The Fovea – See Sharpest in One Small Area

The eye muscles have one important task. They must work as a team to focus the light correctly onto the retina. We control the muscle adjustments in two ways, by looking with a wide area view and a narrow area view. Sometimes we need a wide view, known as “divergence”, to get a sense of an area. Other times we need a narrow view, known as “convergence”, to see details. Convergence is important for seeing details. The eye muscles must focus the light onto a specific place in the retina call the macula. The macula is a small area (5.5mm) used for sharp vision. It is dense with specialized photoreceptor cells (cone cells) needed for details and color, however it does not work well in low light. The cone cells get denser at the center of the macula. This center area is called the fovea. This small area (1mm) allows for the sharpest and most colorful vision. With such a small area for sharp vision, it is necessary to use a narrow view or converge to ensure that the correct detail area we want is focused within the macula.

As we move farther from the macula, a more light sensitive photoreceptor cells called rod cells populate the retina. Rod cells allow us to see in low light but only in black and white. A mix of cone and rod cells in this area of the retina allow us to see clear, color and in low light, although it will not be as sharp as the macula.

Accommodation and convergence work together to help us focus light correctly onto the fovea for sharp vision. Our eyesight is perfect if nothing interferes with them. However, when we read, we are trained to see an entire word or phrase at one glance. When we watch TV, we tend to look at the entire person or car. We train our eyes to use divergence to see. Eventually, we use divergence to look at everything including to see sharp details. Divergence is not good for details. In order to see sharp details using divergence, we must move the object closer so more of the correct detail area fall into the macula. This is why a nearsighted person tend to move closer to the objects in order to see clearly. The person uses divergence for both wide view and narrow view. It is necessary to learn to use convergence and divergence correctly again.

We need to use convergence for sharp vision. Since our eyes are designed to see best one small area at a time, we must be conscious of how we look at something and remind ourselves to converge to see details clearly.