The VISX Star Iris Registration System (IR), is the latest step in CustomVue technology pioneered by VISX. The idea is to insure the best alignment of the laser treatment pattern possible. The eye tends to rotate when a person changes from a seated to the lying position. This is often a fairly small amount of true rotation but is clinically significant when applying a laser vision correction application. With other Excimer Lasers, registration marks need to be applied to the eye by the surgeon before surgery and then compensated for under the laser manually. It was the surgeon’s responsibility to adjust the patient’s head position to compensate and correct for the ocular rotation. If this was not perfectly performed, it could result in misalignment of the laser treatment pattern. While the surgeon must always be prepared to make any necessary adjustments, the IR system aids the surgeon in this task by a computerized matching technique.
Rotation can occur when the patient changes from the seated to the lying position. This can result in misalignment of the laser treatment pattern.
How Does Iris Registration Work?
It starts at the examination, when an infrared image of the iris is obtained in the seated position and analyzed for the various characteristic features of the individuals’ iris. At the time of the surgery, another infrared image is taken when the patient is lying down under the laser and these images are compared and superimposed. Any recognized rotation is then compensated for by the laser rotating the treatment plan using sophisticated software. This all occurs prior to initiation of the treatment pattern. The Iris Registration system recognizes and corrects any misalignment in the laser treatment pattern. The better the alignment of the laser treatment, the higher quality of the surgical result.
In addition to the rotational capabilities of the Visx IR system, the final benefit is achieved by precisely centering the laser application. This is referred to as “pupil centroid shift”, which is a compensating technique unique to the Visx IR system. When the rotation alignment and pupil centroid shift systems are used, aberrations are reduced, and clinical studies have shown visual results are improved.
While the Wave Light Allegretto laser system lacks Iris Registration (IR) and does not compensate for eye rotations and possible misalignment, the VISX Iris Registration (IR) System recognizes and corrects any misalignment in the laser treatment pattern.