Is hypertensive retinopathy related to the severity of hypertension

Introduction

Inadequately controlled hypertension not only affects the heart, kidneys, brain, and large arteries but also the eyes. Hypertensive retinopathy is caused when the retinal (eye) vessels are damaged by high blood pressure. Increased occurrence of this condition is associated with the severity and duration of hypertension.

Statistics

The prevalence of retinopathy in hypertensive individuals increases with age. The Framingham eye study reported a prevalence of 6.2% among individuals below 65 years of age, while 8.7% in individuals above 75 years of age.

Etiology

Besides hypertension, there are several factors which are responsible for the occurrence of this condition. This includes
  • Genetic factors
  • Smoking
  • Renal dysfunction
  • Increased levels of leptin

Pathophysiology

Retinal (eye) blood vessels have distinctive features, which distinguish them from other blood vessels.

  • Lack of sympathetic nerve supply
  • Autoregulation (blood flow)
  • The existence of retinal blood barrier

Thus, an increase in blood pressure is directly transferred to the blood vessels which initially constrict. However, a further rise in BP damages the muscle layer and endothelium.

Clinical features

Signs and symptoms of hypertensive retinopathy do not develop early in the course of the disease. In the early stage, fundoscopy helps identify the condition. Possible signs and symptoms include

  • Decreased vision
  • Double vision
  • Headache
  • Eye swelling
  • Subconjunctival haemorrages (ruptured blood vessel)

Complications

Complications of hypertensive retinopathy include retinal artery occlusion, retinal vein occlusion, glaucoma, retinal arteriolar emboli, epiretinal membrane formation, and cystoid macular edema.

Diagnosis

History and physical examination

Medically history helps identify hypertensive individuals. Clinically the condition is diagnosed by fundoscopy examination. Keith Wagner Barker classification helps identify hypertensive retinopathy using an examination of the fundus with an ophthalmoscope.

Keith Wagner classification
  • Group 1: Minor constriction of retinal arterioles
  • Group 2: Group 1 + narrowed retinal arterioles + AV nicking
  • Group 3: Group 2 + haemorrhages (flame shaped) + cotton wool spots + hard exudates
  • Group 4: Group 3 + swelling of the optic disc
Meticulous examination of the retina of the eye can be performed using
  • Slit lamp
  • Ophthalmoscope
  • Retinal camera
  • Fluorescein angiography (observes the retinal vessels using a specialized monitor after injecting dye into the bloodstream)

Treatment

Effective treatment involves adequate control of the blood pressure using a combination of drugs and lifestyle measures.

1. Lifestyle alterations

Regular dietary intake of fruits, vegetables helps lower blood pressure. Furthermore, when the diet is supplemented with measures like limited salt intake, and alcohol it provides additional benefits in hypertensive individuals.

2. Drugs
Medications that control hypertension includes
  • Diuretics (Bumetanide, Ethacrynic acid, Furosemide)
  • Beta-blockers (Metoprolol, Atenolol, Propanolol)
  • ACE inhibitors (Benazepril, Captopril, enalapril, fosinopril)

It is important to note that BP should be lowered in a controlled fashion. This is essential to prevent ischemic damage to vital organs such as optic nerve and brain.

Prevention

By adequately controlling the blood pressure this condition can be prevented. This can be achieved by altering the lifestyle factors related to hypertension. This includes

  • Maintain a healthy weight
  • Eat diet low in salt and fat
  • Exercising regularly
  • Smoking cessation
  • Limit the intake of alcohol
  • Manage stress with relaxation techniques

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