week 4 and 5

Question 1

T/F: today there are more presbyopes than non-presbyopes

Answer 1

true

Question 2

List a few characteristics of older eye that makes them harder to fit with CLs:

Answer 2

1) Decreased sensitivity—both lid and corneal sensitivity
•Beneficial in fitting them with a lens that is thicker or a GP lens
2) Decreased lid tonicity–lids will get looser with age
Good for soft lenses, not so much for GP that require stability and centration
3) Decreased tear production can cause dry eye complications

Question 3

what are some advantages of monovision CLs?

Answer 3

– Economical: specialty lens designs are not required

– Relatively high success rate: 60 to 80%

Question 4

what are some disadvantages of monovision CLs?

Answer 4

decreased stereo
not good for amblyopes
not good for pts with high powers at D or N

Question 5

In monovision, all binocular summation lost at adds greater than ___

Answer 5

+2.00

Question 6

In monovision CLs, binocular summation for middle and high frequencies lost at up to ___ power of ADD

Answer 6

+1.50

Question 7

How long do monovision patients need to adapt?

How long should you let them settle in office?

Answer 7

2-3 weeks

20-30 minutes to settle

Question 8

what is the procedure for blur acceptance test?

Answer 8

1) Have distance correction in place
2) Use trial lens with plus power equal to the add
3) Place trial lens over each eye alternately while patient
views distance chart
4) If plus lens causes less visual disturbance when placed
over one eye vs. the other, use it as near eye

Question 9

what shouldn’t the pt do during adaptation period?

Answer 9

no night driving, don’t compare eyes

Question 10

about what % of people prefer multifocal CLs over monovision or readers over D CLs?

Answer 10

68% of CL wearing presbyopes prefer

multifocal lenses over monovision or over-readers

Question 11

measure VA for multifocal CLs in what illumination?

Answer 11

medium/moderate

Question 12

what are the 2 categories of multifocal CL systems?

Answer 12

1) alternating

2) simultaneous

Question 13

what are 2 advantages of simultaneous VA multifocals?

Answer 13

– The contact lens does not have to orient or
move in any specific manner
– Easier to fit

Question 14

what are 2 disadvantages of simultaneous VA multifocals?

Answer 14

– Centration is critical but not always achievable
– Light refracting through the wrong set of
optics will cause blur

Question 15

what are 2 advantages of alternating VA multifocals?

Answer 15

• Clearer vision at distance and near than with
  simultaneous designs
  – Best optics of any multifocal lens design

Question 16

what are 3 disadvantages of alternating VA multifocals?

Answer 16

• More challenging to fit
  – Must have inferior lens position: decreased
  comfort, corneal staining more likely
  – Increased center thickness due to prism ballast

Question 17

what is one of the advantages of the segmented GP lenses? disadvantage?

Answer 17

High add powers available (up to +3.50)
– Because these lenses are not limited by asphericity, true high adds are possible
disadvantage: requires prism to stabilize, makes lens thicker which may be uncomfortable

Question 18

what is truncation?

Answer 18

Method of cutting off the lower portion of the lens to improve rotational stability
-used to improve rotational stability
– flat portion of the lens aligns with lower lid to keep the lens in place
–more effective with plus lenses bc as material is taken off periphery, truncated edge that sits on the lower lid becomes thicker
– Lenses are truncated 0.4 to 0.5 mm
-can also help with translation

Question 19

For alternating/segmented GP lenses, at least __% of the pupil should be covered by the near zone for optimal near vision

where should seg line be?

Answer 19

At least 80% of the pupil should be covered by the near zone for optimal near vision

Segment line should be at the inferior pupil margin (or w.in 2 mm, and position of the pupil margin should
be determined under moderate lighting)

Question 20

T/F: For alternating/segmented GP lenses, temporal rotation is usually ok in near vision

Answer 20

False, temporal rotation is usually detrimental to

near vision

Question 21

For alternating/segmented GP lenses, what kind of fit allows for good translation?

Answer 21

A flat fitting lens promotes good translation (~0.50 D flatter than K)

Question 22

Which will translate more, a smaller diameter or larger lens?

Answer 22

The upward movement of the lens is limited by the superior limbus, so a large diameter lens will not translate as much as a smaller lens

Question 23

soft multifocals are primarily alternating or simultaneous vision designs?

Answer 23

soft multifocals are primarily simultaneous vision designs

Question 24

WHy aren’t soft alt/segmented CLs very common?

Answer 24

Because they rely upon translation of 2-3 mm, and because soft lenses translate less than 1 mm in most cases

Question 25

For aspheric soft multifocals, where are the powers at in the lens?

Answer 25

almost all cases, the center of the lens has the most plus power while the lens becomes more minus towards the periphery

Question 26

For aspheric soft multifocals, why are they pupil dependent?

ADD powers up to what are available?

Answer 26

Patients with small pupils will therefore not appreciate the total add power of the lens
-ADD powers up to +2.50 available:(more plus power put in the lens, less area there is for distance power, and the worse the distance vision)