How do rigid gas permeable lenses work?

Rigid gas permeable (RGP) lenses work primarily by changing the shape of the cornea through the interaction with the tear film beneath the lens. When RGP lenses are placed on the eye, they maintain a tear film reservoir between the lens and the cornea. This tear film helps to create a new anterior surface of the eye, effectively reshaping the cornea to improve vision.

As the lens creates a slight indentation on the cornea due to its rigidity, it redistributes the tear film and alters the corneal curvature, which is essential in correcting refractive errors such as myopia and astigmatism. The design of RGP lenses allows oxygen permeability, ensuring that the cornea remains healthy while benefiting from the enhanced visual acuity provided by these lenses.

In contrast, options that mention adding moisture to the cornea, filtering light, or providing a soft cushion do not accurately describe the primary function of RGP lenses. While moisture is essential for eye health, RGP lenses do not directly add moisture; they rely on the natural tear film. They also do not filter light in the same way that colored or tinted lenses do, nor do they provide cushioning, as their rigid structure is not designed for that purpose. Instead,