What Can Be Fixed? If you are under 45 years of age and you wear correction for myopia (short vision), hyperopia (long vision) or astigmatis...
What Can Be Fixed?
If you are under 45 years of age and you wear correction for myopia (short vision), hyperopia (long vision) or astigmatism, most likely you can have corrections to eliminate your glasses or contact lenses . The strength of your glasses will determine which method is best.
If your problem is none of the above, but instead you are simply presbyopic (over 45 and cannot read anymore) read the section on presbyopia and monovision because your problem is different and requires a different approach. Is
Basic principles of vision correction
There are two methods needed to correct the vision problems mentioned above.
alter the surface of the cornea using a laser technology such as LASIK or PRK
Change lens in the eye (clear lens exchange)
Place a new lens in the eye, in front of your existing lens (implantable collamer lens)
As a general principle, corneal procedures are typically performed in younger patients and lens procedures in older patients. Implantable collamar lenses are commonly used in people who require high correction or where the corneal surface is abnormal
LASIK vs. PRK vs. Lens Exchange vs. Phakic Lens Implant (ICL)
In LASIK, a corneal flap is created. Traditionally with a microkeratome (knife) but nowadays with a femtosecond laser.
In PRK, the surface epithelium is removed and a laser is applied directly to the corneal stroma. Hence there is no flap construction and hence it leaves a rough base.
LASIK has largely replaced PRK because it is much more comfortable with virtually no discomfort and visual recovery is a matter of days versus weeks. However the end results are not really different and in fact there has been a resurgence of PRK in recent years in some individuals.
LASIK will be the procedure of choice for young people with nearsightedness up to about 9 diopters and nearsightedness up to about 3 diopters. Astigmatism can be corrected up to about 4 diopters.
For people whose refractive error is outside the range of LASIK, a lens may be implanted within the eye. This lens is called an implantable collamer lens or sometimes called a phakic intraocular lens. It sits behind the iris. This is a kind of contact lens within the eye. The Vision implantable collimator lens (ICL) is an example of one that sits behind the iris and in front of the natural lens.
In older patients, usually in the late forties or older, refractive lens exchange is usually a better option. In this procedure, the natural lens of the eye is removed and replaced with an artificial lens. This is usually done firstly because accommodation (the ability to focus) is largely gone by this age and secondly because the cataract is approaching age so it is avoided by a second operation for cataract later. Also, at older ages, LASIK is less predictable.
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