A thin flap of epithelium and superficial cornea is cut and reflected exposing a central area of deeper cornea. A UV laser removes corneal tissue from the deeper surface in the central area. The flap is repositioned and allowed to naturally adhere.
Brief description of procedure
After instillation of a drop of anaesthetic, the area is cleaned and sterilized. The eyelids are held widely open by a speculum to allow good access. A suction ring is applied to the eye this stabilizes the eye, increases the pressure in the eye and securely attaches to the eye. Once the microkeratome (a motorised plane) is attached to the suction ring it can pass across the cornea, cutting a thin flap as it goes. The flap consists of the surface epithelium and some of the anterior stroma of the cornea. The flap is left attached (hinged) at one edge so it can be gently reflected. The layer of the cornea deep to the flap is then reshaped using the excimer laser (very similar to PRK). The flap is then repositioned and sticks back in place. Because the front surface has been replaced there is less pain than in PRK and vision recovers very rapidly with good vision common after 1 day.
Initial studies began in 1995. Dr Peter Stewart (Laser Sight of Australia) started treating patients in 1996. There has been a rapid rise in popularity since then to become the most commonly performed refractive operation.
Excellent results can be expected in the range to +4 to -10 diopters provided corneal thickness is adequate. Sufficient remaining corneal thickness must be left deep to the flap after ablation with the laser. This may limit treatment range and compromise optical zone especially in thinner corneas and higher corrections. The corneal flap does not become totally secure for some time and there is a small risk of trauma displacing the flap especially in the first few weeks.
LASIK Patient Information
This information sheet is designed to help you understand the operation and expected postoperative course. If you know what to expect during the operation you should be more relaxed and able to assist me making the whole procedure much easier for both of us.
The operation will be performed under topical anaesthetic as an outpatient at the Eye Surgery Foundation. This is a purpose built operating complex with a state of the art laser (the Technolas 217) and other fully equipped operation rooms. The laser operating room is precisely controlled for both temperature and humidity so light comfortable clothes are all that will be needed. It is better to have only a light snack and drink well prior to the operation as anxiety and a full stomach can make you uncomfortable when lying flat.
The staff will greet you when you arrive at the centre and then prepare you for the operation. Some antibiotic eyedrops will be instilled in your eye to prevent infection. Prior to the operation several drops of local anaesthetic will be inserted. These are the same drops I used when I first examined you and sting a little for a second. Then you will be taken into the laser theatre and will lie flat on a bed with your head under a microscope. Initially the light from the microscope is a little bright but you will rapidly adjust and it should not be any problem. After I have cleaned your eye and eyelids with antiseptic I will use a sterile plastic drape to cover your eyelashes, eyelids, cheek and forehead. To prevent blinking a metal speculum is used to hold your eyelids held wide. This feels a little tight but does not hurt. Only once I am perfectly happy with your position will the operation start. The process is quite complex so we have a series of safety checks in place. You will hear me talking to the staff as well as to you. I will endeavour to talk to you at every step so you know exactly what to expect and what I would like you to do. You can talk to me and ask questions as we proceed. There are some times when movement is not allowed and I will ask you then to keep still and quiet.A suction ring will be placed on your eye. This holds your eye steady and raises the pressure in the eye to enable the flap to be cut. As the suction is applied you will hear a sucking sound and feel slight pressure then your vision should grey then black out. This is a good sign as it means that the pressure is correct for creating the flap. The microkeratome is attached to the suction ring and the flap created. As the flap is created there is quite a loud vibrating buzz and it is much easier and safer if you do not squeeze your eye or move during the few seconds that this will take.
The microkeratome and suction ring are removed. If I am totally happy with the flap we can proceed to the laser reshaping. There are a few steps getting organised and setting the laser to track your eye movements, then the laser treatment commences. The computer controlling the laser divides the treatment into a number of fractions and I will be monitoring your eye and telling you how the treatment is progressing. The laser makes quite a loud noise and does smell a bit but is painless and over in about 1 minute. On completion the flap is repositioned and washed with sterile saline. After about 3 minutes of drying the flap has adhered so the speculum and drape are removed. Antibiotic drops are instilled and a clear plastic protective shield is applied. Often, despite the after effects of the microscope light and the shield you may see quite well immediately.
Once the anaesthetic wears off the eye will feel quite gritty and irritable for a few hours. You may find the best solution is to go to bed for those few hours and keep both eyes still and closed. It is imperative that the eye should not be rubbed in the first week as the flap could be dislodged. Please leave the shield undisturbed, as I prefer to remove it myself. Vision will fluctuate the first night but if there is severe pain with reduced vision the flap may have been displaced and you should contact me.
Normally vision is quite reasonable the next morning and will improve over the next week. Most normal activities can be resumed immediately but remember that the flap is not secure for some time. For safety swimming should be avoided for 2 weeks, rubbing should be avoided and any situation where the eye could be knocked (eg. contact sports) avoided for at least 3 months. Eyedrops are routinely used for 2 weeks to help the eye heal and prevent infection. It is not uncommon for the eye to feel a little dry and irritable for several months and during this time a lubricant eyedrop may be used for comfort.