Ask some medical terms of ophthalmology.

The first one. stereoscopic vision

Let's do a little experiment: hold a ballpoint pen in each hand, stretch your hands horizontally, and slowly close the nib, and you will find it easy to align the two nibs; It won't be so easy if you close one eye and try. Why is this? When our eyes look at an object, the object forms two images on the retina of the left eye and the right eye respectively. However, because there is a certain interval between the left and right eyes, the left eye can see the image slightly to the left and the right eye can see the image slightly to the right, so the two images are not exactly the same and cannot completely overlap. In this way, visual images are introduced into the brain, and through the synthesis and discrimination of the brain, objects have a sense of depth and a sense of three-dimensionality, which is stereoscopic vision, also called depth vision or stereoscopic vision. When we close one eye, only a single image is transmitted to the brain, so we can't establish a three-dimensional sense. All the objects we see are on the same plane. So after closing one eye, it is not easy to aim at the nib. Stereovision can be checked with the same camera or stereovision inspection pictures. People without stereoscopic vision lack stereoscopic vision, can't distinguish the distance of objects, and can't be competent for drivers, machining and painting. With the increase of distance, the images of objects in our eyes are very close. Generally, after more than 500m, the images of the object on the two retinas basically coincide, so the stereoscopic effect is not obvious, right? Why does a bright moon seem to hang on a tree? Using the principle of stereoscopic vision, people have developed three-dimensional aerial photos. Two plane aerial photographs are placed under the stereoscope. The left eye looks at the left photo through the left eyepiece, and the right eye looks at the right photo through the right eyepiece. With a little adjustment, you will find that the mountains, deep valleys, waterfalls and glaciers in the photo are all "standing", as if you were looking down at the earth from an airplane. In addition, people have developed stereoscopic photography, stereoscopic movies and stereoscopic paintings to serve production, life and entertainment.

The second one. Refraction.

The refractive system and photosensitive system of eyeball are two important parts to ensure normal visual function, which can be compared with the lens and film of camera. Transparent tissues such as cornea, aqueous humor, lens and vitreous body constitute the refractive system of the eye, while retina is the photosensitive system. To take a clear picture, the focus of the camera lens must be aimed at the film. Similarly, if the eyes want to see the object clearly, the imaging must focus on the retina. The parallel light of external objects, through the function of eyeball refraction system, is just imaged on the retina, and the object is very clear. The chart of standard hyperopia shows that hyperopia is above 65438 0.0. Near vision at a distance of 30 cm can also reach 1.0. It's called looking straight at the eye. If the imaging falls before or after the retina, the vision will be blurred and poor. This is called ametropia.

Ametropia can be divided into myopia, hyperopia, astigmatism and presbyopia.

Myopia: Parallel rays from a distance pass through the refractive system of the eyeball and form images in front of the retina. The impression on the retina is blurred, and the vision is not good when you look far away. However, when looking near the target, because the light is scattered, the imaging can still fall on the retina, so the myopia vision is not affected. The reason of myopia refraction may be that the anterior and posterior axes of the eyeball exceed the normal length, or the refractive power of the refractive system is too strong. The cause of myopia is not completely clear. The inheritance of high myopia is certain. When parents are highly nearsighted, their children are more likely to suffer from myopia than ordinary people, but environmental factors can not be ignored. Both clerical workers and young students suffer from myopia, which tells us that there seems to be a close relationship between long-term close work and myopia. Bad eye hygiene habits will accelerate the development of myopia. For example, reading in poor light or unstable environment, books or work targets are too close to the eyeball, and the eyes are used for too long. The general health status also has obvious influence on the occurrence and development of myopia. Improper rest, malnutrition, irregular life and lack of attention to exercise will all promote the development of myopia.

Because myopia mostly begins in school-age children and adolescents, it is of great significance to vigorously carry out the prevention and treatment of myopia in schools.

Schools and parents should care about children's eye hygiene, keep the classroom well lit, read and write correctly, don't lie down or read books while riding, don't read books for too long, and pay due attention to rest and outdoor activities.

In recent years, people have made many explorations on the treatment of myopia, but there is no conclusion. For teenagers with low myopia and short onset time, you can try acupuncture, eye exercises, wearing glasses or dropping cycloplegic agents. These treatments may temporarily improve some people's eyesight, but they must be closely combined with preventive measures, otherwise it is difficult to achieve tangible results. At present, the more reliable treatment is still wearing glasses. After wearing glasses, the eyesight is improved, which is not only beneficial to work and study, but also can alleviate fatigue symptoms and prevent further development of myopia.

Hyperopia: Because the refractive power of the eyeball is too weak or the anterior and posterior axes of the eyeball are shorter than normal people, the parallel light of external objects passes through the refractive system and falls behind the retina. In order to keep clear vision, hyperopia patients should use accommodation power whether they are near or far, especially when they are near the target, so they are often accompanied by headaches, especially eye pain, and visual fatigue such as reading and writing can not last long.

Hyperopia should be corrected with convex lens, and the correction should be as complete as possible. Children must dilate their pupils with atropine before they can get proper glasses.

Astigmatism eye: Astigmatism refers to that the refractive power of the meridians on the eyeball surface, especially the cornea surface, is different, and the refractive power in one direction is stronger or weaker than that in the other direction, so that the imaging on the retina is not on the same plane. Astigmatism can be divided into myopia astigmatism and hyperopia astigmatism. Astigmatism can also cause symptoms of vision fatigue, so wear it often after glasses.

Presbyopia: When a person reaches a certain age, the texture of the lens becomes hard, and the elasticity decreases or disappears. Therefore, the ability (accommodation ability) required for lens thickening to adapt to the near target also decreases. It is very difficult to read, write or do external work, and you need to put it far away to see it clearly.

The age of presbyopia is not consistent, which is related to personal health and refractive status. The average age is about 45 years old. Old glasses are only worn when reading, writing or doing fine close work.

The third one. Organ diseases.

Pathomorphological changes of organs or tissues during organic diseases. Including pathological morphological changes observed by naked eyes, histological lesions seen under optical microscope and subcellular lesions seen under electronic microscope. Organic diseases are often accompanied by functional changes of the affected tissues or organs, such as liver cirrhosis, which is often accompanied by abnormal liver function. However, some organic diseases have no obvious dysfunction due to various reasons (such as early stage and body compensation). ), such as hemangioma and cutaneous lipoma.

The fourth one. Macula.

Macula is an oval concave area located at the posterior pole of retina, with a diameter of about 1mm ~ 3mm and an area slightly larger than that of optic papilla. It turns yellow soon after death, hence the name macula. The center of macula is fovea, and small reflective spots with a diameter of 0.2 mm can be seen in fundus examination. The retina in this area is very thin and consists only of cone cells, so it is the most sensitive part of central vision. Macula occupies a small area in the retina, but because of its important position and special structure, it determines people's vision and is the most important part of fundus examination.

Except refractive stroma (cornea, lens and vitreous), the central visual quality of human beings is closely related to the state of macula. As long as the macula changes a little, it will affect the central vision and bring inconvenience to people's work, life and study. Many eye diseases also easily affect macula, such as trauma, retinitis, cataract surgery and so on. , seriously affecting vision. Macular lesion is one of the common eye diseases that lead to blindness in patients. So be careful.

The fifth one. Mydriasis.

Mydriatic optometry is an optometry under the condition that drugs completely paralyze the ciliary muscle of the eye and make it lose its adjustment function. This is mainly because teenagers have strong eye adjustment ability. If the pupil is not dilated during optometry, the adjustment of ciliary muscle can make the lens bulge and enhance the refractive power, but it can not remove the so-called pseudo-myopia, which affects the accuracy of the results. Therefore, mydriatic optometry is necessary for adolescent myopia patients.

Mydriasis optometry is mainly used in the following situations: (1)1children under 2 years old. Because of its strong adjustment function, if optometry does not mydriasis, the error will be great. (2) 12 ~ 4o-year-old patients with myopia, hyperopia or astigmatism should, in principle, mydriasis in the first optometry, and if the diopter does not change much in the second optometry, the pupil optometry can be increased or decreased according to the original diopter. (3) The fundus and refractive stroma are normal, but the vision is poor, so mydriasis optometry is needed to eliminate ametropia. (4) More complicated ametropia, such as high myopia, high hyperopia or high astigmatism, myopia or hyperopia with astigmatism. (5) Teenagers' eyesight is unstable, good for a while and poor for a while, which is suspected to be pseudomyopia. Once the pupils of these patients are dilated and the accommodation function disappears, the pseudomyopia will be eliminated.

There are also some cases that are not suitable for mydriatic optometry: (1) Patients with glaucoma are prohibited from mydriatic optometry, otherwise it will induce acute glaucoma attacks. (2) Patients suspected of glaucoma should be very cautious if they find shallow anterior chamber, high intraocular pressure or at the high limit of normal value. (3) Patients over 40 years old generally don't need mydriasis optometry because of their weakened accommodation ability.

Patients of different ages have different methods of mydriasis optometry. At present, the commonly used methods are: 3 ~ 12 years old, apply 1% atropine eye ointment to eyes for 3 days 1 day, optometry on the fourth day, and try on glasses after 3 weeks; 12 ~ 18 years old, apply 2% thick matopine eye drops every 5 minutes 1 time, a total of 6 times, optometry after 1 hour, and try on glasses after 10; After 18 years old, use compound tropicamide eye drops, 1 time, once every 5 minutes, 6 times in total. Optometry after half an hour, try glasses the next day.

The following personnel must mydriasis when optometry:

Children under (1) 15 have strong eye accommodation, and the younger they are, the stronger their eye accommodation will be. If the accommodation is not paralyzed, the optometry result will be extremely wrong and the pupil must be dilated. A powerful mydriatic agent-atropine is usually used.

(2) Myopia 16-30 years old and hyperopia 16-40 years old require mydriasis for the first optometry, but an intermediate mydriatic agent-Houmatopin can be used. The pupil can be enlarged or not according to the situation when the glasses are fitted for the second time and later.

(3) For more complicated ametropia, such as high myopia astigmatism, high myopia mixed astigmatism and high astigmatism, mydriasis optometry is more accurate, and if it is not mydriasis, the error will be greater.

(4) In some diagnostic optometry, the fundus and refraction smell are normal, but the vision is poor, so optometry is needed to eliminate ametropia, so mydriasis optometry is needed.

(5) After small pupil optometry, if the vision correction is not good or there is refractive interstitial opacity, mydriatic optometry should be performed.

(6) Teenagers with poor or unstable eyesight (good eyesight for a while, bad eyesight for a while) should undergo mydriasis optometry.

The following people should not or do not need mydriasis:

(1) If primary angle-closure glaucoma is diagnosed or suspected, or examination shows shallow anterior chamber and high intraocular pressure, mydriatic agents are prohibited. Because mydriasis will induce the attack of angle-closure glaucoma, the intraocular pressure will increase and the consequences will be more serious. The mydriatic agent must be used under the guidance of a doctor.

(2) Over 40 years old, the accommodative power is weak, which generally has little influence on optometry, so there is no need to mydriaze.

(3) Severe refractive interstitial opacity, such as cataract and severe vitreous opacity, cannot be optometred, so mydriasis is not needed.

(4) Pupil adhesion is serious, and pupils cannot be dilated.

God, please take your time ~ ~ ~ I'm exhausted. . . .

But I advise you to take care of your eyes. .