WHAT CAN BE CORRECTED ?
If you are under 45 years of age and you wear correction for myopia (short sightedness), hyperopia (long sightedness) or astigmatism then you can most likely you can have a correction to eliminate your glasses or contact lenses. The strength of your glasses will govern which modality is best
If your problems is none of the above but instead you are just presbyopic (older than 45 and can’t read anymore) then read the sections on presbyopia and monovision as your problem is different and needs a different approach
BASIC PRINCIPLES OF VISION CORRECTION
There are essential two ways to correct the vision problems mentioned above.
- Change the surface of the cornea using a laser technique such as Lasik or PRK
- Change the lens in the eye (Clear lens exchange)
- Implant a new lens in the eye, in front of your existing lens (Implantable Collamer Lens)
As a general principle, corneal procedures are generally performed in younger patients and lens procedures in older patients.Implantable Collamer lenses are generally used in people requiring high corrections 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 applied directly to the corneal stroma. Therefore there is no flap creation and therefore it leaves behind a thicker base.
LASIK has largely replaced PRK because it is much more comfortable with virtually no discomfort whatsoever and visual recovery is a matter of days versus weeks. The end results however are really no different and in fact there has been a resurgence of PRK in recent years in certain individuals.
LASIK would be the procedure of choice for younger people with shortsightedness up to about 9 diopters and longsightedness up to about 3 diopters. Astigmatism can be corrected up to about 4 diopters.
For people whose refractive error is out of the range of LASIK, a lens can instead be implanted within the eye. This lens is called an implantable Collamer Lens or sometimes also called, a phakic intraocular lens. It sits behind the iris. It is in a sense, a contact lens within the eye. The Visian implantable Collamer lens (ICL) is an example of one that sits behind the iris and in front of the natural lens.
We offer the Visian ICL for patients out of range of Lasik.
In older patients, usually late forties or beyond, refractive lens exchange is usually a better option. In this procedure, the eye’s natural lens is removed and replaced by an artificial one. This is usually done because firstly accommodation (ability to focus) is largely gone by this age and secondly because the age for cataract is arriving so it avoids a second operation for cataract later on. Also, at an older age, LASIK is less predictable.
This video below is a good overview of the various options.