Introduction:
Diabetes has become a lifestyle-related epidemic in recent days. It is a vascular disease that manifests in blood vessels throughout the body. The eye is the only region where the changes in the blood vessels can be observed in vivid detail. Hence, diabetic retinopathy is given a lot of importance, and screening for diabetic retinopathy is done in many diabetic people. The symptoms of diabetic retinopathy should not be ignored and one must undergo timely screening to diagnose the condition in the early stages.
What Are the Stages of Diabetic Retinopathy?
The following are the two stages:
-
Nonproliferative Diabetes-Related Retinopathy (NPDR): This is the early stage of the condition in which the blood vessels can leak into the retina. Its manifestation can be seen in the form of hemorrhage, fluid, or lipid. With time, these blood vessels can close resulting in poor blood flow (ischemia).
-
Proliferative Diabetes-Related Retinopathy (PDR): As the disease progresses, abnormal blood vessels can develop to compensate for poor blood flow. This process is called neovascularization. Since the newly formed blood vessels are fragile, they can leak blood into the vitreous (the gel-like substance of the eye) which can get accumulated. These new blood vessels can result in the formation of scar tissue which can lead to a detached retina. This is a serious condition that can affect both central and peripheral (side) vision.
Why Is the Retina Important?
The retina is the tissue situated in the back of the eye that sends signals to the brain similar to the film present in a photographic camera. The retina is involved in converting the light rays into electrical impulses that are sent to the brain which interprets them. These impulses are responsible for vision in humans.
Who Is at Risk of Developing Diabetic Retinopathy?
Anyone with diabetes can develop diabetic retinopathy and the following could be at risk of developing diabetic retinopathy:
-
Those with Type 1 diabetes.
-
Those with Type 2 diabetes.
-
Gestational diabetes (elevated levels of blood glucose during pregnancy).
-
Hypertension.
-
Uncontrolled blood sugar.
-
Duration for which one has had diabetic retinopathy.
-
Hyperlipidemia (a condition characterized by high levels of fat in the body).
What Are the Symptoms of Diabetic Retinopathy?
The symptoms are as follows:
-
Blurred vision. This can happen because of various vascular retinal changes caused by diabetes.
-
A sudden severe blackout over a matter of minutes to seconds can be due to vitreous hemorrhage.
-
A distorted image can be due to diabetic macular edema (leakage of blood vessels into the part of the retina called the macula). It can also be due to secondary retinal vein occlusions.
-
A retinal detachment can happen in advanced proliferative diabetic retinopathy.
-
Developing new color blindness or appearance of faded colors.
-
Poor vision at night (night blindness).
-
Streaks or small dark spots (eye floaters) in the vision.
-
Difficulty in reading or seeing distant objects.
-
A sudden or complete loss of vision.
-
An empty or dark spot in the center of vision.
-
Other vision-threatening problems are ischemic optic neuropathy and severe dry eyes.
How Is Diabetic Retinopathy Diagnosed?
A dilated eye examination is done by an ophthalmologist (eye doctor) using eye drops. These drops widen the pupils facilitating a good look at the inside of the eye by the physician. The physician will check for swelling, abnormal blood vessels, scarring, and optic nerve damage. Other diagnostic tests include:
-
Fluorescein Angiography: In this test, a dye is injected into the arm enabling the physician to determine how the blood flows into the eye. When the pupils are dilated, pictures of the dye that circulates inside the eye are taken to identify which vessels are leaking, blocked, or broken.
-
Optical Coherence Tomography (OCT): Light waves are used in this imaging test to capture images of the retina. The thickness of the retina can be estimated using these images. This test enables the doctors to determine the level of fluid that has accumulated in the retina.
-
Visual Acuity Test: This test is done to determine how clearly a person can see things.
-
Intraocular Pressure: The intraocular pressure is checked to rule out glaucoma.
-
The function of the eye muscles is checked to see how well one can move their eye.
-
Examination of peripheral or side vision.
-
The response of pupils to light is checked.
How Is Diabetic Retinopathy Treated?
Diabetic retinopathy is treated in the following ways:
1. Medical Treatment for Diabetic Retinopathy: This includes:
-
The mainstay treatment for diabetes is oral or injectable antidiabetic medication.
-
Injectable medications like anti-VEGF drugs block the protein that is responsible for forming new, leaky blood vessels. It also aids in reducing swelling and improving vision. These medications include Aflibercept, Bevacizumab, and Ranibizumab. The physician will numb the eye to avoid any discomfort. Injections might be required monthly in the beginning and with time the frequency may decrease and ultimately may not be required.
-
Ocular medication only becomes relevant in the case of neovascular glaucoma, a form of glaucoma resulting from the growth of new vessels over the anterior chamber angle causing a rise in pressure inside the eye. The treatment for this involves the use of antiglaucoma medications such as Timolol maleate and/or Brimonidine, but even with these measures, patients with neovascular glaucoma rarely improve.
2. Surgery for Diabetic Retinopathy:
-
Surgery for retinal disorders, in general, is only done as a palliative measure and will not result in any visual gains. These are usually required by diabetic people in the advanced stage of the disease and those suffering from complications such as vitreous hemorrhage require vitrectomy. In a vitrectomy, a small incision is made in the eye, the blood vessels are repaired, and scar tissue is removed.
-
Laser surgery is done to reduce the growth of new blood vessels and to minimize the swelling in the retina. Laser surgery can shrink blood vessels or control leaking. The overall prognosis for such cases is poor. Patients should control their sugar consumption so as not to land on such complications.
-
Retinopathy, in the proliferative stage, is usually treated with an argon green laser, through a process called photocoagulation wherein the bleeding vessels are heat-sealed using lasers. This prevents bleeding into the eye and loss of further vision.
What Is the Importance of Screening for Diabetic Retinopathy?
The importance is as follows:
-
As diabetic retinopathy is a disease that can be prevented from worsening through screening, screening of all patients with diabetes is of utmost importance. There are several known instances wherein an asymptomatic person would be diagnosed with diabetes by merely performing retinal screening for diabetes.
-
Patients already diagnosed with diabetes, whether on medication or not, will need to be screened for diabetic retinopathy as soon as possible, so as to not miss out on diabetic retinopathy. This helps to prevent any future complications that might arise due to the retinopathy not being adequately managed.
-
The usual follow-up schedule is yearly for mild to moderate cases, while severe cases will need three-monthly monitoring. The more severe the disease, the more frequent the follow-ups. Advanced cases will need to be reviewed every three months.
-
Screening is a hassle-free and non-invasive process that requires a dilated examination of the fundus. A few cases with serious diabetic damage inside the eye will also need an estimation of their intraocular pressure, gonioscopy to check for blood vessels in their anterior chamber angles and slit lamp examination to look for bleeding vessels in their iris on every screening visit apart from the fundus examination.
What Is the Importance of Controlling Diabetic Changes in the Retina?
The retina is nerve tissue, and just like any other nerve in the body, it has no regenerative potential. So, damage once done would be irreparable except in the very early stages of the disease in some patients.
The main dictum that applies in the treatment of diabetic retinopathy is the same as in the treatment of retinal disorders in general, that is, vision once lost cannot be recovered and treatment would only be aimed at minimizing the loss in visual potential. Hence, it is more important to screen and prevent diabetic complications than to manage them later.
When Should One Consult an Ophthalmologist?
In general, diabetic people with retinopathy can expect a wide range of visual symptoms, but the symptoms which need a visit to an ophthalmologist (eye doctor) are:
-
Sudden onset of blurring or deterioration of vision.
-
Multiple floating objects in front of the eye.
-
Experiencing a sensation such as falling of curtains followed by deterioration of vision.
-
Pain in and around the eye with blurred or foggy vision.
Can Diabetic Retinopathy Be Prevented?
Diabetic retinopathy can be prevented in the following ways:
-
Maintaining the blood sugar level under control.
-
Refraining from smoking.
-
Exercising regularly.
-
Undertaking eye examinations annually.
-
Keeping the blood pressure in the normal range.
-
Taking the medications appropriately as prescribed by the physician.
Conclusion:
Diabetic retinopathy is a preventable and treatable disease, provided patients have good compliance to follow-ups and present early during the disease progression. Proper treatment with control of sugars in the diet can mitigate vision loss and support a healthy eye and good vision.