Updates In Diabetic Macular Edema & Diabetic Retinopathy

Updates In Diabetic Macular Edema & Diabetic Retinopathy

March 17, 2021

Over 430 million people have diabetes worldwide, with the number projected to increase close to 680 million in the next two decades. In the United Kingdom alone, there are over 6 million people with diabetes.

As the most common microvascular complication of diabetes, diabetic retinopathy (DR) is therefore expected to remain as a global threat to vision and economy.

Diabetic macular oedema (DMO) is now the most prevalent vision-threatening form of DR, particularly among adults with type 2 diabetes. The global prevalence of DMO has been estimated to be 6.8%. Thus, about 27 million adults are affected by DMO worldwide.

Fortunately, since 2010, the advent of ocular anti-vascular-endothelial-growth-factor (VEGF) therapy has greatly improved visual prognosis for patients with vision loss due to center-involved DMO. It has become the standard-of-care treatment for these patients in many developed countries.

Besides DMO, ocular anti-VEGF therapy has similarly shown clear benefits for other retinal angiogenic diseases, such as proliferative DR, neovascular age-related macular degeneration, and macular oedema secondary to retinal vein occlusion.

Its widespread use over the last two decades has undoubtedly saved sight for millions of patients worldwide. However, increasing evidence for the expanding indications of anti-VEGF therapy have also created tremendous stress to the healthcare system.

Many countries are struggling to cope with the continually rising number of patients requiring this, often regular and long-term, treatment. Furthermore, this treatment burden could be compounded by clinicians who might be tempted to use the current body of evidence to assume its efficacy beyond proven clinical indications.

A DISCUSSION OF EXPERTS

Diabetic eye disease is the leading cause of blindness in working-age adults, which underscores the disease’s community impact.

Experts discussed current physician challenges ranging from diabetic eye examinations to collaborations between MDs and ODs, coronavirus disease 2019 (COVID-19), and available and upcoming treatments.

Here are some highlights of the virtual discussion:

OCULAR EXAMINATIONS

  1. Paul Chous, OD, MA, FAAO, who has a private practice in Tacoma, Washington, specializing in diabetic eye care and education, explained that for patients with diabetes a good dilated stereoscopic view of the inside of the eye is imperative.

Imaging is useful especially at the baseline examination to facilitate later comparisons; he values fundus photography highly, particularly widefield or ultra widefield imaging and performs optical coherence tomography (OCT) at every visit to detect subclinical diabetic macular edema (DME).

He also underscored the value of good case histories regarding glucose and blood pressure control and lipids.

Anat Loewenstein, MD, a professor of ophthalmology at Tel Aviv University in Israel, also emphasized the importance of the clinical evaluation and widefield photography for screening.

She performs angiography on patients at baseline if they have diabetic retinopathy (DR) but not in those without DR. Loewenstein said she relies on OCT to identify very mild DR possibly missed in the clinical evaluation.

She also said she avoids OCT angiography (OCT-A) at baseline because of reimbursement issues.

Steven Ferrucci, OD, FAAO, chief of optometry at Sepulveda VA Hospital in North Hills, California, said he finds OCT-A helpful with diabetic patients without edema who have unexplained visual loss. OCT in these patients identified macular ischemia.

Rishi Singh, MD, staff surgeon at the Cole Eye Institute, Cleveland Clinic, and moderator of the discussion, touched upon the controversy surrounding the correct way to perform the diabetic eye examination.

He said he finds OCT-A useful in patients with diabetes without DR but with temporal microaneurysms. OCT-A often showed that patients actually had juxtafoveal telangiectasia or another masquerade syndrome.

He noted that he does not use OCT for patients with good vision. ODS AND MDS Ferrucci underscored the role of optometrists in instructing patients about asymptomatic DR and DME. “Good vision on an eye chart or in the real world does not mean their eyes are healthy,” he said.

Education about metabolic memory is also important—that is, early tighter blood glucose control has a protective effect decades down the line. Patients also should be educated about diabetes medications that can lower the risk of fatal infarctions/stroke.

Ferrucci encouraged ODs to obtain a second opinion if necessary. The American Optometric Association guidelines recommend referral to retinal specialists at the earliest signs of severe nonproliferative DR, PDR, and center-involved DME to discuss treatment options.

Communication via letters to retina specialists can provide a brief patient background with ODs’ concerns.

All of the panelists urged consistency in messages to patients and that all primary eye care providers send a note to the primary care physicians (PCPs) informing them of the development of DR in their patients, whether they need referrals to retina specialists, and asking about the follow-up interval.

DR is linked to other diabetes comorbidities and communication is an opportunity to collaborate with PCPs and other subspecialists, Chous pointed out. The panelists also discussed challenges such as asymptomatic disease and the importance of routine checkups to start treatment as soon as possible.

Patients and their families must be educated about the importance of eye care.

COVID-19 & TREATMENT GUIDELINES

Chous said he believes that an annual examination by an optometrist is appropriate if a patient has mild/ no disease and believes there is value in habituating patients to annual dilated examinations.

With disease worsening, a referral is needed. Ferrucci added that he feels safe examining patients with mild/moderate NDR. Loewenstein follows patients with good visual acuity (VA), but if follow-up is problematic, she said she prefers to treat.

In patients with central macular edema, she explained that she generally treats if the patient has very good VA and noted that bevacizumab (Avastin; Genentech), ranibizumab (Lucentis; Genentech), and aflibercept (Eylea; Regeneron) are good options.

In patients whose vision is 20/50 or worse, she said she prefers bevacizumab. A major disruption of the pandemic has been the slowing of diabetic, routine, and annual examinations.

Elderly diabetic patients, Chous said, should be informed of their increased risk for poor outcomes related to glycemic control if they are hospitalized for COVID-19.

Poor glycemic control translates to 5 to 10 times greater likelihood of a fatality. He assures patients that proper in-office disinfection protocols are followed and advises minimal face-to-face time because patient risk is higher in an enclosed room.

Loewenstein has offered patients 3 options during the pandemic: a safe office visit, remote clinic of the hospital, and an injection clinic.

DRUG TREATMENTS

Loewenstein considers faricimab (Genentech) the most promising future drug for managing patients because it is anti-Ang-2, enhances VEGF activity, and is anti-inflammatory. Brolucizumab (Beovu; Novartis) also seems promising, but Loewenstein is concerned about the inflammatory response.

KSI-301 (Kodiak Sciences) and gene therapy are promising but not close to large-scale clinical use. The Port Delivery System with ranibizumab (Genentech) is being studied for diabetes; safety issues are concerns.

Chous mentioned that the retinal flavoproteins, although not specific to diabetes, are the earliest marker of photoreceptor oxidative stress in diabetes, and he looks to them as an early marker in improving glucose control and thus avoiding ocular damage. His goal is elimination of the need for ocular injections or photocoagulation.