Eye gaze tracking (EGT) allow us to estimate the direction of gaze and the point of regard. This technique has been successfully used as pointing device in computer interfaces for people with disabilities, but significant technological advances are still required to make EGT appropriate to be used in general computer interfaces. In order to improve the EGT technology, a testbed where new devices and algorithms can be evaluated must be defined. This paper presents a survey of the methods used for EGT, and organize them into a computer vision framework, that we use to support the development and evaluation of new techniques. As an example of application of the framework, the calibration function used in the EGT developed in our laboratory is tested, and the results show the precision of the method. Higher accuracy of the testing results is achieved using synthetic images generated by ray tracing, from a physically based model of the eye.