Afakia Eyes

Afakia is the absence of the lens. The eye without the lens is called aphakic. Congenital aphakia is rare.

Usually the lens is removed surgically due to its turbidity or dislocation. There are cases of loss of the lens with penetrating wounds.

The pathological state of the visual apparatus, in which there is no lens in the eye, is aphakia. Consider its features, causes, symptoms and treatment.

According to the International Classification of Diseases of the tenth revision of ICD-10, aphakia refers to two categories simultaneously:

1. Purchased form

VII Diseases of the eye and its adnexa (H00-H59).

• H25-H28 Diseases of the lens.

2. The congenital form

XVII Congenital malformations (malformations), deformations and chromosomal abnormalities (Q00-Q99).

Q10-Q18 Congenital malformations of the eye, ear, face and neck.

• Q12 Congenital malformations (malformations) of the lens.
  • Q12.3 Congenital aphakia.

The absence of the lens in the eyeball is an ophthalmic disease that often occurs with the deepening of the anterior chamber of the eye. Against this background, a pathological bulge is formed - a hernia. For aphakia is characterized by the trembling of the iris, i.e. Iridodonez. This symptom is also evident with the preservation of a part of the lens. Trembling of the shell is aimed at restraining the tremors of the vitreous body when moving the eye.

The disease is both acquired and congenital. It can develop after surgery, in which the eye traumatized. The aphakic eye is characterized by a violation of the refractive power of the visual structure. There is also a significant reduction in visual acuity and lack of accommodation.

[1], [2],

Epidemiology

Medical statistics indicate that the diagnosis of aphakia annually receives about 200 thousand people. This pathology is not fatal, so no cases of death were recorded.

Disease is 27% more likely to be diagnosed in men than in women. The risk group includes elderly patients, people whose work is associated with a risk of eye injuries. The congenital form is associated with an abnormal course of pregnancy and the transmitted infectious diseases of the expectant mother during gestation.

[3], [4], [5]

Causes of the afakia

The main causes of aphakia are associated with traumatism of the visual apparatus. Penetrating wounds and injuries can lead to the loss of the lens and the development of blindness. In medicine, cases of a congenital defect are recorded when a child is born with this pathology.

On this basis, the causes of the disease can be congenital and acquired. In ophthalmology distinguish such varieties of congenital pathology:

• Primary - due to aplasia of the lens.
• Secondary - develops during the intrauterine resorption of the lens.

Depending on the prevalence, the disorder can be monocular (one-sided) and binocular (bilateral).

[6], [7]

Risk factors

Risk factors for aphakia directly depend on the form of the disease: congenital and acquired. The latter is most often associated with such factors:

• Self-loss of the lens as a result of injuring the eyeball.
• Dislocation of the lens, requiring its removal or surgical cataract treatment.

Congenital pathology is associated with impaired fetal development during the intrauterine formation of all organs and systems.

[8], [9], [10], [11], [12]

Pathogenesis

The mechanism of origin and development of aphakia depends on its causes. The pathogenesis of the primary congenital form is based on a violation in the genes PAX6 and BMP4. Because of the delay in the development of the eyeball structure, pathology develops at the stage of the cornea-lens contact.

The secondary form of the disease is associated with idiopathic lens absorption. Its pathogenesis is based on mutation and disruption of the formation of the basal membrane, from which the lens capsule develops.

With regard to the pathogenesis of acquired ophthalmic pathology, the focus is on dislocation and subluxation of the lens, surgical extraction of cataracts, penetrating wounds or eye contusion of the eyeball.

[13], [14], [15], [16], [17], [18], [19]

Symptoms of the afakia

Ophthalmic pathology has its characteristic features. Symptoms of aphakia are manifested by a violation of binocular vision and lack of accommodation. Against the background of jittery irises due to the absence of the lens, the visual acuity decreases.

Patients complain of the appearance of fog in front of the eyes, developing a low ability to fix the doubling of the image. Often there are headaches, weakness, irritability, deterioration of general well-being.

[20], [21], [22], [23]

First signs

Disturbance of the visual apparatus has different causes of origin. The first signs of the disease largely depend on the factors that caused it. Let's consider the main clinical manifestations of pathology:

• Deepening of the anterior chamber of the eyeball.
• The remains of the lens in the area of the iris.
• Iris trembling while moving eyes.
• Formation of a hernia.

The above symptoms are an occasion to immediately consult a doctor. Without timely medical attention, the disease can lead to a complete loss of vision.

[24], [25], [26], [27], [28]

Stages

Afakia has certain stages, which are determined by the degree of loss of the lens and visual acuity.

Consider the main stages of ophthalmic disease and their characteristics:

Degree of violation	Characteristics of violations	Disability group
I	Afakiya monocular. Violations of mild severity. Reduction of visual acuity within 0,4-1,0 diopters with the possibility of correction on a better seeing eye.	Restriction of the CWC
II	Monocular or binocular aphakia. Significant reduction in visual acuity on a better seeing eye, but with the possibility of correction. With the monocular form of the disease, a pathological narrowing of the field and visual acuity is possible, which can not be corrected.	Group III
III	The absence in the eyeball of the lens proceeds with other diseases that affect the healthy eye. Visual acuity is within 0,04 - 0,08 with the possibility of correction on the better seeing eye.	Group II
IV	Monocular and binocular form of pathology with severe changes in various ophthalmological structures. Pathological reduction of visual acuity.	Group I

 

Depending on the stage of the disease and the degree of disturbances, the methods of treatment, that is, the correction of vision, are selected.

[29], [30], [31]

Forms

The absence of the lens in the eyeball, is a pathological condition that leads to cardinal changes in refraction and reduced visual acuity. The types of illness depend on whether both eyes are affected or one.

Afakia is divided into two types:

• Single-sided (monocular) - is diagnosed most often, characterized by the absence of the lens in only one eye. It can be accompanied by aniseikonia. That is, a vision of objects of different sizes, both sick and healthy eyes. This significantly complicates the quality of life.
• Two-sided (binocular) - most often occurs as a result of a severe form of cataract, which caused deformation of the lens of both eyes. Characterized by a violation of the refractive power of the visual structure. There is no accommodation, that is, a clear vision of objects at different distances, visual acuity falls.

With progression, the disease can occur with various complications. A complete loss of vision is possible on one and the same eye.

Monocular afakia

One-sided or monocular aphakia is characterized by the presence of a healthy lens in only one eye. All moving objects and objects falling within the field of vision can be perceived only by one eye. Monocular type of vision gives information about the shape and size of the image. While the binocular is characterized by the perception of the image in space, that is, the ability to record how far from the eyes the object is located, its volume and a number of other characteristics.

Monocular aphakia is of two kinds. In the first case, visual information is fully perceived by one eye. In the second case monocular alternating vision, i.e., aniseikonia, is observed. The patient alternately sees one or the other eye.

In addition to aphakia, there are other pathologies with a monocular type of vision:

• Monocular diplopia - due to the deflection of the axis of view, objects falling in the field of view, seem to be double. Doubling occurs with partial opacification or displacement (subluxation) of the lens. Similar occurs at congenital pathologies or traumas of an eye.
• Monocular strabismus is an abnormal violation of the parallelism of one of the visual axes. Mowing only one eye, his visual acuity drops sharply. The brain is rebuilt to receive information only from a healthy eye. Because of this, the visual functions of the diseased eye drop even more. In some cases, alternating strabismus is diagnosed when a person alternately sees one or the other eye.
• Monocular blindness - this pathology is characterized by temporary attacks of blindness. It is due to a variety of diseases. Most often these are vascular and non-vascular lesions of the retina, optic nerve or brain disease.

The diagnosis of monocular aphakia is not difficult. Various methods and apparatus are used for this. Regardless of the cause, pathology requires specialized medical treatment

[32]

Afakia, artifacty

Disturbance of the visual apparatus, in which there is no lens in the eye - is aphakia. Artifakia is the presence in the eye of the artificial lens. His implantation is carried out to correct aphakia. The advantage of this treatment method before the glasses in the normalization of the field of view, the prevention of distortion of objects, and the formation of an image of normal magnitude.

To date, there are many designs of lenses. There are three main types that differ in the principle of attachment in the chambers of the eye:

1. Prechamber lenses - are located in the anterior chamber of the eye, relying on its angle. They are in contact with the iridescent and cornea, that is, the most sensitive tissues of the eye. They can cause the formation of a synechia in the corner of the anterior chamber.
2. Pupillary - papillary or iris-clip-lens. They are inserted into the pupil as a clip, fixed with the help of the front and back support elements. The main disadvantage of this type of lens is the risk of dislocation of support elements or the entire artificial lens.
3. Zadnekamernye - are placed in a bag of the lens after the complete removal of its nucleus with cortical masses. They take the place of a natural prototype in the optical system of the eye. Provide the highest quality of vision, strengthen the connection between the anterior and posterior organ barrier. Warn the development of postoperative complications: secondary glaucoma, retinal detachment and others. They contact only with the lens capsule, in which there are no nerve endings and which does not cause inflammatory reactions.

Artificial lenses for artifacts with aphakia are made from soft (hydrogel, silicone, copolymer collagen) and hard (polymethylmethacrylate, leucosapphire) material. They can be multifocal or in the form of a prism. Treatment is carried out by surgical methods, which are based on increasing the refractive power of the cornea.

Posttraumatic aphakia

One of the causes of aphakic eyes is injuries and injuries. Posttraumatic aphakia develops due to the destruction of the lens or its loss during extensive corneal or corneal scleral injuries. In a number of cases, the dislocation of the lens under conjunctiva was diagnosed in cases of concussive ruptures of the sclera.

Very often, a pathological condition develops when traumatic cataracts are removed or when the lens is dislocated after a contusion injury. Traumatic cataract can cause tears of the sphincter and mydriasis, the formation of scars on the iris, the appearance of traumatic colobomas, ectopia of the pupil, aniridia.

In addition to aphakia, secondary pleural cataracts lead to clouding of the vitreous humor, partial atrophy of the optic nerve. Cicatricial changes in the choroid and retina, peripheral chorioretinal foci are also possible. Various methods of correction and optic reconstructive operations are used for treatment.

Complications and consequences

The pathological condition, in which the lens lacks the lens, causes serious consequences and complications. First of all, it should be noted that in the absence of a lens, the vitreous humor is retained by its anterior border membrane. This leads to the formation of protrusion in the pupil, that is, the hernia of the vitreous. The progression of the hernia is dangerous by rupturing the anterior border membrane and the exit of vitreous fibers into the anterior chamber of the eye. Another common complication of ophthalmic disease is the opacification and swelling of the corneal shell.

The monocular form of the disease is very often complicated by aniseikonia. For this complication, it is characteristic to obtain images of different sizes to the diseased and healthy eye. This greatly complicates the life of the patient. A congenital form of aphakia or a disease caused by the removal of the lens in childhood can be complicated by microphthalmia. Without proper treatment, pathology leads to a significant deterioration in vision, loss of efficiency and even disability.

[33], [34], [35]

Diagnostics of the afakia

The diagnosis of aphakic eye does not cause difficulties, since the absence of the lens is noticeably visual. Diagnosis of aphakia begins with examination of the fundus by a microscope and a slit lamp. Surveys are necessary to determine the severity and stage of the disease, as well as to choose the method of treatment and correction.

The main diagnostic methods used for the violation of the visual apparatus:

• Ophthalmoscopy
• Refractometry
• Biomicroscopy with slit lamp
• Ultrasound (to exclude detachment of the retina)
• Visometry
• Gonioscopy

Visometry determines the degree of visual acuity reduction. Gonioscopy is used to establish the severity of the deepening of the anterior chamber of the eye. With the help of ophthalmoscopy, it is possible to identify associated pathologies, as well as cicatricial changes in the retina, choroid, atrophy of the optic nerve.

The main diagnostic criteria for aphakia are: the trembling of the iris with the movement of the eye, the lack of supporting lens function, the deep anterior chamber, astigmatism. If there was a surgical intervention, then a scar is determined.

[36], [37], [38], [39]

Analyzes

Laboratory diagnostics of visual apparatus disorders is performed both at the stage of diagnosis and during treatment. Analyzes with aphakia consist of:

• General blood analysis
• Blood for sugar
• Blood on RW and Hbs antigen
• General urine analysis

According to the results of the conducted studies, the doctor makes a plan for therapy, both the underlying disease and the accompanying ones.

[40], [41]

Instrumental diagnostics

Surveys with aphakia, conducted with the help of various mechanical instruments - is an instrumental diagnosis. In ophthalmic disease, such methods are used: visometry, perimetry (determination of the field of view), biomicroscopy, tonometry (intraocular pressure), ophthalmoscopy, ultrasound. They allow you to determine the severity of the disease and other features of its course.

When studying the aphakic eye, attention is drawn to the deep anterior chamber and the iris of the iris (iridonas). If the posterior capsule of the lens is retained in the eye, then it restrains the tremors of the vitreous with movements of the eye and the trembling of the iris is less pronounced. With biomicroscopy, the light section reveals the location of the capsule, as well as the degree of its transparency. In the absence of the lens bag, the vitreous body, held only by the anterior border membrane, presses and slightly permeates the pupil area. This condition is called a hernia of the vitreous. When the membrane ruptures, vitreous fibers emerge into the anterior chamber. This is a complicated hernia.

Differential diagnosis

In most cases, for the statement of such a diagnosis as afakia, it is enough to collect an anamnesis. Differential diagnosis is carried out both in congenital and acquired forms of the disease. Differentiation requires monocular and binocular types of pathology. Violation is compared with similar symptoms of ophthalmic disorders.

The aphakic eye is characterized by such signs:

• Deterioration and change in visual function.
• Sensation of a foreign body in the eye, flies and a veil before the eyes.
• Vagueness and fuzziness of the image due to the violation of accommodation.
• Iris and vitreous humor.
• Destruction of the posterior capsule of the lens and extrusion of the vitreous or lens parts through the pupil.
• Cicatricial changes of the cornea (if the disease is caused by severe forms of conjunctivitis).
• Koloboma in the upper parts of the iris.

For differentiation, both instrumental and laboratory diagnostic methods are used.

Treatment of the afakia

After removal of the lens, the refraction of the eye changes dramatically. There is hypermetropia of a high degree.

The refractive power of the lost lens must be compensated for by optical means-glasses, a contact lens or an artificial lens.

Ophthalmic and contact correction of aphakia is currently rarely used. To correct the aphakia of the emmetropic eye, a glass glass with a force of +10.0 D is required, which is substantially less than the refractive power of the distant lens, which on average is 19.0 Dpt. This difference is due primarily to the fact that the spectacle lens occupies a different place in the complex optical system of the eye. In addition, the glass lens is surrounded by air, while the lens is a liquid with almost the same refractive index of light. For a hypermetrop, the force of the glass should be increased by the required amount of diopters, in myopia, on the contrary, it will be thinner, less than the optical power. If before the operation myopia was close to 19.0 D, then after surgery too strong optics of myopic eyes are neutralized by removal of the lens and the patient will do without glasses for distance.

Afakichny eye is not capable of accommodation, so to work at close range appoint points 3.0 dpts more than for distance. Ocular correction can not be used for monocular aphakia. The lens +10,0 Dpt is a strong magnifying glass. If it is placed in front of one eye, then in this case the images in the two eyes will be too different in size, they will not merge into a single image. With monocular aphakia, contact or intraocular correction is possible.

Intraocular correction of aphakia is a surgical operation, the essence of which is that the turbid or dislocated natural lens is replaced by an artificial lens of the appropriate force. Calculation of the dioptric force of the new eye optics is performed by the doctor using special tables, nomograms or computer program. For calculation, the following parameters are required: the refractive power of the cornea, the depth of the anterior chamber of the eye, the thickness of the lens and the length of the eyeball. General refraction of the eye is planned taking into account the wishes of patients. For those of them who drive a car and lead an active life, they often ask emmetropia. It is possible to schedule low-grade myopic refraction if the second eye is short-sighted, as well as for those patients who spend most of the day at the desk, want to write and read or perform other precise work without glasses.

Correction of aphakia in children

To achieve high visual acuity in children with aphakia, careful correction of refractive disorders is necessary. As the eye grows and its refraction decreases, periodic replacement of contact lenses is required. Correction of aphakia can be carried out by the following methods.

[42], [43]

Glasses

This is the main method for correcting bilateral aphakia, but with one-sided aphakia glasses are rarely used, only in case of intolerance to contact correction. One of the advantages of spectacle correction is the relatively low cost. Disadvantages include the difficulty of fitting heavy glasses to a young child, since a small nose can not support many of the spectacle frames.

Contact lenses

Contact lenses remain the main method of correcting both unilateral and bilateral aphakia. For children of this group, soft gas permeable and even rigid contact lenses are used. In the first months of life, silicone contact lenses are especially effective. Frequent loss of the lens and the need to replace it with the growth of the eye increase the cost of this method of correction. Despite the fact that there are reports of keratitis and scarring of the cornea in children with aphakia, these problems are extremely rare.

[44], [45], [46], [47], [48]

Epikeratophacia

This procedure with the use of a superficial laminar corneal transplant proved to be inappropriate. Currently used rarely.

[49], [50], [51], [52], [53], [54],

Intraocular lenses

In children, intraocular lenses are more often used to correct aphakia after removing progressive and post-traumatic, less often congenital cataracts. Many authors point out the possibility of their implantation even in children of 2 years of age. In these terms, the growth of the eye basically ends and it becomes possible to calculate the strength of the lens for the child as for an adult patient. The question of implantation of intraocular lenses in congenital cataracts remains controversial.

Implantation in the first weeks of a child's life in the process of primary surgical intervention is inexpedient. The upcoming eye growth complicates the problem of calculating the strength of the intraocular lens; In addition, this pathology often accompanies the microphthalmos. There is a question, whether the intraocular lens itself influences the physiological growth of the eyeball.

Thus, in most cases, one should not go for primary implantation with true congenital cataracts, although secondary implantation of the intraocular lens in older children and with high visual acuity is becoming increasingly popular.

In children of the older age group with traumatic cataracts, implantation of the intraocular lens is a common method of treatment. Currently, the most common intra-capsular fixation of a monolithic IOL from PMMA.

Prevention

Specific methods for preventing congenital form of aphakia are absent. Prophylaxis is necessary for acquired pathologies of the visual apparatus. For this purpose it is recommended to undergo annual examinations with an ophthalmologist. The doctor will be able to identify diseases that require surgical removal of the lens. For people who are at risk for eye injuries due to the characteristics of the profession, prevention consists in using protective masks and glasses.

To maintain a healthy vision, you must follow these rules:

• Balanced diet.
• A full night's rest.
• The minimum visual overload.
• Correct mode of work at the computer.
• Carrying out gymnastics for the eyes.
• Regular preventive examinations at the ophthalmologist.
• Observance of safety precautions when performing hazardous operations for eyes.
• Eye protection against ultraviolet radiation.

Afakia is a serious disease that can lead to loss of vision. Observance of preventive measures allows minimizing the risk of this pathology.

[55], [56], [57], [58], [59], [60], [61]

Forecast

The most unfavorable prognosis is the one-sided form of aphakia. This is due to the risk of complication with aniseikonia. Congenital forms are characterized by a progressive decrease in visual acuity, which without timely treatment can cause blindness. With regard to the posttraumatic form of the disease, it is characterized by an increase in symptoms with an early pain syndrome, pronounced local edema and a progressive decrease in visual acuity.

Afakia leads to temporary disability, and in some cases, disability. If there are no changes in the neuromuscular apparatus of the eye and the correct optical correction is made, then the prognosis is favorable, since high visual acuity and ability to work persist.

[62], [63], [64]