Fovea

The small, central area of the retina responsible for sharp, detailed vision, covering approximately 1 degree of visual angle. The fovea contains the highest density of cone photoreceptors and provides the clearest visual acuity, which is why people move their eyes to point the fovea at objects they want to see clearly. In eye-tracking and assistive technology, the fovea's small size creates a fundamental limitation for eye-gaze pointing: the area of clear vision is only about 1 degree wide, meaning that targets on screen must subtend a sufficient visual angle to be reliably fixated and selected. This inherent positional tolerance of approximately 1 degree is a key factor in the accuracy limitations of eye-controlled interfaces.