Diabetic retinopathy occurs when high blood sugar levels in diabetic patients cause damage to blood vessels in the retina.
When prolonged and poorly controlled diabetes causes damage to the blood vessels in the back of the eye (the retina), it is called diabetic retinopathy. The condition can be seen as a spectrum of disease severity, that can be divided into two stages, non proliferative vs proliferative. There is also another aspect of the disease that affects the central vision called macular edema, which can occur at any stage of the retinopathy.
- NPDR (non-proliferative diabetic retinopathy), develops with longer duration of diabetes as well as with poorly controlled DM. Due to damage of the small blood vessels, small ballooning or outpouching of the vessel wall forms, called microaneurysms. When this occurs in the central area responsible for detailed vision (macula), it causes leakage of serum and lipid, causing retinal swelling, called macular edema.
- Macular edema can occur at any stage of the diabetic retinopathy and when mild may not cause any noticeable symptoms or signs to the patient. Left untreated it leads to gradual, progressive loss of vision.
- Macular edema can be treated and controlled with proper care.
- PDR (proliferative diabetic retinopathy), is the more advanced stages of the disease when the retina grows new, fragile, abnormal blood vessels which bleeds and can lead to bleeding into the vitreous, resulting in sudden, major loss of vision. More advanced stages of PDR lead to abnormal scarring which pulls on the retina, causing retinal detachment, which can lead to severe loss of vision. PDR requires prompt diagnosis and treatment. Macular edema can occur at this stage also.
Proper and timely treatment can reduce the risk of severe vision loss and help maintain vision. Treatment consists of intravitreal injection of medications into the eye, laser surgery, and major surgery called vitrectomy in more advanced cases. On going diabetes control and treatment with the PCP and endocrinologist is critical in stabilizing and preventing further damage.
Treatment for diabetes causing macular edema (swelling and fluid build up causing blurred vision)
Macular edema occurs when the central retina responsible for detailed vision becomes swollen due to leaking (microaneurysms) and damaged blood vessels caused by diabetes. This results in blurry central vision, difficulty reading, seeing signs, or areas of missing or greyed out vision. In very mild cases, it may not lead to any noticeable symptoms. Treatment helps to reduce the leakage and swelling, and treatment consists of an injection into the center of the eye, called intravitreal injection, or laser surgery.
Laser Surgery for bleeding inside the eye caused by PDR, proliferative diabetic retinopathy
PDR, or proliferative diabetic retinopathy is a more advanced, higher risk stage of the disease that causes sudden bleeding from abnormal fragile bleeding vessels called neovascularization. When this occurs patients notice sudden floaters that are dark or red, and over several hours or days can cause complete blur and loss of vision as the blood spreads throughout the vitreous gel inside the middle space of the eye (vitreous hemorrhage). When this occurs, treatment needs to be done to stop the bleeding vessels and well as progression of the disease which can lead to a more serious stage, called traction retinal detachment. Treatment for the bleeding involves intravitreal injections, laser surgery, and sometimes requires major surgery called vitrectomy.
Vitrectomy surgery for vitreous hemorrhage or traction retinal detachment
In cases where the vision does not improve due to severe vitreous hemorrhage (bleeding inside the eye cavity), surgery can help remove the blood and improve the vision. In more advanced stages of traction retinal detachment due to diabetes, surgery may also be necessary to stabilize further worsening.
Treatment with intraocular medication injections (intravitreal injection) can help improve the signs of retinopathy, for example with less leakage and hemorrhages, but it does not reverse the damage already done by the diabetes, such as level of microaneurysms present or level of poor blood flow circulation and oxygenation, called ischemia. Treatment does improve and reduce bleeding and swelling of the retina, ultimately resulting in the best vision possible given the retinal health.
Diabetes is an ongoing disease, and similar to needing to take medications regularly for the disease, the retina needs ongoing maintenance treatment until it reaches a stage of having less risk of having more bleeding or swelling, which can impact the quality of vision in a serious way. Studies have demonstrated that patients who are compliant to the treatment regimen ultimately do better with less complications and severe vision loss than those who have treatment sporadically or are non-compliant.
Multiple studies have confirmed that rapid improved control of diabetes will paradoxically cause a worsening of retinopathy and macular edema. It is not fully understood why this occurs. However, proper and timely treatment of the retina and consistent control of diabetes will result in the best outcome. With good diabetes control the beneficial effects on the retina can be seen 1 to 2 years later.