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Diabetic Retinopathy - A definitive guide

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Author : Dr Deepak Garg

What Is Diabetic Retinopathy?

Diabetic retinopathy is one of the most predominant complications in patients with diabetes and can develop in people with type 1 or type 2 diabetes, and it generally affects both eyes. It is a blinding, irreversible eye disease.

There are approximately 425 million people with diabetes. This number is projected to grow to 629 million by the year 2045. Out of all patients with type 1 and 2 diabetes, 80% of diabetic patients will eventually develop some stage of diabetic retinopathy.2 The longer the duration of diabetes, the more likely they are to develop diabetic retinopathy.

The condition develops gradually over many years. It is irreversible and thus, it is essential to undergo regular eye tests when you have Diabetes. Prevention of retinopathy or slowing down of the progression can be achieved by keeping excellent control of blood sugar levels. 

Diabetic retinopathy affects the blood vessels and thus the blood supply of the retina. The retina is the light-sensitive layer in the back part of the eye. 

Diabetic Retinopathy has various stages of the disease

  1. NPDR - Non-proliferative diabetic retinopathy
  2. PDR - Proliferative diabetic retinopathy

Non-proliferative diabetic retinopathy

NPDR is further divided into 3 subtypes

  1. Mild
  2. Moderate
  3. Severe

Mild NPDR

Small areas of balloon-like swelling in the retina's tiny blood vessels, called microaneurysms, occur at this earliest stage of the disease. These microaneurysms may leak fluid into the retina. Patients with mild NPDR most likely won't complain of blurred vision.

Moderate NPDR

As the disease progresses, blood vessels that nourish the retina may swell and distort. They may also lose their ability to transport blood. Both conditions cause characteristic changes to the appearance of the retina and may contribute to DME.

Severe NPDR

This is a more severe form the moderate subtype. There are more haemorrhages and areas of vessel dilation known as IRMA (Intraretinal microvascular aneurysms). One may also get leakage of fluid from the blood vessels in the macula (central part of the retina). This is known as macular edema and results in blurry central vision. The patient may notice that the peripheral vision is clear or better. Sometimes this fluid is absorbed leaving behind deposits in the retina which are known as exudates. These hard and soft exudates also cause loss of vision.

Patients with severe NPDR have a 52% risk of developing PDR within 1 year, are at a high risk of disease progression and permanent vision loss, and are most likely experiencing neuropathy elsewhere.

Proliferative Diabetic Retinopathy

Progression of retinopathy leads to PDR. In this stage, abnormal blood vessels (retinal neovascularization) begin to grow in the retina. These abnormal blood vessels bleed easily leading to a sudden drop in vision. These abnormal blood vessels also lift off from the surface of the retina dragging the retina along with them leading to what is known as tractional retinal detachment. This detachment leads to severe vision loss.

What are the symptoms of Diabetic Retinopathy? 

The early stages of the disease have no symptoms. Or at least no significant symptoms to alarm individuals. This allows the disease to progress to advanced stages till you notice a drop in vision.

Early symptoms

  1. Slight blurring of vision - eye power changes because of varying blood glucose levels
  2. Occasional floaters - these come and go away

Later symptoms

  1. Blurry vision
  2. Sudden blackout or drop in vision
  3. Floaters
  4. Seeing cobweb-like structures in your vision
  5. Halos around lights

Can Diabetic Retinopathy Go Away?

There have been reports of reversal of early diabetic retinopathy. This occurs mainly due to strict blood sugar control. It does not happen as a rule. In fact, more often than not the disease progresses.

Once you develop a more advanced disease diabetic retinopathy cannot go away. One can reduce the speed of progression by controlling one's blood sugar. One can also reduce vision loss by taking timely and appropriate treatment. 

Taking timely and appropriate treatment is not as easy as it sounds because over time people who have vision loss get frustrated and feel that the treatment is not helping them. The repeated injections that they have to take make them feel that the injections don't work. The fact is that the injections work only for some time just like any other drug. Once the effect of the drug reduces the swelling returns and vision drops.

What’s the treatment for diabetic retinopathy?

Diabetic retinopathy has multiple treatment options depending on the stage of the disease

When your doctor diagnoses early stages of diabetic retinopathy there is no treatment at that point in time. Your doctor would inform you that you have the beginnings of the condition and that its important that you control your blood sugar.

As the disease progresses one may notice a decrease in vision. This blurred vision could be because of the following

  1. Macular edema 
  2. Vitreous hemorrhage
  3. Tractional retinal detachment

Macular edema treatment

Macular edema is treated with eye injections. These are also known as Anti-VEGF treatments. These injections help in reducing the macular edema thus reducing retinal damage as well as improving vision. For centre involving macular edema (CIDME), this is the only treatment option your doctor would choose. One of the best ways to know the degree of edema and treatment response is to perform an OCT eye test.

There is another treatment for non-centre involving macular edema (NCIDME). Your doctor may ask you to undergo a test called FFA (Fundus Fluorescein Angiography). This test will reveal the point or area of leakage that is causing the macular edmea which is not centre involving. Once this point or area is identified a spot or grid laser can be done to reduce the leakage and thus reduce the edema.

Vitreous Hemorrhage

Bleeding in the eye occurs because of retinal neovascularization. This is when one has Proliferative diabetic retinopathy. PDR is treated with aser. Multiple laser marks are applied on the peripheral retina. Usually 3 sittings are needed per eye. Sometimes because of significant amount of bleeding the retina is not visible and your doctor would have to wait for the blood to clear before the laser can be used. Sometimes the bleeding does not resolve and patients continue to see blurry. In this situation the patient may need surgical removal of blood known as vitrectomy. Your doctor usually does the laser during the surgical treatment itself. Injections can also be given during the surgical treatment.

Tractional retinal detachment

This is a complication of PDR and is the advanced stage of this ocular disease. Here the retina has moved from its position and causes blurry vision. One must undergo surgery if this detachment is causing blurry vision. During your surgery your retinal surgeon may choose to insert silicon oil in the eye to help keep the retina in its position.  If inserted this silicon oil needs to be removed a few months later.

Eye Drops

Sometime certain eye drops are used to help with the treatment. These could be used after an injection to prevent any eye infections. Eye drops may also be used after laser to reduce the slight discomfort that patients may experience. The eye drops are

  1. Antiinflammatory eye drops 
  2. Steroid eye drops
  3. Antibiotic eye drops

Types of Laser Treatment

Lasers can be done in two ways to treat this ocular disease

  1. PRP - Pan retinal photocoagulation
  2. Grid / Focal laser treatment

PRP 

This involves hitting the laser at multiple spots on the peripheral retina. Usually 3 sittings are needed for each eye. Both eyes can undergo one sitting at the same time which means 3 visits to the eye hospital. 

This is done when there is PDR and your doctor can see new blood vessels in the retina or on the optic nerve. It is also done if there is bleeding in the eye.

Grid or focal laser 

This is done when there is leakage causing macular edema but the macular edema is not in the centre. This is done after an FFA.

The laser almost exclusively used today is the green laser. It is also known as the double frequency Nd-Yag Laser is different from the Yag laser used for other treatments like glaucoma and PCO.

Argon laser was used popularly at one point in time but is hardly used today.

5 Ways to Prevent Vision Loss from Diabetic Retinopathy

The most important way to prevent vision loss from diabetic retinopathy is to prevent it from occurring in the first place.

1) Maintain strict control of your blood sugar levels by visiting your diabetologist as often as required. We find that patients are reluctant to start insulin therapy.  Some feel that starting insulin would mean that their diabetes is of a severe kind. That is far from the truth. Your diabetologist would titrate the medicines that have been prescribed to achieve optimum control of blood glucose. This titration requires frequent and regular visits.

2) Regularly visit your diabetologist and physician. Diabetologist will control your blood sugar levels and your physician will make sure other parameters like blood pressure and cholesterol are under control. Controlling these parameters makes overall health better and indirectly improves the retinal condition.

3) Get regular and routine comprehensive eye exams where the doctor dilates your eyes and examines the retina. There complete eye exams help in a few ways. These examinations would also include getting regular Macular OCT tests (Optical Coherence Tomography) to check for macular swelling.

4) Once you have diabetic retinopathy you may have to visit your retina specialist more often to reduce the risk of progression and if it is progressing then take appropriate treatment

5) Take timely and appropriate treatment. Patients who have diabetic retinopathy sometimes get frustrated with taking repeated injections to reduce macular edema. While the frustration is understandable, it is very important to understand that the progression of this disease is slowed and treatments would help with that. One must remember that this condition is irreversible.

What other problems can diabetic retinopathy cause?

Diabetes can cause two other problems in the eyes. All these conditions together are referred to as diabetic eye disease

  1. Cataract
  2. Glaucoma
Before Cataract surgery
Near Total Cataract

DIabetics get cataracts much earlier than non-diabetics. The cataracts are also very visually disturbing. Fortunately, treatment for cataracts is very well established with a very high success rate.  Treatment for cataracts is cataract surgery. One can read more about the costs of cataract surgery.

Glaucoma on the other hand is a chronic problem. There are various types of glaucoma. Glaucoma that occurs in people with diabetes is known as neovascular glaucoma. It occurs because of the formation of new blood vessels which tend to block the drainage channels for the fluid in the eye. This type of glaucoma is very serious and can lead to blindness. Another reason is to make sure your blood sugars are under control and you are getting your routine eye examinations.

Injections used for diabetic retinopathy treatment

Eylea Injections
Administring the Eylea Injection

Some stages of diabetic retinopathy can cause Macular edema. Here there is leakage of fluid from the blood vessels in the central retina or the macula. This leakage leads to a drop in vision and is known as macular edema.

When there is macular edema it's important we reduce this edema so that further damage to the retina is slowed as well as vision improves. This is achieved by giving eye injections.

The current standard of care is to give what is known as Anti-VEGF therapy. These drugs act against VEGF (Vascular endothelial growth factor). This is the agent that is causing the formation of new blood vessels as well as causing leakage from the blood vessels. 

Currently, there are 4 types of Anti-VEGF therapies available

  1. Bevacizumab - Avastin is the brand name
  2. Ranibizumab - Accentrix is the brand name
  3. Brolicizumab - Pagenax is the brand name
  4. Aflibercept - Eylea is the brand name

Clinical trials suggest that for patients with visual acuity, 20/40 or better, each agent effectively and similarly improves visual acuity. However, in eyes with lower levels of acuity, 20/50 or worse, aflibercept appears to be most effective at improving visual acuity. 

The frequency of giving these injections depends on the macular edema. Sometimes however, your doctor may choose intensive treatment. Here your doctor may give monthly injections for the first year or so even if you don't have significant macular edema. This intensive therapy requires fewer injections later on to maintain the retina in good condition. That being said every now and then there may be a need to give another injection because of macular edema.

Summary

While diabetic retinopathy treatment is important, its much more important to maintain very good glycemic control to prevent these types of diabetic complications. Apart from this one should be under good medical care to control blood pressure and cholesterol. 

Next its important to get regular dilated eye exams to diagnose and treat this condition in time and prevent diabetic complications.

Frequently asked questions

What is an argon laser treatment used for diabetic retinopathy treatment? 

The argon blue-green laser was introduced in 1968. More conventional argon laser photocoagulation of diabetic retinopathy was then described in 1971. Various studies who argon laser to be effective in treating diabetic retinopathy. However, newer treatment modalities have since been introduced and found to be as effective or better than argon laser. 

The Argon laser is used to treat the retina just like the double frequency Nd-Yag laser.

How much does diabetic retinopathy treatment cost?

Treatment of diabetic retinopathy may involve some or all of the following

  1. Detailed eye examination would include dilation of the pupils and examination of the retina. - Rs 1500
  2. Eye injections - These are Antivegf injections and help in reducing macular edema and thus improve vision. - 13000 per injection to 75000 per injection depending on the type of drug used.
  3. Eye Lasers - Pan retinal photocoagulation is a treatment done for diabetic retinopathy. Here the peripheral retina is lasered to reduce the oxygen requirement of the retina. This leads to a reduction in the abnormal blood vessels and thus a reduction in complications of diabetic retinopathy - Rs 5000 / per eye / Sitting.  Usually, 3 sittings are required per eye.
  4. Eye Surgery - A retina surgery may be needed to remove the membranes formed on the retina and to make the retina go back in its place. Surgery is performed when there is tractional retinal detachment. - Rs 85000 to Rs 120000 depending on how complex the surgery is and on the materials used.

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