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Diabetic Retinopathy

What is diabetic retinopathy

People with diabetes can develop an eye disease called diabetic retinopathy.  This is when high blood sugar levels cause damage to blood vessels in the retina.  These blood vessels can swell and leak.  Or, they can close, stopping blood from passing through resulting in injury. Sometimes abnormal new blood vessels grow on the retina due to insufficient blood circulation to the retina tissue. These changes ultimately may lead to irreversible vision loss.  At least 50 percent of all diabetics will develop diabetic retinopathy (abnormal retinal blood circulation), and the incidence increases with the duration of the disease. After 20 years of having diabetes, more than 90 percent of diabetics have some degree of diabetic change.

Picture of a normal retina
Normal Retina
Picture of Diabetic Retinopathy
Picture of Diabetic Retinopathy affecting the left eye

Stages of diabetic eye disease (diabetic retinopathy)

There are two main stages of diabetic retinopathy.

Non-proliferative diabetic retinopathy (NPDR): Is the early stage of diabetic eye disease.  Many people with diabetes have it. Tiny blood vessels leak, making the retina swell because all the fluid escaping the vessels accumulates in the space of the retina.  When the macula swells, it is called macular edema. Sometimes tiny particles of lipid, called exudates, deposit in the retina and affect vision too (appear yellow in the picture above).  The macula is the central part of the retina responsible for detailed sight.  Macular edema is the most common reason why people with diabetes lose their vision.

When blood vessels in the retina close off this is called retinal ischemia.  When this happens in the center of the retina, where blood cannot reach the macula, it is called macular ischemia.  This may cause permanent vision loss centrally.  

Picture of diabetic macular swelling
OCT scan of diabetic macular swelling
Normal OCT scan of retina
OCT scan image of a normal macula

Proliferative diabetic retinopathy (PDR): Is the more advanced stage of diabetic eye disease.  It happens when the retina starts growing new blood vessels due to widespread impairment of retinal nutrition that is caused by blood vessel closure and leakage. The poorly nourished retina sends out a chemical “distress signal” which causes new blood vessels to grow (proliferate) on the retinal surface. When new blood vessels grow this process is called neovascularization.  These fragile new vessels often bleed into the vitreous. If they only bleed a little, you might see a few floaters that may appear as cobwebs, strings or dots floating in your sight.  If they bleed a lot, it might block all vision. 

These new blood vessels can form scar tissue. Scar tissue can cause complications with the macula or lead to a detached retina.  PDR is very serious and can steal both your central and peripheral vision.  The proliferative form of diabetic retinopathy is present in approximately 20 percent of patients with diabetes of ten years duration.

Picture of Proliferative diabetic retinopathy
PDR with scar tissue (white) and new vessel growth (neovascularization) on optic nerve

What are diabetic retinopathy symptoms?

You can have diabetic retinopathy and not know it.  This is because it often has no symptoms in its early stages.  As diabetic retinopathy gets worse, you will notice symptoms such as:

  • Seeing increased number of floaters
  • Having blurry vision
  • Having vision that changes sometimes from blurry to clear
  • Seeing blank or dark areas in your field of vision
  • Having poor night vision
  • Noticing colors appear faded or washed out
  • Losing vision

How is diabetic retinopathy diagnosed?

Eye drops will be instilled on your eye to dilate your pupil.  This allows your ophthalmologist to look through a special lens to see the inside of your eye.

Your doctor may do fluorescein angiography to see what is happening with your retina.  Yellow/Orange dye called fluorescein is injected into a vein, usually in your arm.  The dye travels through the blood circulation.  A special camera takes photos of the retina as the dye travels through the retina circulation.  This reveals the integrity of the retina blood vessels and shows if there is any damage to the retinal blood vessels.

Optical coherence tomography (OCT): is another way to look closely at the retina.  A machine scans the retina and provides detailed images of its thickness.  This helps your doctor find and measure swelling of your macula.

How is diabetic retinopathy treated?

Your treatment is based on what your ophthalmologist sees in your eyes.  Treatment options may include:

  • Medical control: Controlling your blood sugar and blood pressure can stop vision loss. Carefully follow the diet your nutritionist or physician has recommended.  Take the medicine your diabetes doctor prescribed for you.  Sometimes, good sugar control can even bring some of your vision back.  Controlling your blood pressure keeps your eye’s blood vessels healthy.
  • Medicine: One type of medicine offered is called anti-VEGF medication. This helps to reduce swelling of the macula, slowing vision loss and improving your chances of improving vision. These medications include Avastin, Lucentis, and Eylea. The medicine is delivered to your eye through a very slender and short needle. While the thought of an “eye shot” might cause many to cringe, in our experience, there is little, if any, patient discomfort.  The injection of steroids, such as Ozurdex implant or triamcinolone, is another option to reduce macular swelling. This is also given as injections in the eye or around it. It has also been found to be of benefit. Side effects of steroid injections include increased eye pressure and cataract formation.  You may require multiple treatments to treat macular swelling.
  • Laser surgery: Laser surgery might be used to help seal off leaking blood vessels. This can reduce swelling of the retina.  Laser surgery can also help shrink blood vessels and prevent them from growing again, sometimes more than one treatment is needed.   Large clinical trials have shown that a procedure called pan retinal laser photocoagulation (PRP) can be effective in halting or reversing new vessel growth. PRP is usually indicated for treatment of PDR. Many eyes, even without visual problems, need to begin laser treatments if there are certain abnormal vessels present. PRP lessens the risk of developing a significant vitreous bleed by 50%.  The laser treatment consists of applying multiple laser burns to the peripheral retina, often divided into several sessions. Although mildly uncomfortable, the treatment usually can be done without the need for local anesthesia.
  • Vitrectomy surgery: If you have advanced PDR, your ophthalmologist may recommend surgery called vitrectomy. Your ophthalmologist removes the vitreous gel and blood from leaking vessels in the back of your eye.  This allows light rays to focus properly on the retina again.  Scar tissue also might be removed from the retina if a retinal detachment develops.

NOTE: Patients may need multiple procedures or a combination of treatments to control diabetic retinopathy.

Vitreous hemorrhage and tractional retinal detachment

In cases where laser treatment is not successful in preventing diabetic retinopathy progression, a vitrectomy is often helpful. In the operating room, a microsurgical instrument is inserted into the eye and is used to surgically remove the vitreous gel from the middle of the eye. After removing the vitreous gel, the surgeon may treat the retina with a laser (photocoagulation), cut or remove fibrous or scar tissue from the retina and flatten areas where the retina has become detached. Vitrectomy remains an operation performed only on eyes in which no other treatment is useful. Approximately 60 percent to 70 percent of selected eyes, otherwise hopelessly damaged, can be visually restored to at least ambulatory vision. Some eyes have returned to very good or near-normal vision.

Illustration of vitrectomy procedure
Illustration of vitrectomy procedure

Preventing vision loss from diabetic retinopathy:

  • If you have diabetes, talk with your primary care doctor about controlling your blood sugar. High blood sugar damages retinal blood vessels that results in vision loss.
  • Do you have high blood pressure or kidney problems? Ask your doctor about ways to manage and treat these problems.
  • See your ophthalmologist regularly for dilated eye exams. Diabetic retinopathy may be found before you even notice any vision problems. It is recommended that diabetics attain an annual dilated eye exam to check for development of diabetic retinopathy.
  • If you notice vision changes in one or both eyes, call your ophthalmologist right away.

Do you have diabetes and need an exam for eyeglasses?

Changes in blood sugar levels can affect your vision.  Make sure your blood sugar is under control for at least a week before an eye exam for eye glasses.  Eyeglasses prescribed when your blood sugar levels are stable work best! Your general ophthalmologist or optometrist will prescribe glasses for you when you return.

Protecting your vision

It is critical for all diabetics to have a comprehensive eye exam at least once a year to evaluate for the presence of retinopathy. Patients should remember that both macular edema and proliferative retinopathy can develop without symptoms. Patients with visual symptoms and/or visual loss, at any stage of the disease, should be evaluated without delay to find out the cause of the visual change. Early detection and timely treatment can prevent vision loss.


High blood sugar levels can affect your retina and macula, leading to vision loss.  This is called diabetic retinopathy.  In its early stages, diabetic retinopathy often has no symptoms.  But as it gets worse, eye damage from diabetes leads to vision loss and if left untreated to blindness.  Furthermore, the overall maintenance of diabetes is important in avoiding circulation damage to other vital organs such as the brain, heart and kidneys. Although perfect solutions are not available for the prevention of visual loss, the outlook for maintenance of useful vision is favorable. Early detection and appropriate therapy can be sight-saving. All diabetics should work to lower their vascular risk factors. Important advice includes:

  • Eat healthy and moderately
  • Exercise regularly – remember physical education (P.E.) that you learned in elementary, middle and high school.
  • Avoid smoking
  • Control your blood pressure and blood sugar
  • Regulate your body weight and body mass index
  • Lower your cholesterol levels and have your cholesterol checked as indicated.
  • Carefully follow your medical doctor’s instructions
  • Keep your A1c levels below 7. Near 6 or below is optimal.
  • And remember to avoid to much stress

NOTE: I, Dr. Calderon, personally abide by these points above, which I strongly recommend to my patients.

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