Medical review by Elizabeth Gomez MSN, FNP-BC

Macular edema is the most common cause of vision loss among people with type 1 and type 2 diabetes. It occurs when high blood sugar and other metabolic dysfunction causes swelling in the macula, the part of the retina that is used for our highest-quality vision.

There is no cure for diabetic macular edema, but it doesn’t always get worse, and treatment can significantly slow its progression. For those that have already experienced declining vision, it may be possible to reverse any damage before it becomes permanent with treatment.

This article will explain the details of diabetic macular edema (DME): what it is and what it means for you.

I Have Diabetic Macular Edema. Am I Going Blind?

This distressing question is common in the diabetes online community, in places such as the Diabetes Daily forums.

No, macular edema does not always lead to blindness. While there is no cure for diabetic macular edema, some cases do improve spontaneously, and there are a variety of treatments that can slow and halt its progression. Some people are able to reverse their eyesight damage before it becomes permanent. 

Many members of our community have lived with DME for years. Some require regular injections of special drugs; others have emerged from an initial course of eye treatment with improved vision, and now rely on metabolic control to prevent their condition from worsening.

Make no mistake, DME absolutely requires treatment, even if your vision seems fine right now. The medications that have been developed for DME can not only improve your vision in the short term, but they can prevent further permanent damage. Without proper treatment — focused on both eye health and metabolic health — DME can lead to severe visual impairment.

One other thing is abundantly clear: even the most advanced DME therapies are reliant on good diabetes management for lasting success. DME, like other diabetes complications, is fundamentally caused by hyperglycemia. Good blood sugar control – along with weight loss, healthy blood pressure, and other improved metabolic parameters — significantly determines your prognosis.

Diabetes and Complications of the Eye

The eyes are one of the most vulnerable parts of the body in people with diabetes. The retina — the part of the eye that actually senses light and sends signals to the brain — has many small veins that are particularly sensitive to high blood sugars. When they are subjected to chronically elevated blood sugar levels, these little veins can swell, burst, and leak. Other metabolic factors, including high blood pressure and high cholesterol, contribute to the risk. 

Other parts of the eye are also at an elevated risk of harm in diabetes, including the lens (cataracts) and the optic nerve (glaucoma). But it is the retina that suffers the most damage; when diabetes causes retinal dysfunction, this is known broadly as diabetic retinopathy.

Marc Schulte/Pexels

If you see an eye doctor regularly — the American Diabetes Association recommends annual dilated eye exams — you may be able to identify and address diabetic retinopathy long before you notice any decline in your vision. 

But not everyone is so lucky, and for some, diabetic retinopathy will cause macular edema, a condition that should be treated quickly in order to prevent permanent vision impairment. Macular edema can develop at any stage of diabetic retinopathy, even during earlier stages, although it is more likely to develop after the condition has already progressed to a more severe state.

What is Diabetic Macular Edema?

The macula is an especially important part of the retina, right in the retina’s center, where the lens focuses most of the light that enters the eye. The macula is used for our highest-quality, keenest vision: the direct center of our eyesight in good lighting. When your eyes focus on a face or a book or a television screen, that light is concentrated on your macula. Unsurprisingly, then, any damage to the macula can have a profound effect on vision quality.

Diabetic macular edema occurs when leaking blood vessels cause swelling in the macula. That swelling disrupts healthy vision.

Macular edema is not only caused by diabetes. Other causes include age-related macular degeneration, retinitis pigmentosa, uveitis, and side effects of eye surgery.

How Common is DME? 

A 2012 analysis of data from around the world suggested that about seven percent of people with diabetes have DME. Only a minority, though, have gone on to experience severe vision impairment or blindness. The World Health Organization estimates that 3.9 million people across the globe suffer from “moderate or severe distance vision impairment or blindness” due to diabetic retinopathy; that’s fewer than one percent of the world’s people with diabetes.

The risk of DME is higher for people with type 1 diabetes and for those with type 2 that use insulin. Another analysis confirms that likelihood of developing DME increases dramatically with longer diabetes duration and higher levels of hyperglycemia.

Some evidence also suggests that Black Americans are more likely to develop DME than white Americans, and are more likely to suffer from severe outcomes such as blindness. It is unclear if this difference is due to genetic factors or if it’s a result of the systemic racial disparities that plague modern American healthcare. Either way, Black readers (or caretakers of Black people with diabetes) should be aware that their risks may be elevated, which makes routine diabetic eye care even more critical.

The Symptoms of DME

Ideally, DME is diagnosed during a routine eye exam, before any symptoms become noticeable.

If it’s been a while since you’ve seen an eye doctor, and you’re wondering about your vision changes, you should schedule an appointment as soon as possible.

The early stages of macular edema are generally characterized by blurry vision. According to the National Eye Institute, you may also notice:

  • Objects look wavy, especially when you look straight ahead
  • Objects look like they’re different sizes if you look out of one eye and then the other
  • Colors look dull or faded

If macular edema continues to develop, it can eventually cause severe central vision loss. Although some patients may retain some of their peripheral vision, it can become difficult to read, drive, or even recognize the face of a person you’re speaking to.

The Diagnosis of DME

Everyone with diabetes is advised to have an annual dilated eye exam. This is not merely a check of vision quality to update a corrective lens prescription, although that can usually take place in the same visit. In a dilated eye exam, an eye doctor (ophthalmologist) will apply a solution to your eyes that will cause the pupil to dilate, or grow wider, allowing a better look at the interior of the eye.

Many doctors will also use optical coherence tomography (OCT) to examine the surface of the retina. This non-invasive exam allows an ophthalmologist to see the retina in distinct layers and measure their thicknesses.

If there’s some evidence of retinopathy, your ophthalmologist may perform Fluorescein angiography to identify which parts of the eyes are leaking fluid. This exam involves an injection of a special dye into the arm in order to highlight the blood in the eye.

If your doctor sees evidence of macular edema, they may also ask to examine measurements of your metabolic health, including A1C, blood pressure, and lipid profile. This can help connect your eye issues to diabetes.

A traditional eyesight exam can help determine the extent to which your vision already has or has not deteriorated.

I Have DME. What Happens Next?

Some DME cases resolve spontaneously without treatment, although they may recur later. Nevertheless, it would be foolish to hope that you are among the lucky minority. Diabetic macular edema should be treated as quickly as possible. Here’s a review of the options: 

Blood Sugar Control and Metabolic Risk Factors

The first line of defense against DME is to improve diabetic and metabolic risk factors. Getting your A1C, blood pressure, and cholesterol into recommended ranges is the primary way of directly addressing the root cause of diabetic eye disease. Studies have shown that improvement of these factors “can produce measurable effects in macular thickness in as little as 6 weeks.”

Unfortunately, ophthalmologists “frequently underemphasize” the importance of these risk factors, perhaps not wishing to step on the toes of the primary care doctors and endocrinologists that usually advise patients on such matters.

If you’ve been diagnosed with DME, it’s a great opportunity to renew your commitment to diabetes management. The judicious use of a healthy diet, exercise, and glucose-lowering medication can help preserve your eyesight for years to come. You should make sure your primary care physician is well-informed about your eyesight, as they may be able to advise new lifestyle changes or medications to help intensify your diabetes management efforts.

Injections

Not all DME cases require immediate intervention. If yours does, the first line of treatment is a series of injections with an anti-vascular endothelial growth factor (anti-VEGF). This medicine will help control the swelling of the macula and block abnormal blood vessel growth.

These injections are delivered directly to your eye, which is to say that, yes, a doctor will insert a needle into your eyeball. We understand that many people in the diabetes community are terrified of the idea, and understandably so. But these injections are the best remedy for the condition. We’ve also heard that the injections are not nearly as bad as they sound: uncomfortable but not actually painful. Your doctor will apply a numbing medicine to your eye, and the needle is extremely small. The injection is over quickly and does not require much recovery; you will probably be able to go right back to your regular activities.

The standard treatment of anti-VEGFs is a first course of six monthly injections, with a number of follow-up injections based on the effectiveness of the initial treatment. According to the American Academy of Ophthalmology, “on average, patients are given 6-8 injections in the first year, 2-4 injections in the second year, and 0-1 injections beginning the third year.”

Unfortunately, these drugs do not work for everyone. A significant minority of patients will continue to experience worsening DME.

If anti-VEGFs are not effective, doctors may add injections of corticosteroids. These drugs powerfully reduce inflammation, which may be hampering the progress of the anti-VEGF treatment. In a majority of cases, these steroid injections also lead to the development of cataracts, which may necessitate another surgery down the road.

Laser Photocoagulation

Laser treatment was once the standard therapy for DME, but in the United States it has been largely replaced by anti-VEGF injections. This somewhat less invasive technique is now sometimes used in conjunction with injections for a subset of DME patients with a particular pattern of retinal thickening, or for those for whom anti-VEGF treatment has not been effective. Laser treatment is also still favored in resource-limited parts of the world. In this procedure, after the use of numbing medicine, a laser is aimed into the eye to seal or shrink leaking blood vessels on the retina. Patients may need multiple laser treatments.

Laser photocoagulation is associated with significant risks, including loss of peripheral, color, and night vision — but for those at risk of losing their central eyesight, the trade might be worth making.

Surgery

Finally, your doctor may recommend a vitrectomy, in which much of the vitreous humor — the clear gel that fills the eye — is removed. A vitrectomy is a more invasive procedure than the shots or laser treatments described above. Sometimes general anesthesia is called for, and only one eye can be operated on at a time.

It is uncertain how effective a vitrectomy is for DME, and therefore its use may be restricted to patients that have other eye issues in addition to DME, such as vitreomacular traction syndrome. Like any other surgery, it carries a risk of complications.

If you want more details on all of the above methods, the official treatment guidelines for diabetic macular edema are outlined in a document authored by the American Academy of Ophthalmology. This plain-English explanation may be even more helpful.

Takeaways

Diabetic macula edema (DME) is a serious complication of the eyes that affects people with diabetes. The earlier DME is diagnosed and treated, the better the outcome is likely to be, just another reason for people with diabetes to see an eye doctor regularly. If you (or a loved one) have recently experienced vision declines, you should get your eye health evaluated as quickly as possible.

In some cases, DME will lead to significant visual impairment. However, most people with the condition will have a more favorable prognosis, especially if they seek treatment as soon as it’s recommended. In many cases, treatment will reverse the eyesight damage caused by DME.

DME is fundamentally caused by hyperglycemia and other metabolic dysfunctions characteristic of diabetes. Successful treatments are likely to combine both targeted eye health therapies and improved diabetes management, such as tighter blood glucose control.

Read more about complications, eye health, eye screening.

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