Myopia, commonly known as nearsightedness, is a widespread vision condition where objects far away appear blurred and indistinct. This refractive error means the eye is not focusing light correctly onto the light-sensitive tissue at the back of the eye, which is called the retina. A person with myopia experiences significant difficulty with visual clarity for anything beyond a short distance.
Understanding Myopia
Myopia occurs due to a mismatch between the eye’s length and its focusing power. The primary causes are the eyeball being too long (axial myopia) or the cornea having too much curvature, which increases its refractive power. In a normal eye, the cornea and lens bend incoming light rays so they meet precisely on the retina, creating a sharp image.
When a person has myopia, the light rays converge and focus at a point in front of the retina, rather than directly on it. This results in the light being spread out by the time it reaches the retina, which the brain interprets as a blurry image for objects far away. This is akin to a camera lens fixed at a short focus distance, where nearby objects are sharp but distant landscapes are out of focus. Axial elongation, the lengthening of the eyeball, is the most common reason for this incorrect focusing point.
Visual Impairment Caused by Myopia
A person with myopia will have trouble reading anything positioned at a distance, as their far vision is compromised. The degree of blurriness increases the further away an object is from the eye. Near vision, such as reading a book or viewing a phone screen, remains clear because these items are held within the eye’s limited range of focus.
Common Reading Difficulties
Reading difficulties manifest in common daily scenarios. A student might struggle to see a whiteboard or screen projection from the back of a classroom. Drivers struggle to read street signs and highway exit signs until they are very close, which creates a safety concern. In entertainment settings, it is nearly impossible to clearly read subtitles on a movie screen or discern the details of a distant performance stage.
A myopic person might also notice that faces across a large room are indistinct, making it hard to recognize others. They often resort to squinting to temporarily improve clarity by reducing the size of the light aperture. This effort to sharpen distant objects can lead to symptoms like eye strain and headaches. While reading small print on packaging is usually unaffected, reading a restaurant menu board from across the room becomes a challenge.
Addressing Myopic Vision
Myopic vision is easily managed using corrective lenses that redirect the light to the correct focal point. Glasses and contact lenses contain concave lenses, often called “minus lenses,” which are thinner in the center. These lenses work by slightly diverging the light rays before they enter the eye.
This divergence effectively pushes the focus point backward, ensuring the light converges precisely onto the retina’s surface. The strength of the concave lens required is measured in diopters, indicated by the minus number on a prescription, with a higher number corresponding to a greater degree of myopia. For adults seeking a more permanent solution, refractive surgery, such as LASIK, uses a laser to reshape the cornea. This procedure alters the cornea’s curvature to correct the eye’s focusing power.