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| Corneal thickness |
Understand why LASIK corneal thickness intraocular surgery is an important one, is assumed to be the most common questions about LASIK and corneal thickness ratio.
The thickness of the cornea normally varies between people with an average of about 550 microns, (which is about 1/2 mm), the Caucasians. It is less the black (520 microns), and even less, to Western Europe.
Corneal thickness is measured by a device known as the pachymeter. The most common method is ultrasound Pachymetry, but specific description of the systems, such as the Orbscan corneal and Pentacam can also be used. The latter systems may provide a representative of the relative thickness of the cornea in different places on the map.
Is not ideal for LASIK corneal thickness. It should, however, you know that LASIK surgery to improve vision, according to the United States Census Bureau, you should have a sufficient number of corneal thickness. This amount depends on the type of Medical error.
It is important to determine the corneal thickness before the LASIK procedure, because the LASIK improves the user's perspective of reshaping your cornea and reshapes it, inter alia by deleting some of the tissues in your cornea. If the cornea is too thin, Visio can vary depending on the quality and the weak.
The depth of ablation excimer laser has been deleted is called the stroma, the middle layer of cornea tissue. If you are shortsighted, depreciation is a user in the middle of the cornea. If you have developed your cornea, from a circle.
Ablation depth depends on the amount of treatment, which in turn depends on the degree of Medical error. Size and the selected parameters in excimer laser are other factors that affect the depth of ablation.
Can we assume that, in General, with a size 6.0 mm, the excimer laser to remove each LASIK for the treatment of the tissues of the diopter of 12 microns.
If you have 4 diopters, correcting shortsightedness to Visio, for example, the depth of ablation should be 4 x 12 = 48 micrometers.
LASIK Surgeon in such a way as to ensure that, when you have created a Corvette and excimer laser corneal tissue when applying the minimum amount is not affected by changes you make to the LASIK procedure. This critical called residual Stromal bed and it is important to maintain the integrity of the user and the strength of the cornea after LASIK procedure and to avoid serious complications such as corneal LASIK ectasia.
When the U.s. food and Drug Administration (FDA) approved LASIK, it is recommended that at least 250 microns thickness should be left to the remainder of the stromal Corvette LASIK surgery pursuant to avoid corneal ectasia.
Currently, most LASIK surgeons prefer to leave the 275-300 microns for the rest of the stromal bed safety and also to add the LASIK enhancement (retreatment), if necessary.
Residual Stromal thickness is calculated by taking the Central corneal thickness before the LASIK flap thickness and by reducing and, in particular, by tilting the calculated ablation depth.
For example, if the Central corneal thickness of 550 microns in thickness flap is estimated to be 160 microns and the depth of ablation-refraction is 60 microns, the thickness of the remaining stromal bed would be 550 – (160 + 60) = 330 microns.
If you have a thin cornea and Refractive error should be corrected, it will not be able to be great to leave at least 250 microns in the stromal bed for the rest of the Corvette.
Sometimes, the surgeon can you solve this problem by creating a thinner flap, which allows more processing is carried out at least 250 microns corneal bed. A thinner LASIK flaps can be created either in the femtosecond laser during the flap Maker IntraLASIK or specific types of microkeratomes conventional LASIK.
If it is not possible to create a thinner LASIK flap, other options such as PRK, LASEK, or Epi-LASIK may be the better option for you.
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