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Laser eye surgery to reduce or eliminate glasses began in Canada
in 1990. The treatment zone size was quite small at that time, and
a fairly significant number of people complained of night vision
problems (like halos or starbursts appearing around lights). Over
the years, the treatment zone size gradually increased, as did the
range of prescriptions that could be treated. In the early days,
astigmatism and farsightedness was not correctable with the laser.
That is no longer true.
Another aspect the lasers have changed is the size of the laser
beam. Originally, the entire treatment zone diameter was treated
with each pulse of the laser. Now, most lasers use a ‘flying spot’
laser that has many advantages over the old broad beam versions.
One of the most significant factors is the ability to do
customized wavefront treatments. By having a small laser beam, it
can allow more treatment to be done in certain parts of the cornea
than others. It also leaves a smoother surface than the old lasers
were able to, thus increasing the quality of the image focused
inside the eye and improving the accuracy of the treatment.
Some lasers, including the laser used by Boyd Vision Centre
(MEL-80), are
able to leave the cornea in a prolate shape. This means that the
focusing power of the centre of the cornea is greater than the
periphery. This is a key element in reducing night vision effects
(starburst and halos around lights). In fact, some people who
suffer night vision problems with older lasers are able to have
some additional laser treatment done with new lasers to improve
the quality of their vision.
For more information visit: the Zeiss Mel 80 website.
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