Why Does My Health Check Always Flag 'Refractive Error'?

In health check-up reports, the ophthalmology section often lists the result as "refractive error". Consequently, patients frequently bring their reports to the ophthalmology outpatient clinic to ask about "refractive error".

So, what exactly is a refractive error?

A refractive error refers to a condition where, when the eye is not accommodating, parallel light rays from a distance of five metres or more fail to form a clear image on the retina after passing through the eye's refractive system, instead focusing either in front of or behind the retina.

Refractive errors include hyperopia, myopia, and astigmatism.

The refractive status of the human eye is influenced by various factors, including genetics and the environment. Under normal circumstances, most infants are born in a hyperopic state. As they grow and develop, their eyes gradually shift towards emmetropia, basically reaching emmetropia by preschool age. This process is known as "emmetropisation".

Let us now briefly explain refractive errors.

The main structures that make up the optical system of the eyeball, from the outside in, are: the cornea, aqueous humour, crystalline lens, and vitreous humour.

When light passes from one medium into another with a different refractive index, the light rays bend at the interface; this phenomenon is known as refraction in ocular optics. The objects we look at are refracted by the eye's optical system and focused onto the retina, which is the prerequisite for obtaining clear vision.

If, when the eye's accommodation is relaxed, the image of an object five metres away is focused precisely on the retina, this is termed "emmetropia"; if the image is not focused accurately on the retina, it is termed a "refractive error".

Refractive Errors

If the light focuses in front of the retina, it is called myopia;

if the light focuses behind the retina, it is called hyperopia;

and if light rays in different meridians fail to focus on the retina, it is called astigmatism.

What harms can refractive errors cause?

1. Reduced visual acuity: Many objects appear unclear and blurred, leading to a decreased quality of life, reduced efficiency in study and work, and impaired mobility.

1. Strabismus: Individuals with moderate to severe hyperopia in both eyes are prone to strabismus.

1. Amblyopia: Amblyopia commonly occurs in patients with moderate to severe refractive errors or significant anisometropia.

1. Impaired visual function: Such as deficits in stereopsis.

So, how are refractive errors treated?

(1) Correcting refractive errors: Optical correction with spectacles, laser refractive surgery, ICL surgery, etc.

(2) Wearing spectacles: Based on the mechanism of refractive errors, myopia is typically corrected with concave lenses, hyperopia with convex lenses, and astigmatism with cylindrical lenses. Pseudomyopia does not require spectacle correction. Spectacles should be prescribed scientifically and must be fitted under the guidance of an ophthalmologist.