CLINICAL

  POSTERIOR

‘BLURRY FOR A YEAR’

IS THIS PATIENT’S DIABETES MELLITUS THE CULPRIT?

SHERROL A. REYNOLDS, O.D., F.A.A.O.

A 68-YEAR-OLD black female with a 12-year history of Type 2 diabetes mellitus (DM) presented complaining of blurry vision OU, which she said she’d been experiencing for one year.

She explained that her prior O.D. told her a year ago that she had “severe diabetic changes in both eyes” and to see a retinal specialist for “injections or laser surgery.” The patient said she never went because she feared surgery on her eyes. She did not say why she sought a new O.D.

The patient reported taking medications for diabetes, hypertension and hypercholesterolemia and added that she had poor glycemic control HbA1c value of 10.

Her BCVA was 20/60 OD and 20/40 OS with no improvement on pinhole testing OU. Pupils were sluggish with no afferent pupillary defect, and other preliminary testing was unremarkable. Slit lamp exam was negative for iris neovascularization OU, and IOPs were 16mmHg OD and OS. Dilated exam revealed bilateral proliferative diabetic retinopathy (PDR) with extensive neovascularization at the optic nerves and retina, widespread hemorrhages, cotton wool spots and exudates OU. Extensive proliferative fibrosis was noted OD, and SD-OCT showed edema of the macula OD>OS.

Here, I discuss DM, its ocular manifestations, diagnosis/management and the outcome of this patient’s visit.

DIABETES

DM is climbing at an alarming rate, affecting more than 29 million Americans, according to the CDC. What’s more, one in four people are unaware they have it, while another 86 million pre-diabetic patients are on their way to the incurable condition without intervention. If current trends continue, the prevalence of diabetes will have increased by 50% between 2011 and 2030, reveals Diabetes Research and Clinical Practice.

The risk factors for Type 2 diabetes, a progressive disorder with insulin resistance, are older age, cigarette smoking, family history/genetics, hypercholesterolemia, hypertension, kidney disease, obesity, gestational diabetes, obstructive sleep apnea, physical inactivity, polycystic ovary syndrome, vitamins D, B12 and carotenoid insufficiency and African, Hispanic, Asian and Native American race, as diabetes develops at earlier ages and carries a higher incidence of complications in these races, according to Diabetes Care. Although genetics is the major cause of Type 1 diabetes, an autoimmune disease in which the insulin-producing beta cells of the pancreas are destroyed, exposure to some viral infections, such as the Epstein–Barr, and diseases of the pancreas can lead to the condition.

Diabetic eye disease (diabetic retinopathy [DR] and its associated pathology, including diabetic macular edema [DME]) is the leading cause of visual impairment and vision loss in adults between the ages of 20 and 74. Specifically, from 2000 to 2010, the number of cases of DR doubled, from about 4 million to almost 8 million, reveals the National Eye Institute (NEI). Also, the NEI projects DR will climb to 14 million by 2050.

Note the bilateral PDR with extensive neovascularization at the optic nerves and retina, widespread hemorrhages, cotton wool spots, exudates OU and fibrosis OD in this patient.

DR is classified as non-proliferative diabetic retinopathy (NPDR) with microaneurysms, intraretinal hemorrhages, venous dilation, cotton wool spots, intraretinal microvascular abnormalities or venous beading. NPDR can be mild, moderate, severe or very severe.

As the disease progresses, proliferative diabetic retinopathy (PDR), characterized by neovascularization at the disc (NVD) or neovascularization elsewhere (NVE) in the retina, a pre-retinal hemorrhage, vitreous hemorrhage or tractional retinal detachment, can occur. Vision-threatening DME or clinically significant macular edema (CSME) can occur at any stage of DR and has been found in about 3% of Type 2 DM at diagnosis, according to Archives of Ophthalmology.

The risk factors associated with the development of DR are:

• Duration of DM. About 25% of patients who have Type 1 DM develop DR after 5 years, with greater than 80% after 15 years, reveals Archives of Ophthalmology. On the other hand, many who have Type 2 DM have DR at the time of their diagnosis, as the disease is often present several years before diagnosis, according to Diabetes Care. In fact, DR may be the initial sign of DM in more than 30% of Type 2 DM patients, says the American Diabetes Association.

• HbA1c. Major studies, such as the Diabetes Control and Complications Trial and the United Kingdom Prospective Diabetes Study, establish that good glycemic control (7 or less) delays the development and progression of DR. For every 1% decrease in HbA1c, there was a corresponding 35% risk reduction in retinopathy, reveals The Lancet. Yet, the average HbA1c value for U.S. DM patients is 9.5, according to Scientific Research’s Health.

• Blood pressure and cholesterol. Management of systemic diseases, such as hypertension and cholesterol, has also been shown to reduce retinopathy progression. Good blood pressure control (≤ 140/90, according to the Eighth Joint National Committee on Hypertension) can reduce DR progression about 34%, according to the British Journal of Medicine. The “bad” low-density lipoprotein cholesterol and triglycerides have been linked to DR progression. Studies, such as the Fenofibrate Intervention and Event study, show that cholesterol-lowering medication lowers the need for treatment of DR by about 30%.

Despite the data, only 50% to 60% of DM patients report receiving annual dilated eye exams, according to BMJ Open Diabetes Research and Care. Further, many DM patients are unaware of it, while others with significant sight-threatening retinopathy are often asymptomatic for the disease and, therefore, don’t know they have it.

DIAGNOSIS/MANAGEMENT

The following tests aid in the diagnosis of DR:

• Gonioscopy. This is essential when iris neovascularization is detected or IOP is elevated, so you can detect neovascularization in the anterior chamber angle.

• Fundus photography. This can aid in the detection of DR, and it also captures subtle changes, such as microaneurysms and macular thickening. Further, the technology is valuable for documenting the severity of the diabetes, the presence of NVE and NVD, treatment response and patient education.

• SD-OCTA. This can show exquisite resolution of retinal microvasculature changes, such as microaneurysms, capillary non-perfusion (i.e. enlarged foveal avascular zone), vascular anomalies (vascular loops, tortuosity and dilations of the vessels), intraretinal microvascular abnormalities and superficial neovascularization. Microaneurysms are the earliest sign of DR and often not seen via dilated fundus exam. These early changes often result in hemorrhage, leakage and exudates and, if found near the macula, may be associated with DME.

• SD-OCT. This provides high-resolution imaging of disease changes at the vitreoretinal interface, neurosensory retina and subretinal space. You can use it to quantify retinal thickness, monitor DME and treatment response.

• Ultrasonography. Use this to assess retina status in the presence of a vitreous hemorrhage or other media opacity.

In terms of management, patient education about disease management (glycemic control, blood pressure and cholesterol via staff discussions and/or literature), scheduling of timely exams (annual starting 3 to 5 years after diagnosis of Type 1 and at the time of Type 2 diagnosis), providing appropriate intervention, such as proper follow-up, depending on the presence and severity of DR (at least every 3 to 4 months for signs of progression) and working with the patient’s entire health care team are imperative to preserve the patient’s vision. A total of 57% of diabetes patients age 40 or older were more likely to report seeing an eye care provider in the previous 12 months when provided diabetes education, according to Diabetes Care.

As DR can worsen during pregnancy, diabetics who become pregnant should have an exam within the first trimester. Those with gestational diabetes do not require an exam, as they do not appear to be at increased risk of retinopathy during their pregnancy, reveals the new American Academy of Ophthalmology diabetes guidelines.

Finally, patients who have CSME or DME, severe NPDR or PDR should be co-managed with a retinal specialist who can recommend laser photocoagulation, intravitreal anti-VEGF therapy, an intravitreal steroid or a vitrectomy.

Early detection and timely treatment may be 90% effective in preventing severe vision loss, according to the Journal of the American Medical Association.

THAT PATIENT

The patient mentioned above was immediately referred to a retinal specialist. Explaining that she has a 50% chance of blindness within 5 years without treatment of her PDR — per Ophthalmology — this time, she complied.

She was treated with pan-retinal photocoagulation and multiple injections of intravitreal bevacizumab (Avastin, Genentech) OU. Her PDR progressed to a tractional retinal detachment OD, and her vision OD declined to 20/100, while OS stabilized to 20/50. She is being closely monitored at three-month intervals. OM

DR. REYNOLDS is an associate professor at the Nova Southeastern University College of Optometry and clinical preceptor/attending in the college’s diabetes and macular clinic. She is a fellow of the Optometric Retina Society and chairperson for the Florida Optometric Association Healthy Eyes Healthy People Committee. Comment at tinyurl.com/OMcomment.