Laser Vision CorrectionLaser Vision Correction | Lasik | PRK
The eye and vision errors
The cornea is a part of the eye that helps focus light to create an image on the retina. It works in much the same way that the lens of a camera focuses light to create an image on film. The bending and focusing of light is also known as refraction. Usually the shape of the cornea and the eye are not perfect and the image on the retina is out-of-focus (blurred) or distorted. These imperfections in the focusing power of the eye are called refractive errors. There are three primary types of refractive errors: myopia, hyperopia and astigmatism. Persons with myopia, or nearsightedness, have more difficulty seeing distant objects as clearly as near objects. Persons with hyperopia, or farsightedness, have more difficulty seeing near objects as clearly as distant objects. Astigmatism is a distortion of the image on the retina caused by irregularities in the cornea or lens of the eye. Combinations of myopia and astigmatism or hyperopia and astigmatism are common. Glasses or contact lenses are designed to compensate for the eye's imperfections. Surgical procedures aimed at improving the focusing power of the eye are called refractive surgery.
Columbia Laser Vision Correction uses several technologies to give our patients the best possible outcomes ensuring excellent vision.
Laser Refractive Surgery
The importance of Safety cannot be overemphasized when performing elective procedures, such as laser refractive surgery. The health of the eye must be carefully evaluated to meet the immediate and long terms visual needs of the patient and to minimize the potential for untoward effects to occur.
The basic health and structural integrity of the eye must be evaluated to assure that the surgery can be safely done. The optical analysis of the eye, extraocular muscle balance and ocular dominance all must be determined to assure that the planned surgery meets the visual needs of the patient.
There are two main types of Refractive Surgery that may be selected depending upon the status of the eye: PRK, or photorefractive keratectomy, or LASIK, laser-assisted in situ keratomileusis. Both PRK eye surgery and LASIK eye surgery are used to treat myopia, hyperopia, and astigmatism. Both procedures work by using an excimer laser, an ultraviolet light beam, to precisely remove ("ablate") very tiny bits of tissue from the cornea to reshape it and correct vision. In near-sighted corneas, the excimer laser flattens a steep cornea. In far-sighted corneas, the excimer laser steepens a flat cornea. The PRK and LASIK procedures are performed differently and have distinct advantages and disadvantages. Nevertheless, both LASIK and PRK produce similar vision correction results.
If you are interested in laser vision correction, a specialist can explain PRK vs. LASIK in more detail and help you determine if either procedure is right for you.
PRK involves removing the outermost layer of the cornea, the epithelium, to access the main refractive component of the cornea, the stroma. An excimer laser is then used to reshape the stromal portion of the cornea to change the eye’s refractive power. After the procedure, the patient regenerates the epithelial layer usually within a week’s time.
LASIK involves the creation of a corneal flap with a blade, or microkeratome, or a femtosecond laser, such as Intralase. The flap is then lifted to gain access to the stroma of the cornea and the excimer laser is used to reshape the cornea. As the flap cannot be used to change the cornea’s properties, eyes with thin corneas may not qualify for LASIK. For such cases, PRK may be a better option. Modern LASIK uses a smaller and thinner flap, a variant that has increased the safety of the procedure by increasing the thickness of the residual corneal bed, and minimizing damage to the corneal nerves.
Careful analysis of the corneal topography using assessment of the anterior and posterior corneal curvature is done for every patient. This has proven to be the most sensitive way to assess the structural integrity of the cornea and to avoid those patients who show a tendency towards keratoconus or irregular astigmatism.
Consideration is given to low levels of mono-vision to increase those years in which spectacles will not be necessary for reading.
It is of course essential to search for other pathology within the eye. Cataracts, glaucoma and retinal diseases may also be present and must be evaluated. In the older patient, a cataract extraction may well be the preferred approach to improving the patient’s vision.
In all cases, we seek the safest and most effective approach to meet the patient’s visual needs.