Diabetic retinopathy refers to the damage that occurs on the inner lining of the eye, known as the retina, as a complication from the systemic disease of diabetes. While there are many complications associated with diabetes in the eye, diabetic retinopathy remains the most significant because it can be responsible for progressive loss of sight and eventually blindness. The early diagnosis of this disease is essential in its management which may consist of numerous interventions including lasers, injections or even surgical options.
WHAT IS THIS DISEASE?
The two versions of this disease are non-proliferative and proliferative diabetic retinopathy.
Non proliferative diabetic retinopathy refers to the development of aneurysms, bleeding capillaries, and/or dying capillaries near the retina, as well as the swelling of the retina due to diabetes. Although gradual, these symptoms lead to vision loss and eventually full blindness. Of those who have non-proliferative diabetic retinopathy, ten to fifteen percent tend to develop proliferative diabetic retinopathy.
Proliferative diabetic retinopathy consists of the growth of new abnormal capillaries on the retina. These capillaries appear either adjacent to the optic nerve or on the periphery of the retina. They grow along the retina or extend into the vitreous body. After these abnormal capillaries undergo fibrosis or dry out, they cause retinal detachment due to their pull on the retina.
Without intervention, up to 50% of patients with proliferative diabetic retinopathy can go fully blind. Moreover, even treatment cannot stop certain patients with this condition from going blind due to the effects of renal failure, high blood pressure, high blood sugar, and other conditions associated with diabetes.
In addition, clinically significant macular edema can develop alongside diabetic retinopathy, which can cause progressive vision loss because the leaking capillaries can dry up and die within the macular region. Although this condition causes the severe deterioration of vision over time, it does not cause full blindness by itself.
Other than leaving this condition untreated, pregnancy can significantly accelerate the decline of vision due to diabetic retinopathy making it especially important for diabetic women to treat their eye disease with a retinal specialist before and during pregnancy.
PROLIFERATIVE DIABETIC RETINOPATHY
Patients who develop proliferative diabetic retinopathy are at high risk for blindness. Up to fifty percent of patients who have proliferative disease can go on to become blind without intervention. With treatment, which can consist of lasers, intraocular injections or surgical interventions, the progression to blindness can be prevented in most cases. However some patients, despite the best efforts at intervention by your surgical team, may still go on to become blind. Patients at the highest risk for blindness are those who have poorly controlled sugars and those who have numerous other medical problems including renal failure, high blood pressure, or other complications associated with their diabetes.
CLINICALLY SIGNIFICANT MACULAR EDEMA
Patients who have clinically significant macular edema that is not treated inevitably notice that there is further progression of their visual loss. Clinically significant macular edema does not lead to complete blindness. However, patients can become legally blind if they have significant impairment in their visual function. Despite treatments such as injections, laser, or surgical intervention, patients may still continue to progress and lose vision because the blood vessels not only lead to swelling, but the small blood vessels can also die off inside of the eyes leading to significant visual loss. Accordingly, the hallmark of clinically significant macular edema treatment is early intervention.
Treatments for both proliferative and non-proliferative diabetic retinopathy tend to be the same. The first option is usually a laser treatment called pan-retinal coagulation using the micropulse laser or thermal laser. People whose conditions progress further even after laser treatment are then intraocularily injected with the anti-VEGFs Lucentis, Eylea, or Avastin to slow down and halt the progress of their disease. If their disease persists however, or there is a chance that the fibrosis, or drying out, of the abnormal capillaries on the retina may cause retinal detachment, a surgery called a vitrectomy is performed.
The Kenalog intraocular injection is targeted at patients with cases of clinically significant macular edema, cystoids macular degeneration, or cysts within the retina, as well as those with proliferative diabetic retinopathy that has been resistant to laser treatment. This procedure is meant to use the anti-inflammatory and anti-vascular properties of the steroid to stop the progression of each of these conditions in order to preserve the vision of the patient as much as possible. Kenalog is also used pre-operatively in patients who have had inadequate laser treatments before surgery to stop the bleeding of their retinal capillaries and destroy abnormal peripheral retinal tissue to prevent further growth of abnormal capillaries. An intraocular injection of Kenalog or any other chemical also carries with it the risk of blindness from infection and retinal detachment among other complications.
LUCENTIS, EYELEA, AVASTIN
Although Lucentis, Eyelea, and Avastin are anti-VEGF traditionally used to treat the wet form of age-related macular degeneration (AMD), the hormone which causes abnormal blood vessel growth in the disease is similar to the one which causes the same symptom in proliferative diabetic retinopathy. Because of this, these injections are used as off-label drugs which help stop abnormal blood vessel growth in patients with proliferativediabetic retinopathy.
Treatment of diabetic retinopathy by a vitrectomy surgery is only reserved for patients who have clinically significant macular edema which has been resistant to treatment and those with advanced proliferative diabetic retinopathy. Additionally, vitrectomy surgery can be used to treat advanced tractional retinal detachment from diabetic retinopathy by reattaching the retina to the back of the eye. The success rate of both surgeries however, can be reduced depending on the number of extra complications in the retina due to diabetes, such as full thickness holes and rhegmatogenous retinal detachment.