Before I describe the events of my surgery day, I suppose I should provide some basic background info on LASIK and explain those “three key technologies” that I mentioned in the last post. The LASIK procedure is often referred to as “flap and zap.” A thin surface layer of the cornea is cut away in an incomplete circular arc (the corneal flap), the flap is lifted up, a laser pulses away at the corneal tissue underneath to reshape the eye, then the flap is reset.
Normally, to cut the flap, a medieval torture device known as a microkeratome is used. Just do a Google image search for microkeratome and try not to cringe. There was no freaking way I was going to have one of those get anywhere near my eyeball. With all-laser LASIK (IntraLase®), the flap is precisely cut with a femtosecond laser. Now granted, a speculum is still used to keep the eye open, and a suction device holds the eyeball steady, but the key is that there is no hand-held metal blade. Apparently, most complications from LASIK arise from poorly cut flaps that can’t reseat properly after the operation.
Once the flap is cut and moved aside, the corneal tissue is pulsed away with an ultraviolet excimer laser. Older generation systems used a broad-beam laser (6-8 mm) that is less accurate and often caused night-vision complications.
Flying spot lasers use a combination of a smaller beam (1-2 mm) and an active tracking system that continually monitors the exact position of the eye and adjusts accordingly. The smaller beam is more accurate and produces a smoother corneal shape.
When the laser pulse hits the eye, it does not burn away the cornea; instead it disrupts the tissue at a molecular level without any transfer of heat and creates a tiny puff of water vapor and carbon dioxide. This cloud could distort the laser beam, diminishing its precision, so the tracking mechanism moves the pulses in a pattern that allows the debris to clear first before contacting the area again.
The latest advance in laser eye surgery is a technology that I had seen in a Discovery channel special, and it was what prompted me to finally seek out a laser eye surgeon and make a consultation appointment. Invented by Bausch and Lomb, and sometimes referred to as Custom Cornea, the Zyoptix™ system scans the cornea to create a detailed three-dimensional map of the surface. That map is saved to disk and input into the laser system to be used to precisely guide the laser treatment.
This procedure tacked an additional $1000 on to the overall price of the surgery. However, normal eye surgery only corrects low-order aberrations; higher-order aberrations in the shape of the cornea, such as those that cause halos or astigmatism are usually not treated. There are many factors that affect one’s quality of vision beyond one’s ability to read an eye chart. Custom cornea tries to remove as many imperfections in the shape of the cornea as possible.
Whew, all of this medical jargon is exhausting. Looks like surgery day will have to wait for the next installment.
To be continued…