When your doctor assesses your eyes for correct refractive surgery, an essential factor to consider is your corneal thickness. Most doctors will take into consideration your age, degree of refractive error and the presence of a disease called keratoconus in your eye for correct refractive surgery. He or she will then calculate the corneal thickness that remains after performing LASIK on your eyes to determine the eligibility. It is always advised to get proper eye nutrition from the beginning itself to avoid any eye issues later.
Although a corneal thickness of 485 µm may be normal for correct refractive surgery, which was earlier thought to be a cut off for LASIK, you will be considered suitable for LASIK only in the deficiency of forme fruste keratoconus, skew deviation, or keratometric readings greater than 47.00 D. These are determined by advanced studies of the shape of your cornea, called corneal topography. In this case, you will not be a suitable candidate for the correct refractive surgery
Studies have observed no enhanced risk for patients with a corneal thickness of 485 µm who had LASIK or Sub Bowman Keratomilieusis, SBK. Surface ablation is usually addressed as a treatment option, in thin corneas, since it does not require a corneal flap, or raises a flap which includes only the epithelium and not the stroma, and is consequently thinner. It means that a residual corneal bed may be thicker than after a conventional LASIK, but many experts believe that the cornea is just as strong after SBK as it is after surface ablation.
To understand the difference, one must know what happens during LASIK and Surface Ablations. Both the refractive surgery correct the refractive power of the eye by modulating the shape of the cornea.
Differences between LASIK and Surface Ablations
Throughout LASIK, a thin flap of cornea is raised, using either a mechanical keratome (conventional LASIK) or using the laser itself (bladeless or blade-free or all-laser LASIK). This flap is constituted by the epithelium of the cornea, and part of the stroma. Following this, the laser, which is regulated by a powerful computerized algorithm, shapes the surface of the cornea by ablating its stroma (component tissue) so that the refractive power of the eye is corrected, and one doesn’t need glasses for perfect vision.
During Photorefractive Keratotomy, PRK, the surgeon will remove the topmost layer of the cornea. The topmost layer called the epithelium is removed using an alcohol solution, to expose the stroma. The ophthalmologist then reshapes your cornea using a laser to ensure a spectacle-free vision. There is no flap raised, and only the epithelium is removed, which grows back over three to four days. After the procedure, the surgeon inserts a bandage contact lens to protect the cornea until the epithelial layer grows back. The thick contact lens also helps decrease the discomfort during this time, which has been variably described from being mild to moderate, along with the sensation of having “something,” or a foreign body, in the eye.
Advanced Surface Ablations, ASA
ASA collectively refers to a group of surgeries including LASEK (in which a trephine removes the epithelial flap, which is replaced at the end of surgery), Epi LASEK (which uses a particular microkeratome, the Epi-keratome to remove the epithelial flap, which is replaced at the end of surgery) and Supra LASIK or touch-less LASIK (which is surface laser procedure that manages a technologically advanced excimer laser to remove the surface cells before performing the reshape of the cornea).
The disadvantages of the surface ablations, including Supra LASIK, are:
- Discomfort for the first two or three days following treatment, till the epithelium grows back.
- Vision recovery takes longer as compared to LASIK.
- Small risk of corneal haze since the epithelium is removed during the procedure.
The obvious advantage of ASAs is that they are useful for patients who have had a cornea transplant before. However, the potential advantage that they are deemed to offer to people with thinner corneas is now being challenged.
LASIK technology grows more advanced and customized to the needs of the individual cornea. Thus surgeons prefer to offer one of the newer variants of LASIK, even to patients with thinner corneas.
Procedures for People with Thin Corneas
This technology uses computerized imaging technology to create a very detailed three-dimensional “map” of the patient’s cornea to program the excimer laser for reshaping the cornea. Wavefront technology can measure very minute irregularities in the surface of the cornea, taking 200 measurements, to achieve more effective and safer vision correction than conventional LASIK.
Contoura Vision Topography Guided LASIK
This technology is the latest FDA approved LASIK eye surgery available in the U.S, and other parts of the world. It corrects the blurred vision based on the eye’s unique shape. While other technologies based on the current glasses or contact lens prescription. It measures 22,000 points as against the currently available wavefront-guided LASIK that measures around 200 points on the cornea. This means that the smallest defects of shape, optics, and curvature, even in the periphery can be considered for, resulting in the correction of refractive errors with an accuracy not achieved till now.
Contoura Vision Topography Guided LASIK technology allows the computer to generate an individualized treatment algorithm. It controls the extremely specific laser machine.
Because of this precision and accuracy, Contoura Vision Topography Guided LASIK offers the following distinct advantages:
- Easier night driving, with decreased incidence of haloes and starburst
- Lessened light sensitivity and glare
- Better reading speed and clarity
- Excellent quality of vision than glasses or contact lenses
- Lesser higher-order aberrations, and higher visual comfort
The creation of the flap is so accurately measured in the newer versions of LASIK. Because of this, the chances of corneal complications, even in thin corneas are significantly reduced. There is sufficient evidence to say that this provides the patient with a better quality of vision.
If you are also looking for Correct Refractive Surgery in Thin Corneas, visit EyeMantra today.
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