Eye detection is very important for automatic face recognition and gaze tracking. In this paper we propose an algorithm for eye detection under active infrared (IR) illumination. A simple hardware enables us to make use of a physiological property of the eyes. A new thresholding method is introduced in order to effectively search the regions of interest (ROI). An appearance model is then used to verify the pupil candidates. However, the existence of eyeglasses has a negative effect on selection of candidates. Regarding this the generalized symmetry transform (GST) is exploited. By using a simplified distance weight, we reduce the computational cost of the original transform. Experimental results demonstrate the effectiveness of the proposed eye detection method.