2
$\begingroup$

I am in a undergrad Vison Science class where the professor recently talked about LASIK surgery. In the surgery, a special type of laser that could heat up a specific point (a sphere actually) and nothing else. According to how much he knew, there were two beams of what I assume are electromagnetic waves that intersect and heat only that point of intersection and nothing else (with emphasis on not heating any other point in the paths of the beams).

I become very interested in this laser and searched about it on the internet. However, my knowledge in light and lasers is primitive, and I could not understand most of the vocab. Can someone explain how this works in language that a high school graduate can understand? Also, it may be possible that this property is only due to the nature of the tissue. In that case, what is this property called?

Is there a law that could help us predict the maximum precision of this heated point (the minimum radius of the sphere)?

$\endgroup$
2
$\begingroup$

In cool laser ablation, there is a characteristic thermal diffusion time that is the quantity you seek. For a certain pulse width and energy density per pulse, ablation can take place without heating the surrounding tissue to damaging levels if the thermal diffusion time is sufficiently short. If heat does transfer too quickly, thermal damage from the ablation procedure can happen and cause damage to the surrounding tissue.

This thermal diffusion time is a property of the tissue and is oftentimes measured empirically. This paper https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3206930/ includes a simulation of temperature rise in the cornea during the Lasik procedure. Note that different laser types have different penetration depths in tissue so you may not get the same results for an excimer laser as you would for a Yag laser.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.