1.What is visual acuity? What is normal visual acuity? Visual acuity is: the maximum ability of the eye to distinguish the shape, size and fine structure of objects, also called visual acuity. Many people think that as long as the visual acuity can reach 1.0 or more, it is normal. In fact, 1.0 visual acuity can only mean that part of a person’s vision is normal. The criteria for normal vision also include: (1) central vision; (2) peripheral vision; and (3) stereopsis. In medicine, only when the central vision, peripheral vision and stereopsis all meet the physiological requirements can be considered as normal vision. 2.Why is it necessary to check visual acuity before going to the ophthalmology department? One of the main symptoms of eye disease is vision loss, and vision check is an important basis for detecting and diagnosing eye diseases. It has been found that a normal child’s visual acuity can reach 1.0 at the age of 3. Frequent vision checks can detect many diseases that affect visual health. Therefore, it is necessary for people of any age to have their vision checked once a year. 3.What is visual field? How large is the normal range? When we look at an object directly in front of us, without turning the eye, in addition to the object, the scene around the object can also be seen, this kind of spatial range that can be seen with the eye is called the visual field in medicine, which is what we said earlier about peripheral vision. The range of normal monocular visual field: temporal side about 90° above, below about 70°, nasal side about 65°, above about 55° (the latter two due to the influence of the nasal bridge and upper eyelid). The range of various color visual fields is not consistent, white is the largest, followed by blue, red again, and green is the smallest. When both eyes are gazing at the same time, most of the visual fields on the nasal side overlap each other. 4.What is the significance of checking the visual field? Visual field changes can help in the differential diagnosis of the disease, various diseases caused by the visual field defects and the scope of different, the doctor can distinguish the two diseases according to the different morphological characteristics of the visual field damage, such as central retinitis and retrobulbar optic neuritis, they both have a central dark spot, if the early detection of other methods such as ophthalmoscopy is not easy to detect, the use of visual field examination, general retrobulbar optic neuritis central blind spot red > Blue, central plasma retinal chorioretinopathy central point blue > red. In addition, to understand the progression of certain eye diseases and determine the prognosis, such as early glaucoma, the central visual field examination appears physiological blind spot enlargement, physiological blind spot exposed, gradually progressing to flame-like blind spot, bow dark spot. If the upper and lower bowed dark spots are articulated with each other, a ring-shaped dark spot can be formed. A wedge-shaped defect appears early in the peripheral visual field, and gradually the nasal visual field narrows and narrows centripetally, eventually leading to a tubular visual field, or even disappearing completely. Therefore, the examination of visual field, fundus, intraocular pressure and anterior chamber angle can be used to understand the progress, treatment effect and prognosis of glaucoma disease. 5.What is color vision? What kinds of color vision abnormalities are there? Normal human eyes can not only perceive the intensity of light, but can also distinguish different colors. The ability to discriminate colors is called color vision, in other words, it refers to the perceptual properties of the retina for different wavelengths of light, i.e. the ability to decompose different colors in general natural light. Clinically, color vision can be divided into color blindness and color deficiency according to the degree of color vision impairment. Red-green color blindness is more common, while blue color blindness and total color blindness are less common. Colorblindness is a mild color vision disorder in which the ability to distinguish colors is slow or easily fatigued. 6.What is stereo vision? Let’s do a small experiment: hold a ballpoint pen in each hand, both hands are flat, the nibs slowly come together, you can find it easy to align the two nibs; when we look at an object with both eyes, the object forms two images on the retina of the left and right eyes respectively, but 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 The two images are not identical and cannot overlap completely. This visual image into the brain, after the brain synthesis, discrimination, so that the object has a sense of spatial depth, a sense of three-dimensional, which is stereo vision, stereo vision is also known as depth perception or stereoscopic. 7.What people need to do stereo vision examination? Stereo vision function has an important role in daily life and work, such as surgeons, car and airplane pilots, painters and all those who need to visually detect objects near and far and fine work are required to use stereo vision. 8.What is the significance of slit lamp microscopy? Slit lamp microscopy provides a comprehensive view of the cornea, iris, and crystal, and can reveal the curvature and thickness of the cornea, the presence of foreign bodies and posterior corneal deposits (KP), as well as the level and shape of infiltrates, ulcers, and other lesions, corneal epithelial or endothelial edema, posterior corneal deposits, neovascularization, minor scarring, and corneal clouding, such as thin opacities, blisters, perforations, and wounds. It can observe the cloudiness of the crystal and the lesion in the front 1/3 of the vitreous; it can examine the floating particles in the atrial aqueous, observe the subtle changes in the anterior and posterior corneal and anterior and posterior capsules of the crystal, it can observe the pupil dilator, intra-iris hemorrhage, iris vessels, corneal vascular opacities, etc. Slit lamp examination is an essential and important part of the ophthalmic examination. 9.What is intraocular pressure? What is the normal range? A: Intraocular pressure is the pressure of the atrial fluid, lens and vitreous humor on the inner wall of the eye. From a clinical point of view, the definition of normal IOP should be the level of IOP that does not cause damage to the optic nerve. However, because there is a great deal of individual variation in the tolerance of the optic nerve to IOP, normal IOP cannot be defined by a precise value. From a statistical concept, normal IOP is usually defined in the range of 10-21 mm Hg. 10. Why should I have my IOP checked? About 10-15% of the blind population in China and abroad is caused by glaucoma, and about 2% of adults over the age of 40 have glaucoma. Glaucoma is caused by damage to the optic nerve and atrophy due to high intraocular pressure, which in turn causes various visual impairments and visual field deficits. The eye pressure test is one of the three most important tests to detect glaucoma and is also the simplest test. Therefore, patients should have an IOP test to rule out the possibility of high IOP and glaucoma for early detection and treatment. 11.What are the methods of IOP examination and what are the differences? The main methods of IOP detection are finger pressure measurement and IOP meter measurement. Generally, normal is Tn, high IOP is T +1, 2, 3, and low IOP is T-1, 2, 3. IOP measurement method is divided into two types: contact and non-contact. Contact tonometer is divided into indentation type and flattening type, which is commonly used in clinical practice. This method is accurate and easy to use, but the tonometer should be in contact with the cornea, so it is not suitable for patients with keratitis, conjunctivitis and other diseases. And after measurement, patients should not rub their eyes with their hands to avoid hurting the cornea due to the temporary loss of sensation. The non-contact tonometer method is simple, fast, does not require anesthesia, does not come in contact with the cornea, and does not cause cross-infection, but this method may have deviations for patients with high intraocular pressure and corneal lesions, which must be noted. 12.What is the significance of corneal topography examination? Corneal topography is used clinically to diagnose corneal astigmatism, quantitatively analyze corneal traits, display corneal refraction in data or different colors, and the difference between its two axes of refraction is corneal astigmatism. The introduction of corneal topography has made possible the early diagnosis of subclinical stage cone corneas and cone corneas, with an accuracy rate of 96% for cone corneas. In addition, it can be used for the diagnosis of corneal distortion induced by corneal contact lenses. Corneal topography can also be used for preoperative examination and postoperative outcome evaluation of keratoconus surgery. Preoperative corneal topography is used to fully understand corneal properties, especially astigmatism, and to rule out cone corneas and contact lens-induced corneal distortion; postoperative corneal topography is used to evaluate the outcome. The aim of modern cataract surgery is not only to reduce surgically induced astigmatism, but also to neutralize preoperative astigmatism through the surgical incision. Therefore, surgery can be guided by the corneal topography examined prior to surgery. Based on the corneal topography, the required curvature and degree of refractive error patients’ prescription can be calculated to guide the fitting of data lenses for corneal contact, which improves its accuracy. 1.Who needs to do corneal endothelial count test? (1) To understand the density, morphology, size and regular shape of corneal endothelial cells, and to assess the morphology, function and compensatory ability of corneal endothelial cells in the same age group; (2) To observe the morphological changes of corneal endothelial cells in corneal congenital and acquired abnormalities; (3) To observe the effects of various corneal surgeries and internal eye surgeries (such as cataract and glaucoma) on corneal endothelial cells; (4) To perform routine examinations before and after fitting various types of contact lenses, and to observe the effects of corneal endothelial cells. (4) routine examination of contact lenses before and after fitting, to observe the effect of contact lenses on corneal endothelial cells for a short time and after long-term use, so as to further evaluate the oxygen permeability and safety performance of contact lenses. 2.What is the fundus examination? What are the items included? There are two methods of fundus examination: direct examination method and indirect examination method. When using the above methods, we should pay attention to the following: ① whether the optic nerve papilla (optic disc) is normal in shape and color, whether the border is clear, whether the physiological depression is enlarged or deepened, whether the ratio of optic cup to optic disc is normal, whether the optic papilla is elevated or defective, and whether there is arterial pulsation; ② how thick and thin the retinal vessels are, how curved they are, whether there is arterial and venous cross-compression or arch bridge phenomenon, whether there is vascular obstruction, neovascularization and vascular (3) the existence of macular central recess reflection, whether there is edema, exudation, hemorrhage, pigment disorder, cystic degeneration and fissure in the macula; (4) whether there is edema, exudation, hemorrhage, neovascularization, pigmentation, detachment, rupture hole and tumor in the retina. 3.What is fundus fluorescence angiography? What kind of people need fundus fluorescence angiography? Fundus fluorescence angiography is an examination method in which a fluorescent dye is rapidly injected into the blood vessels and observed or photographed with a fundoscope or fundus camera with a color filter. Most of the lesions in the fundus can cause vascular lesions in the fundus, and occlusion or hemorrhage of small vessels is difficult to detect only under the naked eye. It provides valuable information for the diagnosis, treatment, efficacy observation and mechanism research of various fundus diseases. 4.What is indocyanine green choroidal angiography? Who needs to do this test? A: Indocyanine green is a contrast agent that reflects the condition of choroidal vessels and helps to detect choroidal neovascularization, leakage, etc. This test is usually done when there is a suspicion of fundus disease that cannot be clearly diagnosed or when treatment needs to be guided, such as diabetic fundus lesions, to guide the scope and energy of laser treatment according to the area of fundus ischemia. If the patient has serious liver and kidney dysfunction, or is allergic to fluorescein, the patient cannot perform this test. 1.What is OCT and what is its significance? OCT is the abbreviation of optical coherence tomography, which is an emerging non-contact, non-invasive ophthalmic imaging diagnostic technology, it is used to clearly distinguish the tissue structure by the different reflection absorption and scattering ability of various tissues, and its axial resolution is up to 10µm. Optical coherence tomography (OCT) is used in retinal disease, macular disease, glaucoma, etc. Optical coherence tomography (OCT) is of great value in clinical studies of retinal diseases, macular diseases, optic nerve diseases, glaucoma, etc. It can provide valuable basis for the diagnosis and differential diagnosis of retinal diseases, especially macular diseases, such as macular fissure, macular anterior membrane, macular edema, vitreous macular traction syndrome, etc. It reduces the chance of misdiagnosis and omission, makes up for the deficiencies of other fundus examination methods and fundus fluorescence imaging, can observe the morphological changes of subtle lesions, clinical staging of idiopathic macular fissure; can detect some diseases It can be used to explore the pathogenesis of certain diseases, such as macular lesions combined with congenital optic disc hollows and idiopathic macular fissures. 2.What is wide-angle fundus laser scan and what is its significance? Wide-angle laser funduscope panoramic 200 adopts super wide-angle oval scanning mirror technology, which makes this instrument have the function of scanning and imaging the retina at 200° under a small pupil. It is possible to examine a wide range of fundus without dilating the pupil, and because of its strong penetrating ability, it is also possible to obtain clearer fundus images for patients with cataracts and corneal opacities. It is often used clinically for screening of fundus diseases around the physical examination of healthy people and for the examination of fundus diseases in patients with diabetes, myopia, hypertension, kidney diseases, etc. It can also be used for the comparison of the effect before and after treatment of fundus diseases. .