Diabetic retinopathy is the leading cause of blindness in the working population in the UK. In diabetic retinopathy, there is damage to the blood vessels in the retina (the tissue lining the back of the eye that detects light and allows us to see), which usually happens due to poorly controlled blood sugar level. Diabetic retinopathy can affect persons with Type I or Type II diabetes. Usually some changes in the retina is visible after one has been diabetic for over 5 years.
Most people with mild diabetic retinopathy have good vision, but there are two types of sight-threatening diabetic retinopathy: diabetic macular oedema (DMO) and proliferative diabetic retinopathy (PDR).
Diabetic Macular Oedema (DMO):
In DMO, there is leakage of fluid from the retinal blood vessels (capillary network) The fluid accumulates in the macula (the central part of the retina) which is responsible for reading vision. Patients with untreated diabetic macular oedema eventually develops poor central vision and are unable to read or drive, but the peripheral vision usually remains normal, unless they have had extensive laser treatment.
Proliferative Diabetic Retinopathy (PDR):
In this condition, there is formation of new fragile abnormal blood vessels on the surface of the retina. They tend to bleed into the vitreous, which can cause severe vision loss or even blindness. This happens as these blood vessels grow, bleed and scar, when they can detach the retina (tractional retinal detachment). Regular eye checks are essential for all diabetics and this happens in the UK as a part of well-established diabetic retinopathy screening programme, so that signs of diabetic retinopathy can be detected and treated if needed as early as possible.
Treatment of Diabetic Retinopathy
Systemic Control
Having good control of blood sugar levels and blood pressure helps prevent progression of diabetic retinopathy. However, treatment will be needed, if complications such as diabetic macular oedema or proliferative retinopathy develop.
Anti-VEGF Treatment
These injections (Eyela, Lucentis, and Avastin) have become the mainstay in controlling diabetic macular edema and used as first line of treatment for center involving macular odema. These injections work by decreasing the leakage from the retinal blood vessels and improving the grade of diabetic retinopathy. Recent clinical trials have demonstrated their safety and effectiveness as a treatment for diabetic macular edema. Treatment involves regular injections in the first year, which decreases in subsequent years. On an average over the 2-year period of beginning the treatment one requires 10-15 injections. Once the macular oedema resolves, less frequent injections are necessary and often laser treatment is used to augment and prolong the effect of anti-VEGF injections for treatment diabetic macular edema.
Laser Therapy
Lasers have been the mainstay for treatment of proliferative diabetic retinopathy and diabetic maculopathy for more than 35 years. The way lasers work is not completely understood, but in some way stimulates the pigment layer underneath the retina and helps decrease the macular oedema. The laser treatment is used in conjunction with intraocular injections, unless the odema is non central in which case laser is used as first option.
Intraocular Steroids for Diabetic Macular Edema
Intraocular steroid injections (Ozurdex, Triamcinolone Acetonide) are used in conjunction with anti-VEGF injections or laser therapy in patients who do not respond well to them in the first instance. The side effects include elevated eye pressure and cataracts, which can generally be managed with simple treatments, and rarely requires aggressive therapy.
Laser Treatment for Proliferative Diabetic Retinopathy
The abnormal fragile new blood vessels of proliferative diabetic retinopathy are treated with panretinal (scatter) laser photocoagulation or PRP. During this procedure, the peripheral retina, which is not receiving adequate blood flow, is treated, in order to stop the development of these abnormal blood vessels.
This treatment requires many laser applications, which is usually divided into two or more separate sessions. Treatment stops the formation of new abnormal blood vessels and in most cases causes existing ones to shrink. PRP does not improve vision, but it can prevent the blinding complications of diabetic retinopathy in the majority of cases. Side effects include some loss of peripheral and a decrease in night vision. Some patients experience blurry vision, which can be temporary or continue indefinitely. Regardless of these side effects, PRP has been shown to decrease the risk of vision loss by more than 50%.
