DIABETIC RETINOPATHY
(Concluding Part)
Management
There are three major treatments for diabetic retinopathy, which are very effective in reducing vision loss from this disease. In fact, even people with advanced retinopathy have a 90 percent chance of keeping their vision when they get treatment before the retina is severely damaged.
These three treatments are: laser surgery,
injection of corticosteroids
or anti-VEGF agents into the eye, and
vitrectomy.
Although these treatments are very successful (in slowing or stopping further vision loss), they do not cure diabetic retinopathy. Caution should be exercised in treatment with laser surgery since it causes a loss of retinal tissue. It is often more prudent to inject triamcinolone or anti-VEGF drugs. In some patients it results in a marked increase of vision, especially if there is an edema of the macula.
Avoiding tobacco use and correction of associated hypertension are important therapeutic measures in the management of diabetic retinopathy.
The best way of addressing diabetic retinopathy is to monitor it vigilantly and achieve euglycemia.
Since 2008 there have been other therapies (e.g. kinase inhibitors and anti-VEGF) drugs available.
Laser photocoagulation
Laser photocoagulation can be used in two scenarios for the treatment of diabetic retinopathy. It can be used to treat macular edema by creating a Modified Grid at the posterior pole and it can be used for panretinal coagulation for controlling neovascularization. It is widely used for early stages of proliferative retinopathy.
Modified Grid Laser photocoagulation
A 'C' shaped area around the macula is treated with low intensity small burns. This helps in clearing the macular edema.
Panretinal photocoagulation
Panretinal photocoagulation, or PRP (also called scatter laser treatment), is used to treat proliferative diabetic retinopathy (PDR).
The goal is to create 1,600 - 2,000 burns in the retina with the hope of reducing the retina's oxygen demand, and hence the possibility ofischemia. It is done in multiple sittings.
In treating advanced diabetic retinopathy, the burns are used to destroy the abnormal blood vessels that form in the retina. This has been shown to reduce the risk of severe vision loss for eyes at risk by 50%.
Before using the laser, the ophthalmologist dilates the pupil and applies anaesthetic drops to numb the eye. In some cases, the doctor also may numb the area behind the eye to reduce discomfort. The patient sits facing the laser machine while the doctor holds a special lens on the eye. The physician can use a single spot laser or a pattern scan laser for two dimensional patterns such as squares, rings and arcs. During the procedure, the patient will see flashes of light. These flashes often create an uncomfortable stinging sensation for the patient. After the laser treatment, patients should be advised not to drive for a few hours while the pupils are still dilated. Vision will most likely remain blurry for the rest of the day. Though there should not be much pain in the eye itself, an ice-cream headache like pain may last for hours afterwards.
Patients will lose some of their peripheral vision after this surgery although it may be barely noticeable by the patient. The procedure does however save the center of the patient's sight. Laser surgery may also slightly reduce colour and night vision.
A person with proliferative retinopathy will always be at risk for new bleeding, as well asglaucoma, a complication from the new blood vessels. This means that multiple treatments may be required to protect vision.
Intravitreal triamcinolone acetonide
Triamcinolone is a long acting steroid preparation. When injected in the vitreous cavity, it decreases the macular edema (thickening of the retina at the macula) caused due to diabetic maculopathy, and results in an increase in visual acuity. The effect of triamcinolone is transient, lasting up to three months, which necessitates repeated injections for maintaining the beneficial effect. Best results of intravitreal Triamcinolone have been found in eyes that have already undergone cataract surgery.
Complications of intravitreal injection of triamcinolone include
cataract,
steroid-induced glaucoma and endophthalmitis.
Intravitreal anti-VEGF drugs
There are good results from multiple doses of intravitreal injections of anti-VEGF drugs such as bevacizumab. Present recommended treatment for diabetic macular edema is Modified Grid laser photocoagulation combined with multiple injections of anti-VEGF drugs.
Vitrectomy
Instead of laser surgery, some people require a vitrectomy to restore vision. A vitrectomy is performed when there is a lot of blood in thevitreous. It involves removing the cloudy vitreous and replacing it with a saline solution.
Studies show that people who have a vitrectomy soon after a large hemorrhage are more likely to protect their vision than someone who waits to have the operation. Early vitrectomy is especially effective in people with insulin-dependent diabetes, who may be at greater risk of blindness from a hemorrhage into the eye.
Vitrectomy is often done under local anesthesia. The doctor makes a tiny incision in the sclera, or white of the eye. Next, a small instrument is placed into the eye to remove the vitreous and insert the saline solution into the eye.
Patients may be able to return home soon after the vitrectomy, or may be asked to stay in the hospital overnight. After the operation, the eye will be red and sensitive, and patients usually need to wear an eyepatch for a few days or weeks to protect the eye. Medicated eye drops are also prescribed to protect against infection.
Vitrectomy is frequently combined with other modalities of treatment.
Light Treatment
Light mask treatment is designed to be worn at night, to deliver a precise dose of light therapy during a patient’s normal hours of sleep. It comes in two parts – a plastic “Pod” part, which is inserted into a soft cushioned Fabric Mask. The Pod contains the light sources which, when worn, emit light into the eyes through closed eyelids. Nothing is inserted into the eyes – the treatment is non-invasive. The mask is programmed to administer the correct dose of light each night as part of a continuing therapy.
The colour of the light has been specifically chosen as the most effective for the treatment of Diabetic Retinopathy. The light may initially appear bright when the mask is first worn, but the eyes adjust within a few minutes as the brain learns to ignore the light, by what is known as the Troxler effect. The light from the mask stops the retina from dark adapting, which is thought to affect Diabetic Retinopathy.
How does it work?
In the human eye an image is projected through the lens to the retina at the back of the eye. There are two sorts of cells in the retina that detect the light (the image) and send a signal to the brain. These cells are called rods and cones. The cones work well during the day when there is a lot of light, but at night time the rods, which are more sensitive to low light levels, take over and dark adapt.
As the rods dark adapt they require more oxygen. In a healthy eye there is just enough oxygen to cope with demand, but in a diabetic person’s eye where circulation is compromised, the retina becomes starved of oxygen, a condition known as hypoxia. The body responds by producing a chemical known as VEGF (Vascular Endothelial Growth Factor) that results in the growth of new blood vessels in the eye to supply extra oxygen. In the diabetic eye these new vessels are weak, which makes the retina thicker. The build-up of fluid is termed Oedema and further reduces the amount of oxygen available, creating a vicious cycle. If the new blood vessels reach the macula (central part of the eye) and there is a build-up of fluid, then a patient’s eyesight, particularly their central vision, is affected. This is known as Macular Oedema.
Light treatment combats this cycle by illuminating the eye overnight through closed eyelids. The colour of the light is specially chosen to be absorbed primarily by the rods without affecting the cones (which would keep people awake), and the brightness is tuned to ensure that the rods do not dark adapt. As the rods do not dark adapt, their oxygen requirements remain at low daytime levels. The effect of this is to slow or stop the production of VEGF, bubblyavoid the formation of weak new blood vessels, avoid fluid leakage and oedema and allow the retina to repair itself to the best of its ability.
(Concluding Part)
Management
There are three major treatments for diabetic retinopathy, which are very effective in reducing vision loss from this disease. In fact, even people with advanced retinopathy have a 90 percent chance of keeping their vision when they get treatment before the retina is severely damaged.
These three treatments are: laser surgery,
injection of corticosteroids
or anti-VEGF agents into the eye, and
vitrectomy.
Although these treatments are very successful (in slowing or stopping further vision loss), they do not cure diabetic retinopathy. Caution should be exercised in treatment with laser surgery since it causes a loss of retinal tissue. It is often more prudent to inject triamcinolone or anti-VEGF drugs. In some patients it results in a marked increase of vision, especially if there is an edema of the macula.
Avoiding tobacco use and correction of associated hypertension are important therapeutic measures in the management of diabetic retinopathy.
The best way of addressing diabetic retinopathy is to monitor it vigilantly and achieve euglycemia.
Since 2008 there have been other therapies (e.g. kinase inhibitors and anti-VEGF) drugs available.
Laser photocoagulation
Laser photocoagulation can be used in two scenarios for the treatment of diabetic retinopathy. It can be used to treat macular edema by creating a Modified Grid at the posterior pole and it can be used for panretinal coagulation for controlling neovascularization. It is widely used for early stages of proliferative retinopathy.
Modified Grid Laser photocoagulation
A 'C' shaped area around the macula is treated with low intensity small burns. This helps in clearing the macular edema.
Panretinal photocoagulation
Panretinal photocoagulation, or PRP (also called scatter laser treatment), is used to treat proliferative diabetic retinopathy (PDR).
The goal is to create 1,600 - 2,000 burns in the retina with the hope of reducing the retina's oxygen demand, and hence the possibility ofischemia. It is done in multiple sittings.
In treating advanced diabetic retinopathy, the burns are used to destroy the abnormal blood vessels that form in the retina. This has been shown to reduce the risk of severe vision loss for eyes at risk by 50%.
Before using the laser, the ophthalmologist dilates the pupil and applies anaesthetic drops to numb the eye. In some cases, the doctor also may numb the area behind the eye to reduce discomfort. The patient sits facing the laser machine while the doctor holds a special lens on the eye. The physician can use a single spot laser or a pattern scan laser for two dimensional patterns such as squares, rings and arcs. During the procedure, the patient will see flashes of light. These flashes often create an uncomfortable stinging sensation for the patient. After the laser treatment, patients should be advised not to drive for a few hours while the pupils are still dilated. Vision will most likely remain blurry for the rest of the day. Though there should not be much pain in the eye itself, an ice-cream headache like pain may last for hours afterwards.
Patients will lose some of their peripheral vision after this surgery although it may be barely noticeable by the patient. The procedure does however save the center of the patient's sight. Laser surgery may also slightly reduce colour and night vision.
A person with proliferative retinopathy will always be at risk for new bleeding, as well asglaucoma, a complication from the new blood vessels. This means that multiple treatments may be required to protect vision.
Intravitreal triamcinolone acetonide
Triamcinolone is a long acting steroid preparation. When injected in the vitreous cavity, it decreases the macular edema (thickening of the retina at the macula) caused due to diabetic maculopathy, and results in an increase in visual acuity. The effect of triamcinolone is transient, lasting up to three months, which necessitates repeated injections for maintaining the beneficial effect. Best results of intravitreal Triamcinolone have been found in eyes that have already undergone cataract surgery.
Complications of intravitreal injection of triamcinolone include
cataract,
steroid-induced glaucoma and endophthalmitis.
Intravitreal anti-VEGF drugs
There are good results from multiple doses of intravitreal injections of anti-VEGF drugs such as bevacizumab. Present recommended treatment for diabetic macular edema is Modified Grid laser photocoagulation combined with multiple injections of anti-VEGF drugs.
Vitrectomy
Instead of laser surgery, some people require a vitrectomy to restore vision. A vitrectomy is performed when there is a lot of blood in thevitreous. It involves removing the cloudy vitreous and replacing it with a saline solution.
Studies show that people who have a vitrectomy soon after a large hemorrhage are more likely to protect their vision than someone who waits to have the operation. Early vitrectomy is especially effective in people with insulin-dependent diabetes, who may be at greater risk of blindness from a hemorrhage into the eye.
Vitrectomy is often done under local anesthesia. The doctor makes a tiny incision in the sclera, or white of the eye. Next, a small instrument is placed into the eye to remove the vitreous and insert the saline solution into the eye.
Patients may be able to return home soon after the vitrectomy, or may be asked to stay in the hospital overnight. After the operation, the eye will be red and sensitive, and patients usually need to wear an eyepatch for a few days or weeks to protect the eye. Medicated eye drops are also prescribed to protect against infection.
Vitrectomy is frequently combined with other modalities of treatment.
Light Treatment
Light mask treatment is designed to be worn at night, to deliver a precise dose of light therapy during a patient’s normal hours of sleep. It comes in two parts – a plastic “Pod” part, which is inserted into a soft cushioned Fabric Mask. The Pod contains the light sources which, when worn, emit light into the eyes through closed eyelids. Nothing is inserted into the eyes – the treatment is non-invasive. The mask is programmed to administer the correct dose of light each night as part of a continuing therapy.
The colour of the light has been specifically chosen as the most effective for the treatment of Diabetic Retinopathy. The light may initially appear bright when the mask is first worn, but the eyes adjust within a few minutes as the brain learns to ignore the light, by what is known as the Troxler effect. The light from the mask stops the retina from dark adapting, which is thought to affect Diabetic Retinopathy.
How does it work?
In the human eye an image is projected through the lens to the retina at the back of the eye. There are two sorts of cells in the retina that detect the light (the image) and send a signal to the brain. These cells are called rods and cones. The cones work well during the day when there is a lot of light, but at night time the rods, which are more sensitive to low light levels, take over and dark adapt.
As the rods dark adapt they require more oxygen. In a healthy eye there is just enough oxygen to cope with demand, but in a diabetic person’s eye where circulation is compromised, the retina becomes starved of oxygen, a condition known as hypoxia. The body responds by producing a chemical known as VEGF (Vascular Endothelial Growth Factor) that results in the growth of new blood vessels in the eye to supply extra oxygen. In the diabetic eye these new vessels are weak, which makes the retina thicker. The build-up of fluid is termed Oedema and further reduces the amount of oxygen available, creating a vicious cycle. If the new blood vessels reach the macula (central part of the eye) and there is a build-up of fluid, then a patient’s eyesight, particularly their central vision, is affected. This is known as Macular Oedema.
Light treatment combats this cycle by illuminating the eye overnight through closed eyelids. The colour of the light is specially chosen to be absorbed primarily by the rods without affecting the cones (which would keep people awake), and the brightness is tuned to ensure that the rods do not dark adapt. As the rods do not dark adapt, their oxygen requirements remain at low daytime levels. The effect of this is to slow or stop the production of VEGF, bubblyavoid the formation of weak new blood vessels, avoid fluid leakage and oedema and allow the retina to repair itself to the best of its ability.
