LASIK & Refractive Surgery Overview

If you have a refractive error, such as near-sightedness(myopia), farsightedness (hyperopia) or astigmatism, refractive surgery is a method for correcting the refractive error and reducing the dependence on spectacles. There are various surgical procedures for correcting or adjusting your eye's focusing ability by reshaping the cornea or by implanting a lens inside the eye. The most widely performed type of refractive surgery is LASIK (Laser-assisted in situ keratomileusis), where a laser is used to reshape the cornea.

Refractive surgery might be a good option for you if you:

• Want to decrease your dependence on glasses or contact lenses
• Are free of eye disease
• Accept the inherent risks and potential side effects of the procedure
• Understand that you could still need glasses or contacts after the procedure to achieve your best vision
• Have an appropriate refractive error

Refractive surgeries are performed by ophthalmologists, medical doctors who are specialized in the surgical treatments of the eye. It is an outpatient procedure and will require postoperative drops for a period of 6 weeks to minimize inflammation and discomfort. The postoperative visits are usually scheduled on day 1, 1 week and 1 month after the procedure.

Standard LASIK ( Laser in situ Keratomileusis)

Standard LASIK involves correcting of the refractive error like myopia, hyperopia or astigmatism as calculated in the standard refractions.

• Under standard LASIK, initially after creating the corneal flap, your doctor uses an advanced excimer laser to reshape the cornea by removing a pre-determined amount of corneal tissue.
• The amount of the tissue that will be removed is determined by the pre-operative assessment. These measurements are made with the recent prescription for glasses and/or contact lenses.
• The flap is then replaced, and within minutes, natural forces hold the flap down on the cornea. Within some hours, the surface layer of the cornea (epithelium) starts to develop over the cut edge of the flap to seal it into position. In a few days, collagen bonds form within the cornea surrounding the edge of the flap, permanently sealing it.
• This is a painless and safe technique which takes nearly 10 minutes in the operating theatre, during which the laser is used for less than a minute on each eye.

Photorefractive Keratectomy (PRK)

Photorefractive Keratectomy (PRK) is an elective outpatient laser eye surgery for vision correction to improve vision and reduce or eliminate the need for eyeglasses or contact lenses.

In PRK surgery, the surgeon uses the excimer laser to reshape the curvature of the cornea. Prior to LASIK, PRK surgery was the most commonly performed laser eye surgery for vision correction. PRK differs from LASIK, in that the surgeon does not create a flap. PRK surgery is best suited for patients with thinner cornea, or with vocational or sports-related limitations where a corneal flap is contraindicated.

Here’s how the PRK surgery procedure works:

• There are no scalpels or incisions with the PRK laser eye surgery for vision correction.
• The laser is properly calibrated before your PRK procedure begins.
• An instrument is used to prevent blinking during the procedure.
• Anaesthetic drops are applied to numb your eye and prevent discomfort.
• The protective surface layer (epithelium) is removed. The epithelium will regrow within five days.
• Your PRK surgeon then applies computer-controlled pulses of cool laser light to reshape the curvature of the eye. Deeper cell layers remain untouched.

The PRK laser vision correction process is completed in approximately five minutes. Upon completion, the surgeon places a clear bandage contact lens on the cornea to protect it and applies eye drops. Often, both eyes are treated on the same day.

Implantable Contact Lens (ICL)

An Implantable Contact Lens (ICL), also known as a phakic intraocular lens (IOL), is a type of refractive surgery used to correct vision problems such as myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. The ICL is a thin Collamer lens implanted inside the eye, between the iris and the natural lens. It works by refracting light properly onto the retina, improving vision. ICLs are suitable for patients with high refractive errors or those who are not candidates for LASIK or other laser vision correction procedures. The procedure is reversible, and the lens can be removed or replaced if needed. Benefits include improved vision, reduced dependence on glasses or contact lenses, and quick recovery. However, as with any surgery, there are potential risks and complications.

Preoperative Assessment for LASIK

The preoperative assessment for LASIK is a comprehensive evaluation to determine a patient's suitability for refractive surgery. The assessment includes a thorough medical history, visual acuity testing, refraction, corneal topography (corneal curvature), pachymetry (corneal thickness) and retinal evaluation. The patient’s pupil size, dry eye status, and overall ocular health are evaluated.

This assessment helps identify potential risks and ensures that the patient has realistic expectations from the procedure. By carefully selecting suitable candidates, the risk of complications can be minimized, and optimal outcomes can be achieved, resulting in improved vision and patient satisfaction. If a person is a contact lens wearer, contact lenses are to be discontinued for two weeks prior to assessment, in order to obtain accurate measurements.