Hypertensive retinopathy is defined as a set of changes that appear in the back of the eye as a result of high blood pressure. 

Up to 40% of the population suffers from high blood pressire according to data provided by the Spanish Society of Hypertension. This indicates that a large part of those affected are unaware of it. An in-depth retina examination can point out if a patient is suffering from this condition.

High blood pressure goes unnoticed for quite some time, causing changes to the patient's vascular tree without them being aware of the chronic damage they are suffering. Furthermore, if other risk factors coexist like diabetes mellitus, obesity or tabacco use, then there is an increased risk of suffering thrombotic changes in the retina. 

The retina is the only part of our body where you can see the blood vessels (boths veins and arteries) directly and, in many cases, they are a reflection of the vasculature of the rest of our body. For this reason, it's important for patients with high blood pressure to have regular check-ups of the back of the eye. 

According to their stage, they can be divided into: 

• Accute hypertensive retinopathy. It is seen in cases where in a short period of time there is a very apparent increase in blood pressure. It usually causes blurred vision and a characteristic headache. In more severe cases in terms of the stage of progression and parameters of high blood pressure, clinical signs can be seen in the back of the eye such as haemorrhages and even inflammation fo the optic nerve head. This retinopathy presents itself in clinical contexts like pre-eclampsia and tumours like pheochromocytomas, etc.
• Chronic hypertensive retinopathy.  lt is the most common form of this retinopathy as high blood pressure is essentially a chronic pathology, evasive over time and silent in its symptoms. In advanced cases, different lesions in the retina can be seen such as anomalous crosses between the arteries and the veins (causing branch retinal vein occlusion), focal dilations of the veins called aneurisms, dispersed haemorrhages in the retina surfacce, a reduction in the calibre of the veins and, in more severe cases, oedema of the optic papilla. 

The majority of patients remain asymptomatic for a long period of time, even when they present the clinical signs described above.

The main complication of hypertensive retinopathy is thromboembolic occlusion of the blood vessels. There are three types: 

• Arterial obstruction. The patient notices a severe and sudden change to the visual field which may compromise visual acuity if the area affected includes the central zone of the retina called the macula. The greater the calibre of the occluded vessel, the greater the functional repercussion on the patient. No standardised treatment for retinal artery occlusion currently exists.
• Venous obstruction. The beginnings are also acute and the symptomology is similar to arterial obstruction although it is not noticed so suddenly. With respect to treatment, the lesions must be determined and the administration of intravitreal injections associated (or not) with laser photocoagulation must be assessed. 
• Ischaemic optic neuropathy. It is the blood supply to the optic nerve head that is damaged. With regard to symptoms, the patient may see changes to their visual field in terms of altitude (they lose vision in the middle of the visual field, normally the lower area).

If there is any pathology where it is necessary to be very strict in terms of prevention, then it's high blood pressure. The values need to be checked regularly and even more insistently among those who are already suffering from it. Regardless of the medication prescribed, different tips for a healthy lifestyle should be followed, for example, smokers should give up smoking, you should do exercise frequently and eat healthy food that is low in salt. 

Furthermore, you are advised to visit the ophthalmologist annually where you can have your pupils dilated and the state of your retina can be assessed, in order to rule out any of the clinical signs describd above.