If the comea is to be reshaped (this can be done surgically or with contact lenses) to correct myopia, should its curvature be made greater or smaller? Explain.

Myopia, commonly known as nearsightedness, is a refractive error where the eye can clearly see objects that are close by, but struggles with objects at a distance. In essence, this is because light rays entering the eye converge or 'focus' at a point in front of the retina instead of directly on it. If we imagine the eye as a camera, myopia occurs when the lens of the camera focuses the image before it reaches the sensor, resulting in a blurry picture.

The primary reason for this inappropriate focusing is due to an elongated eyeball or, as commonly found, an excessive curvature of the cornea. The cornea acts as the eye's front window and plays a vital role in focusing vision. The degree of curvature of the cornea affects how well it can bend and focus incoming light.

Correction of myopia aims to shift the focal point onto the retina, thereby clarifying distant vision. To correct myopia, a decrease in the corneal curvature is necessary, making it flatter, which in turn reduces the eye's refractive power and moves the focal point back onto the retina.

The cornea is the eye's outermost lens and contributes between 65% to 75% of the eye's total refractive power. The refractive power of the cornea is determined by its curvature; the steeper the curvature, the higher the refractive power. When the curvature is too steep, as in the case of individuals with myopia, the light is over-focused, leading to visual images being focused in front of the retina. This results in a blurry vision for objects that are far away.

To correct vision errors such as myopia, the corneal refractive power must be carefully altered, which is done by changing the shape of the cornea.

A Less Steep Cornea for Myopia

For myopic eyes, the goal is to 'flatten' the cornea slightly, which reduces its refractive power. As the refractive power decreases, the focal point of the light moving through the eye is pushed back toward the retina, allowing for clearer distance vision.

When it comes to the surgical correction of myopia, one of the most popular and effective methods is Laser-Assisted In Situ Keratomileusis, more commonly known as LASIK. This procedure utilizes a specialized laser to precisely remove corneal tissue, reshaping the cornea to correct its curvature.

In the LASIK procedure, surgeons create a small flap in the cornea to access the underlying corneal tissue. Then, with the precision of a computer-guided laser, small amounts of corneal tissue are ablated or removed. By doing so, the overall curvature of the cornea is reduced, thereby lessening its refractive power, which shifts the focus of light directly onto the retina and improves distance vision.

Recovery from LASIK surgery is relatively quick and the procedure is known for its efficiency and effectiveness. Nevertheless, it is a surgical procedure, and therefore carries inherent risks and considerations. Therefore, it is crucial for individuals to consult with an eye care professional to determine if LASIK is an appropriate option for their specific condition and lifestyle needs.