How much do you know about high myopia?

Abstract: lacquer cracks and atrophic foci in the retina of high myopia predict poor visual prognosis, because these eyes are at risk of subretinal neovascular membrane, and the central visual acuity will decline sharply.

what is high myopia? ·

myopia is divided according to the degree. Ametropia with myopia degree greater than 600 degrees (children > 400 degrees) is called high myopia. Because this kind of myopia often has ocular pathological changes, high myopia is equivalent to pathological myopia or degenerative myopia. The cause of high myopia is unknown. Pathological myopia occurs in a genetic relationship. Acquired environment plays an important role in the pathogenesis of myopia.

pathophysiology

eye axis lengthening is the pathoanatomical basis of myopia. The main lesions were in the posterior part of the eyeball, which was pear shaped or egg shaped.

(1) the posterior elastic layer of cornea in high myopia may be broken.

(2) scleral thinning in scleral myopia is one of the characteristics of pathological changes. Longitudinal fibers become thinner and transverse fibers separate or disappear. This is related to abnormal scleral collagen.

(3) ciliary body mainly shows atrophy and can be limited to annular fibers.

(4) due to degeneration and liquefaction of vitreous body, the normal grid structure is damaged, and gray fibers and vacuoles increase. Adhesion can occur around and detachment can occur at the rear.

(5) choroid mainly changes to progressive atrophy and thinning of choroid, including degeneration, destruction of melanocytes and neovascularization. The elastic layer is cracked, showing lacquer crack

(6) because the eyeball is extended backward, the choroid around the optic disc is pulled away from the optic disc. Bruch’s membrane also terminates here, and the sclera is exposed at the absence of the outer layer of the retina and pigment epithelium, forming a white arc spot.

(7) The retina mainly shows degenerative changes, including atrophy and degeneration. The normal hexagonal arrangement of retinal pigment epithelial cells is replaced by an irregular cell layer. There are many pigments outside the cells. There is hyperpigmentation and accumulation of pigment at the crack of Bruch membrane. Circular Fuchs spots can be formed in the macular area. The absence of elastic layer makes the retina choroid fuse together, and finally scars and pigments appear 。 Choroidal neovascularization can break through Bruch membrane and grow under the retina to form subretinal neovascularization membrane. Rupture of neovascularization causes macular hemorrhage. The vitreous body can attach and draw the atrophic retina. It can cause retinal hole and detachment.

clinical manifestations

1) decreased vision.

(2) myopia develops rapidly: different from simple myopia, some high myopia continue to develop even in adulthood, so it is also called progressive myopia.

(3) exophthalmos: most high myopia are axial, the eyeball is significantly longer, the anterior chamber is deeper, the ciliary muscle shrinks, and some people’s eyeballs protrude outward.

(4) poor dark adaptation function: the pigment epithelial cells of the retina have pathological changes, which affect the photochemical reaction process of visual cells.

(5) immediate shadow: high myopia can cause vitreous degeneration, liquefaction, posterior vitreous detachment, etc.

disease harm

the harm of high myopia mainly lies in complications.

(1) vitreous, choroidal and retinal degeneration caused by abnormal eye structure and nutritional disorder.

(2) macular degeneration, atrophy and posterior staphyloma caused by axial elongation, scleral elongation and biomechanical abnormalities.

(3) amblyopia and strabismus caused by low vision and dysregulation of radiation function.

diagnosis differential diagnosis

examination diagnosis

(1) optometry and cycloplegia optometry.

(2) flattening tonometer to measure intraocular pressure. For high myopia, Schiotz tonometer measurement value is lower than the actual intraocular pressure.

(3) Mydriasis: check the fundus with indirect ophthalmoscope: look for retinal holes and detachment.

(4) check the macular area with slit lamp combined with trihedral mirror or 60d and 90d lens to find the new blood vessels under the choroid.

(5) fluorescent angiography of fundus.

(6) optical coherence tomography (OCT) can show the macular detachment above the posterior scleral staphyloma.

disease differentiation

(1) choroidal neovascularization (CNV) can appear in age-related macular degeneration (ARMD). The macular area is similar to high myopia, but there are typical vitreous warts, without the above myopic optic disc changes.

(2) perioptic atrophy in ocular histoplasmosis, which is in danger of choroidal neovascularization. A pigment ring separates the optic disc from perioptic atrophy, while the myopic arc separates the atrophic area from the adjacent retina. Circular chiseled choroidal scars are scattered in the whole fundus.

(3) The inclination of the optic disc is irregular. The optic disc is combined with an arc sclera and often tilts to the lower part of the nose. When emitted from the optic disc, the blood vessel shape is irregular (the position is opposite to normal), and the fundus of the eye expands towards the inclined direction (lower part of the nose). Many patients have myopia and astigmatism, and there is no chorioretinal degeneration or lacquer crack.

(4) Gyriform chorioretinal atrophy is rare. It occurs in the middle and peripheral part of the retina in childhood. Multiple chorioretinal atrophy spots with clear boundaries gradually fuse and involve most areas of the fundus. The level of blood ornithine increases. Patients often have high myopia. It is autosomal recessive.

(5) Chorioretinal scar with clear boundary and no typical choroidal neovascularization (CNV) in toxoplasmosis. The active stage is characterized by retinitis and vitreitis.

disease treatment

operation treatment

(1) At present, excimer laser corneal refractive surgery is widely used in corneal surgery, especially femtosecond laser, which can be used to correct high myopiaThe effect of weaving remains to be observed.

(2) anterior and posterior chamber intraocular lens implantation.

(3) lens and intraocular lens surgery.

(4) posterior scleral reinforcement. The safety and exact effect of such reinforcement need to be further observed.

other therapies

(1) wear glasses frame glasses and corneal contact lenses.

(2) symptomatic retinal holes should be treated with laser photocoagulation, condensation or scleral buckling.

(3) suspected glaucoma patients with progressive visual field defect without progressive myopia suggest that glaucoma needs treatment.

(4) Choroidal neovascularization outside the fovea or adjacent to the fovea can be treated by laser photocoagulation within a few days after fundus fluorescence.

disease prognosis

high myopia has lacquer cracks and atrophy in the fundus retina, indicating a poor prognosis of vision. Because these eyes are at risk of subretinal neovascularization, the central vision will decline sharply.

disease prevention

and

include the prevention of the development of high myopia and the prevention of myopia complications.

   (1) Development methods to prevent high myopia: continuous close eye use should not be too long. Actively participate in outdoor activities. Reasonable adjustment – collective training. Usually ensure adequate sleep, combination of work and rest, balanced diet, reasonable nutrition, etc. special attention should be paid to rational eye use, select appropriate work, and avoid excessive eye use and adverse visual stimulation. It may reduce or terminate close eye contact Depending on the development measures, Including glasses (bifocal lens, high oxygen permeability rigid contact lens), drugs, surgery, etc.

(2) The main cause of blindness caused by high myopia is complications, such as retinopathy, glaucoma and amblyopia. In addition to paying attention to the changes of vision, we should also pay attention to any other abnormal phenomena in the early stage of the eye, such as flash sensation, flying mosquito disease, visual field defect, progressive or sudden decline of vision, as well as eye acid swelling, pain and night blindness. If necessary Perform other special eye examinations.