Refractive errors in the eye could cause vision problems among people from different age group. To address refractive problems like nearsightedness or myopia, farsightedness or hyperopia and completely blurred vision or astigmatism, some people use corrective eyeglasses, while others use contact lenses.
In the past few years, laser surgery has also been employed to fix refractive errors of the eye. The procedure works on reshaping the cornea or natural outside lens of the eye so that the patient gets the ideal visual acuity.
Over time, developments in the field of medical science has brought varying techniques used for laser eye surgery. Each of these techniques uses different equipment designed to perform the procedures on the eye with utmost precision.
LASIK versus Photorefractive Keratectomy
Both LASIK and PRK use laser to reshape the cornea of the eye to achieve ideal contour and help the eye see clearer. PRK removes the epithelium or the membrane covering the cornea in the process of reshaping the cornea. LASIK, on the other hand, keeps the epithelium by creating a flap that is folded away from the treatment zone before actually reshaping the cornea. This approach helps speed up the recovery as the epithelium serves as a natural bandage to the eye.
It has been observed that patients undergoing LASIK has faster recovery period with lesser irritation compared to those who had PRK. However, these patients appear to experience dryness of the eye more than those who went through PRK surgery.
Risks Associated To Flap Creation
While creating and keeping the epithelial membrane seems ideal to promote faster healing, there are associated risks that are unique only to LASIK. The following are examples of flap-related complications.
Epithelial ingrowth. The epithelial membrane that is placed back after the corneal ablation is allowed to heal completely through natural processes. However, there are reported cases of epithelial ingrowth wherein the cells from the surface layer grows underneath the corneal flap.
Slipped flap. In some cases the flap detaches from the rest of the cornea. The risk of dislodged flap is greatest immediately after the procedure. To avoid this, patients are advised to get a good rest and wear protective gears like goggles when sleeping to avoid touching and moving the flap while it reattaches itself to the cornea through natural healing processes.
Diffuse lamellar keratitis. There are reported cases of diffuse lamellar keratitis or eye allergy after laser eye surgery. This complication is not exclusive to LASIK and could happen on other types of laser eye surgeries. However, chances of inflammation is higher in LASIK due to the creation of the flap as this process makes room for cells between the cornea and the epithelial membrane.
Displaced flap or fold. The flap must be properly placed after corneal ablation to avoid instances of displaced flap or fold. It is also important not to touch or move the flap to avoid the said complication. Although instances or occurrence of displaced flap are small and decreases with the surgeon’s experience, it can affect the vision of the patient. As such, correction might be necessary.
Flap interface particle. Surgeons must carefully and skillfully put the flap back in place after ensuring that there are no particle or air bubble on the flap that might be trapped. These interface particles does not have clinical significance determined yet but are observable.
LASIK Procedures
LASIK surgery starts by applying alcohol on the epithelial membrane to weaken the cells. A flap is then created and is folded away from the cornea or the range of the laser. The creation of the flap might be done through mechanical blade or microkeratome or through femtosecond laser depending on the technique used.
After the flap is folded, actual reshaping of the cornea takes place through the use of excimer laser that ablated corneal tissues causing them to evaporate. The laser ablates tissues that are few micrometers thick until the desired shape and contour of the cornea is achieved.
Reshaping the cornea usually takes just a few minutes on each eye. After the said procedure, the flap is carefully placed. There are instances wherein re-placing the flap is not ideal, such as when the flap dislodges. The process therefore becomes more of an alcohol-treated PRK than that of LASIK. Healing process becomes much like of PRK.
Further Developments
The idea of keeping the flap in LASIK surgery comes with both advantages and disadvantages. Developments in the field of eye medicine tries to get the best of LASIK with lesser complication that comes with keeping the epithelial membrane.
Although it is still in the stage of advanced testing and evaluation and therefore not yet available for the general public, the idea of an all-laser, flapless LASIK is being considered. This means that the patients gets the benefit of keeping the epithelial membrane to provide continuous nourishment for the eye to fasten recovery with much lesser flap-related complications.
The procedure includes the reshaping of the cornea through laser and the lenticule that is created inside the cornea is extracted through a small incision which is about three millimeters long. The procedure is still being tested and is in its advanced stages but so far, results collected over a year interval appears promising.
Positive observation include the minimal occurrence of dry eyes and faster healing. Complication associated with the creation of the flap is also eliminated.
While LASIK has been observed to be of high success rate, developments in the field like flapless LASIK is surely something every patient is very glad to welcome. This should help future generations perform laser surgeries to correct refractive issues affecting clarity of vision.
Thanks to the people who tirelessly work on developing new techniques that are useful in the field of medicine and those surgeons who are willing to test the processes together with their expertise for actual application, and the researchers who keep track of the developments, we have something exciting to look forward to. This development brings LASIK a little bit closer to perfection, with lesser risks and complications with better chance of success.
