A computing device, comprising: an eye-tracking system comprising an image sensor (102, 800); a logic device; and a storage device comprising instructions executable by the logic device to tracking an eye gaze direction by acquiring an image of the eye via the eye-tracking system, determining a determined location of a center of a lens of the eye from the image of the eye, the location being determined on a pixel scale by determining a boundary of an iris of the eye and determining a center of the iris based upon the boundary of the iris, adjusting the determined location of the center of the lens of the eye on a sub-pixel scale by applying a predetermined sub-pixel offset to the determined location of the center of the lens of the eye to produce an adjusted location of the center of the lens, wherein the predetermined subpixel offset is determined based on a machine-trainable model, wherein the model is trained utilizing a training set that comprises a plurality of eye image frame and corresponding ground truth location pairs, each eye image data frame comprising image data capturing a human eye while a gaze target was displayed on a display at the corresponding ground truth location; determining a gaze direction from the adjusted location of the center of the lens; and performing an action on a computing device based on the gaze direction. an eye-tracking system comprising an image sensor (102, 800); a logic device; and a storage device comprising instructions executable by the logic device to tracking an eye gaze direction by acquiring an image of the eye via the eye-tracking system, determining a determined location of a center of a lens of the eye from the image of the eye, the location being determined on a pixel scale by determining a boundary of an iris of the eye and determining a center of the iris based upon the boundary of the iris, adjusting the determined location of the center of the lens of the eye on a sub-pixel scale by applying a predetermined sub-pixel offset to the determined location of the center of the lens of the eye to produce an adjusted location of the center of the lens, wherein the predetermined subpixel offset is determined based on a machine-trainable model, wherein the model is trained utilizing a training set that comprises a plurality of eye image frame and corresponding ground truth location pairs, each eye image data frame comprising image data capturing a human eye while a gaze target was displayed on a display at the corresponding ground truth location; determining a gaze direction from the adjusted location of the center of the lens; and performing an action on a computing device based on the gaze direction. acquiring an image of the eye via the eye-tracking system, determining a determined location of a center of a lens of the eye from the image of the eye, the location being determined on a pixel scale by determining a boundary of an iris of the eye and determining a center of the iris based upon the boundary of the iris, adjusting the determined location of the center of the lens of the eye on a sub-pixel scale by applying a predetermined sub-pixel offset to the determined location of the center of the lens of the eye to produce an adjusted location of the center of the lens, wherein the predetermined subpixel offset is determined based on a machine-trainable model, wherein the model is trained utilizing a training set that comprises a plurality of eye image frame and corresponding ground truth location pairs, each eye image data frame comprising image data capturing a human eye while a gaze target was displayed on a display at the corresponding ground truth location; determining a gaze direction from the adjusted location of the center of the lens; and performing an action on a computing device based on the gaze direction.