes, when the peripheral tear cannot be easily visualized or treated well because of the presence of opacities in the media, such as a cataract or hemorrhage, we may use cryotherapy to treat the peripheral tear. Cryotherapy can also sometimes be used to treat vascular lesions in the retina. It can also be used to treat certain ocular inflammatory diseases.

This is an efficient and effective way of treatment. Cryotherapy uses a special cryoprobe that cools with liquid nitrogen -60 to -70°C, which causes a freeze to develop through the wall of the eye to the retina. This allows the retina to become sticky to the wall of the eye and seals the tear.

Usually, cryotherapy requires the use of an anesthetic injection around the eye so that pain can be minimized. You may feel pressure and a mild “ice cream headache” type sensation when cryotherapy is performed. After cryotherapy, you may be required to use some topical eye drops. Sometimes a patch is worn temporarily after the treatment. There may be some restrictions on your activity after such therapy. Cryotherapy is often utilized in conjunction with the placement of an intraocular gas bubble for the treatment of retinal detachment in the office. This is called a pneumatic retinopexy.

Pneumatic Retinopexy

A pneumatic retinopexy is often performed for the treatment of a retinal detachment in the office. In this office procedure, we use a cryo probe to freeze the tear or tears causing the detachment, remove a small amount of fluid from the front of the eye, and place a gas bubble that expands in the back of the eye to seal and splint the tears closed to heal the retinal detachment. The gas bubble usually lasts 2 to 6 weeks in the eye.

Restrictions of positioning, oral pressure-lowering medication (acetazolamide), and topical eye drops may be necessary after the procedure. This is a more extensive, but office-based treatment done for selected retinal detachments. Risks of this procedure include intraocular infection and intraocular hemorrhage. There is also a possibility that despite the successful performance of this procedure, the detachment may not heal, and more extensive surgery in the operating room may be required. You will be assessed very closely after a pneumatic retinopexy to make sure the retina is healing properly. Usually, you will be seen a day or two after the treatment and then a few times over a few months.