L.2 - Types of CLs & Materials

Question 1

What is Cellulose Acetate Butyrate (CAB)?

Answer 1

The first gas permeable (GP) contact lens material approved by the FDA in 1978

CAB marked a significant advancement in contact lens technology.

Question 2

What are corneal lenses?

Answer 2

The most common type of rigid and gas-permeable lenses

Corneal lenses are designed to cover the cornea and allow for oxygen permeability.

Question 3

What is Fluoro Silicone Acrylate (FSA)?

Answer 3

A combination of fluorine and silicone that provides high gas permeability in contact lenses

FSA retains a stable and wettable product ideal for lens wearers.

Question 4

What causes Giant Papillary Conjunctivitis (GPC)?

Answer 4

Allergy or deposits on soft contact lenses

Potential allergens include ocular allergies, materials of soft lenses, and cleaning solutions.

Question 5

What is Hydroxyethyl Methacrylate (HEMA)?

Answer 5

FDA approved in 1971, it was the first ‘soft contact lens’ sold by Bausch and Lomb

HEMA revolutionized the contact lens market by introducing a softer alternative.

Question 6

What are papillae in relation to GPC?

Answer 6

Big bumps that appear over the tarsal conjunctiva of the eyelids

Papillae are a clinical sign of GPC, indicating inflammation.

Question 7

What is Polymethylmethacrylate (PMMA)?

Answer 7

Also known as Plexiglass, it was first used to manufacture contact lenses in the U.S. in 1938

PMMA was a key material in the early development of contact lenses.

Question 8

What distinguishes scleral contact lenses from corneal lenses?

Answer 8

Scleral lenses vault the cornea and land on the sclera

This design is beneficial for patients with irregular corneas or other conditions.

Question 9

What are semi-scleral lenses?

Answer 9

Lenses designed to vault the cornea, also referred to as corneo-scleral lenses

Semi-scleral lenses provide a compromise between corneal and full scleral lens designs.

Question 10

What is Silicone Acrylate (SA)?

Answer 10

FDA approved in 1982, it represented the next generation of gas permeable contact lens materials after CAB

SA improved oxygen transmission and comfort for contact lens wearers.

Question 11

What are silicone hydrogel lenses known for?

Answer 11

Received FDA approval in 1981 for extended (overnight) wear due to high gas permeability

Compared to traditional ‘hydrogel’ lenses, silicone hydrogel lenses offer better oxygen flow to the cornea.