RGP lenses are, as the name implies, rigid, but the plastics of which they are made are somewhat more flexible than hard lenses. Newer RGP lenses offer the advantage of allowing more oxygen to pass through to the eye. They are available in daily wear and extended wear options. RGP lenses have the following advantages and disadvantages:

Advantages:

• Good visual acuity
• Correct most corneal astigmatism
• Good durability
• Good handling characteristics
• Easier care

Disadvantages:

• Less comfort than soft lenses
• Longer adaptation than soft lenses
• More easily dislodged
• Can scratch, break
• Intermittent wear less feasible

Hard (Rigid) Lenses

Hard lenses are made of a rigid plastic (called PMMA) which does not allow oxygen to pass through the lens to the cornea. Today, material developments, especially related to rigid gas permeable lenses, have made hard lenses of less use.