Types & Materials

Question 1

General Types of Contact Lenses

Answer 1

Scleral
Rigid
Soft

Question 2

Scleral Lenses:

Diameter

Answer 2

13mm to 25mm

Question 3

Scleral Lenses:

Materials

Answer 3

PMMA (fenestration)
Silicone Acrylates
Flurosilicone Acrylates

Question 4

Scleral Lenses:

Comfort

Answer 4

Excellent

Surface drying/deposits may reduce comfort

Question 5

Scleral Lenses:

Vision

Answer 5

Excellent

Question 6

Scleral Lenses:

Prescription Availability

Answer 6

+40D to -40D and prim

Question 7

Scleral Lenses:

Advantages

Answer 7

Never lose them

No foreign bodies once inserted

Question 8

Scleral Lenses:

Disadvantages

Answer 8

Insertion and removal uncomfortable
Chair time - lens dispense on going process
Reduced corneal sensitivity

Question 9

Rigid Lenses:

Diameter

Answer 9

5mm-12mm

avrg 7.3mm to 9.8mm

Question 10

Rigid Lenses:

Materials

Answer 10

Flurosilicone Acrylates

PMMA

Question 11

Rigid Lenses:

Comfort

Answer 11

Initial - very poor
Lens felt on blink
(damaged, dry & scratched will reduce comfort)

Question 12

Rigid Lenses:

Vision

Answer 12

Good VAs

Question 13

Rigid Lenses:

Prescription Availability

Answer 13

+40D to -40D in 0.25 steps

2 Base DN prism

Question 14

Rigid Lenses:

Advantages

Answer 14

Lots of oxygen
Better tear exchange
Accessible price

Question 15

Rigid Lenses:

Disadvantages

Answer 15

Long adaption
Chair time
Easy to lose
Flare

Question 16

Soft Contact Lenses:

Diameter

Answer 16

12mm-15mm

Question 17

Soft Contact Lenses:

Materials

Answer 17

Hydrogel

Silicon hydrogel

Question 18

Soft Contact Lenses:

Comfort

Answer 18

Good general comfort

Worse if dry, especially in high water content

Question 19

Soft Contact Lenses:

Vision

Answer 19

Pretty good

Question 20

Soft Contact Lenses:

Prescription Availability

Answer 20

Max +30D to -30D
Generic -12D to +8D
Cyl -6D

Question 21

Soft Contact Lenses:

Advantages

Answer 21

Great for infrequent use
Extended wear - material dependent
Cost

Question 22

Soft Contact Lenses:

Disadvantages

Answer 22

Prone to infections - absorbs
Restricted fitting ranges
Prone to deposits - but replaced

Question 23

Rigid Lens Materials (PMMA):

Advantages:

Answer 23

Good wetting
No deposits
Mechanically strong
Optically very good

Question 24

Rigid Lens Materials (PMMA):

Disadvantages:

Answer 24

Low oxygen supply

Question 25

Rigid Lens Materials (Silicone Acrylates): Advantages:

Answer 25

Availability Good oxygen supply Dimensional stability Stable vision

Question 26

Rigid Lens Materials (Silicone Acrylates): Disadvantages:

Answer 26

Attracts deposits 3 and 9 o'clock staining Poor wetting Prone to breakage

Question 27

Rigid Lens Materials (Flurosilicone Acrylates): Advantages:

Answer 27

Excellent oxygen supply Possible in extended wear Good wetting Deposit resistant

Question 28

Rigid Lens Materials (Flurosilicone Acrylates): Disadvantages:

Answer 28

Very prone to breakage Corneal adhesion Careful manufacture required