Starting from a personal request, I was starting a thread to explain what is LASIK surgery. But then xterm asked about Pulse Dye Laser treatment. Anticipating the fact that there might be more questions about various forms of laser-based surgeries, I'm starting a thread dubbed "Laser Based Surgeries". Upon request, I'll post everything I know about a certain procedure, so please note that my opinion given is based on a biomedical engineer's knowledge unless stated otherwise. Topics will be handeled in FIFO form: first come first serve. So I'll start by LASIK and then move to Pulse Dye Laser treatment.

LASIK Surgery

What does the term LASIK mean? What does it concern?

LASIK is the acronym for "Laser-Assisted in Situ Keratomileusis", where "situ" is latin for "in position" and "keratomileusis" means surgically improving the refractive state of the eye's cornea (changing the shape of the cornea by forming a thin hinged flap). It is the most commonly performed refractive surgery procedure for correcting myopia (nearsightedness), hyperopia (farsightedness), and astigmatism (blurry vision caused by inability of the optics in an eye to focus a point object into a sharp image on retina).

How does it differ from other laser-based optholomy procedures (operation, risks and complications, and recovery rate)?

Other laser-based optholomy procedures include the photorefractive keratecomy (PRK) and Laser-assisted sub-epithelial keratecomy (LASEK; not the same as LASIK). Though PRK and LASEK are technically the same, there are minor diferences: the epthelium (basic type of human/animal tissue that lines cavities like the eye socket and surfaces of structures throughout the body) is removed while treating the layer below with laser in PRK, but in LASEK, an alcoholic solution is used to weaken the structure of the epithelial cells (but not destroyed) so as to fold it, reshape the cornea with laser, and then fold it back into place. When the epithelial flap is viewed to be too weak to return back into original position, it is removed and the LASEK surgery ends up being a PRK surgery.

Advantages of PRK/LASEK over LASIK & LASIK Risks and Complications:
PRK doesn't create a flap in deep cornea tissues, so the integrity of the cornea's structure is more preserved with PRK. Furthermore, it doesn't create the risk of dislocated corneal flaps which may happen at any time with LASIK surgeries (especially after trauma). However, you should note that such complications are extremely rare (at the start in 1995, it was 5%; now, it's below 1%). In case a complication arises, there are medical treatments and corrective surgeries that can be done. Such LASIK surgery complications can be avoided by choosing the right doctor (see sections "Before Surgery" and "What to ask your doctor?"). The right doctor would tell you upfront if you're a good candidate for the surgery or not.

Advantages of LASIK over PRK/LASEK:
LASIK is less painful and has a higher visual recovery rate than PRK/LASEK. Good vision is acheived usually within the next day.

What happens before, during and after surgery?

Before Surgery:

Choose your surgeon wisely. Most post-surgery complications can be avoided by selecting the right surgeon to perform the operation. Your doctor should first conduct an eye exam to determine whether your eyes are healthy enough to go through the procedure (never ever do it before having an eye exam first). The eye exams also reveals what kind of vision correction you would require (though this is obvious already cause of your glasses or contact lens prescriptions) and most importantly how much laser ablation (removal by erosive process) is required. The surgeon should also clear out if you have a case of dry eyes (when you tear film has a certain disorder that doesn't allow proper lubrication of the eye to maintain proper vision and eye comfort) which should be treated before LASIK surgery.As a precaution of developing dry eyes after LASIK, some doctors recommend treatment even if you have a normal tear film.

An ideal surgeon would conduct a corneal topography to develop a detailed map of your cornea and to measure eye curvature. Preferable, it is based on a wavefront analysis system which gives a more detailed and precise map of the cornea and consequently what aberrations are affecting your vision. The wavefront analysis system merely sends light waves to generate this map.

Finally, the surgeon should ask about medications and health conditions, such as diabetes, as they can directly disqualify you from being a good candidate for LASIK surgery.

During Surgery:

I've already explained a bit about it, but a picture is worth a thousand words. A slideshow is even better: http://www.allaboutvision.com/video-library/video-lasik.htm. For those with a strong stomach, you can find a real-time surgery here.

Note that the whole duration of the surgery will not exceed 10 minutes. Your doctor will give you numbing eye-drops (to avoid any discomfort) and sometimes an oral sedative (just to make you loosey-goosey and avoid jittering during the procedure), but you'll be awake the whole time. Have someone with you so they can drive you home afterwards.

After Surgery:

After the surgery, you'll get a few minutes to rest, then you can go home. [/b]Follow your doctor's instructions to the letter: any rest required and medications to take.[/b] It's always better to rest a couple of hours at home after the surgery. Take at least two days off, because streneous activities affect the healing process. Also, avoid exercising for at least a week and avoid rubbing your eye (you don't want to traumatize your eye or dislodge the corneal flap, though slim the chances better be safe than sorry).

Blade Versus Bladeless LASIK

Alot of doctors debate the issue of which method is better: the blade based LASIK surgery (just like seen in the video, where a blade is used to cut the flap in the cornea) or the pure-laser based surgery (where the flap is cut by a laser). In both cases, a laser beam (called the excimer laser, which is a form of ultraviolet laser) will be used to treat the corneal stroma. Though the dual-laser treatment reduces the level of erroneous flap-cutting, both will be penetrating the cornea, so less radiation better than more radiation => Blade-based is my engineerish recommendation. Plus, all-laser treatment is more costy (more radiation exposure = more money payed). Besides, we already agreed that you'll be going to a qualified surgeon with a good reputation to do your surgery, so why should you be scared of erroneous flap-cutting?

The all-laser LASIK procedure emits first femtosecond laser beams (ultrashort pulses; to cut the corneal flap) and then excimer laser beams (to treat the cornea).

What to ask your doctor?

In your consultation appointment, ask the following:

1) What is your complication rate, and how does this compare with national averages? (No it's not a rude question, it's to know more about the surgeon's qualifications. Unfortunately, some doctors have excellent credentials but when I meet them they make me wonder how they survived medical school).
2) Has the surgical center you use ever had an outbreak of serious eye infections? If so, what caused this?
3) If a complication does occur, what is your specific policy regarding follow-up?
4) Do you charge extra if an enhancement is required?
5) If you do charge extra for enhancements, what kind of a price break can be expected?
6) If you don't charge extra for enhancements, what is your cutoff date (one year, for example) for addressing problems after the initial procedure?
7) What excimer laser machine do you use?

What LASIK laser machine is best?

This is directed to those who are interested in knowing what excimer laser machine is best to use for a LASIK surgery. Selecting an excimer laser machine to perform your LASIK surgery is a far-fetched idea. Still, I found this nice comparison table from which I'll select the best (again, acccording to my opinion as an engineer):

Note:

OZ: Optical zone = maximum size of pupil allowing light to pass through the eye that can be targeted effectively for correction with a specific laser.
TZ: Treatment zone = maximum treatment area, including a transition zone that can be used in an ablation to achieve vision correction in the targeted area.

Best machine: Wavelight ALLEGRETTO Wave
Why: Because wave-front guided excimer laser machines are better than normal excimer laser machines: smoothest post-op corneas and the lowest degrees of higher order aberrations in vision. All types of corneal refractive problems are targeted (myopia, hyeropia, and astigmatism). Plus, the scanning beam allows centralization of energy (i.e. the energy is directed to the spot which the surgeon is applying the laser beam at => better results). Finally, it's German, Deutchland: where the elite of design engineers reside.
Alternative: Visx Star S4 IR & CustomVue (commonly used, wave-front guidance, variable scanning beam).

Hope this helps.