DIABETIC EYE DISEASE

To examine the retina, an ophthalmologist will dilate or widen your eyes during a comprehensive examination using eye drops. A retina specialist then uses a special magnifying lens to examine your retina. The dilation will reverse after several hours. You should bring sunglasses, and a driver is advisable.

Diabetic eye disease often has no early warning symptoms or pain. It is possible to have diabetic retinopathy for a long time without noticing symptoms until substantial damage has occurred. In its early stages, diabetic retinopathy has no symptoms. A person may not notice vision changes until the disease advances. It can cause blurred vision, floaters or total visual loss but don’t wait until you notice problems with your vision. Blurred vision may occur when the macula swells from the leaking fluid (called macular edema). If new vessels have grown on the surface of the retina, they can bleed into the eye, blocking vision. Diabetic retinopathy usually affects both eyes but one can be involved before the other. Symptoms may include:
● Blurred vision.● Difficulty reading.● The appearance of spots—known as “floaters”—in your vision.● A shadow across the field of vision.● Eye pain or pressure.● Difficulty with color perception.● A partial or total loss of vision.
Symptoms are often not noted in spite of extensive leakage if it does not involve the very center of the vision. It may only involve the non-dominant eye and will not be noticed until the other eye is covered. There may be extensive growing blood vessels about to bleed that cause no symptoms until hemorrhaging begins. Conversely, if blood sugar is extremely high, or changing rapidly, it can change the power of the lens and blur vision at close or near and eyeglass changes.

You may be able to have diabetic screening performed by your doctor using a sophisticated retinal camera. Several high-quality flash photographs are taken, usually without dilation of the pupil and preferably in a dimly lit room. The operator requires minimal training since the camera has autofocus and autoexposure and often self-aligns. The digital images are sent to a retinal specialist or reading center skilled in diagnosing diabetic retinopathy and other ocular conditions. If the quality of the pictures is good, and there is no problem, a report is sent back indicating that there is no pathology noted and a visit to the retinal specialist can be avoided, but yearly follow-up is required. If the quality of the images is unsatisfactory or there is any pathology noted, the patient is referred to the retinal specialist for confirmation and possible additional testing and/or treatment. Tele-ophthalmology is not as good as a dilated retinal examination and only screens for certain eye problems, it is better than no examination at all, but it is not a substitute for regular eye checkups to maintain the health of your eyes.

The primary cause of diabetic retinopathy is diabetes. This is a condition in which the levels of glucose (sugar) in the blood are too high. Elevated sugar levels from diabetes can damage the small blood vessels that nourish the retina and may make them leak, grow, or become blocked. As a result, the blood supply to the retina from these damaged capillary blood vessels is impaired or wiped out, and vision is affected.
In response to the lack of blood supply, the eye may create growth and inflammatory factors that lead to leakage from the capillaries in the retina. As the leakage increases, the retina swells like a wet newspaper, called diabetic macular edema, causing blurred or decreased vision. In addition, the growth factors promote growing abnormal blood vessels called proliferative diabetic retinopathy, which can lead to bleeding, and vision loss. The abnormal blood vessels also grow into the vitreous gel inside the eye and form adhesions that result in a pull on the retina, and when lifted from the inner wall of the eye, this is a tractional retinal detachment.

Anyone who has diabetes is at risk of developing diabetic retinopathy. There are, however, additional factors that can increase the risk:
● Disease duration: the longer someone has diabetes, the greater the risk of developing diabetic retinopathy.● Poor control of blood sugar levels over time.● High blood pressure.● High cholesterol levels.● Smoking.● Pregnancy can accelerate progression of diabetic retinopathy.

● Background diabetic retinopathy (BDR or Non-proliferative diabetic retinopathy).● Proliferative diabetic retinopathy (PDR).
Background diabetic retinopathy (BDR or Non-proliferative diabetic retinopathy) is usually the earliest stage of diabetic retinopathy. It develops when capillary blood vessels in the retina are damaged and leak plasma, the clear fluid portion of the blood, lipid or tiny amounts of blood. These changes include microaneurysms, hard and soft exudates, and retinal hemorrhages. The leakage, bleeding, swelling of the retina and small hemorrhages determine if the background diabetic retinopathy is mild, moderate or severe.

Diabetic macular edema is swelling, or thickening, of the macula, a small area in the center of the retina. The macula must function normally for us to see fine details and is used for sharp, straight-ahead vision as for reading. It is nourished by a fine network of capillary blood vessels that are damaged and begin to leak as a result of the high blood sugar caused by diabetes. This causes the central part of the retina to become thickened or swollen and can lead to decreased vision. Diabetic macular edema is the most common cause of visual loss in diabetes. Vision loss may be mild to severe, but even in the worst cases, peripheral vision continues to function so it does not cause total blindness.

Diabetes can cause more severe damage to the small blood vessels in the retina by obstructing them, resulting in poor circulation to the retina, also known as macular ischemia. Vision may be lost because the small capillaries are closed, and the lack of blood supply to the macula is called macular ischemia and may irreversibly cause central blurred vision or even central blindness.

Proliferative diabetic retinopathy (PDR) develops when abnormal blood vessels are stimulated to grow on the retina and into the vitreous cavity. These abnormal new blood vessels (neovascularization) serve no useful purpose and, if left untreated, continue to grow. The neovascular blood vessels begin to bleed, and without treatment, recurrent hemorrhages continue and fill the eye with vitreous hemorrhage, and vision will be lost without treatment.
The neovascular membranes also adhere to the vitreous and form membranes that adhere tightly to the retina. When they shrink, they can pull the thin retina layers and elevate them off the nourishing bed of the retina in a tractional retinal detachment requiring delicate vitreous microsurgery. Occasionally, these blood vessels may grow in the front of the eye, where fluid normally exits. When these neovascular vessels grow like vines over the meshwork of the drain and block it, the fluid cannot escape. High pressure builds up in the eye, creating a serious type of glaucoma (neovascular glaucoma) that can damage vision rapidly and cause severe eye pain.

Once present and if untreated, Diabetic macular edema typically progresses and causes gradual loss of fine visual acuity but not blindness. While variable, for most patients, the natural history of untreated diabetic macular edema average visual loss was typically 1-2 lines of vision yearly. In addition to increasing efforts to control underlying diabetes, treatment for diabetic macular edema includes focal laser therapy and intravitreal pharmacologic therapy.
Focal laser therapy
From 1984 until recently, laser treatment for background diabetic retinopathy with clinically significant macular edema was the standard of care. With a focal laser, precise laser spots are directed to microaneurysms, bulging leaking retinal capillaries close to but outside the very center of the vision. When the leakage is more diffuse, a grid laser pattern may be used. The laser seals the leaking capillaries and slows the rate of visual loss.
The laser is a very bright, finely focused light. It passes through the clear cornea, lens, and vitreous without affecting them in any way. Laser surgery shrinks abnormal new vessels and reduces macular swelling. Treatment is often recommended for people with diabetic complications of macular edema, proliferative diabetic retinopathy (PDR), and neovascular glaucoma.
Laser surgery is usually performed in an office setting. For comfort during the procedure, an anesthetic eyedrop is often all that is necessary, although an anesthetic injection is sometimes given next to the eye. The patient sits on an instrument called a slit-lamp microscope. A contact lens is temporarily placed on the eye in order to focus the laser light on the retina with pinpoint accuracy. Unfortunately, only 15% of patients receiving focal laser treatment show visual improvement after 3 years, and the laser spots may cause irreversible blind spots near the center of vision, especially with repeat treatments.

In some cases, intravitreal injections of anti-VEGF and steroid medications may be used to help treat diabetic retinopathy. As a result of major government and industry-sponsored scientific research trials involving thousands of patients over the years, there are several treatments for diabetic retinopathy now in addition to laser, and many more under development and testing. These treatments currently require tiny injections of medications into the middle cavity of the eye, the vitreous. These procedures are quickly and safely performed in an office or hospital setting to prevent, treat, or reverse damage from diabetes in the retina. These injections may result in better vision than laser treatment alone for patients with diabetic macular edema. Medication treatments may be given once, but usually, a series of injections are required at regular intervals, usually around every four to six weeks or as determined by your doctor based on your vision, examination, and test results. Some medications already have up to three years of activity. The medications can also be given in combination or in conjunction with adjunctive laser therapy. The Retina Group of New York has been working with these medications for years. Our doctors work with many of the industry-leading pharmacology companies, serving on the medical advisory board or providing clinical investigation or education of patients or retinal specialists around the country. We have no economic incentive to offer patients any particular treatment other than what we think is best for their particular problem and we often use off-label medications.
Classes of Medications for Diabetic Macular Edema:
Anti-VEGF.
● Lucentis.
● Eylea.
● Avastin (Off label).
Steroids.
● Ozurdex.
● Iluvien.
● Triescence (Off label).
Currently, four FDA medications approved for the treatment of diabetic macular edema have been proven to stabilize or improve visual acuity in many patients. These include the anti-VEGF FDA-approved medications Lucentis and Eylea and the off-label use of Avastin. Anti-VEGF medication works by blocking a substance known as vascular endothelial growth factor, or VEGF. This substance contributes to abnormal blood vessel growth in the eye which can affect your vision. An anti-VEGF drug can help reduce the growth of these abnormal blood vessels and abnormal leakage from damaged capillaries due to its anti-permeability factor. The key to these treatments is their ability to block vascular endothelial growth factor (VEGF), a chemical signal in the body that stimulates blood vessel growth. Repeated doses of anti-VEGF medications may be needed to prevent blood vessels from leaking fluid and causing damage to the eye.

After your pupil is dilated and your eye is numbed with anesthesia, antiseptic and antibiotic drops are placed in the eye. The eyelids are held open with an eyelid speculum. The medication is injected through a safe zone on the white of the eye using a tiny needle into the vitreous jelly-like substance that fills the back of the eye. The injection is nearly painless and takes a few seconds. Additional antibiotic drops are placed in the eye, and the lid speculum is removed. You may see some swirls from the medication, and a few black bubbles from the air in the tip of the needle may be noted for a day. The doctor verifies that you can still see out of the eye, and you receive artificial tears to use as soon as you get home since the antiseptic is irritating, like shampoo.

In proliferative diabetic retinopathy, PDR, the laser is applied to all parts of the retina except the macula with a brief office procedure called PRP, or panretinal photocoagulation. This treatment causes abnormal new vessels to shrink and often prevents them from growing in the future. It also decreases the chance that vitreous bleeding or retinal distortion will occur. Panretinal laser has proven to be very effective in preventing severe vision loss from vitreous hemorrhage and traction retinal detachment. Since 1976, laser treatment for proliferative diabetic retinopathy (PRP) has been the standard of care when it was shown to prevent blindness in 90% of patients. Multiple laser treatments over time may be necessary. Laser surgery does not cure diabetic retinopathy and does not always prevent further loss of vision.

Following a test of your visual acuity, you will receive dilating eyedrops to enlarge the pupil. This allows better visualization of the structures inside the eye, especially the peripheral retina. The best way to diagnose diabetic retinopathy is a dilated eye exam. During this exam, the physician places drops in the eyes to make the pupils dilate (open widely) to allow a better view of the inside of the eye, especially the retina tissue.
Common diagnostic examination equipment used to detect, track and manage diabetic retinopathy include slit lamp examination with a wide-field magnification lens and indirect ophthalmoscopy.
● Fundus Photography: Digital color fundus photographs of the back of the eye are useful for the detection and documentation of diabetic retinopathy and other pathology. Photographs and testing are helpful for documenting the state of the retina over time. They are also used for the education of patients, students, diabetic educators, and physicians and for discussions with colleagues for complicated case management.
● Fluorescein Angiography: To evaluate the circulatory system of the retina that is often affected in diabetes, a retinal photography test called fluorescein angiography is commonly performed. After dilating the pupils, the physician will inject a teaspoon amount of yellow dye into the patient's arm, which circulates through the eyes. The dye works like a food coloring; however, it does not affect the kidneys and is unlike the iodine-based dye that is used with MRIs or CAT scans.
As the dye circulates, the physician takes pictures of the retina to accurately detect blood vessels that are closed, damaged, or leaking fluid. The pictures are black and white to facilitate the detection of these changes. The study is done with a blue laser light or flashes without the use of any X-rays or radiation. Although serious reactions are rare, prior to the examination, ask your physician to discuss the risks and benefits of obtaining these images and notify the staff if you are pregnant.
● Optical coherence tomography (OCT): Diabetic retinopathy is evaluated by an optical coherence tomography (OCT) exam. This laser scanning test of the eye provides cross-sectional images of the retina that show its thickness, helping determine whether fluid has leaked into retinal tissue. It may also show membranes on the surface of the retina that may pull on the retina.
With proper examinations, the earliest signs of diabetic retinopathy in the retina can be detected before vision loss begins.
If the physician detects signs of diabetic retinopathy, she/he often can determine how frequently follow-up examinations will be required in order to detect changes that would require treatments.
● Flicker ERG: The flicker ERG is used to measure faint electrical signals from the retina, similar to the way an EKG captures the electrical signals from the heart. Diabetic retinopathy screening with flicker ERG can identify diabetics at risk of developing retinopathy even before it is visible on examination. It may be helpful for following disease progression. It is a painless, quick test where the patient looks at a flashing light with one eye at a time. The electrode is attached to the skin under the eyelid to collect the signals that are then quickly analyzed.