How does high blood pressure affect the eyes?

18/02/2021

High blood pressure is a systematic illness that may severely compromise the vital organs such as the brain, heart, kidney and eyes. It progresses slowly, gradually damaging the tissue before the harmful effects to the organs are clinically noticeable.

The retina is the only place in the body where we can clearly see the blood vessels using a simple and non-invasive technique: the ophthalmoscopy. It offers the possibility of equating the damage to the back of the eye with other parts of the body.

Hypertensive retinopathy is a set of ocular manifestations that occur in the retina as a consequence of high blood pressure. The higher the blood pressure and the longer the time of evolution, the higher the likelihood of severe damage to the eye, and therefore, the rest of the body.

There are other factors that may aggravate hypotensive retinopathy, including arteriosclerosis, old age, diabetes, high cholesterol and triglycerides and smoking. 

The seriousness of retinopathy will also depend on the retinovascular tree and the speed at which low blood pressure is established. We can distinguish between:

Chronic hypertensive retinopathy

The majority of patients suffer from this variant. They are usually asymptomatic at the start but as the blood pressure rises, they end up with visual problems. They are diagnosed by chance through an examination of the back of the eye, where we detect the following findings:

1. Diffuse or focal decrease in vascular calibre. 

2. Pathological arteriovenous crossings (an artery compressing a vein, inhibiting blood flow).

3. Changes in vascular reflex (difficulty visualising the blood inside the vessels).

4. Retinal aneurysms: micro and macro aneurysms (abnormal vascular dilation both small and large respectively). 

Acute hypertensive retinopathy also called malignant or accelerated

It appears suddenly and is characterised by high pressure, bad headaches and a striking visual loss. In the clinical examination we will find:

1. Retinal, preretinal, choroidal or vitreous haemorrhages (through vessel rupture).

2. Soft or hard exudate (yellowish-white deposits from extravasation of plasma materials or from ischaemia).

3. Papillary oedema (optic nerve inflammation).

4. Macular oedema (inflammation of the central part of the retina).

Treatment

There is no specific treatment for hypertensive retinopathy, blood pressure must be strictly controlled and maintained. Although some patients with very poorly controlled blood pressure may suffer permanent damage and visual sequelae, a dip in pressure translates into a significant resolve for retinal lesions.

Therefore, any hypertensive patient is advised to undergo an ophthalmoscopy on a regular basis, which should be individualised based on the seriousness of the hypertension, age and the coexistence of other cardiovascular risk factors. 

Dr. Sònia Viver, ophthalmologist