Types of Lasers & Eye Tracking Software in Laser Eye Surgery

There are a number of different lasers used in corrective laser eye surgery procedures. The first laser to be used was the excimer laser, which was created especially for laser eye surgery. Recently we have seen many different types of technology come on to the market, such as femtosecond lasers,  wavefront guided treatment and Zyoptix technology. There are two main types of laser, these are the broad beam and scanning lasers. The scanning category can be further subdivided into slit scanning and spot scanning lasers. Each has its own advantages and disadvantages.

Broad Beam Lasers

As it suggests in the name, broad beam lasers produce a wide beam with a diameter of over half a centimetre. This allows the procedure to be done much faster, whilst decreasing the risk of over or under correction problems. As the beam is slightly larger, the risk of creating side effects and complications such as higher order aberrations is slightly increased. This can be minimised somewhat by improved operative techniques.

Slit Scanning Lasers

The slit scanning lasers use a small laser beam that is linked to a rotating head, which removes larger areas of tissue depending on the size of the slits that are used as the device rotates. The major disadvantage of this type of laser is the potential of causing over correction in the patient, especially if eye tracking software isn’t employed.

Spot Scanning Lasers

The spot scanning laser are the most widely used in today’s market. Unlike broad beam lasers, they have a very small diameter of around 1 millimetre. Instead of moving through specified slits, the laser is guided by a machine over the eye, gradually removing tissue as it scans the surface. This type of laser is a lot safer and produces much better results.

Eye Tracking Software

All of the laser systems used in corrective procedures today use some form of eye tracking software. This ensures that the natural movements of the eye that occur during the surgery are compensated for when the laser starts to thin the cornea. Many surgeons consider this type of software vital, as if it is not used, you must keep your eye fixed throughout the procedure as moving it can cause errors in correction.

Currently there are two types of eye tracking software being used. The oldest type is called ‘open loop’ tracking. This uses a video system to check that the eye is kept in the same position. If your eye moves a specified amount during the procedure, the laser is automatically stopped. This prevents any incorrect tissue removal.

The second type of tracking is called ‘closed loop’. This is the most advanced system, able to monitor the position of your eye and adjust the position of the laser to match it. This ensures that the procedure is done correctly and is not stopped prematurely.

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