What helps a rigid lens to mask corneal astigmatism?

The ability of a rigid lens to mask corneal astigmatism is primarily due to the lacrimal lens created between the back surface of the contact lens and the front surface of the cornea. When a rigid gas permeable (RGP) lens is placed on the eye, it forms a tear-filled layer beneath the lens, known as the lacrimal lens. This fluid layer acts as a smoothing agent, effectively neutralizing the corneal irregularities and astigmatic shape. This phenomenon allows the lens to provide clearer vision by refocusing light onto the retina, compensating for the imperfections in the cornea's shape.

Understanding this mechanism emphasizes the significance of tear film dynamics in contact lens fitting and performance, particularly for individuals with corneal astigmatism. The other aspects, such as the material of the lens, colors, or blinking, do not directly contribute to the masking effect of corneal astigmatism as effectively as the lacrimal lens created by the rigid lens.