Vision plays an important role for humans. Without normal blood supply to the eyes, they will not function fully. The structure of the organ is complex, a malfunction in the circulatory or nervous system can lead to complete loss of vision. Timely diagnosis and treatment can reduce the risk of developing the disease.
Eye structure
Eyes are the primary link in obtaining visual information. Further, the picture is transmitted along the optic nerve to the occipital lobes of the brain. The brain processes and forms a picture.
Stereoscopic vision makes the presence of two eyes. One side of the retina transmits information to one hemisphere of the brain, the second part acts similarly. The task of the brain is to connect the image together.
If there is a violation of the blood supply to the eyes, a malfunction in the binocular vision occurs. Eye movements become inconsistent. A person sees a forked picture or at the same time a different image.
The main parts of the eye:
- cornea - a transparent membrane covering part of the eye;
- iris - a circle responsible for the color of the eyes;
- pupil - hole in the iris;
- the lens is the lens of the eye;
- the retina consists of photoreceptors and nerve cells;
- the choroid lines the back of the sclera.
Vascular function
Poor blood supply to the eyes leads to a decrease in 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
Blood supply includes arteries, veins, and capillaries. The main supplier of blood is the artery. The upper branch of the carotid artery through the optic nerve approaches the eyeball. 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 artery of the retina. Its main function is the nutrition of the optic nerve. It passes through the disk 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 oxygen to the iris
- The muscle vessels that engage in muscle nutrition are engaged and pass into the anterior ciliary arteries.
- The upper and lower arteries forming a circular blood flow, due to which the blood supply to the eyelids occurs.
- The lacrimal artery, which additionally feeds the eyelids and supplies the lacrimal gland with nutrients.
Venous eye pattern
Spent blood is returned back through the vein. The blood supply to the eye is designed in such a way that a vein draws blood from the departments that fill the artery with blood. Vorticose veins depart from the choroid, which come to the superior and inferior ophthalmic veins.
Venous blood supply resembles arterial in the reverse order. Most of the veins go into the superior vein, the inferior vein has only two branches. The first part also goes into the superior vein, the second into the lower orbital fissure.
The venous system of the organs of vision, face and brain are interconnected and do not have valves. Therefore, blood flows freely into the brain. This is dangerous if infectious inflammation occurs in the eyes.
This structure of the eye allows you to regulate the body's metabolism, take away harmful and unnecessary substances and remove from the body. Each artery has its own vein, so the eye has full blood supply.
Innervation of the eye
Innervation of the eye - the presence in the tissues of the visual apparatus of the nerves that allow communication with the brain. The innervation and blood supply of the eye allows the organs of vision to function fully.
The first branch of the ternary nerve enters the orbit of the eye through the upper gap and is divided into three processes:
- lacrimal
- nasolabial;
- 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 to the nerve endings, which needs to be done.
Types of Nerves
All nerves of the eye can be divided into three groups:
- sensitive;
- motor;
- secretory.
The main function of the sensory nerves is to respond to the appearance of a foreign body or to feel pain. In case of inflammation or malfunction, a signal is sent to the brain. The trigeminal nerve is part of the sensory group.
The motor nerves monitor the work of the eyeball, its mobility, control the activity of the eye pupil, and control the expansion of the gap of the eye. The muscles that move the eye are activated by a brain signal using the lateral, abducent and oculomotor nerves. The facial muscle is driven by the facial nerve. The muscles responsible for the expansion and contraction of the pupil are controlled by the autonomic system.
The secretory nerves are interconnected with the secretory muscles that drive the lacrimal gland, conjunctiva of the eyelids, skin of the lower and upper eyelids.
The 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 begin 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;
- deflecting;
- side;
- facial;
- ternary.
The trinity is the largest. The nasociliary nerve enters the ternary, is divided into the 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 the muscles, except the external, it controls the muscle that raises the lower eyelid, the expansion of the pupil and ciliary muscle.
The lacrimal nerve activates the lacrimal gland, conjunctiva and skin of the upper and lower eyelids. Small nerves go to the ciliary node, three long ciliary nerves go to the eyeball. Near the ciliary body, they form a plexus and penetrate the cornea. The ciliary node is located in the orbit on the outside of the nerve and consists of sensitive fibers of the nasolacrimal nerve.
The frontal nerve is divided into the supralateral and infraorbital part. Block-like - puts the upper oblique muscle into operation. The abducent is responsible for the external rectus muscle. The facial nerve controls the circular muscle of the eye.
Signs of poor blood supply
Disruption of blood supply to the eyes is the main cause of decreased visual acuity or complete blindness. Such a disease is called ischemia. Chronic eye diseases, diabetes, hypertension, atherosclerosis lead to its development.
The main symptoms are a sharp decrease in vision, a split in the eyes. In 15% of cases diagnosed, short-term blindness appears, which is a harbinger of a serious illness. Complete blindness is observed in 10% of patients who applied. Most often, significant loss of vision occurs. When the central artery is damaged, the image becomes blurry or doubles.
On examination, the ophthalmologist notes a narrowing of the arterial mesh. The retina becomes cloudy, the color changes to gray. The optic nerve disc becomes cloudy last. By these signs, you can determine how long the disease appeared. A bright red spot appears on the retina, at which point the retina becomes thinner.
If the decrease occurred as a result of a spasm, then the probability of regaining 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. With a violation of the main artery, treatment does not give the desired effect.
With embolism of the main artery of the retina, the prognosis is pessimistic. In the case of a spasm, vision in young people may return, but in patients at an advanced age the prognosis is less favorable. In acute thrombosis of the central artery, vasodilator drugs are taken. Anticoagulant therapy is also performed. For an auxiliary effect, anti-sclerotic drugs and vitamins are taken.
Violation of the blood supply to the retina is the main problem with visual impairment. In this case, the work of the whole eye is disrupted, which leads to atrophy of some elements.
Symptoms of eye nerve damage
Damage to the optic nerve entails various diseases. The main symptoms of impaired nerve endings are:
- painful movement of the eyeballs;
- decreased visual acuity;
- color distortion;
- swelling of the eye;
- photopsy;
- decrease in peripheral vision;
- nausea;
- darkening in the eyes;
- blindness;
- redness of the disc.
Optic nerve disease and blood supply
Violation of the nervous system and blood supply to the cornea of the eye leads to various diseases:
- Paralytic strabismus is a violation of the movement of one of the eyeballs.
- Marcus-Gong syndrome - the eye spontaneously opens and closes when the jaw moves.
- Paralysis of the oculomotor muscles leads to a split image and pain when the eyeball moves in any direction.
- Horner's syndrome appears due to 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 alcoholic or narcotic substances.
- Neuropathy - damage to nerves from the retina to the brain. Additionally, blood circulation to the eyes is impaired.
- Transient ischemic attacks - short-term cessation of blood circulation.
- Cerebral crises.
- A stroke leads to impaired circulation of the eyeball.