Myopia and its Correction

Myopia, commonly known as nearsightedness, is a refractive error of the eye that causes distant objects to appear blurry, while close objects can be seen clearly. It occurs when the eyeball is too long or the cornea is too curved, causing the light rays to focus in front of the retina instead of directly on it. To correct myopia, concave lenses are used.

Explanation:

1. Myopia and its Causes
Myopia is a common vision problem that affects people of all ages. It is primarily caused by the shape of the eyeball, which can be either longer than normal or have a cornea that is excessively curved. These structural abnormalities prevent light rays from focusing directly on the retina, resulting in a blurred image when looking at distant objects.

2. Image Formation in Myopia
In individuals with myopia, the image is formed in front of the retina, rather than on it. This happens because the eyeball is elongated, causing the focal point to fall short of the retina. As a result, the light rays converge before reaching the retina, leading to a blurred image.

3. Correction of Myopia
To correct myopia, concave lenses are used. These lenses are thinner at the center and thicker at the edges. When placed in front of the myopic eye, they diverge the incoming light rays before they enter the eye. This divergence compensates for the excessive convergence caused by the elongated eyeball, allowing the light rays to focus directly on the retina.

4. Working of Concave Lenses
Concave lenses are designed to diverge light rays. When light passes through a concave lens, it refracts the light rays outward, causing them to spread apart. This divergence counteracts the excessive convergence of light that occurs in myopia, allowing the image to be correctly focused on the retina.

5. Advantages of Using Concave Lenses for Myopia
Using concave lenses for myopia correction offers several advantages:
- They are highly effective in correcting myopia and providing clear distance vision.
- Concave lenses are easy to wear and do not require any surgical intervention.
- They are a non-invasive solution that can be easily adjusted if the prescription changes over time.
- Concave lenses also provide a wider field of vision compared to other corrective methods.

In conclusion, myopia is a refractive error where the image is formed in front of the retina. This defect can be effectively corrected using concave lenses, which diverge the light rays and allow them to focus directly on the retina.