Your eyesight should be stable for the past year, with no increase in degree.
You should not have eye problems such as cataracts, glaucoma or keratoconus.
Before surgery, you will undergo a comprehensive examination to assess your suitability for LASIK.
You'll have ample opportunity to discuss all aspects of the surgery with your surgeon.
LASIK may not be suitable for you if you have the following problems:
Pre-existing structural abnormality of the cornea (e.g. keratoconus)
In Microkerotome LASIK, the cornea flap is created by using a microscopic blade. This method of flap creation has been employed for the last 15 years in millions of people who had LASIK. It, therefore, has a long track record of safety.
2. Intralase (Bladeless)
Instead of using the automated microkerotome to create the corneal flap, the IntraLase laser is used to cut the flap.
The advantage of using the laser to create the flap is that the diameter, thickness and hinge position can be customised. This is especially useful in patients with high degrees, thinner corneas or corneas with unusual shapes.
3. Epikeratome
In this method, a blunt microscopic blade is used to rub off the skin layer of the cornea (epithelium) in the form of a sheet. The skin layer is then folded back and laser is then applied to the cornea to correct the refractive error. After that, the skin layer is then replaced over the cornea. This technique is called Epi-LASIK, which is an advanced form of surface treatment.
Standard LASIK involves using a conventional laser software program to correct low to moderate myopia and astigmatism (less than 600 degrees). It is a good option for people with normal corneal thickness and curvatures.
2. Customised Ablation
(a) Tissue Saving
Tissue-saving (TS) LASIK is a form of LASIK in which the laser software is designed to remove less cornea tissue for a given degree of correction. It is ideal for high myopia and astigmatism and especially for people with thinner corneas so that full correction can be achieved and still retaining sufficient corneal tissue for structural strength and for future LASIK enhancement.
(b) Aspheric
Unlike conventional LASIK, where the central part of the cornea is flattened, aspheric laser ablation is specially designed to retain the original curved shape of the cornea. This is an improvement over standard LASIK, and is intended to give sharper vision with less glare and haloes at night.
(c) Wavefront
Perfect Optical System
Human Eye - Imperfect
Developed more recently than standard LASIK, wavefront LASIK customises the laser treatment to each eye's minute optical imperfections. In addition to correcting myopia and astigmatism, wavefront LASIK also simultaneously corrects these optical imperfections to produce better contrast sensitivity and reduces glare and haloes at night.
To achieve the best possible visual outcome after LASIK surgery, the laser pulses must be well centered and aligned with the eye during surgery. If your eye moves during the surgery, it will affect the location of where the laser pulse is applied. This can result in a less desirable vision outcome. However, our eyes often move during surgery which may affect the accuracy of the treatment.
Modern LASIK machine has an eye tracker that is able to track these eye movements to allow laser spots to be correctly placed on the cornea. This is especially important for correction of astigmatism in which the astigmatism axis must be well aligned for effective correction.
The ACE technology, in the Bausch and Lomb Technolas 217Z machine, utilises an iris-recognition system to recognise the eye for tracking eye movements. Like our thumbprint, the iris pattern of the eye is unique to each eye, thus allowing precise matching of the laser pulses with the intended treatment position on the cornea. This therefore maximizes the accuracy and safety of the procedure.
With eyetracker
Without eyetracker
(B) PRK
In PRK, the most superficial layer of the cornea, called the epithelium, is removed. The excimer laser is then used to reshape the surface of the cornea, changing its curvature and therefore correcting the refractive error.
Because the surface layer of the cornea is removed, there will be more discomfort, longer healing time and a higher risk of corneal haze and scarring compared to LASIK.
