Overview and Definition

Diabetic Retinopathy is an eye disease caused by diabetes. Retinopathy is a condition that affects the retina, which is the nerve layer that lines the back of the eye that takes visual images and sends the information to the brain for proper interpretation. Diabetic retinopathy initially leads to blurry vision, which can progress to blindness when left untreated. It can also lead to swelling of the macula (macula edema), which makes vision even worse for diabetic sufferers.

Causes of Diabetic Retinopathy

Diabetic retinopathy is caused mainly by diabetes. In order to work, the retina must be constantly supplied with blood through its blood vessels. Diabetes is a condition that impairs the body’s natural ability to store and use up sugar. People with diabetes usually have high blood sugar levels. Continuous supply of high blood sugar levels can cause impaired vision in two ways:

  1. The blood vessels narrow down, leak or bleed, depositing fluid and fatty material in the retina leading to a condition called macular edema, which results in blurry or poor vision.

  2. As a natural response, damage in the blood vessels of the retina can stimulate the growth of unwanted, fragile new vessels, an occurrence referred to as neovascularization. If new vessels grow around the pupil of the eye, glaucoma can ensue due to increased intra-ocular pressure. These new vessels are very weak; they can easily break and bleed causing unwanted scar tissue that can, in turn, cause the retina to detach from the back of the eye. If untreated, retinal detachment can cause severe vision loss that can easily progress to blindness.

Not all diabetic patients develop diabetic retinopathy. However, patients who have untreated diabetes are about 25 times more likely to develop an eye condition. Patients with diabetes who also have high blood pressure and elevated blood cholesterol levels are at higher risk of developing retinopathy. Furthermore, the longer the diabetes has taken effect in an individual, the higher the risk for diabetic retinopathy. Regular and proper eye treatment can reduce the possibility for retinopathy to lead to serious, permanent vision problems.

Signs and Symptoms of Diabetic Retinopathy

Early stages of retinopathy usually do not cause noticeable symptoms. Signs of retinal damage start to become observable in later stages, where vision impairment is usually irreversible. Symptoms of progressed diabetic retinopathy include the following:

  • Blurred vision
  • Difficulty in seeing well at night
  • Dark strings or spots that float in your vision (called floaters)
  • Fluctuating vision
  • Inability to properly identify colors
  • Dark or empty spots in your vision
  • Loss of vision (for advanced stages)

Diagnosis and Confirmatory Tests

Diabetic retinopathy is diagnosed through a series of eye examinations apart from a comprehensive evaluation of patient history. Eye tests focused mainly on determining the health of the retina and the macula. These may include the following:

  • Tests for measuring visual acuity to determine whether vision has been affected
  • Refraction tests to determine whether prescription eyeglasses are necessary
  • Evaluation of ocular structures including determining the health of the retina and pupils
  • Tests to measure ocular pressure
  • Retinal photography or tomography to determine the retina’s current status
  • Fluorescein angiography to check for abnormal growth of blood vessels in the eyes
  • Optical coherence tomography (OCT) which takes cross-sectional images of the retina

Who To See and Available Treatments

When you are diagnosed with diabetes, it is important to also see an ophthalmologist aside from consulting with a diabetes specialist and/or endocrinologist. Even with an apparently healthy vision, careful management of diabetes is the only way to prevent diabetic retinopathy. A yearly eye exam with an ophthalmologist will lessen your chances of developing this debilitating eye disease. Furthermore, you must see an ophthalmologist right away if you notice any vision changes or if your vision becomes hazy, blurry or spotty.

Treatment for diabetic retinopathy would depend on the severity of the condition. Early to moderate diabetic retinopathy usually does not require immediate treatment, and would only require proper management of your diabetes and blood sugar level control. Advanced stages of retinopathy would require prompt surgical treatment through any or a combination of the following:

  • Focal laser treatment. Also known as photocoagulation, this laser treatment method can stop or slow down the leakage of fluid from the eye

  • Scatter laser treatment. Referred to as pan-retinal photocoagulation, this process involves the use of scattered laser beams to shrink newly formed fragile blood vessels

  • Vitrectomy. This involves making a small incision in the eye to remove blood and fluid as well as scar tissue that is damaging the retina

Treatment of retinopathy can also be done through medications. Anti-VEGF therapy involves injecting medication to remove excess growth factor known to cause advanced retinopathy. Steroid intra-ocular injections may also be administered to reduce the amount of inflammation in the retina and improve vision.

Since diabetes is a life-long condition, these treatment methods will not guarantee that retinopathy will not recur. Even after successful treatment, regular eye examinations are necessary and possible continuous treatment may be suggested.

References:

  • National Eye Institute: "Dietetic Retinopathy." van Hecke, MV. Diabetes Care 2005; 28:1383. Lecaire, T. Am J Epidemiol 2006; 164:143. Aiello, L. N Engl J Med 2005; 353:839.
  • American Academy of Ophthalmology Retina Panel. Preferred Practice Pattern Guidelines. Diabetic retinopathy. 2012. Available at: www.aao.org/ppp.
  • American Diabetes Association. Standards of medical care in diabetes -- 2014. Diabetes Care. 2014;37 Suppl 1:S14-S80.
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