Module 8.3 - Diabetic Retinopathy

Question 1

What is diabetic retinopathy?

Answer 1

Ocular disease of the retina resulting from systemic diabetes mellitus. Diabetics should get a comprehensive dilated eye exam at least once a year.

Question 2

What causes diabetic retinopathy?

Answer 2

Inhibition of aldose reductase pathways results in increased blood flow and pressure; thereby diminishing the integrity of the blood-retina barrier.

1. Entry of large cells into the extracellular space of the retina causes macular edema.
2. Microaneurysms, intraretinal microvascular leaking, and hemorrhage may result leading to scarring and proliferation of new capillary vessels and ischemia of existing retinal vasculature.

• Retinopathy is associated with poor glycemic control
• Sustained glucose levels greater than 130mg/dl have been associated with an increase in microvascular complications.

Smoking, uncontrolled hyperglycemia, and hypertension are associated with greater risk.

Question 3

Describe the incidence of diabetic retinopathy

Answer 3

• Most common cause of blindness in the United States.
• Diabetic eye disease comprises a group of eye conditions such as diabetic retinopathy, diabetic macular edema – a swelling in the macula (DME), cataract (clouding of the eye’s lens) and glaucoma (increased intraocular pressure).

Question 4

What are and describe the 4 stages of diabetic retinopathy?

Answer 4

1. Mild nonproliferative retinopathy

• Small areas of balloon-like swelling in the retina’s tiny blood vessels, called microaneurysms, occur at the earliest stage. These microaneurysms may leak fluid into the retina.

2. Moderate nonproliferative retinopathy

• Blood vessels that nourish the retina may swell and distort. They may also lose their ability to transport blood. Both conditions cause characteristic changes to the appearance of the retina and may contribute to DME.

3. Severe nonproliferative retinopathy

• Many more blood vessels are blocked, depriving blood supply to areas of the retina. These areas secrete growth factors that signal the retina to grow new blood vessels.

4. Proliferative diabetic retinopathy (PDR)

• At this advanced stage, growth factors secreted by the retina trigger the proliferation of new blood vessels, which grow along the inside surface of the retina and into the vitreous gel, the fluid that fills the eye. The new blood vessels are fragile, which makes them more likely to leak and bleed. Accompanying scar tissue can contract and cause retinal detachment.

Question 5

What are the subjective/fundoscopic exam findings associated with diabetic retinopathy?

Answer 5

Symptoms that may be present are as follows:

• Flashing lights in peripheral visual fields
• Blurred vision
• ‘Cobwebs’
• Black spots
• Loss of central vision
• Difficulty with color perception

Fundoscopic findings:

• Sudden loss of vision, a funduscopic examination may reveal exudates (hard or soft) and microaneurysms seen as dot and flame hemorrhagic markings.
• Hard, bright-yellow markings may be noted arising from lipid transudation via leaky capillaries.
• Soft exudates produced by infarcted nerve tissue appearing as pale, yellow, irregular; cotton wool spots may be present.

Question 6

How do you manage diabetic retinopathy?

Answer 6

1. Refer to an ophthalmologist
   
   • Macular edema can be ascertained only via stereoscopic examination or by fluorescein angiography.
   • Visual acuity is not a sufficient indicator of retinopathy.
2. Laser photocoagulation for focal macular edema
3. Vitrectomy and laser therapy, as indicated
4. Tight glycemic control is paramount
5. Management of blood pressure.
6. Smoking cessation.