Certified Paraoptometric (CPO) Practice Exam 2025

What type of lens is made from materials that absorb water?

1. Rigid

2. Soft

3. Silicone hydrogel

4. Hard gas-permeable

The correct answer is: Soft

The correct choice, soft lenses, is made from materials that are designed to absorb water, which contributes to their comfort and flexibility. These lenses are typically constructed from hydrophilic polymers, which can contain a significant percentage of water. This water content is critical for providing a soft, pliable surface that closely resembles the natural shape and feel of the eye, allowing for improved oxygen transmission and comfort during wear. Soft lenses are advantageous for many wearers due to their ability to maintain hydration and adaptability to the curvature of the eye, which enhances their overall comfort compared to other types of lenses. The ability of these lenses to absorb water helps to create a smooth optical surface that can minimize irritation and improve wearability. Other choices, such as rigid, silicone hydrogel, and hard gas-permeable lenses, do not absorb water the same way. Rigid lenses are typically made from harder materials that do not incorporate water, providing a different kind of visual correction. Silicone hydrogel lenses, while allowing for higher oxygen permeability and moisture retention, primarily do not absorb water like soft lenses do; they instead have water content that is a characteristic of their material but not due to the absorption process. Hard gas-permeable lenses are also designed to be rigid and do