Eye crossing pictures: Stock photos, royalty-free images, graphics, vectors & videos

14.05.202309.06.2023 by alexxlab

Содержание

What Is Adult Strabismus? – American Academy of Ophthalmology

Adult strabismus (crossed eyes) is when your eyes are not lined up properly and they point in different directions. One eye may look straight ahead while the other eye turns in, out, up, or down. The misalignment can shift from one eye to the other.

Strabismus affects vision, since both eyes must aim at the same spot together to see properly.

There Are Six Eye Muscles That Control Eye Movement

One muscle moves the eye to the right, and one muscle moves the eye to the left. The other four muscles move the eye up, down, and at an angle. In order to focus on a single image, all six eye muscles must work together.

What Causes Adult Strabismus (Crossed Eyes)?

To line up and focus both eyes on a single target, all muscles in both eyes must be balanced and working together. The brain controls these muscles. People who have strabismus usually have a problem that can affect eye muscles. Some of those problems may include:

Health problems such as diabetes, thyroid disease (Graves’ disease), Myasthenia gravis, brain tumors, or a stroke

Accidents or head injury

Damage to eye muscles during some kind of eye surgery

Most adults with strabismus have had it since they were children. But sometimes it starts later in life.

How Does Adult Strabismus Affect Vision?

With normal vision, both eyes aim at the same spot. The brain combines the two images from our eyes into a single, three-dimensional (3-D) image. This is how we can tell how near or far something is from us (called depth perception).

When one eye is out of alignment, two different pictures are sent to the brain. In a young child, the brain learns to ignore the image of the misaligned eye. Instead, it sees only the image from the straight or better-seeing eye. As a result, the child loses depth perception.

Adults who develop strabismus after childhood often have double vision. This is because their brains have already learned to receive images from both eyes. Their brains cannot ignore the image from the turned eye, so they see two images.

What Are the Symptoms of Adult Strabismus (Crossed Eyes)?

The most obvious symptom is having eyes that appear out of alignment. Adults with strabismus also may notice these other symptoms:

Weakness in or around the eye, or feeling like something is pulling around your eyes.

Vision changes, such as double vision (seeing two of one image), blurry vision, trouble reading, or a loss of depth perception.

Constantly tilting or turning your head to see an image clearly.

Strabismus symptoms can be constant, or they can come and go.

Adult Strabismus (Crossed Eyes) Treatment

There are several ways to treat strabismus in adults.

Adult strabismus (crossed eyes) surgery

This is the most common treatment for strabismus. Surgery can improve eye alignment and help restore proper vision.

Typically, strabismus occurs when the muscles around the eyes are either too stiff or too weak. An ophthalmologist can loosen, tighten, or move certain eye muscles so that the eyes line up properly to work together. More than one surgery may be needed to treat strabismus.

Surgery is usually done as outpatient surgery in a hospital or surgery center, using either general or local anesthesia. Your ophthalmologist makes a small cut in the tissue covering the eye to reach the eye muscles. The muscles are then repositioned to help the eyes point in the same direction. This may need to be done in one or both eyes. After strabismus surgery, you can get back to your daily routine within a few days.

Eye muscle exercises

An ophthalmologist can teach you exercises to help you focus both eyes inward. These exercises can help if you have “convergence insufficiency.” That is when your eyes do not align properly for close tasks, like reading or computer work.

Prism eyeglasses

A prism is a clear, wedge-shaped lens that bends (refracts) light rays. A prism can be attached to eyeglasses or made as part of the lens. Prisms can help some people with mild double vision see one image, not two.

Botulinum toxin (Botox®)

In some cases, an injection (shot) of this drug in the eye muscles can help treat strabismus. It paralyzes the muscles that keep your eyes from aligning properly. The effect can last for just a few months, or it could permanently improve eye alignment.

It Is Never Too Late to Treat Strabismus

You do not have to live with the discomfort and problems caused by misaligned eyes. With your ophthalmologist’s help, you can find a treatment for your strabismus.

crosseyed photos on Flickr | Flickr

Eye Refractometry | Refractometry interpretation

Visual acuity and other important features of vision depend on how the optical system of the eyeball refracts and then focuses light rays. Refractometry is a fast, accurate, informative and safe method of diagnostic examination. The method allows, even at an early stage, to detect astigmatism, myopia, hyperopia or other ophthalmic pathology, determine the severity of the anomaly and predict the rate of development of the disease.

Without a correct assessment of the refraction of the eye, it is impossible to establish an accurate diagnosis, obtain the necessary personal recommendations from an ophthalmologist, correct the disorder and improve the quality of life of a child or an adult.

What the refraction of the eye says

Light rays pass through several refractive structures: the cornea, aqueous humor of the anterior and posterior chambers of the eye, the lens and the vitreous body. After that, they fall on the retina.

In turn, the light-sensitive tissue transforms the rays into nerve impulses. Through the optic nerve, electrical signals enter the brain and form a picture in the departments that process visual information.

Clinical refraction – the focus of the intersection of light rays relative to the retina. If it is located:

directly on the light-sensitive tissue, ophthalmologists speak of 100% vision;
in front of her, doctors diagnose myopia;
behind the retina, reveal farsightedness;
in the case of astigmatism, the light beam after refraction is focused not at one point, but at several at once.

Any pathology of refraction negatively affects visual acuity, causes discomfort to a person, complicates the learning process, interferes with work activities and causes inconvenience in everyday life.

Reasons for the examination

The procedure is used to diagnose visual impairment, to clarify the medical opinion and the degree of the identified anomaly. In addition, it is part of a comprehensive assessment of the health of the optical system.

Eye refractometry is indicated:

in case of sharp or gradual deterioration of vision;
in case of change in vision of nearby objects or objects far away;
after laser vision correction, surgical intervention in the optical system;
before surgical treatment.

Examination is required for any distortion of visible objects. From their blurring and doubling to the inability to see small objects at close range.

Refractometry Diagnosis

In order to expand the pupils and get more accurate results, the ophthalmologist prescribes a three-day preparation. For 3 days, a person should instill drops of Atropine into the eyes in the morning and evening. The concentration of the drug depends on the age of the patient. Adults and children over three years of age are prescribed a 1% solution, children who have not reached the age of three are 0.5% composition, infants under 1 year old are 0.1% drops.

The study itself is carried out using a computer autorefractometer, it takes no more than 3-5 minutes.

The ophthalmologist disinfects the surfaces that the patient will come into contact with, then:

Seats the person in front of the apparatus.
Helps to correctly position the head on the stand, turn it to the right angle.
Examines the right eye.
Shows the patient images that gradually change in clarity.
Adjusts the device so that infrared rays are directed to the center of the pupil of the eye.
Repeats diagnostic manipulations with the left eye.
Prints out the examination results.

During the procedure, the patient must not turn or move his head to the side, but is allowed to blink.

Harmless infrared rays pass through the optical system of the eye, are refracted, reach the retina and are then reflected. The device fixes the volume of the sent and reflected beam of light, the time it spent on it. The result is processed and issued after printing on a sheet. Based on accurate and reliable information, the doctor makes a diagnosis and determines which method of vision correction is suitable for the patient.

Designations and their interpretation

The vision test sheet reflects the parameters and digital indicators for the right and left eyes.

Index	Refractometry interpretation
Ref	Examination result
L	Left eye
R	Right eye
Sph	Refractive power of a spherical lens. The designation “-” indicates myopia, “+” indicates hyperopia, “0” indicates the norm.
Cyl	Anomalies of the cornea, shape of the eye or lens – optical power of a cylindrical lens. Reflects the degree of astigmatism, therefore it is taken into account when choosing lenses.
PD	Distance between two pupils
AVG/AVE	The radius of curvature of the cornea is its average value.
Axis/Ax	Angle to set lenses for astigmatism. Depending on the age of the patient, the value of the norm may vary.
VD	The distance that should be between the eye and the frame of the glasses. The vertex distance is 12 to 14 mm.
Ker	Curvature of the anterior wall of the cornea. This parameter is important when choosing contact lenses.
S.E.	Spherical equivalent. This is the summed value of the largest and smallest refraction of the eye.
R1, R2	The radius of curvature of the cornea, which was measured in its minimum and maximum meridian.

Ophthalmologists take into account that illness, fatigue and a number of other reasons can distort the results of the examination. Therefore, if the need arises, doctors prescribe a second study.

How Refractometry is Performed in Children

If a child’s head is fixed, this will automatically lead to pupil tension. In this regard, for children under the age of 4 years, the skiascopy method is often used. Other names for the procedure are retinoscopy, shadow test, and keratoscopy.

How an ophthalmologist examines the refractoriness of children’s eyes:

Seats the child on a chair.
It has a lamp on its side.
Sits in front of the child at a distance of 1 m.
Directs the light of the lamp at the mirror at an angle so that it hits the fundus of the eye.
Moves the skiascope up and down.
Tracks the displacement of the shadow area on the surface of the fundus.

When the doctor is examining a newborn, he or she may use medication to relax the eye muscles. To study the organs of vision of children 4-6 years old, an autorefractometer is used. Before the procedure, they are prescribed dilating pupil drops.

For the convenience of small patients, special corrective nozzles are used and they are allowed to be on the parent’s lap during the diagnosis. They, as in the diagnosis of adults, gently fix their heads on a stand and show pictures with changing clarity.

Immediately after a five-minute examination, parents receive the results on the form, a transcript from a specialist and personalized recommendations for correcting their child’s vision.

When computer diagnostics are contraindicated

Diagnosis can be hampered by a violation of the transparency of the light-refracting elements of the eye and some temporary human conditions.

Refractive analysis is not performed if the patient has:

Complete or partial clouding of the lens.
Vitreous opacity.
Clouding of the cornea.
Alcohol or drug intoxication because the person is unable to focus.
A mental disorder that prevents the patient from remaining still and following the instructions of the ophthalmologist.
Inflammatory eye diseases.
Allergic reaction to pupillary dilator.

If a person has ocular hypertension, then refractometry is performed, but without the use of Atropine solution or its analogues.

How refraction changes with age

People have different values of the curvature of the cornea and lens, the distance between these elements. All this makes the characteristics of refraction purely individual. At the same time, parameters change with age.

Babies, for example, are farsighted. People in their forties develop age-related farsightedness. In young people aged 20 years, 40% of cases are diagnosed with myopia, 30% with hyperopia, and 30% with normal vision.

In addition, it should be borne in mind that when examining the left eye, myopia can be detected, the other hyperopia, in addition, both anomalies can be combined with astigmatism. Often, diseases of the optical system and the body, corneal injuries provoke a decrease in visual acuity. Therefore, every year it is advisable to visit an ophthalmologist for a preventive check. Such a reasonable approach will stop the development of pathology and carry out a suitable correction.

05/06/2022

Services

Doctors

Ochirov Sanal Alexandrovich

Ophthalmic surgeon (Yaroslavl), the highest category

Semechkova Victoria Alexandrovna

Ophthalmic surgeon (Yaroslavl)

Edemskaya Olga Sergeevna

Ophthalmologist

Eliseeva Olesya Vasilievna

Ophthalmologist

Perova Tatyana Valentinovna

Pediatric ophthalmologist, 1st category

Article

Vision as it is

In the simplest sense, vision is primarily two eyes that receive and process information about the world around us. In fact, human vision, of course, is much more complicated, and information from the sense organs (that is, the eyes) goes through several stages of processing: both by the eye itself and then by the brain. Together with the 3Z Ophthalmological Clinic, we tell how the human visual system forms an image of reality, and explain why we do not see the world upside down, small, shaking and divided into two parts.

From your school physics course, you may remember lenses – devices made of a transparent material with a refractive surface, which, depending on their shape, can collect or scatter the light falling on them. We owe it to lenses that there are cameras, video cameras, telescopes, binoculars and, of course, contact lenses and glasses that people wear in the world. The human eye is exactly the same lens, or rather, a complex optical system consisting of several biological lenses.

The first of these is the cornea, the outer shell of the eye, the most convex part of it. The cornea is a concave-convex lens that receives rays from every point on an object and transmits them further through the moisture-filled anterior chamber and pupil to the lens. The lens, in turn, is a biconvex lens, shaped like an almond or an oblate sphere.

Biconvex lens – converging: the rays passing through its surface are collected behind it at one point, after which a copy of the observed object is formed. An interesting point is that the image of an object formed at the back focus of such a lens is real (that is, it corresponds to the same observed object), inverted and reduced. The image that forms behind the lens is therefore exactly the same.

The fact that the image is reduced allows the eye to see objects that are several tens, hundreds and thousands of times larger than it. In other words, the lens compactly folds the image and in the same form gives it to the retina, which lines most of the inner surface of the eye – the place of the back focus of the lens. Together, the cornea and lens are thus a component of the visual system that collects the scattered rays emanating from an object into one point and forms their projection on the retina. Strictly speaking, there is actually no “picture” on the retina: these are just traces of photons, which are then converted by the receptors and neurons of the retina into an electrical signal.

This electrical signal then travels to the brain where it is processed by the visual cortex. Together, these departments are responsible for converting signals about the location of photons – the only information that the eye itself receives – into meaningful images. At the same time, the brain is an interconnected system, and not only our eyes and visual system, but also other sensory organs that can receive information are responsible for how we perceive what is happening in reality. We do not see the world upside down due to the fact that our vestibular apparatus has information that we are standing straight, with two feet on the ground, and a tree growing from the ground, accordingly, should not be upside down.

Confirmation of this is an experiment that American psychologist George Stratton set up on himself in 1896: the scientist invented a special device – an invertoscope, whose lenses can also flip the image that the one who wears them looks at. In his device, Stratton walked for a week and at the same time did not go crazy from having to move in an inverted space. His visual system quickly adapted to the changed circumstances, and after a couple of days the scientist saw the world the way he used to see it since childhood.

In other words, there is no special section in the brain that flips the image received on the retina: the entire visual system of the brain is responsible for this, which, taking into account information from other senses, allows us to accurately determine the orientation of objects in space.

3Z Clinics

As for the retina itself, in order to understand how vision works, you also need to take a closer look at its functioning and structure. The retina is a thin multilayer structure that contains neurons that receive and process light signals from the optical eye systems and send them to each other and to the brain for further processing. In total, three layers of neurons are distinguished in the retina and two more layers of synapses that receive and transmit signals from these neurons.

The first and main neurons involved in the processing of light stimuli are photoreceptors (light-sensitive sensory neurons). The two main types of photoreceptors in the retina are rods and cones, named for their rod and cone shape, respectively. Rods and cones are filled with light-sensitive pigments – rhodopsin and iodopsin, respectively. Rhodopsin is many times more sensitive to light than iodopsin, but only to light with one wavelength (about 500 nanometers in the visible region) – this is why rods containing rhodopsin are responsible for human vision in the dark: they catch even the smallest rays, helping us to distinguish the outlines of objects, while not allowing you to accurately determine their color. But the “daytime” photoreceptors – cones – are already responsible for color perception.

Light-sensitive iodopsin, which is part of cones, is of three types, depending on the wavelength of light it is sensitive to. In the normal state, the cones of the human eye respond to light with long, medium and short wavelengths, which roughly corresponds to red-yellow, yellow-green and blue-violet colors (or, more simply, red, green and blue). There are different numbers of cones that contain one or another type of iodopsin in the retina, and their balance helps to distinguish all the colors of the surrounding world. In the case when cones with one or another type of iodopsin are not enough or simply not present, they speak of the presence of color blindness – a feature of vision in which recognition of all or some colors is not available. The type of color blindness directly depends on which cones “do not work”, but deuteranopia is considered the most common in a person – with it there are no cones whose iodopsin is sensitive to medium wavelength light (that is, they perceive green color poorly or do not perceive it at all) .

In this case, rods and cones do not cover the entire corresponding layer of the retinal surface: it contains the so-called blind spot, which does not contain photosensitive receptors at all. Since there are none, there is nothing to process the light within the borders of the spot – that is why those objects that fall into the “field of view” of the blind spot are invisible to humans. The vision of any person (fortunately or unfortunately) does not allow you to see these blind spots, but some diseases lead to the appearance of a scotoma (that is, a blind area in the visual field) and outside the corresponding place on the retina.

The signal received and processed by photoreceptors then passes to another layer of neurons – bipolar cells. Such cells are a kind of intermediaries that connect cones and rods with ganglion cells – retinal neurons that generate nerve impulses and then transmit them along the optic nerve to the visual cortex of the brain through the lateral geniculate body (a small tubercle on the surface of the thalamus).

The lateral geniculate body, having received signals from retinal ganglion cells, first transmits them to the primary visual cortex, the most evolutionarily ancient part of the visual system of the brain (also called V1 for convenience and brevity). At this point, the formation of an actual image of what is happening around us begins – the photons received by the eye begin to take shape, and the color, shape, presence of movement and other aspects of the image turn into electrical activity. Depending on what these signals convey (the movement of an object in space or its shape), they are then sent for processing along the ventral and dorsal pathways to other parts of the visual cortex. For example, the middle temporal visual area (its serial number is five, that is, it is briefly called V5) is considered part of the dorsal pathway, as it is responsible for motion processing, and the fourth zone (V4) is responsible for color processing, therefore it belongs to the ventral pathway.

Modern technologies help to solve vision problems. For the correction of myopia, hyperopia and astigmatism, 3Z clinics have collected 6 of the world’s best vision correction practices: ReLEx SMILE, ReLEx FLEx, Femto Super LASIK, Super LASIK, PRK and implantation of phakic intraocular lenses. The technology is selected individually for each patient to ensure the best result. Therefore, visual acuity after surgery is often 120% or even 150%.

The departments responsible for processing information from the sense organs and, as we have already found out, helping to recreate a picture of the real world to the visual system, are not the only parts of the brain that are involved in the process of vision. The motor cortex, which is responsible for processing movements, also plays an important role. The motor cortex is important because the eyes are constantly moving: shifting your gaze helps you follow a moving image or see something that is not entirely in the field of view.

In a calm state (when we look at a static object or even at the background), the eyes still move, making very fast synchronous movements (up to 80 milliseconds) – saccades. Information that the eye needs to change position is sent to it from the motor cortex. A little earlier, exactly the same (or at least similar) signal is sent to the visual cortex as a so-called “efferent copy”. This gives the visual cortex information that the eye will move before the movement even starts, which helps the visual cortex to ignore possible small movements.

Finally, it remains to deal with one more point – why the picture of reality that we see is not divided into two parts. Humans, like other vertebrates, have one pair of eyes. They are located quite close to each other: the holes in the eye sockets of the skull provide the location of the eyes in such a way that each of the eyes, on the one hand, has its own field of view (about 90 degrees for each eye – that is, a little more than 180 in total), and on the other – 60 degrees of the central field of view, which intersect with each eye. Due to this intersection, the images received by one and the other eye are combined into one image in the center of the common field of view. The same intersection of visual fields provides us with stereoscopic (or binocular) vision and the ability to perceive depth. Binocularity of vision is lost in some forms of strabismus – and with them the normal ability to perceive depth is also lost.

Therefore, the mechanism of how the image of reality is formed in our brain is not only optics and chemical reactions occurring on the retina. The most important role in creating this picture is played by our brain – and not only the visual cortex, which makes the figures voluminous, separates them from the background and paints them in the right colors, but also other departments that are responsible for vital functions.

The 3Z clinic treats all types of visual impairments due to an irregular shape of the eye (nearsightedness and farsightedness) or excessive curvature of the cornea (astigmatism). Until July 15, vision correction in 3Z can be done in installments without an advance payment and overpayments.
The promotion is valid for all types of laser vision correction, as well as for the implantation of phakic intraocular lenses (PIOL).