Vision plays an important role for a person. Without a normal blood supply to the eyes, they will not fully function. The structure of the organ is complex, a malfunction of the circulatory or nervous system can lead to complete loss of vision. Timely diagnosis and treatment can reduce the risk of developing the disease.
The structure of the eye
Eyes are the primary link in receiving visual information. The image is then transmitted along the optic nerve to the occipital lobes of the brain. The brain processes and forms the picture.
Stereoscopic vision makes the presence of two eyes. One side of the retina transmits information to one hemisphere of the brain, and the other side does the same. The task of the brain is to connect the image together.
When the blood supply to the eyes is disturbed, binocular vision fails. Eye movements become inconsistent. A person sees a split image or a different image at the same time.
Basic parts of the eye:
- cornea - a transparent membrane that covers part of the eye;
- iris - circle responsible for eye color;
- pupil - a hole in the iris;
- lens - the lens of the eye;
- the retina is made up of photoreceptors and nerve cells;
- the choroid lines the back of the sclera.
Vascular functions
Poor blood supply to the eyes leads to reduced visual acuity. The blood vessels of the organs of vision have a complex structure. They provide the eyes with essential nutrients. The circulatory system of the eyes begins with the carotid artery. Thanks to the developed blood supply system, the vessels of the eye perform the following functions:
- saturation of the organs of vision with oxygen and nutrients;
- removal of harmful substances, components of the decay of metabolic processes and carbon dioxide.
The structure of the arterial system of the eye
The blood supply includes arteries, veins and capillaries. The main blood supply is the artery. The superior branch of the carotid artery approaches the eyeball via the optic nerve. Inside, there is a branch of several vessels that are responsible for their part of the organ of vision. If one of the vessels is disturbed, the general blood flow is disturbed. The arterial system of the eye includes:
- Central retinal artery. Its main function is to nourish the optic nerve. Passes through the disc and stops at the fundus. Several vessels are responsible for the inner layer of the retina.
- Short ciliary posterior arteries feed the nerve endings. Located in the sclera.
- Long ciliary posterior arteries supply oxygeniris of the eye
- Muscular vessels that feed the muscles are engaged and pass into the anterior ciliary arteries.
- The upper and lower arteries that form the circular blood flow, due to which the eyelids are supplied with blood.
- The lacrimal artery, which additionally feeds the eyelids and supplies the lacrimal gland with nutrients.
Venous scheme of the eye
The spent blood is returned back through the vein. The blood supply to the eye is built in such a way that the vein takes blood from those departments that the artery fills with blood. Vorticose veins depart from the choroid and come to the superior and inferior ophthalmic veins.
Venous blood supply resembles arterial blood supply in reverse order. Most of the veins go to the superior vein, the inferior vein has only two branches. The first part also goes into the superior vein, the second - into the inferior orbital fissure.
The venous system of the organs of vision, face and brain are interconnected and do not have valves. Therefore, blood flows freely to the brain. This is dangerous when an infectious inflammation occurs in the eyes.
This structure of the eye allows you to regulate the metabolism of the body, take away harmful and unnecessary substances and remove them from the body. Each artery has its own vein, so the eye has a full blood supply.
Innervation of the eye
Innervation of the eye - the presence in the tissues of the visual apparatus of nerves that allow you to communicate with the brain. Innervation andblood supply to the eye allows the organs of vision to fully function.
The first branch of the trigeminal nerve enters the orbit of the eye through the superior fissure and divides into three processes:
- tearful;
- nasociliary;
- frontal.
Signals from all parts of the eye about actions and sensations occur due to receptors that cover a significant part of the visual organ. Information enters the brain, is processed, the brain sends a signal through the nerve endings, what needs to be done.
Types of nerves
All the nerves of the eye can be divided into three groups:
- sensitive;
- motor;
- secretory.
The main function of sensory nerves is to respond to the appearance of a foreign body or to feel pain. When inflammation or malfunction occurs, a signal is sent to the brain. The trigeminal nerve is part of the sensory group.
Motor nerves monitor the work of the eyeball, its mobility, control the activity of the eye pupil, control the expansion of the eye slit. The muscles that move the eye are actuated by a signal from the brain via the lateral, abducens, and oculomotor nerves. The facial muscle is driven by the facial nerve. The muscles responsible for pupil dilation and constriction are controlled by the autonomic system.
Secretory nerves are interconnected with secretory muscles that activate the lacrimal gland, eyelid conjunctiva, skin of the lower and upper eyelids.
Structure of the nervous system of the eye
The nervous system of the eye controls the muscles, is responsible for the state of blood vessels and blood supply to the eyes. Nerves originate in the cerebral cortex and consist of 12 pairs of nerve endings. Some of them are responsible for the work of the visual organ:
- oculomotor;
- diverting;
- side;
- front;
- ternary.
Trinary is the largest. The nasociliary nerve enters the ternary and divides into posterior, ciliary, anterior and nasal parts.
The maxillary nerve is also part of the ternary, divided into infraorbital and zygomatic. The oculomotor nerve is responsible for the work of nerve fibers, for all muscles except the external one, controls the muscle that lifts the lower eyelid, pupil dilation and the ciliary muscle.
The lacrimal nerve activates the lacrimal gland, conjunctiva, and skin of the upper and lower eyelids. Small nerves go to the ciliary ganglion, three long ciliary nerves go to the eyeball. Near the ciliary body, they form a plexus and penetrate into the cornea. The ciliary ganglion is located in the orbit on the outer side of the nerve and consists of sensory fibers of the nasociliary nerve.
The frontal nerve is divided into supratrochlear and supraorbital parts. Block-shaped - brings to work the upper oblique muscle. Abductor - responsible for the external rectus muscle. The facial nerve controls the orbicular muscle of the eye.
Signs of poor blood supply
Impaired blood supply to the eyes is the main cause of reduced visual acuity or total blindness. Suchthe disease is called ischemia. Chronic eye diseases, diabetes mellitus, hypertension, atherosclerosis lead to its development.
The main symptoms are a sharp decrease in vision, double vision. In 15% of diagnosed cases, short-term blindness appears, which is a harbinger of a serious illness. Complete blindness is observed in 10% of the applied patients. Most often there is a significant loss of vision. If the central artery is affected, the image becomes blurry or doubles.
On examination, the ophthalmologist notes a narrowing of the arterial network. The retina becomes cloudy, the color changes to gray. The optic disc becomes cloudy last. By these signs, you can determine how long ago the disease appeared. A bright red spot appears on the retina, in this place the retina becomes thinner.
If the decrease occurred as a result of a spasm, then the probability of returning vision is quite high. The removal of spasm leads to an improvement in the blood supply to the human eye and an improvement in vision. In case of violation of the main artery, the treatment does not give the desired effect.
In case of embolism of the main artery of the retina, the prognosis is pessimistic. In the case of spasm, vision in young people may return, but in elderly patients the prognosis is less favorable. In acute thrombosis of the central artery, vasodilators are taken. Anticoagulant therapy is also carried out. For an auxiliary effect, anti-sclerotic drugs and vitamins are taken.
Impaired blood supply to the retinais the main problem with visual impairment. In this case, the work of the entire eye is disrupted, which leads to atrophy of some elements.
Symptoms of eye nerve damage
The defeat of the optic nerve entails various diseases. The main symptoms of a nerve ending disorder are:
- painful eye movement;
- decrease in visual acuity;
- color distortion;
- eye swelling;
- photopsy;
- reduced peripheral vision;
- nausea;
- blackout eyes;
- blindness;
- disc redness.
Diseases affecting the optic nerve and blood supply
Violation of the nervous system and blood supply to the cornea of the eye leads to various diseases:
- Paralytic strabismus - a violation of the movement of one of the eyeballs.
- Marcus-Goon syndrome - the eye spontaneously opens and closes when the jaw moves.
- Paralysis of the oculomotor muscles leads to double vision and pain when moving the eyeball in any direction.
- Horner's syndrome occurs due to an underlying eye disease.
- Trigeminal neuralgia is expressed by severe pain at the site of inflammation.
- Neuritis - inflammation in the tissues of the nerve.
- Toxic damage occurs after taking alcohol or drugs.
- Neuropathy is nerve damage from the retina to the brain. Additionally, the blood circulation of the eyes is disturbed.
- Transient ischemic attacks - short-term cessation of blood circulation.
- Cerebral crises.
- Stroke leads to impaired circulation of the eyeball.
