Diabetic Retinopathy

Diabetic retinopathy (DR) is a medical condition occurring in patients with diabetes mellitus affecting the retinal layer of the eyes due to the microangiopathy caused by long-standing diabetes. Longer duration of diabetes, poor control of sugar levels, older age group people, hypertension, and smoking increase the risk of developing this condition. Diabetic retinopathy initially presents with no symptoms. Later the patients present with progressive gradual loss of vision not associated with pain, moving of worm-like structures in front of the eyes(floaters) can be complained in patients with severe cases due to the detachment of the retina.

The condition mainly occurs due to microangiopathy affecting the arterioles, venules, and capillaries causing microvascular occlusion and leakage leading to the decrease in oxygen supply to the retina and in turn, releases various factors like VEGF that initiates the development of new vessels causing bleeding in the retinal layers, due to the fibrovascular proliferation traction bands are formed which pull the retina causing its detachment

Diabetic retinopathy progresses slowly. Diabetic retinopathy is explained in stages such as non-proliferative DR, Proliferative DR, and advanced diabetic eye disease. Regular examination of the eyes in patients with diabetes can identify the condition in its early stages and intervening early can help to prevent blindness. The diagnosis is mainly done by the fundus examination of the eyes to look for the various signs of diabetic retinopathy. Initially, no treatment is required other than controlling the sugar levels but when severe retinal damage is present, requires photocoagulation and retinal tear with vitrectomy.

Diabetic Retinopathy: Causes

Diabetic retinopathy occurs because of the microangiopathy caused by high sugar levels in patients with diabetes. Some of the factors make the person vulnerable to developing diabetic retinopathy.

The following factors influence the development of diabetic retinopathy −

• A longer duration of diabetes is more important. If the patient is diagnosed before the age of 30 years 50% risk of developing DR after 10 years and 90% DR after 30 years

• Poor control of sugar levels can damage the retina early.

• Increased levels of HbA1c are associated with increased risk.

• Pregnancy causes rapid progression of DR if poor pre-pregnancy control of DM, too rapid control during the early stages of pregnancy, pre-eclampsia, and fluid imbalance is done

• Hypertension in these patients increases the risk of retinal damage

• In patients with diabetic nephropathy is associated with worsening of DR

• In patients with diabetic nephropathy is associated with worsening of DR

Diabetic Retinopathy: Symptoms

The patient with diabetic retinopathy mainly presents with the following symptoms that include −

• Gradual diminution of vision not associated with pain

• Floaters are worm-like moving objects in front of the eyes when there is associated retinal detachment

• Sudden loss of vision can be present in patients due to associated vitreous hemorrhage or retinal detachment due to progression of the diabetic retinopathy

• Altered color vision

• Decreased night vision

• Complete blindness in severe cases

Diabetic Retinopathy: Diagnosis

The diagnosis of diabetic retinopathy is mainly done based on history and clinical examination of the eyes with some of the ophthalmological scannings required to confirm the changes in the retina that include the following −

• Visual acuity − Testing of visual acuity using Snellen’s chart to assess the amount of loss of vision

• Fundus examination − Fundus examination of the eyes can be done by using instruments such as direct ophthalmoscopy, indirect ophthalmoscopy, or using a 90D lens with a slit lamp. Fundus changes in patients with diabetic retinopathy vary from person to person depending on the severity of the retinal damage. Fundus examination shows −

• Reddish small dots called microaneurysm

• Multiple circular yellowish small lesions present in clumps

• Whitish or yellowish fluffy lesions are cotton wool spots

• Flame-shaped or dot and blot hemorrhages

• In severe cases, bleeding in the vitreous can happen to make the visualization of the fundus hazy

• New vessels can develop in the retina due to retinal hypoxia which leaks to cause bleeding

• Tractional bands can be present later and can contract to form the tractional retinal detachment

• Due to the leakage of the microaneurysms, the fluid can get collected near the macular area causing cystoid macular edema

• Optical coherence tomography is advised to confirm the cystoid macular edema

• Fundus camera is advised to take the retinal imaging to show the various changes that occurred in the retina

• Fundus fluorescence angiography involves injecting the dye and looking for any leakage in the retinal vessels

• B scan is required in patients to look for retinal detachment in patients with vitreous hemorrhage as the media is hazy fundus cannot be visualized.

Diabetic Retinopathy: Treatment

The treatment is based on the severity of the retinal damage. Your doctor may advise conservative or surgical treatment.

Conservative Treatment

Conservative treatment includes −

• In the early stages the treatment is not required. Controlling the blood sugars can delay the progression of the disease

• In the presence of cystoid macular edema anti VEGF injections are advised

• In severe cases, pan-retinal photocoagulation is done. This involves giving the laser spots in the periphery of the retina to prevent the progression of the disease.

Surgical Treatment

Surgical treatment may be required in severe cases which include −

• Surgery is required in patients with non-resolving vitreous hemorrhage and patients with tractional retinal detachment

• Vitrectomy and retinal repair are done

Diabetic Retinopathy: Prevention

Some of the measures that can help to prevent the occurrence and progression of diabetic retinopathy that include −

• Keeping the blood sugar levels under control with proper medications and insulin

• Blood pressure and cholesterol levels should be controlled

• Regular ophthalmology visits are advised in diabetes patients. Eyes should be examined immediately on diagnosis of diabetes in type 2 DM and within 5yrs of onset in type 1 DM. If there is no DR then one annual examination is required. If any level of DR, progression and, sight-threatening, then the examination will be required more frequently.

• Following a healthy diet includes more fruits, vegetables, and proper nutrients. A balanced diet with fewer carbohydrates, less fat, and high in dietary fiber should be advised.

• Avoid smoking and alcohol consumption

• Regular physical activity

Conclusion

Diabetic retinopathy is a complication seen in diabetes patients as a result of microangiopathy caused by increased blood sugar levels. Patients present with gradual painless loss of vision, floaters, and flashes of light.

Regular visits to an ophthalmologist in diabetes patients are advised to identify the retinal changes early and to prevent the progression. If left untreated, the patient can become completely blind. The condition can be prevented by controlling sugar levels, following a proper diet, and avoiding smoking and alcohol.