Amblyopia

Introduction to amblyopia Amblyopia (amblyopia) is a common childhood eye disease in ophthalmology. There is no organic lesion inside or outside the eye. Corrected visual acuity is not normal (below 0.9). It is called amblyopia. Amblyopia is closely related to strabismus. Monocular deviation can cause this. Amblyopia, and amblyopia can form strabismus. In addition to ophthalmology diagnosis, treatment and prevention, the study of amblyopia involves related disciplines such as physiology, physics, and psychology. The boundary between amblyopia and normal eye vision is not very clear. Some patients complain of decreased vision, but objective examination, vision is still 1.0 or 1.2. This may be because the patient feels decreased vision compared to their previous vision. In addition, there may be certain obstacles in the visual cells of the central fossa or the conduction system behind it, with a very small central dark spot, consciously having visual impairment, but not objectively. basic knowledge The proportion of sickness: 0.01%-0.05% Susceptible people: children Mode of infection: non-infectious Complications: ametropia anisometropia congenital cataract

Cause of amblyopia

Strabismus amblyopia (30%):

Occurs in a single eye, the child has strabismus or has strabismus, is common in patients with monocular constant strabismus under the age of four, because the cerebral cortex actively inhibits the visual impulse of the squint, long-term inhibition of the formation of amblyopia, visual inhibition and amblyopia are only quantitative The difference is generally that the inhibition can be relieved when the squint is injected, and the amblyopia is the persistent vision loss. The earlier the age of strabismus occurs, the faster the inhibition occurs and the deeper the degree of amblyopia.

Anisometropic amblyopia (30%):

Because of the different visions of the two eyes, the retinal imaging of the two eyes is different in size and resolution. The imaging of the macular part with higher diopter is large and blurred, which causes insufficient fusion of the two eyes and can not form a single eye, which leads to passive suppression. Those with a light phase above 3.00D often have amblyopia and strabismus. Passive and active suppression exist simultaneously. The depth of amblyopia is not necessarily related to the degree of anisometropia, but it is related to the nature of gaze. The paracentral observer has a deeper degree of amblyopia. The nature of this type of amblyopia is similar to that of strabismic amblyopia. It is functional and reversible. Clinically, it is sometimes difficult to distinguish whether amblyopia is caused by anisometropia or secondary to strabismus. If this type can be found early, wearing glasses in time can prevent it.

Refractive amblyopia (15%):

Mostly binocular, children or adults with high myopia, myopia and astigmatism without corrective glasses, most of myopia is above 6.00D, hyperopia is above 5.00D, astigmatism is 2.00D or both have astigmatism. The binocular vision is equal or similar, and there is no binocular object like fusion dysfunction, so it does not cause functional inhibition of the macula. If appropriate glasses are worn in time, the visual acuity can be gradually improved.

Disuse amblyopia (15%):

In infancy, due to ptosis, corneal opacity, congenital cataract or too long covering time after eyelid surgery, light stimulation can not enter the eyeball, hinder or block the macula to receive form stimulation, resulting in amblyopia, so Also known as interruption of visual irritating amblyopia.

Congenital amblyopia or organic amblyopia (5%):

Due to the macular hemorrhage at birth, the cone cells are arranged irregularly, which occurs before the formation of the eyes after the baby is born, and the prognosis is not good. Although some retinal and central nervous system can not detect obvious lesions, it is still considered to be an organic disease. It can not be found because of the existing examination methods. This type is conserved amblyopia and the treatment is ineffective.

Pathogenesis

1. Visual Deprivation Wiesel and Hubel first published the physiological changes in the visual cortex and the histological changes in the lateral geniculate body caused by visual deprivation caused by suturing the eyelids of immature kittens. These experiments indicated that after the kitten was born 12 Peripheral unilateral orbital in the week can significantly reduce the functional changes in the visual center of the cortical cells stimulated by the deprived eye and connected to the eyes, and the histological changes of the lateral geniculate body receiving the deprived eye input. The deprived eyes are significantly smaller than the normal eyes. The work of Wiesel et al. has aroused widespread interest among scholars. The laboratories are eager to follow suit, but the results obtained are also inconsistent due to the different types of experimental animals.

In view of the fact that the monkey's visual system is similar in function and morphology to humans, von Noorden et al. used monkeys for experiments, some for unilateral orbital sutures, and some for extraocular muscle surgery, artificially causing strabismus, and the results were summarized. :1 The mechanism that enables people to produce amblyopia can also cause amblyopia in monkeys; 2 monkeys have the same visual system as humans, only sensitive to visual abnormalities or weakened visual input within a short period of time after birth, resulting in amblyopia; 3 long-term Strengthening the application of the main eye can reverse the main eye that has become amblyopia to the main eye. In short, the pathogenesis of amblyopia is extremely complicated. To simplify the problem, von Noorden summarizes the results of his own and other laboratories into the following: 1 Some experimental animals The visual system is very sensitive to abnormal or weakened visual input within 12 weeks of birth; 2 in this 12-week sensitive period, short-term visual abnormalities can cause a predictable, behavioral, visual system for various animals. Physiological and histological abnormalities, von Noorden called this type of abnormality as visual deprivation syndrome, experimental amblyopia caused by different causes (viewing In the deprivation syndrome, many of the manifestations are the same, so the pathogenesis is the same, that is, visual deprivation, unilateral or bilateral orbital suture can be compared with complete cataract or extensive corneal opacity, they all attenuate into the eye The light inside makes the macula unable to form a clear image. The image of one eye with higher diopter in patients with anisometropia is blurred, and the image of the eye with high hyperopia is also blurred. In the case of strabismus, the focus of the squint eye It seems to be determined by the adjustment of the gaze eye, so the object image of the squint eye is often blurred and unfocused, so all kinds of amblyopia have visual (shape) deprivation problems.

2. Binocular interaction has another important factor in the formation of amblyopia, that is, binocular interaction. Under normal circumstances, the binocular cells located in the lateral geniculate or cortex are in equilibrium, and when the visual abnormality occurs early in life, Deprived eye cells are at a disadvantage in the competition between the two eyes, and growth is hindered, which occurs when the visual input of the two eyes is not equal, such as unilateral orbital suture or hyperopic anisometropia, non-deprivation of eye clarity The image of the object competes with the blurred image of the eye that has the deprivation of the eye or the greater diopter. The image formed on the macula of the squint eye is also different from that on the macula of the gaze, which also causes competition, animal experiments and clinical cases. Both show that in the mechanism of amblyopia formation, binocular competition is also involved, bilateral deprivation amblyopia is purely bilateral congenital cataract, dense corneal opacity or uncorrected bilateral high hyperopia results; and due to strabismus, Unilateral amblyopia caused by paradox, unilateral cataract and occult amblyopia is formed by the combination of form deprivation and abnormal binocular interaction.

3. Active inhibition of the cerebral cortex In recent years, some preliminary experimental reports on biology and pharmacology have confirmed the active inhibition of cerebral cortex in developmental amblyopia.

(1) Physiological proof: It is believed that the main eye of the animal has active cortical inhibition on unilateral developmental amblyopia. For example, Kratz reported that removing the healthy eye after 5 months of visual deprivation can cause the deprived eye to be driven by only 6%. Cortical cells increased to drive 31%, which indicates that the main eye inhibits the function of the driven cells that are deprived of the eye. After the main eye is removed, the deprived eye quickly recovers its function, but it does not reach the original level.

(2) Pharmacological evidence: intravenous injection of bicuculline in animals can respond to cerebral cortical cells that do not respond to deprivation of the eye, in order to reduce the inhibition of the visual system at all levels, the experimenter can make the connection between the cerebral cortex and the deprived eye 60% re-recovery, but intravenous ciucul-line can cause convulsions, intravenous injection of naloxone in visually deprived animals can restore 45% to 50% of cortical cells to receive binocular visual input.

Amblyopia prevention

Amblyopia is a relatively common eye disease in children. The incidence rate is about 3%. Amblyopia occurs only in infants and young children with visual immature age. It is visual because of the critical period of visual development (before 3 years old) and sensitive period (6-8 years old). The fastest period of development, but also the period when vision is most susceptible to permanent damage caused by abnormal environmental stimuli. Therefore, correcting ametropia, anisometropia, strabismus and removing visual deprivation in time during critical and sensitive periods of visual development Factors are the fundamental way to prevent the occurrence of amblyopia. Pediatrics and ophthalmologists should have a strong awareness of preventing the occurrence of amblyopia. It should be observed whether infants and young children have possible factors for amblyopia, and early detection through feasible detection means, and timely correction.

Since the establishment of the national amblyopia and strabismus prevention and treatment group in 1984, regional amblyopia and strabismus prevention and treatment groups have been established in various provinces and autonomous regions in China. Up to now, many national amblyopia, strabismus academic exchange meetings and international academic seminars have been held. In the research on the basic theory of amblyopia, psychophysiology, electrophysiology and other aspects, great progress has also been made. A huge amblyopia prevention and treatment network has been formed, but this is not enough, and more media should be adopted. To promote the knowledge and harm of amblyopia and strabismus, so that more people can understand the basic knowledge about amblyopia and strabismus, and enhance people's conception of amblyopia, strabismus early detection and early treatment, in line with the implementation of the basic national policy of family planning. To improve the physical fitness of children in China, ophthalmologists shoulder important responsibilities.

The structure of the eye is very complicated, fine, and very susceptible to damage. The visual acuity is reduced and the blindness is severe. Therefore, protecting the eyes becomes a problem that cannot be ignored. To develop good habits, you must start with your baby.

First, pay attention to eye hygiene in infants and young children, and let children's towels, handkerchiefs, and washbasins be used separately from adults to avoid infection with acute conjunctivitis, trachoma and other infectious eye diseases; educate children not to dirty eyes; Give your child fun with scissors, needles, and other sharp and hard things to avoid hurting your eyes.

Second, educate children to pay attention to eye hygiene, children are playing with toys, don't be too close when watching comics or painting, keep the correct posture, and the lighting should be sufficient, not too dark or too strong, usually when the child is 4 years old. It is best to go to the hospital to check your eyesight. Once the situation is discovered, it should be treated promptly. After the child reaches the school age, he should pay attention to the combination of work and rest, insist on doing eye exercises and prevent myopia.

Third, children and adolescents are in the period of growth and development. Children should be encouraged to eat more coarse grains, miscellaneous grains, vegetables, fruits, and eat less foods with high sugar content. It is best not to eat snacks, not partial eclipse, and encourage children to go outdoors. Activities, participate in beneficial physical exercise, pay attention to the nutritional supply of the eyes.

Fourth, pay attention to the prevention of infectious eye diseases and systemic diseases. Many infectious eye diseases are transmitted through direct contact. No matter what eye disease is acquired, they should go to the hospital for treatment in time. Some systemic diseases also have a great impact on the eyes, such as tuberculosis. , kidney disease, etc., therefore, we must pay attention to prevention and treatment, to avoid delays in the disease.

Amblyopia complications Complications ametropia ametropia congenital cataract

Children with amblyopia often do not exist alone, generally have refractive errors and strabismus concomitant, refractive error is hyperopia, myopia, astigmatism, most of the complications of pediatric amblyopia are strabismus and hyperopia, astigmatism, however, such children with strabismus and After the correct correction of the refractive error through the lens or surgery, the visual acuity still does not improve much. Therefore, the cause of amblyopia is not the problem of refraction, but the problem of function, which can be complicated by anisometropia, congenital cataract, completeness. Hanging down and so on.

Symptoms of amblyopia Common symptoms Sudden after heavy drinking... Organic amblyopia anisometropic amblyopia strabismic amblyopia deprivation amblyopia reading small characters and difficulty in color discrimination

First, vision and refractive error

The boundary between amblyopia and normal eye vision is not very clear. Some patients complain of decreased vision, but objective examination, vision is still 1.0 or 1.2. This may be because the patient feels decreased vision compared to their previous vision. In addition, there may be certain obstacles in the visual cells of the central fossa or the conduction system behind it, with a very small central dark spot, consciously having visual impairment, but not objectively.

If the amblyopic eye has no organic changes, and its visual acuity is above 0.01, those below 0.2 are often accompanied by fixation abnormalities.

The relationship between amblyopia and refractive error, hyperopia accounted for a lot of weight, +2.00D mild hyperopia accounted for 37.7% of amblyopia, myopia showed more mild amblyopia, so amblyopia and high degree of hyperopia are closely related.

Severe amblyopia strabismus in strabismic amblyopia is more common than exotropia. It may be due to the fact that esotropia is earlier than the incidence of exotropia.

Second, the difficulty of reading

Or crowded.

When visual acuity is checked with the same optotype, illuminance, and distance, the measured values differ depending on the interval of the optotype. Difficulties in reading is a feature of amblyopia.

Difficulties in reading is that amblyopia is better at identifying individual visual targets than identifying sets or dense visual targets. That is, the resolution of a single open font (such as E word) on the eye chart is stronger than that of a line.

There are many reasons for difficulty in reading: It is believed that long-term persistence of strabismus causes a confined axial change in the pyramidal cell population. The visual target appears to be twisted and deformed to one side and is heavier than the visual target of the direction.

Third, amblyopia only occurs in young children

Eye amblyopia is gradually developed from birth to 9 years of age. Amblyopia or loss of shape can cause amblyopia during this development period. If you have the above reasons after 9 years old, amblyopia will not occur.

Fourth, amblyopia only occurs in patients with monocular vision

If you use both eyes alternately, amblyopia will not occur.

Five, fixation abnormalities

Those with deeper amblyopia have poor ability to fix the macular, and often use the omentum next to the macula to replace the macula as a fixation. Eccentric fixation refers to the fixation of the center fossa. There are many theories of its formation, but its manifestations include foveal fixation, peripheral fixation, macular fixation, and migratory fixation.

Amblyopia examination

No special laboratory tests are required.

General examination: visual acuity examination, external eye and fundus examination, refractive examination, strabismus examination, fixation test, binocular single vision examination, retinal correspondence examination, fusion function examination, stereoscopic examination.

Laser interferometric vision

Laser interference visual acuity (IVA) uses laser interference fringe as an index. When the contrast of the visual target is the maximum, the contrast is not changed, and the visual power can be measured only by changing the spatial frequency. Generally, the highest spatial frequency can be determined. /30 to indicate that because Snellen's vision is 1.0 when the resolution of the 1' angle is determined, if the identifiable spatial frequency is 30 weeks/degree (c/d), the angle of view corresponding to each stripe is 1.0. It is exactly 1', so 1/30 of the highest identifiable spatial frequency is the visual acuity corresponding to the visual acuity chart. The laser interference fringe is used as an index. When the visual standard contrast is maximum, the contrast is not changed, and only the spatial frequency can be changed. Vision is measured. Generally speaking, the IVA value represents the retinal vision that removes the influence of the refractive system of the eye, and directly reflects the functional state between the retina and the visual cortex. The IVA value of the amblyopic eye decreases with the amblyopia. And it is closely related to the decline of EVA value, and the IVA value of amblyopia is mostly higher than the EVA value.

2. Contrast sensitivity function

Contrast sensitivity function (CSF) is the ability of the human eye system to recognize sinusoidal grating optotypes of different spatial frequencies under bright contrast changes. It can be used as a sensitive, accurate and quantitative detection from time and space. The visual function index of amblyopia patients not only reflects the resolution of the visual target on small targets, but also reflects the resolving power of the coarse targets. The research shows that there are defects in CSF function in amblyopia, and different CSF changes in amblyopia caused by different causes. In strabismic amblyopia, some people think that only the high spatial frequency CSF declines, which is not consistent with the decline of visual acuity, while others think that there are two changes in strabismic amblyopia, one is that the CSF only shows a high spatial frequency, and the other One is the reduction of CSF at full frequency; there are also two views in anisometropic amblyopia. One thinks that the CSF in the full-frequency region is reduced, and the reduction in vision is almost parallel with the decrease in the CSF curve. Others believe that It can be damaged at full frequency, or it can be impaired in medium and high spatial frequencies. In deprivation amblyopia, the CSF in the low frequency region is roughly Often, the CSF of other frequency bands decreases, the CSF peak shifts to the left, and the cutoff frequency also decreases. Some people think that strabismic amblyopia is caused by the stereoscopic distortion of the central vision, that is, the X channel is damaged, while the anisometropic amblyopia is represented by the entire resolution. Caused by force disorder, a psychophysical examination of CSF does not exclude subjective factors of the subject.

3.VEP vision

Sokol measured VEP (pattern VEP, PVEP) in some infants and adults. It was found that infants and young children responded strongly to the checkerboard with a viewing angle of 7.5' or 15' at 6 months, which was the same as adult 20/20 vision. Infants and young children established a 20/20 visual function at 6 months. The measurement method is to use the checkerboard stimulation, and the squares become smaller until the VEP capable of measuring the minimum amplitude is induced. The highest spatial frequency at this time represents the most. Good vision.

The above describes several visual function inspection methods. Subjectively and objectively, qualitatively and quantitatively reflect visual function from different angles. Various inspection methods have certain advantages and disadvantages. According to China's current conditions, A large number of children over the age of 3 visual acuity test, E eye chart visual acuity test is still the preferred method, I believe that in the near future will be more commonly used in the scientific, more accurate and simpler method to detect visual function.

4. Electrophysiological examination

(1) Electroretinogram: simple light stimulation (F-ERG), there is no significant difference in electrical response between amblyopic eyes and normal eyes. Sokol reported using graph electroretinogram (P-ERG) to examine the b-wave amplitude of ERG in amblyopia. The amplitudes of the post-potentials were all reduced. The experimental study of the Chinese Yin Zhengqin found that the P-ERG response of the strabismus decreased, and that the visual function damage caused by strabismus was related to the retina and the visual center.

(2) Visual evoked potential (VEP): The retinal is stimulated by light or a specific pattern to generate nerve excitation. It is transmitted to the visual center through the visual pathway. Using modern microelectrode technology and computer technology to record these potential activities, visual observation can be made. Evoked potential (VEP), Wagner test P-VEP (Graphic VEP) in normal children and children with amblyopia found that the VEP latency of amblyopia was prolonged, the amplitude was smaller than that of healthy eyes, and the amplitude was not significantly improved when both eyes were stimulated. P-VEP was used to measure amblyopia. Visual evoked potentials in children with non-amblyopia can be found in the contralateral eye of amblyopia and the cured amblyopia. Although the visual acuity is completely normal, VEP is still abnormal, characterized by a significant extension of the P100 wave latency.

(3) Clinical application of VEP: 1 Study the visual development of infants and young children: use VEP to check the spatial discrimination of infants and young children, and find that they develop rapidly, reaching the adult level in 6 months; the infants' time frequency discrimination threshold is higher, mature The earliest, indicating that infants and young children in the first 6 months of visual system development from the macula to the cerebral cortex is very fast, VEP is a new and reliable method in the visual function test of infants and young children, 2 amblyopia pathology, physiological mechanism: amblyopia Animal model experiments show that the occurrence of amblyopia is related to the sharpness of the image on the retina. When the image on the retina in childhood is always blurred, it will lead to the occurrence of amblyopia (peripheral theory), 3 detection stereoscopic: many Experts report that VEP may provide objective indicators for stereoscopic detection. The amplitude of VEP in both normal eyes is higher than that in single eyes. Arden reports that the VEP waveforms of the two eyes are similar in normal stereopsis, and the phase inversion may occur in the eyes without vision.

(4) VEP manifestation of amblyopia and strabismus:

1 Flash VEP: The VEP induced by flash stimulation, most scholars believe that the flash VEP of amblyopia patients is normal.

2Graphic VEP: Most scholars believe that the VEP of the amblyopic eye is abnormal, mainly because the P1 wave is prolonged, the amplitude is reduced, and the P2 wave latency is shortened. This change is especially noticeable in the medium-high spatial frequency pattern stimulation (Fig. 6). Patients with amblyopia not only have amplitude reduction, latency, but also waveform changes.

3 horizontal strabismus VEP performance: domestic Yin Zhengqin and other artificial monocular oblique cat model, using P-ERG and P-VEP to observe the development of spatial resolution of 20 normal eyes and strabismus from 4 to 30 weeks old monocular strabismus cats In the process, it was found that the decrease of P-VEP response in strabismus can occur after 1 week of strabismus. It increases with age and cannot be reversed with age. The decrease of P-ERG reaction in oblique eye mainly occurs in the early stage of strabismus, growth and development. In the late stage, the spatial resolution of the retina has increased and tends to the normal eye level. The functional damage caused by strabismus is related to the retina, the central nervous system, and the central nervous system is seriously damaged.

Domestic Guo Jingqiu, Zhao Kanxing et al. conducted a full-field and half-field checkerboard inversion VEP study in children with amblyopia and exotropia, and found that the VEP amplitudes of both esotropia and exotropia were reduced, the latency was prolonged, and strabismus was found. The amblyopia full-field image stimulation multi-guided VEP topographic map showed a half-field stimuli effect, confirming that the nasal retina of the amblyopia has a certain degree of inhibition in a certain range; the external oblique amblyopia has a certain degree of inhibition in the temporal retina At the same time, the half-field irritating strabismus amblyopia, the slanting amblyopia showed a greater response to the temporal retina than the stimulating nasal retina; the external oblique amblyopic showed a response that stimulated the nasal retina more than the stimulating temporal retina, supporting the internal oblique The abdomen of the amblyopia is inhibited by the retina, the theory of inhibition of the retina of the external ambly amblyopia, anisometropic amblyopia, ametropia amblyopia, and full-field stimuli have no semi-visual stimuli, suggesting its pathogenesis and strabismus Amblyopia is different.

(5) Simultaneous recording of P-VEP and P-ERG: P-VEP has been widely used in clinical detection of visual acuity and stereopsis, assessment of visual acuity function of amblyopia and early diagnosis of amblyopia, monitoring and treatment, P-ERG for amblyopia patients The diagnosis and monitoring of treatment results are different, but the simultaneous recording of the two provides more comprehensive information than a single P-VEP or P-ERG examination, which helps to understand the impact of amblyopia on the entire visual system: The functional status and variation of the tissue, and the observation and analysis of the relationship between each other, such as the retinal-visual cortical conduction timing (RCT), etc., is particularly beneficial for the evaluation of various amblyopia treatment effects and neurophysiological mechanisms, Katsumi et al. Synchronous recording of steady-state P-ERG and P-VEP was used to observe the effects of different human retinas receiving different stimulation fields (upper, lower, nasal, temporal) on the visual system, suggesting the diagnostic value of this method in visual path diseases. , Yin Zhengqin and other P-ERG and P-VEP synchronous recording to study amblyopia, suggesting that the pathological changes of amblyopic eyes are not only in the visual center; but also the retinal ganglion cells are also affected, especially to distinguish the fine pattern structure of type X The cells are damaged significantly.

(6) Full-field or half-field stimulation of multi-visual evoked potential topographic maps: Multi-channel VEPs (12-48 electrodes) can observe a certain moment after stimulation on the entire skull surface (especially the skull surface covering the visual cortex) The distribution and variation of VEPs in two-dimensional space. On this basis, the potential values collected by each electrode are processed by computer, and the points of the same polarity and value are connected to form the equipotential map of VEPs, that is, the topographic map of multi-channel VEPs, which can be dynamic. , image, visually shows the brain electrical activity after visual stimulation.

Zhao Kanxing and other studies have shown that the normal children's binocular or monocular full-field stimulation of multi-channel VEPs is horizontally symmetric. When the strabismus amblyopia stimulates the eye, the topographic map has a half-field stimulation effect, and the distribution is asymmetric. The parasitic amblyopia full-field stimulation of multi-channel VEPs was symmetrically distributed, suggesting that the pathogenesis of the two is different.

5. Positron emission tomography (PET)

The basic principle of PET is to use a tracer (such as 18F, 75Br) to label metabolic substrates (such as glucose; amino acids), according to the absorption of radioactive substances after stimulation of brain neurons, visually reflect brain activity, positron is negative Electron antiparticle, which is emitted by the nucleus, annihilates after encountering negative electrons, emits photons and performs three-dimensional quantitative analysis. Demer et al. used 18F-2-deoxyglucose (FDG) as a tracer for 3 severe adults. Amblyopia (corrected visual acuity 20/200) and 2 normal subjects were tested for PET. As a result, 2 normal people had bilateral cerebral activity symmetry. After double optical lens fog (optical blur, 20/200), their activity decreased by 8%. Amblyopia is less than 5% to 6% of the brain activity in the contralateral eye. In 1 case of amblyopia, the contralateral cerebral hemisphere is 23% less active than the ipsilateral brain, which is asymmetric, especially in the temporal lobe. The area (19th, 7th) also showed high glucose metabolism, supporting the parallel processing theory of visual cortex information, suggesting the extensiveness of amblyopia cortical damage, Kiyosawa et al. using 14F-2-fluorescence-deoxyglucose tracer detection Visual deprivation Effects of glucose metabolism, found from the shape of the eyelid closure side to reduce the metabolic rate of the cortex 14% (P <0.05), but did not change significantly throughout the cerebral metabolism.

The diagnosis of brain function by PET can not only understand the metabolism of brain circulation, oxygen, glucose, amino acids, etc., but also combine with single photon emission tomography (SPECT) to qualitatively and quantitatively study the receptors of neurotransmitters. Azimuth shows the brain function of amblyopia patients and provides a new means to study its pathogenesis.

Amblyopia diagnosis

diagnosis

Diagnosis can be performed based on clinical manifestations and examinations. The relationship between amblyopia and refractive error, hyperopia accounted for a lot of weight, +2.00D mild hyperopia accounted for 37.7% of amblyopia, myopia showed more mild amblyopia, so amblyopia and high degree of hyperopia are closely related. Severe amblyopia strabismus in strabismic amblyopia is more common than exotropia. It may be due to the fact that esotropia is earlier than the incidence of exotropia.

Differential diagnosis

Need to identify similar symptoms with refractive error, strabismus, myopia and other eye lesions.

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