Nearsightedness vs. Farsightedness

In an ideal world, you would see clearly and effortlessly without any vision correction. Unfortunately, this is not often the case, as made evident by the number of people you see wearing glasses on any given day.

Refractive error

Refractive error describes an imperfection in the way light is refracted, or bent. In the absence of refractive error, a state called emmetropia, light focuses perfectly on the retina, the light-sensitive tissue inside the eye.

In myopia (nearsightedness), light focuses in front of the retina. In hyperopia (farsightedness), light focuses behind the retina. In astigmatism, light rays focus in two different areas, either in front of the retina, behind it, or both.

Globally, myopia affects 26.5% of adults; hyperopia affects 30.9% of adults; and astigmatism affects 40.4% of adults. Hyperopia and myopia cannot both be present in the same eye, but astigmatism is often present in combination with either myopia or hyperopia.

Symptoms of nearsightedness versus farsightedness

In nearsightedness, distant targets are out of focus. In mild myopia, only objects in the far distance will be blurry. In higher amounts of myopia, objects even at a moderate distance will be out of focus. As the name implies, nearsighted individuals are still able to see near objects clearly.

In farsightedness, near vision is problematic. The higher the hyperopia, the more this holds true. Again, as the name implies, farsighted individuals are better able to see distant objects.

Compensation for nearsightedness versus farsightedness

You may be able to spot a myope by watching them try to view a distant object without their vision correction. Myopes will squint to see more clearly.

Hyperopes use a different mechanism to compensate for their refractive error, at least when they’re young.

The eyes have a built-in focusing system called accommodation that is used to view something up close. When viewing a near object, the accommodation system is stimulated. Accommodation stimulates the crystalline lens inside the eye to become more rounded, helping to clear up vision.

Without vision correction, hyperopes have to use their accommodative system almost all the time. This can cause a tremendous amount of eye fatigue. As a person gets older, they lose their ability to accommodate in a process called presbyopia.

In mild hyperopia, therefore, the condition may not become obvious until they’re older.

Diagnosis

An optometrist or ophthalmologist makes the diagnosis of nearsightedness or farsightedness. Your eye doctor will measure your visual acuity at distance and near to see where you experience difficulty. He will also do a refraction, which is a measurement of refractive error. The doctor may use an automated machine called an auto-refractor to get a rough idea of your refraction. He may also use a manual instrument called a retinoscope, shining a light in your eye and aiding in the measurement of your refractive error. Your eye doctor will fine-tune their measurement by getting your feedback on the clarity of your vision through various lenses. This is done behind an instrument called a phoropter, which houses the lenses that are presented to you.

Whether you have myopia, hyperopia, or astigmatism, the process of diagnosing the condition is relatively similar.

However, eye drops may be necessary to get a better measurement if hyperopia is suspected. These drops, called cycloplegics, disable the focusing system of the eye in order to measure the hyperopia without the influence of accommodation. Cycloplegic agents also affect the size of your pupils, enlarging them, though this is not why they’re used.

Treatments for nearsightedness or farsightedness

The most common treatments for nearsightedness or farsightedness are eyeglasses and contact lenses. While they don’t cure the actual condition, they enable clear vision by focusing light on the retina.

In high amounts of refractive error, glasses can change the size of objects to the wearer. They can also affect the size of the wearer’s eyes to the observer. Specifically, myopes will see objects as smaller than they really are and their eyes will also look smaller when wearing glasses. Conversely, hyperopes will see objects as larger than they really are and their eyes will look larger when wearing glasses. Contact lenses don’t cause this effect.

Another treatment option for nearsightedness or farsightedness is refractive surgery. There are many procedures available, the most common of which are laser in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

There are limits to how much refractive error can be treated with these procedures, and these tend to be lower for hyperopia as compared to myopia.