Refractive Errors

A refractive error is something about the natural shape of your eyes that makes your vision blurry. Refractive errors are some of the most common vision problems people experience.

 

There are a few types of refractive errors. Some make it hard to focus your eyes on objects close to you. Others make objects faraway look blurry. No matter which type of refractive error you have, an eye care specialist can diagnose and treat it. They’ll check your eyes and vision and prescribe a treatment to help you see clearly again.

 

What are the types of refractive errors?

The four most common types of refractive errors include:

 

• Myopia

 

 Nearsightedness, or myopia, as it is medically termed, is a vision condition in which people can see close objects clearly, but objects farther away appear blurred.

Myopia occurs when the eyeball is too long or the cornea is too curved. As a result, the light entering the eye isn't focused correctly, and distant objects look blurred.

 

Causes of Myopia:

- The exact cause of myopia is unknown, there is significant evidence that many people inherit myopia, or at least the tendency to develop myopia. If one or both parents are nearsighted, there is an increased chance their children will be nearsighted.

- Some people may experience blurred distance vision only at night, a phenomenon known as” night myopia," low light makes it difficult for the eyes to focus properly. Or the increased pupil size during dark conditions allows more peripheral, unfocused light rays to enter the eye.

- Symptoms of myopia may also indicate variations in blood sugar levels in people with diabetes or maybe an early indication of a developing cataract.

• Hyperopia or Farsightedness?

 

Hyperopia, or farsightedness, occurs when you see things that are far away better than things that are up close. Your eyes focus better on distant objects than on nearby ones.

 

Causes of Hyperopia:

- If the length of your eyeball is too short or the cornea has insufficient curvature, near objects cannot be brought into a sharp and clearly focused image on the retina. 

- Hyperopia may be hereditary or may result from environmental factors.

- Having a cornea that is flatter than normal can also contribute to hyperopia.

• Astigmatism?

Astigmatism is a common and generally treatable imperfection in the curvature of the eye that causes blurred distance and near vision. Astigmatism is often present at birth and may occur in combination with nearsightedness or farsightedness. Often it's not pronounced enough to require corrective action.

 

Causes of Astigmatism:

- Astigmatism happens when your cornea is irregularly shaped, bending light in one direction more than another and leaving only part of an object in focus.

- Rarely, a condition called keratoconus can cause astigmatism by making the cornea thinner and more cone-shaped. You’ll probably need contacts (but not glasses) to see clearly.

 

• Presbyopia?

Presbyopia is the gradual loss of the ability to focus on nearby objects. It's a natural, often frustrating part of ageing. Presbyopia usually becomes noticeable in your early to mid-40s and continues to worsen until around age 65.

You may first notice it when you start holding books and newspapers at arm's length to be able to read them. A basic eye exam can confirm presbyopia. 

 

Causes of Presbyopia:

- Age- related changes to your eyes cause presbyopia.

- A tiny circular muscle surrounding the lens either contracts or relaxes, changing the shape of the lens to bring objects into focus. The muscle relaxes for distant objects and contracts for nearby ones.