Active eye tracking technology for the treatment of myopia

I believe many people are worrying about myopia, right? Take a look at the new technologies below. New technologies provide us with better treatments for myopia.

Excimer laser treatment of myopia surgery accuracy In addition to the stability of the energy requirements of the surgical equipment, but also need to have adequate tracking of eye movement, correction technology, in order to ensure accurate laser cutting in the optical center of the eye. In fact, the current research and development process of laser equipment manufacturers in the world has always focused on how to ensure the laser energy stability during surgery, update calculation methods to reduce the corneal cutting volume, optimize the individual cutting program, and track and correct the eye during surgery. The theme of sports is unfolded. At the initial stage of excimer laser surgery, many patients pay the price of visual quality because there is no tracking technology, or tracking technology cannot compensate for the movement of the eye during surgery.

At present, all brands of excimer lasers are generally accompanied by active eye tracking technology, and some have automatic identification of pupil centers. The tracking technology at this stage is mainly where the excimer laser device is closest to the surface of the eyeball, and one or several infrared cameras are installed to record and monitor the changes of the corneal edge and the center of the pupil in real time, and the distance and direction of the displacement according to the center of the pupil. The angle of a reflected laser lens closest to the corneal surface on the excimer laser is adjusted at any time so that the falling point of the laser pulse moves with the eyeball moving in a certain range in an involuntary manner.

For the effectiveness and accuracy of the active eye tracking technology, the tracking sampling frequency of the infrared camera system is a very important parameter, and theoretically it should be larger than the pulse emission frequency of the excimer laser in order to achieve the tracking effect. The more important parameter is the overall reaction time or latency of the excimer laser. The fastest saccade of the eyeball can reach 400 degrees per second, ie 83.7 millimeters per second. Per second, assuming that the overall response time of the excimer laser is 10 milliseconds, this fastest movement can be captured by the eye tracker, and the eye has moved about 0.837 mm before the laser falls to the correct position. Therefore, the shorter the overall response time of the excimer laser, the more accurate the laser's landing point.

There is no such thing as an extremely eyeball tracking technology. The eye tracking technology requires that the frequency of the tracking system should be more than twice the frequency of the excimer laser to achieve the true meaning of eye tracking. For example, the launch frequency of the United States VISX excimer laser often used by bloggers is 6-20 Hz, and the frequency of the tracking system is 60 Hz. This can shorten the overall response time of the laser and improve the accuracy of laser scanning.

In the "personalized" laser scanning guided by wavefront aberrations, the excimer laser must have a small spot-spot scanning mode, but in theory, the smaller the spot size of the laser, the more the treatment for the same degree requires more. Cutting time, the more factors that affect the cutting effect. In order to reduce the influence factors and improve the precision level of laser cutting, the cutting time must be shortened. At this time, the frequency of laser emission must be accelerated, and the frequency of tracking must be accelerated at the same time, so as to ensure that laser cutting does not occur in deviation. Many equipment manufacturers always emphasize how fast the frequency of laser emission is when selling their equipment to hospitals. How short the operating time is, misleading the doctor and thus misleading the patient, arguing that the faster the machine is, the faster the laser emission frequency is. Advanced is actually a wrong understanding. Under normal circumstances, the laser emission frequency should not exceed 250Hz, otherwise the tracking system will become a decoration.

Of course, if the patient only rely on the advanced tracking technology of the equipment is not enough, if the eye repeatedly moves without performing self-control during the operation, the eye tracker will frequently stop the laser firing because the center of the pupil cannot be found. Extending the time of surgery affects the quality of laser cutting. Therefore, it is very necessary for patients to actively cooperate with the doctor before performing surgery and perform gaze training.

I hope that more new technologies will emerge to better help myopia to solve myopic troubles.