Final answer:
Poor visual acuity remains a significant barrier to binocularity even if resolution and directional discrimination are good because it leads to the inability of the eyes to clearly focus light directly on the retina. This causes blurred images and affects the sharp central vision provided by the fovea.
Step-by-step explanation:
When both resolution and directional discrimination are good, poor visual acuity is still a serious impediment to binocularity. Visual acuity is critical in providing the sharp central vision necessary for tasks such as reading, driving, and any activity where fine detail is important. Issues with visual acuity, such as myopia (nearsightedness) or hyperopia (farsightedness), affect the ability of the eyes to focus light directly on the retina, leading to blurred images.
The fovea, a small area of the retina, is responsible for acute vision because it has a high concentration of cone cells, which are responsible for sharp central vision and color perception. Conditions like myopia and hyperopia can prevent light from properly focusing on the retina, causing a blurred image and interfering with foveal vision, thus impacting binocularity — the ability of the two eyes to work together to provide a single, clear, and three-dimensional view of an object.