I am very confused about something. On the frequently asked questions section of this website it says that both the Visx and Autonomous laser remove about 12 microns per diopter for a 6.0 mm treatment zone. Is this correct?

Someone told me that the Autonomous laser removes much more tissue per diopter than Visx, so I went to the Visx website (Visx press section), and this is what I found:

http://www.visx.com/index.php3/news_us.html

"Flying spot scanning treatments, which are limited by a single spot size, have the potential to increase the depth of the ablation by as much as a factor of three.

The VISX STAR™ platform uses an exclusive SmartBeam™ technology which tailors the beam size from 0.65 mm to 6.5mm for the particular area to be treated, sparing precious corneal tissue."

Per Visx, the Autonomous, being a spot scanning laser, will tend to remove much more tissue. I need to get this straight because I want to preserve corneal tissue and have the best laser used for my treatment.

Can anyone shed some light on this issue?

My parameters are: -5.50 with -.50 Astigmatism, both eyes, corneal thickness was measured by a hand probe to be 538 microns. Dark room pupil size was measured to be 6.7mm. I am correctable to 20/15 in both eyes with eye glasses. I would like to have a great result, including good night vision.

Also, if anyone has any comments on whether or not the Visx S3 laser (has eye tracker) is worth waiting for, then please let me know.

Thanks for any replies!

John

The lasers remove corneal tissue based on the size of the optical zones. The VISX laser for example has 2 settings - 6.0 mm and 6.5 mm. The 6.0mm optical zone removes 12 microns per diopters, while the 6.5 mm optical zone removes 14 microns per diopter.
Other lasers treat wider, and the formula is roughly 16.5 microns for 7mm optical zone and 21 microns per diopter for 8mm optical zones.

I hope this helps

Best of luck

Bill Trattler, MD
Miami, FL

Dr. Trattler,

I may not have explained myself clearly, but I was interested in a comparsion of microns per diopter for the same optical zone size, for example, 6.0mm. Since I asked the question, I found a document on the Autonomous Ladar Vision web site that states that this laser removes 12 microns per diopter for a 6mm optical zone, the same as the Visx laser. This corresponds with the data in your frequently asked questions section. I am still a bit confused, since there is this argument that spot scanning lasers take off more microns per diopter (same optical zone), but I assume the Autonomous data are correct.

Regarding pupil size, I was measured with a pupilometer at 6.7 mm, but was later measured with a card in a very dark room with a small penlight device (it was done in what appeared to be a very skillful manner) and my pupils were measured at 8.5mm. I was told by someone else that pupilometers tend to under-measure pupil size since you are focusing on a red light that is close (apparently focusing close tends to close the pupil). Does it make sense that a pupilometer would under-measure my pupil size by this amount?

If the 8.5mm pupil size is correct, then I may have a problem, as the doctor plans to use a 5.8mm optical zone, transitioned to 7.8mm (pupil size was measured to be 6.7 mm at this doctor's office, the 8.5 mm pupil size was measured at a different doctor office). This is due to my relatively thin corneas (latest measurement about 518 microns) and relatively high prescription
(-5.5 with -.5 Astigmatism, both eyes).

Do you have any comments on this? Will I end up with significant night vision problems? Should I not have lasik surgery? Any comments would be appreciated.

Regards,

John