What Is Myopia (Near-Sightedness) | Types & Symptoms | Treatment Of Myopia

What is Myopia (Short-sightedness)?? How To Prevent Myopia??

It is a form of refractive error inability to refract, bend focus the light rays properly in which parallel rays of light i.e. Coming from a distinct object, gets focused in front of the retina instead of on the retina.

ORIGIN

Myopia origin of the word. It comes from the Greek word. Muops meaning short-sighted. These people cannot see distant objects clearly.

Causes

Curvature

Increase of curvature of cornea or lens causes light rays to be focused in front of retina. And hence, myopia occurs

An increase in axial length of the eye 

Increases the converging power and cause light rays to be focused in front of the retina.

Refractive Index

Increase in refractive index, i.e. Light bending focusing power of the lens, for example, in Cataract

Positional anterior displacement of the lens 

After trauma, this displacement causes light rays to be focused in front of the retina.

Stats

·   In some parts of Asia, 80% of the girls in high school are myopic. 

·   In the United States, myopia has increased 66% in thirty years so that now 42% of people aged 12-54 are myopic

·   A recent study estimating that on average, 30% of the world is currently myopic and by 2050, almost 50% will be myopic, that’s a staggering 5 billion people.

·   The hot spots of myopia are East and South East Asia where countries such as South Korea, Taiwan, Singapore, China, and Japan have a prevalence of myopia of 80 to 90%.

·    USA has reported a prevalence of 42%, almost doubling in three decades.

TYPES:

Congenital means from birth, most common starts from 5 to 10 years till 15 to 20 years, and is mostly due to curvature or length problem of eyeball

Pathological myopia is known as a degenerative disease that starts in childhood and worsens in adulthood It might be hereditary, Progressive and is due to degenerative changes in the eyes.

High myopia can increase the risk of retinal detachment, glaucoma, and cataracts.

The higher the number the more short-sighted you are.

• Mild myopia includes powers up to -3.00 dioptres (D).
• Moderate myopia, values of -3.00D to -6.00D.
• High myopia is usually myopia over -6.00D.

SYMPTOMS

·        Blurred vision,

·        Half shutting of eyes

·        Divergent squint

·         Headaches

·         Squinting

·         Eyestrain

·        Eye fatigue

Can We Prevent Myopia?

Progression of myopia can be cut to approximately 50 percent

    1. Visual correction 2. Outdoor activities 3. Orthokeratology (corneal molding and reshaping) 4. Multifocal Soft Contact Lenses

1. Visual correction

Many parents are concerned that if a doctor prescribes glasses to be worn most of the time, their child will become dependent on them or that the glasses themselves will cause more nearsightedness to occur. Some parents may feel that it is best to not correct the condition at all.

However, research shows that not correcting a child’s nearsightedness could actually cause the nearsightedness to worsen. In addition, under-correcting nearsightedness was once thought to have an impact on reducing the progression. However, the current thought is that under-correction is associated with a higher rate of myopia progression.

2. Outdoor activities

Important studies have shown that time spent outdoors can delay the onset or even reduce the progression of nearsightedness. More research needs to be performed but the amount of time spent outside appears to at least be an important risk factor. Most doctors recommend that children spend at least 120 minutes outdoors every day.

The reason why this is true may be related to a reduction in obesity, an increase in vitamin D production, socialized games that occur outside, or may even be related to dopamine levels in the body. One of the strongest mechanisms of action currently being studied is the amount of sun exposure or the amount of illumination or simply brightness that you receive while outside.

3. Orthokeratology

Orthokeratology, also known as corneal refractive therapy (CRT), gentle corneal molding, and corneal reshaping, is a procedure in which special corneal molds are similar to rigid gas permeable lenses, are fit and slept in overnight. The lenses are called reverse-geometry lenses. They flatten the cornea centrally but steepen it peripherally, causing a shape change in the cornea that reduces peripheral hyperopic defocus and creates myopic defocus which can slow the progress of myopia.

Peripheral hyperopic defocus is a complex topic but it seems to be the stimulus for the eyeball to become elongated and to become more nearsighted. A child wearing them during the night only will generally achieve near 20/20 uncorrected vision for the entire day. This induces an effect on the progression of myopia and also boosts confidence for the child so that vision correction does not have to be worn during the day.

4. Multifocal Soft Contact Lenses

Children wearing soft multifocal lenses had 25 percent less myopia progression and 31 percent less axial elongation than those wearing single-vision lenses over two years, according to a 2014 study in Hong Kong children. Doctors believe it works by the same mechanism as orthokeratology.

The “center-distance” multifocal focus light in front of the peripheral retina, and they focus light right on the central retina, which provides people with clear vision.