Bacon conducts extensive studies of lenses and the refraction of light. He understands the basic principles of how lenses can magnify objects and correct vision.

Bacon is one of the first Europeans to describe the use of lenses for correcting vision problems. He suggests the possibility of using lenses to help the elderly see better, paving the way for the development of eyeglasses. It is unknown if he himself made or possessed any eyeglasses.

Bacon demonstrates a relatively accurate understanding of the anatomy of the eye and its function in vision, based on both observation and earlier Arab scholarship. He describes the different parts of the eye and their roles in perceiving light and images.

Bacon performs experiments with light and shadows, studying the properties of light, including reflection, refraction, and diffraction. He uses these observations to develop his theories about optics and vision.