The reliability, the advanced technology and the performance of the VISX STAR Excimer Laser device is world - wide well known. The Visx was entitiled as the first appliable device (FDA approved) in the United States and by continuously improving its technological strenght and for many years
lead the way in numerous novalties of the excimer laser surgery.  The technologies developped by Visx have been recognized in the USA and have been used throughout the world. The latest model developped by the VISX is  STAR *S4 IR.  This model had a significant impact on the success of  the Visx.  This new model excimer laser system is the most advanced development in the current laser technology. 

All information required for excimer laser operation are obtained with all details from the eye by using the JVaveScan WaveFront device which is also developped by VISX. The STAR S4 IR evaluates all these detailed information with high sensitivity and steadyingly implements them to the eye. The main characteristics of the STAR S4 IR excimer laser device which are not included in most of the other excimer laser devices and which enables it to steadyingly implement the detailed information obtained by the WaveScan WaveFront analyzer, to the eye with high sensitivity can be listed as: 

1. VSS : Variable Spot Scanning 

STAR S4 IR has an ability to adjust the diameter of laser rays between 650 micron and 6,5 mm according to the requirement of the treatment. Thanks to this feature a much smoother layer can be formed on the retina and this significantly reduces the treatment duration. The most important benefit of this feature is that it brings the protective quality forth which is one of the most important necessities of the refractive surgery.  In other words, by means of  STAR S4 IR less tissue ablation (tissue vaporazation)  happens and thus better results can be obtained. The result is a significantly reduced corneal dilution rate. For instance, in the treatment of a -4.00 degree astigmatism, the amount of the cornea dilutated by this device is nearly half of the corneal dilution caused by other lasers. Naturally, this ability maximizes the reliability of the operation. 

2. VRR : Variable Repetition Rate

Thanks to the variable repetition rate the duration of the surgery can be reduced to most appropriate levels.

3.  Active Trak 3-D Active Eye Tracking

The system tracks every 3 - d movements of the eye. Thanks to this system, along with the movements of the eye on x - y plane, the upwards - downwards movements of the eye on the z plane are tracked. The eye tracking speed is so coherent with the laser repetition rate that the laser head can track the eye and transmit the ray to the intended point even in the smallest eye movements. The transmission of  laser rays to unintended areas because of sudden movements are in evitable in treatments with other types of laser because the most of the excimer laser device are not as sensitive as required.

4.  Active Trak Automatic Centering 

The laser ray tracker automatically lockson the pupilla. Thus all rays are perfectly directed around the center in the most appropriate way. 

5. IR : Iris Registration Program

This feature is a wonder of technology which is not included in any other excimer laser device in the world and which brings the excellence forth. This is the first and the only FDA approved completely automatic registration method  which can be used for the implementation of intended WaveFront treatment without touching the patient or the eye. This method was well acknowledged in the United States as soon as it has been introduced to the market. Thanks to this advanced feature along with the right - left and upwards - downwards movements, the rotation movements of the eye can be tracked. That is to say: when a person lies on supine position, our eyes rotates (cyclotorsional movement) approximately for 5 - 15 degrees when compared to the position in the stand upright. The importance of this fact is that all the standard measurements related to the eye and high technology product WaveFront maps are taken when the patient stand upright.

In spite of that, the excimer laser is implemented when the patient is in supine position. So, if the eyes are rotated for 15 degree in the supine position, all of the laser rays will be exposed on unplanned areas with 15 degrees of difference. This would produce unintended results especially in astigmatism and WaveFront treatments. In order to prevent such a mistake, the surgeons rotate the head of the patient so as to compansate the rotation of the eye. However, like in all affairs ruled by the human hand, the margin of error would be high in such an operation. The STAR S4 IR has complately solved this problem by the means of its Iris Registration (or to say;  iris tracking) system and maximized the safety. 

In the STAR S4 IR system, the pictures taken from 56 different points of the iris (the colored part of the eye) are taken and registrated, along with the degrees of refractive defects and eye maps taken by WaveScan device in upright position. All of these measurement values and photographs are transferred to the STAR S4 IR system in digital media. When the patient is lied on the chair of the STAR S4 IR Excimer Device in supine position, the device begins to take pictures from the iris and matches these pictures with the pictures taken by the wavescan wavefront device in upright position. Finally, if any cyclotorsional movement (rotation) of the eye has taken place, the laser head of the  STAR S4 IR rotates on the same direction and matches tge pictures. All of these proceedings happens within few seconds. STAR S4 IR continues this matching throughout the whole laser operation. So there will be no offset during the rotations of head or eye hence the laser head rotates at the same degree. This feature has taken its place as an essential component of the WaveFront treatments.