Diabetic retinopathy is the disease that diabetes mellitus causes in the eye. It is, along with macular degeneration, one of the leading causes of blindness in the world. Diabetic retinopathy can develop in the young and the old and occurs in both Type I and Type II diabetes. Almost every patient with diabetes will develop some degree of diabetic retinopathy. With early detection and treatment, visual loss may be limited.
- Blurry Vision
- Sudden Loss of Vision
- “Focal” or “Grid” laser photocoagulation, or laser treatment, is commonly used to prevent additional leakage from developing in the macula. At times, the macular edema, or swelling, may decrease and vision may improve.
- “Scatter” or “Pan-Retinal” laser photocoagulation is the mainstay of treatment for patients that develop the proliferative phase of diabetic retinopathy. This may prevent blindness from glaucoma or retinal detachment.
- Intraocular injection of steroids is occasionally used to treat macular edema.
- Intraocular injections of anti-VEGF medicines may also be used to treat macular edema and proliferative diabetic retinopathy
- Intraocular surgery known as “vitrectomy” is needed to repair complications of diabetic retinopathy leading to retinal detachment.
Diabetic retinopathy has several different stages, but there are really only two distinct groupings that require treatment and affect vision.
Diabetic macular edema (DME), or clinically significant macular edema (CSME), develops when the small retinal blood vessels begin to leak in, or near, the macula. The macula is the functional center of the retina and gives us 20/20 vision and our best color perception. Fluid from leaking blood vessels may accumulate in the macula and cause blurred vision. At times, with longstanding leakage, the visual loss may be severe, but not blinding. Almost every patient with diabetes will develop this stage of diabetic retinopathy.
Proliferative diabetic retinopathy (PDR) exists when abnormal blood vessels develop and grow along the retinal surface or other portions of the inside of the eye. The blood vessels develop as a result of poor oxygenation to the retina, known as ischemia. Ischemia causes the release of vascular endothelial growth factor (VEGF), a protein that causes the abnormal blood vessels, also known as neovascularization, to start growing.
These abnormal “neovascular” vessels may bleed spontaneously causing sudden “floaters.” Bleeding in the vitreous, caused by neovascularization, is one cause of vitreous hemorrhage. Left untreated, proliferative diabetic retinopathy can lead to an uncommon, painful type of glaucoma (neovascular glaucoma) and retinal detachment. Both can lead to complete blindness.
Both Type I and Type II diabetic patients may develop either of the stages of diabetic retinopathy. The odds of developing any stage of diabetic retinopathy increase with the number years a patient has had the disease.
Test and Diagnosis
- Visual Acuity
- Intraocular Pressure
- Slit-Lamp Examination
- Dilated Pupil Exam, Dilated Fundus Exam
- Fluorescein Angiography
- Retinal Photograph
- Optical Coherence Tomography
- Indirect Ophthalmoscopy
- B-Scan Ultrasound
The prognosis for patients with diabetes is excellent when patients begin routine examination, including a dilated eye exam, before any symptoms are noted. Waiting until symptoms develop, such as decreased, blurred vision may decrease you prognosis. Eye doctors are best at preventing visual loss in this disease and treatment is best when a patient has no symptoms, i.e. the vision is still perfect at 20/20.
We are highly successful in preventing severe vision loss, including blindness, when patients are seen in a timely manner. As of 2007, fewer than 0.3% of patients with diabetes now experience severe vision loss.
Preventing visual loss, as noted above, is best with early and routine examination. At the minimum, every patient with diabetes should undergo a dilated eye exam once a year. More frequent examinations may be necessary as recommended by your doctor.
It is likely that sugar control will lessen the complications of diabetic retinopathy, but keeping sugar levels controlled does NOT prevent the disease. This is one of the most common misconceptions among patients and their doctors.
- Permanent loss of vision
- Retinal Detachment
When to Consult Your Doctor
Your medical doctor should refer you for retinal eye examination after the diagnosis of diabetes mellitus has been made. Thereafter, yearly examination, regardless of symptoms, is recommended. Again, more frequent exams may be warranted as prescribed by your eye doctor.
Your eye doctor should be aware of any changes in your vision.
It has been my experience that most patients with diabetic retinopathy actually do well over their lifetime, that is, most patients are able to retain good, useful vision. The patients that have had the most difficulty with permanent loss of vision, including blindness are those that wait way too long to see an eye doctor. Prevention with this disease is paramount.
I commonly treat patients with “focal” laser photocoagulation for diabetic macular edema. This occurs in most patients. The laser has been a great tool for preventing additional leakage, thereby preserving visual acuity. At times, there are situations that are not amenable to treatment with laser and we may discuss the possibility of intravitreal (aka intraocular) injections of steroids or anti-VEGF medicines.
Patients with known retinal swelling (macular edema) or suspected of having edema are often tested with either Optical Coherence Tomography (OCT) and/or fluorescein angiography. These are great tests to confirm the presence of leakage into the macula.
Patients who have developed the proliferative phase of diabetic retinopathy may require PRP, or pan-retinal photocoagulation. The laser is used in this instance to treat the peripheral retina. Enough PRP is treated to reverse the neovascular tissue growing along the surface of the retina. Once the proliferative phase of the diabetic retinopathy is arrested, the chance of blindness is dramatically reduced.
Randall V. Wong, M.D.
Ophthalmologist, Retina Specialist