Diabetic Retinopathy

Commonly known as background retinopathy, is an early stage of diabetic retinopathy.

Tiny blood vessels within the retina leak blood or fluid, causing the retina to swell or form what is known as exudates.

Many diabetics have mild NPDR, which usually does not affect their vision.

If vision is affected, it is the result of macular edema and/or macular ischemia.

Macular edema – swelling or thickening of the macula, which is in the center of the retina and allows you to see fine details clearly. This is the most common cause of vision loss in diabetics. Vision loss can be mild to severe, but peripheral vision usually remains intact even in the worst of cases.

Macular ischemia – occurs when small blood vessels close. Vision is interrupted due to lack of blood supply to the macula.

May cause more severe vision loss than NPDR due to the fact that it can affect central and peripheral vision.

The main cause of PDR is widespread closure of retinal blood vessels, resulting in inadequate blood flow to the retina. The retina then produces additional blood vessels in an attempt to compensate for this issue. Abnormal new vessels are thus formed on the surface of the retina or optic nerve, which is referred to as neovascularization. These new abnormal vessels do not supply the retina with normal blood flow. They are usually accompanied by scar tissue that can cause retinal wrinkling or detachment.

In PDR, vision can be lost in the following ways:

Vitreous hemorrhage – fragile new vessels can bleed into the vitreous (the clear gel-like substance that fills the center of the eye). On a small scale, a patient may notice a few dark floaters, on a very large scale, a vitreous hemorrhage can block out all vision. Recovery can vary from only a few days to years as the blood must be reabsorbed. Vitrectomy surgery can be recommended if the eye cannot reabsorb the blood in a reasonable amount of time. Vitreous hemorrhage does not cause permanent vision loss by itself. Unless the macula is damaged, vision will return upon absorption of the blood.

Traction retinal detachment – if scar tissue is present with neovascularization, it can shrink. This shrinking may cause the retina to pull or wrinkle, causing visual distortion. If the macula or large areas of the retina become detached, more severe vision loss may occur.

Neovascular glaucoma – from time to time, excessive vessel closure in the retina can cause new, abnormal blood vessels to grow on the iris (the colored part of the eye), and in drainage channels in the front of the eye. Because this can block normal flow of fluid into and out of the eye, pressure in the eye can increase. The resulting condition is neovascular glaucoma, a disease that can be severe enough to cause damage to the optic nerve.