I have experience at programming, although none with Matlab, and none with eye tracking.
I imagine that you will aim a camera at the eye. You zoom in so that the iris is easy to observe.
Perhaps you intend to mount a tiny camera on eyeglasses? That will provide a stable image. The camera needs fast optics, because it needs to focus to less than an inch distance.
It could be a challenge to transmit each frame of live video to your Matlab device.
Your software examines the graphic image. It needs to identify the iris as a patch of dark pixels, amid the white areas of the eyeball.
It examines whether the iris is at the left or right, top or bottom. You examine the border of the iris, then calculate where the central point is. The pupil is at center. By locating the pupil, it tells you where the eye is looking.
This is a sophisticated algorithm. If someone writes such a program, they are not likely to give it away for free. Perhaps that is why you are not able to find it easily?