Soft contact lenses are made of:
**Core Concept**
Soft contact lenses are made of hydrophilic polymers that retain water, allowing them to conform to the shape of the eye and provide comfort for the wearer. This property is essential for the lens to move freely on the eye's surface without causing irritation or discomfort.
**Why the Correct Answer is Right**
The correct answer is a type of hydrophilic polymer called **hydroxyethyl methacrylate (HEMA)**. HEMA is a water-soluble monomer that is copolymerized with other monomers to create a hydrogel material. This hydrogel material allows the lens to absorb and retain water, making it soft and comfortable to wear. The hydrophilic properties of HEMA also enable the lens to move freely on the eye's surface, reducing the risk of irritation and discomfort.
**Why Each Wrong Option is Incorrect**
**Option A:** **Silicone** is a type of hydrophobic material that is not suitable for soft contact lenses due to its inability to retain water and its tendency to cause eye irritation.
**Option B:** **Polycarbonate** is a type of rigid plastic material that is often used in hard contact lenses, but it is not suitable for soft contact lenses due to its rigidity and lack of hydrophilic properties.
**Option C:** **Silicone hydrogel** is a type of contact lens material that combines the benefits of silicone and hydrogel materials. While it is a type of soft contact lens material, it is not the most common or well-known type of hydrophilic polymer used in soft contact lenses.
**Clinical Pearl / High-Yield Fact**
It's essential to note that soft contact lenses can be made from various types of hydrophilic polymers, but HEMA is one of the most common and well-established materials used in soft contact lenses.
**Correct Answer: C. Hydroxyethyl methacrylate (HEMA)**