Symptom >> Otorhinolaryngology >> Ophthalmology

Increased farsightedness diopter

Introduction
Cause
Examine
Diagnosis

Introduction

Introduction Hyperopia refers to a refractive state in which the focus falls behind the retina after the parallel rays pass through the refractive system of the eye without adjustment. Therefore, in order to see the distant target, the hyperopic eye needs to use the adjustment to increase the refractive power, and to see the near target, more adjustments are needed. When the adjustment force does not meet this need, near vision or even far vision impairment can occur. Treatment of hyperopia: Presbyopia is corrected with a convex lens. Mild hyperopia, if asymptomatic, does not require correction, such as visual fatigue and esotropia, even if the degree of farsightedness is low, wear glasses. Moderate hyperopia or middle-aged hyperopia should wear glasses to correct vision, eliminate visual fatigue and prevent the occurrence of esotropia.

Cause

Cause

The most common type of hyperopia is axial farsightedness, that is, the anterior and posterior axis of the eye is shorter. This is one of the more common types of refractive abnormalities. At the time of birth, the average eye axis of the person is about 17.3 mm. From the perspective of the length of the eye axis, it is almost all hyperopia. It can be said that the baby's hyperopia is physiological. After that, as the baby's body develops, the front and rear axes of the eye also slowly grow. When the adult is in adulthood, the human eye should be face up or close to face. In the development of the eye, some people stop the development of the eyeball due to the influence of internal (genetic) and external environment, and the eye axis can not reach the length of the normal eye. Therefore, the eye axis of the baby or the child is still maintained in adulthood, which is called the axis. Sexual hyperopia. On the contrary, the development process becomes myopia. A true vision eye with zero true diopter is a minority.

In general, the degree of short-sightedness of the human eye is not very large, rarely exceeding 2 mm. According to the calculation of the optical field of the eye, every 1 mm shortened represents a change of 3D, and thus farsightedness exceeding 6D is rare. But there are also high degree of hyperopia, and some eyes, although not combined with any other pathological changes, will be as high as 24D. In pathological hair loss abnormalities, such as small eyeballs, the degree of hyperopia may even exceed 24D.

The front and rear axes of the eye become shorter and can also be seen in pathological conditions. The inflammatory mass of the eye tumor or eyelid can cause the posterior pole of the eyeball to invade and flatten it; in addition, the new organism or the pelvic tissue after the ball can move the macular area of the retina forward; a more serious The situation can be caused by retinal detachment, and the displacement caused by such detachment can even make it touch the back of the crystal, and the change of diopter is more obvious.

Another cause of hyperopia is curvature hyperopia, which is formed by the small curvature of any of the refractive bodies in the refractive system of the eye, called curvature hyperopia. The cornea is a site that is prone to such changes, such as congenital flat cornea, or caused by trauma or by corneal disease. From optical theoretical calculations, a 6D hyperopia can be increased for every 1 mm increase in the curvature radius of the cornea. In this kind of curvature hyperopia, only a few corneas can remain completely spherical, almost all with astigmatism.

The third kind of hyperopia is called refractive hyperopia. This is due to the reduced refractive power of the crystal. It is caused by physiological changes in old age and pathological changes caused by diabetes in the treatment; hyperopia can also occur when the crystal is dislocated backward, which may be caused by congenital abnormalities or ocular trauma and eye diseases; It can cause high hyperopia when the crystal is lacking.

Optical state of hyperopia:

Whether the distance is due to the shortening of the length of the eye axis, the decrease in the curvature of the refractive body surface, or the decrease in the refractive power, the optical effects are the same. That is, the parallel light emitted from infinity forms a focus in the back of the retina, and the ambiguous image on the retina becomes shorter due to the shorter axis of the eye, and the corresponding retina is closer to the node, and the resulting image is more important than the right eye. Smaller. The light emitted at the point of the macula of the retina of the eye is parallel to the light of the eye. It can also be said that the macula of the emmetropic eye becomes the conjugate focal point with infinity, so no adjustment is used when looking at the infinity. In hyperopia, the light emitted by the macula is scattered. The yoke focus of the eye is behind the eyeball, so it is a virtual focus. Because there is no collection light in the universe, the eye is at rest. It is not clear to see any body. There are two ways to make light into a collection: the first is the regulation of the eye itself.

long sighted:

(1) emmetropia: parallel light focuses on the retina; (2) hyperopic: parallel light gathers behind the retina; (3) hyperopic: due to the use of the lens to adjust the parallel light to focus on the retina; (4) hyperopic: the convex lens placed in front of the eye Instead of adjusting, the retina on the parallel light can also be focused.

The size of hyperopia, elevation and myopia imaging:

AB is an object; N is a node; ab is an inverted image of the retina of light passing through A and B through N; H is hyperopia, E is a front view, M is a myopia; 3>2>1.

The light emitted by the hyperopic eye extends toward the back of the eyeball and becomes the virtual focus R.

Presbyopia adjustment:

Adjustment is the result of the gradual evolution of the eye in order to look close or see the subtle body. The eye is in a resting state, and a clear image is formed on the retina when looking at a distant object. When the near eye is seen, since the light entering the eyeball is scattered and is imaged behind the retina, the image formed on the retina is blurred. . This ambiguous image forms a visual-dynamic stimulus in the visual center, causing excitement in the ciliary muscle, the pupil sphincter and the medial rectus, which are governed by the third pair of cranial nerves, forming a trinity of regulation, assembly, and contraction. The joint movement is called near reflection. Among these three, the regulation is the main one. The anterior-posterior axis of the eyeball is short or the refractive power of the refractive system of the eye is weak. The light emitted from infinity is also imaged behind the retina, and the image on the retina is also blurred. This ambiguous image, like the right-looking eye, forms a visual-dynamic factor in the visual center, producing an adjustment effect similar to that of the emmetropic eye, causing the image to move forward and form a clear image on the retina. We refer to the near-field adjustment of the positive field of view as physiological regulation; the adjustment of the far-sighted eye is called non-physiological regulation. Hyperopia sees any external object to use adjustment, so the adjustment is closely related to the hyperopic eye, so according to the different effects of adjustment on hyperopia, the hyperopic eye can be divided into two types: recessive hyperopia and dominant hyperopia, of which dominant Hyperopia is divided into corrective hyperopia and absolute hyperopia.

Generally speaking, the eyeball of the hyperopic eye is small, and the eyeball becomes smaller not only in the front and rear axes of the eye, but in all the axial directions. The cornea of the hyperopic eye is also small. Since the crystal does not change much in shape, the crystal becomes relatively large as compared with the reduced eyeball, and thus the anterior chamber becomes shallow, making the eye prone to glaucoma. This should be taken care of when using mydriatic drugs. Highly hyperopic eyes can form developmental deformations, such as small eyeballs. The small total eyeball is not necessarily the hyperopic eye, mainly depends on the matching between the anterior and posterior axes of the eyeball and the refractive system of the eyeball. When the eyeball becomes smaller, the refractive power of the eyeball refractive system increases, and it does not necessarily become hyperopia.

Fundus examination can see the typical hyperopic retina, which is characterized by special brilliance, which is caused by reflection, called the retinal flash ring, called pseudo-opic discitis, the optic disc is dark red, the edges are slightly sticky and irregular. Outside the blurry area, it is sometimes surrounded by a gray halo, or surrounded by stripes that radiate from the edge to the surroundings, making it more blurred, and a new form of change is often formed beneath the optic disc. This change is generally considered to be congenital and therefore does not result in a significant reduction in vision. In addition to vascular reflex enhancement, improper bending and abnormal branches of the blood vessels can also be seen. Such changes in the eye should be carefully observed to avoid misdiagnosis. When a hyperopic eye occurs in a single eye, the ipsilateral face tends to develop poorly and becomes asymmetrical on both sides. The asymmetry of development is also often seen in the eye itself, which mostly incorporates astigmatism.

Examine

an examination

Related inspection

Eye and sacral area CT examination far vision test band photorefraction

Highly farsighted, because the eyes are not visible, so the visual symptoms are more obvious.

Mild hyperopia, using adjustment power to overcome its refractive defects, without any visual symptoms. Adolescents have strong accommodation, and even if they have moderate hyperopia, they may not have any visual symptoms.

Because hyperopic eyes need to adjust and correct their refractive defects in addition to looking far, when you look at the near object, you need to add a part of the adjustment force. Therefore, the visual main sensory disturbance symptoms of the hyperopic eye are first manifested when looking at the near material. . For example, when looking at the material at 33cm in front of the eye, it is necessary to use 3.00D adjustment. When the 2.00D hyperopic eye is near, it is necessary to adjust with 5.00D to get the same optical effect. When the degree of remoteness is high and the accommodation power is insufficient to correct the refractive error, another situation may occur, that is, the ability to recognize the object is increased by the increase of the object image. Therefore, occasionally, patients with hyperopia can see the book close to the eyes. If they do not pay attention, they are sometimes mistaken for myopia, which is called "farsighted eye myopia." Thus, the high degree of use of the adjustment can quickly cause fatigue. Even if the degree of hyperopia is not high, sometimes due to age, physical strength or mental weakness, and the ability to adjust to the ability to adjust, the feeling of blurred vision, often occurs after a long period of near work, so only temporarily stop using the eye The ciliary muscles can be rested for a short time to restore clear vision.

Visual fatigue is the most common symptom of presbyopia, accompanied by headaches, dizziness, and physical and mental discomfort. If the fatigue persists for too long, sometimes a short period of ciliary muscle paralysis may occur, resulting in a high degree of visual impairment. However, spastic contractions of the ciliary muscle may also occur, causing pseudomyopia. As for the separation of regulation and aggregation, it can be expressed in two ways: accurate adjustment, with excessive collection; or insufficient adjustment, with a set of appropriateness. However, because of the above-mentioned method, satisfactory visual acuity can be obtained, so it becomes the development trend of general presbyopia, that is, sacrificing two eyes and one eye, in order to obtain the clarity of monocular vision, and thus develop a glance (one eye with better vision) While ignoring the habits of his eyes, the result is an implicit oblique or esotropia.

Diagnosis

Differential diagnosis

Far anisome-parallel amblyopia: no strabismus, but a hyperopia or astigmatism at a glance, blurred vision, resulting in refractive ametropia, due to no change in appearance, often found in school or usual physical examination, children sometimes at home due to It was discovered by looking at the calendar or clock with a single eye.

Refractive amblyopia: Both eyes have obvious hyperopia, myopia, astigmatism, and can not be blurred by the single eye, even if the visual acuity declines quickly. Treatment emphasizes that wearing glasses often, clear vision can restore vision, otherwise it is difficult to recover after serious.

Contrast media turbidity: When the refractive medium of the eye (such as cornea, crystal, vitreous, etc.) becomes turbid or there is ametropia (including myopia, hyperopia, astigmatism, etc.), even the eyesight of the retina functioning well will decrease. The refractive medium of the eye is turbid and can be treated with surgery, while ametropia requires lens correction.