Refractive Errors

The Normal Eye

In the normal eye, light rays that reflect off objects pass through the cornea, the lens, and are focused directly on the retina – producing a clear image.

Thus, a normal eye is able to see far and near without the need for visual aids (glasses, contact lenses. etc.)

What Are Refractive Errors?

Refractive errors refer to a condition where an irregular shape of the eye or lens prevents light rays from focusing correctly on the retina.

As a result, people with refractive errors will have blurred vision unless they use appropriate visual aids.

Refractive errors can be treated through the following methods:

Types of Refractive Errors

Myopia

Also known as nearsightedness.

Myopia (or nearsightedness) is a vision defect where images are focused in front of the retina instead of on the retina. A myopic eye sees blur at far distances but clear at near distances. It is one of the most common refractive errors in the Singaporean population.

Hyperopia

Also known as farsightedness.

Hyperopic eyes have an eyeball that is too short relative to the focusing power of the cornea and lens of the eye. As a result, images that the eye sees become focused behind the retina. People with hyperopic eyes are able to see clearly at far distances but will experienced blurred near vision.

Astigmatism

Astigmatism is caused by an irregularly shaped cornea or lens. In a normal eye, images are focused directly on the retina. Conversely, astigmatism causes images to be focused on different points near the retina. As a result, blur vision can occur at both near and far distances.