What Is Emmetropia?

The definition of orthopaedic eye refraction expressed in the definition of ophthalmology or technical terms means that when the eye is at rest (unadjusted), parallel light emitted by objects 5m away enters the eye and is focused on the retina through the refractive system, that is, Diopter is equal to zero. Generally, when the refractive power of near and far sighted eyes is refraction, the concept of vision is often introduced, that is, when the far and near vision is 1.0 ( 5.0), it can be regarded as emmetropia. A popular understanding is that the emmetropic eye means "normal vision and normal refractive power." Therefore, when observing and discussing refractive problems, two different concepts of emmetropia and emmetropia should be distinguished.

Square eyes

The definition of orthopaedic eye refraction expressed in the definition of ophthalmology or technical terms means that when the eye is at rest (unadjusted), parallel light emitted by objects 5m away enters the eye and is focused on the retina through the refractive system, that is, Diopter is equal to zero. Generally, when the refractive power of near and far sighted eyes is refraction, the concept of vision is often introduced, that is, when the far and near vision is 1.0 ( 5.0), it can be regarded as emmetropia. A popular understanding is that the emmetropic eye means "normal vision and normal refractive power." Therefore, when observing and discussing refractive problems, two different concepts of emmetropia and emmetropia should be distinguished.

Chinese Medicine Name

Square eyes

English name

emmetropia

Affiliated Department

Department of Ophthalmology-Ophthalmology

The main symptoms

Normal vision and normal refractive power

Contagious

Non-contagious

Whether to enter health insurance

no

According to the theory of confrontation, when a person is born,

Although the numbers listed in clinical statistics or individual epidemiological surveys vary widely, they also have common rules, namely:

3.1 The emmetropic eye generally occupies a small proportion

3.2 It is obviously affected by age. Among minors, the proportion of emmetropic eyes is very small.

3.3 In adults, the emmetropic eye has a large variation in refractive composition, which is obviously restricted by the prevalence of myopia.

So far, there is neither a standard nor a recognized authoritative opinion on the emmetropia.

1. The scope is not uniform and varies widely.

2. The smallest distance is 0 and 0.25D, and the largest is 2.24D.

3. Only a few individuals set the emmetropic eye at a diopter of zero. The range is generally biased towards the far-sighted side, such as + 0.5D, + 0.75D or + 1.0D. The number of those who are biased towards the myopia side is relatively small, and some are only relaxed to -0.25D, and only some are -1.0D. Harbin Medical University has started from the practical point of view, in order to facilitate census work, the following emmetropia standards were designed: eyesight 1.0, and vision loss when wearing + 0.5D lenses.

4. Generally, astigmatism is not involved, and only the astigmatism of the emmetropic eye should be less than 0.5D.

How to test the regulation of the emmetropia? It can be calculated by direct measurement or by measuring the near point.

What is astigmatism

"Astigmatism" is generally due to the unevenness of the cornea's curvature, and the light can not form a single focus after it is refracted by the cornea and enters the eyeball, and the image will "blaze out" or become blurred. No matter what is near or far, you can't see clearly. Patients with "astigmatism" need to pass through a cylindrical lens to make the light return to a single focus and focus on the retina to make the image clear.