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myopia (nearsightedness)


+ signs and symptoms
+ common causes
+ treatment methods
+ myopia control
+ degenerative myopia
 
Myopia is one of the most common form of refractive errors, also known as nearsightedness. In myopia the distance vision is blurred while to close vision is clear and focused, depending on the amount of myopia.
 
There has been an increase in cases of Myopia. The exact reason for this jump in Myopia is still elusive, many optometrists feel that it may have something to do with fatigue of the eye from the use of computers and other takes that require extended vision. This is in addition to genetic predispositions for nearsightedness.
 

signs and symptoms

For those that are nearsighted, it is typical to have a hard time with reading signs and seeing objects clearly from a distance. However, they can see well enough for up close tasks like computer usage and reading. Other symptoms and signs of nearsightedness include eye strain, headaches and squinting to see well. If you feel fatigue when participating in sports or when driving, this can also be a sign of untreated myopia. If while wearing your contacts or glasses, you still have these symptoms, it is important to see your doctor for a comprehensive eye examination to find out if you need a different prescription.
 
Eyes that are nearsighted are longer than typical, so when rays of light enter, they come into focus before they reach their destination; the destination being the back of the eyes wall, the retina.
 

common causes

Myopia happens when the eye is too long in relation to the power of cornea focus and the lens. This can cause rays of light to come into focus at just one point at the front of the retina instead of right on the surface where it should be.
 
Myopia can also be caused by the lens or cornea being overly curved as compared to the eyeballs length. There are some cases in which it is due to a combination of factors.
 
Myopia generally starts in childhood and children of nearsighted parents may be at a higher risk of being so themselves. It the majority of cases, myopia stabilizes by young adulthood, but there is still the chance that it will get worse with age.
 
 
myopia / nearsightedness effects

 

treatment methods

Myopia can be treated and corrected by wearing contact lenses or glasses. Refractive surgery is also an option for correction. You might need to wear corrective lenses all the time or just while doing certain tasks depending on the severity of your condition. If you are nearsighted, the first sphere (number) on your eyeglasses or contact less prescription will show a subtraction (-) sign. The higher that number is, the more severe your myopia is.
 
Refractive surgery can either reduce of totally eliminate the need for you to wear contacts or glasses. The procedure that is most common is the excimer laser.
 
In PRK, lasers remove layers (or layer) of tissue from the cornea. This flattens out the cornea and lets rays of light become more accurately focused on the retina. In LASIK, which is the most commonly used refractive surgery, a thin area is made on the corneas surface and a laser takes out some of the corneal tissue. The area is then put back in the original position.
 
There is also Orthokeratology. This is a procedure that is non-surgical where contact lenses are worn that have special rigid gas permeable (RGP OR GP) materials that actually reshape the eye as you sleep. This allows you to see clearly in the daytime without having to use contacts or glasses.
 
Orthokeratology and other BP related lens procedures known as corneal refractive therapy have proven to be effective at temporary correction for moderate cases of myopia. Both options are considered to be good alternatives for surgery for those people who are not old enough for LASIK or are not proper candidates for refractive surgeries.
 
Phakic IOLs are lenses that are implantable. They are a surgical option for myopia correction, especially for those who have high amounts of nearsightedness or corneas that are thinner than usual. People who have this procedure usually do so because there are too many possible complications from LASIK.
 
Phakic works like contacts, but they are instead put in surgically and are usually permanent. This means that there is zero maintenance required. Unlike cataract surgery, this type of procedure does not replace the natural lens of the eye, which are kept intact.
 

myopia control

With more cases of nearsightedness these days, there is much interest in developing ways to control myopia progression during childhood. Several types of techniques have been tried. They include putting bifocals on children, fitting them with progressive lenses and GP lenses. The results have been mixed.
 
Researchers in New Zealand have recently reported that they have seen encouraging results from specially made dual focus soft lenses for nearsightedness control in children with myopia. The lenses, which are still experimental, have much less power as far as the periphery goes, compared to what is in the centre. This may lower the tendency for more eye lengthening that leads to the progression of myopia.
 
A study that was published in 2011 shows that researchers saw that 70% of children with myopia, aged 11 to 14, who used these experimental lenses in only one eye (with a regular lens in the other eye) had a reduced amount of myopia in the one with the experimental lens. The decrease was at 30%.
 

degenerative myopia

In the majority of cases, myopia is just a small inconvenience and carries little, if any, risk to the health of the eye. However, there are cases in which it progresses so quickly, and becomes so severe that it is considered to be a degenerative condition.
 
Degenerative myopia, also known as pathological or malignant myopia, is a rarity that is thought to be genetic. It typically starts in early childhood.
 
For those with malignant myopia, the lengthening of the eye can happen so fast that it quickly leads to severe progression and vision loss. People with this type of myopia are also at higher risk for experiencing retinal detachment and other changes in the back of the eyes that are also degenerative. This includes eye bleeding from neovascularization (blood vessel growth this is abnormal). The risk of developing cataracts is also connected to degenerative myopia.
 
Complications linked to degenerative myopia can be surgically treated. This surgery is usually combined with laser treatments and medications. The laser treatment is known as photodynamic therapy. This procedure is used for treatment of macular degeneration as well.
 
There has been a pilot study done recently that found an oral medication named 7-methylxanthine. It proved to be an effective means of slowing down eye elongation in myopic children between the ages of 8 and 13. Studies like this may eventually lead us to a treatment for degenerative myopia that is effective.