The difference between a standard procedure and a wavefront guided treatment is essentially that in a standard treatment one corrects for a glasses prescription. In a glasses prescription, we treat approximately 90% to 95% of the refractive error that the patient has. In addition to the glasses refraction, there is a small percentage of the vision that cannot be corrected with glasses because it is made up of tiny little irregularities within the visual system. These small irregularities can be measured with the wavefront aberrometer and this can be incorporated into the patient’s treatment and in other words the actual vision can be refined a little further than glasses possibly can do, so essentially the difference between the two types of treatment is very small, but if you are looking to achieve the last extra little bit of focusing power that glasses cannot perform for you, wavefront guided treatment will hopefully offer that to you.
A team from the London Vision Clinic recently visited Nepal where they worked alongside specialists – including Dr Kishore Raj Pradhan and ophthalmic technician Gopal Karmacharaya – at the Tilganga Institute of Ophthalmology in Kathmandu, Nepal. Both Kishore and Gopal spent almost five months last year at the London Vision Clinic gaining experience using the latest laser and diagnostic equipment that – thanks to the London Vision Clinic Foundation – has now been installed in the new refractive surgery unit at Tilganga.
The risk and complications, it is a very difficult question to answer because it is like any other medical procedure. It depends a lot on who is doing the surgery. In expert hands, the surgery is exceedingly safe. It has been said to be the safest surgical procedure that we do. Certainly laser eye surgery is now the most common surgical procedure on the planet. Of all procedures of the whole body, it is the one that is performed most common.
Prior to performing any procedures for any particular patient every single surgery requires a safety check. We will recheck not only in terms of the actual laser equipment itself but actually all the instruments that are used during the actual laser eye surgery processes as well. A lot of the checks are done by nursing staff, this is then double checked by the surgeon, so we do not rely on one set of checks; it is normally double checked in other words.
There are three generally accepted methods of treating patients with laser surgery to correct their refractive errors. In PRK, we perform a surface treatment. There is a layer on the surface of the eye called the epithelium and it is being replaced by the eye every 7 to 14 days. So in that type of procedure we remove that surface layer, we are able to reshape the more permanent layer underneath that. Thereafter we can apply a contact lens as a bandage and it will allow the surface layer to re-grow underneath the contact lens and re-populate the surface of the eye. In LASEK that is a system whereby, very similar to PRK, we remove the surface layer but in this case we do not discard it, we actually just push it to one side.
With the small size of an Excimer laser used for laser eye surgery, we will think of it as a paintbrush size. It is very difficult to do fine art with a house paintbrush. So obviously the smaller the brush you are using the more detail you can paint, you can carve. Of course the smaller the brush, the longer it will take you to paint an area. So there is an interplay between the spot size and the speed of the laser and that is all technical stuff but generally speaking small spot lasers are better than broad area lasers.
IntraLase is the terminology given to one of the laser machines, which is used to create a flap in the cornea. The technology group that it falls under is called a femtosecond laser. There are approximately six different types of femtosecond lasers in the world today, of which IntraLase is one of them. The way these lasers work is that instead of making a cut in the eye to create the flap is that they create a bubble there at a programmed depth within the cornea.
Eye tracking is what it says. I mean basically we have incorporated technology which is probably military derived where we have a camera that is photographing the eye or part of the eye many, many, many times per second, 500 to 1000 times per second. The photograph of the eye is analyzed instantaneously and the position of the eye is analyzed. So it means that during treatment and many people worry what if I move my eye, what if I blink or am I going to go blind, the answer is absolutely not.
If the patient moves or looks the other way or suddenly blinks, none of that really can harm the procedure. We have many systems in place, including the eye tracking system which mean that even if the patient moves, even if they cough, even if they sneeze, even if they fall off the bed, it does not change the results.
It is not essential after the treatment for patients to come with somebody with them to help them home. A lot of patients attend the clinic on their own and they are able to travel home quite safely on their own. At the London Vision Clinic we advise patients to return home or their hotel by means of a taxi, preferably mainly because we ask them to keep their eyes closed for the few first hours after the treatment and the nature of having to get on a tube, up and down stairs, bussing and lots of people around is not really conducive to keeping the eyes closed over the time period. It is a lot easier by cab.
