Review of CL I and II

Question 1

Which type of optics has a varying curvature across the surface of the lens to counter spherical aberration

Answer 1

Aspheric optics

Question 2

What are the 2 types of BCL?

Answer 2

acuvue oasys, air optix night and day

Question 3

What must the power of the lens be to be considered a true BCL?

Answer 3

plano

Question 4

is the Dk of SiHy >/< Hydrogel?

Answer 4

SiHy > Hydrogel

Question 5

Since SiHy has a higher Dk, what type of lenses is it used in?

Answer 5

extended wear lenses

Question 6

What happens to the following properties of a hydrogel contact when water content is increased?
* durability
* Dk
* deposit formation
* dry eye symptoms

Answer 6

All increase except for durability

Question 7

What happens to the Dk of a SiHy contact when the water content is increased?

Answer 7

decreases; silicone content is what increases the oxygen permeability

Question 8

A low/high modulus resists deformation, holds shape better, is easier to handle and provides better visual acuity

Answer 8

high

Question 9

Does a low or high modulus lens experience more edge lift, fluting, superior epithelial arcuate lesions, mucin balls, GPC?

Answer 9

high modulus

Question 10

How do we determine the diameter of a SCL?

Answer 10

HVID + 2

Question 11

What happens to the sag height of a SCL as the diameter increases assuming a fixed base curve radius?

Answer 11

increases

Question 12

Which BC do we start with when fitting SCL if there is more than one available?

Answer 12

steep

Question 13

Is LARS calculated from the patient or doctors perspective?

Answer 13

doctor’s perspective

Question 14

Fill in the blanks

Answer 14

A. Spherical RGP
B. Front Toric RGP
C. Back Toric RGP
D. Bitoric RGP
E. SPE Bitoric
F. CPE Bitoric

Question 15

A GP lens moves along the direction of most/least resistance

Answer 15

least

Question 16

Where is the GP lens the loosest?

Answer 16

Where the cornea is the steepest

Question 17

How much movement is normal in a GP lens?

Answer 17

1.0-1.5 mm

Question 18

How do you increase edge lift of a GP lens?

Answer 18

increase PC width (must narrow OZD or increase OAD)

Question 19

For every _____ mm change in BC, you must change the power by ______ D

Answer 19

0.10 mm; 0.50 D

Question 20

What are the clinically meaningful parameter change values for BCR, OAD/ OZD, PCR, PCW and CT?

Answer 20

• BCR: 0.1 mm (0.50 D)
• OAD/ OZD: 0.3 mm
• PCR: 0.5 mm
• PCW: 0.2 mm
• CT: 0.02 mm

Question 21

How is SPE bitoric special in regards to rotation?

Answer 21

Vision is unaffected by rotation of the lens on the eye; acts like a spherical lens- can rotate while centered

Question 22

When does residual astigmatism occur?

Answer 22

When refractive astigmatism does not equal corneal astigmatism

Question 23

What is unique about writing the prescription for a back toric GP?

Answer 23

Only have to specify power in the most plus meridian

Question 24

When might you need toric peripheral curves?

Answer 24

When edge lift is not equal but it is symmetric

Question 25

How is a front toric GP stabilized?

Answer 25

BD prism (0.75-2.00 BD); can truncate if a slight adjustment is all that's needed

Question 26

What Dk do you order if prism is added?

Answer 26

higher Dk

Question 27

What does simultaneous aspheric mean in regards to multifocal contacts?

Answer 27

change in power from center to periphery; SCL: center near or center distance; GP: mainly center distance

Question 28

Who are the best candidates for aspheric GP's?

Answer 28

low lower lid (and/or loose lids); smaller- average pupil size; low-medium adds; critical vision not essential; computer; athletes

Question 29

Which aspect of fit is critical when fitting aspheric GP's?

Answer 29

centration; optics should be over the pupil

Question 30

What should be modified if the aspheric GP is decentered or moves excessively?

Answer 30

steepen base curve (0.10 mm); or increase lens diameter (0.50 mm)

Question 31

Which type of GPs are segmented like bifocal glasses and use prism ballasting to promote proper orientation?

Answer 31

translating

Question 32

Where should a translating GP rest in primary gaze?

Answer 32

on or near the lower lid

Question 33

What amount of nasal rotation may be helpful for reading?

Answer 33

<15 degrees

Question 34

Where is the segment line on a translating GP?

Answer 34

at or near lower pupil margin