How do glasses help us see?

Are you having trouble with your vision? Did your Optometrist or Ophthalmologist (commonly understood as Eye doctors) prescribe you to wear eyeglasses? Don’t worry, these glasses will only aid your vision. Let’s try and understand the science behind corrective lenses.

What is Refraction?

The primary concept that needs to be addressed when dealing with eye lenses is Refraction. This process can be defined as the deflection of light when it passes from one medium to another. For example, when we view a piece of text or any object through water, it appears a bit distorted to us from the outside. This change can be attributed to the fact that light travels at different speeds through various media.

How does Refraction correlate with our vision?

Our eye has several components that work together to help us see things around us. Two of these being Cornea and the Lens operate by following the laws of Refraction.

Both these components serve by refracting light in such a way that it can be focussed exactly onto the retina. The retina acts as a screen at the back of the eye and sends the brain neural signals which help it recognize the object seen by the eye.

The refractive process undertaken by the Cornea and the Lens often gets impaired, which demands the correction of these refractive errors. The resulting errors cause the object to seem blurry since the image isn’t focussed perfectly onto the retina.

Different types of refractive errors

The various kinds of refractive errors depend on how the light gets focussed after refraction. The refracted light may be focussed either in front of or behind the lens and so it gives rise to different kinds of defects.

  1. Myopia: Those cases wherein the light gets focussed in front of the retina are referred to as this defect, also known as short-sightedness. People experiencing this can see close objects clearly, whereas the ones located far away appear blurry.
  2. Hyperopia: Also called Hypermetropia or Long-sightedness is the case when the light gets focussed behind the retina. The ones experiencing this can see the objects located at a far distance clearly but have to squint to see the ones at a nearby distance.
  3. Astigmatism: Those experiencing this defect have a non-spherical Cornea. In this case, everything seems out of focus, regardless of its distance from the eye.

Does Age impact our vision?

Yes, it definitely does. When we’re younger our eye lens is flexible which helps it get accustomed to all kinds of situations. This ability of the lens to adapt accordingly is called Accomodation.

However, with increasing age, this flexibility of the lens decreases and so it can’t alter its shape to help us view nearby objects. This defect is known as Presbyopia. People aged 40 or more experience this problem.

Finally, we come to the correction of these errors. This can be achieved by using glasses or contact lenses. Additionally, another modern method being adopted nowadays is laser surgery which changes the shape of the cornea. All these methods basically help focus the refracted light precisely at the retina, which in turn helps us see things perfectly.

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