CL fitting for presbyopia

Question 1

What are mono vision lenses

Answer 1

• one eye distance - other eye near
• visual system can alternate suppression
• minimal effect on distance VA
• no effect on near VA

Question 2

How to establish ocular dominance

Answer 2

+1.00DS sensory test
- full correction in frame
- px looks at smallest visible line
- add +1.00 to right lens then left
- ask which is clearer
- if RE clearer then left is dominant - as less blurring effect
- dominate eye = distance
- non dominant eye = near

Question 3

Monovision Advantages + Disadvantages

Answer 3

ADVANTAGES:
- good for early presbyopia
- easy to fit
- reduce chair time
- reduced cost

DISADVANTAGE:
- reduced stereopsis
- glare when driving at night
- adaptation time
- unsuitable for monocular px

Question 4

Modifies monovision

Answer 4

• reduced distance power in dominant eye to help with near
• reducing the add allows most tasks to be performed = reading rx for fine print

Question 5

What is an Alternating design + potential challenges

Answer 5

• distance /near portion
• stabilised with prism
• usually an RGP
• similar to bifocal lens

CHALLENGES:
- lower lid must be lower than inferior limbus otherwise less effective
- need enough lower lid muscle tone to hold lens up as px looks down
-pupil size may interfere with near portion

Question 6

Alternating design fitting

Answer 6

• aim for alignment fit with central touch
• 2mm smaller than HVID to encourage inferior centration
• aim for upper line of wear segment to be in line with lower pupil margin
• when px looks down - 75% of pupil should be at near segment

Question 7

What is simultaneous design

Answer 7

• distance + near are both in front of pupil
• one zone produces clear image + other a blurred image
• reduced image quality compared to SV correction

1. Biconcentric
2. Multizone concentric
3. Aspheric designs

Question 8

1. Biconcentric design

Answer 8

• centre distance/peripheral near = results in improved distance vision in bright light
• centre near/peripheral distance = better distance vision in low light

Question 9

2. Multizone concentric design

Answer 9

• should favour distance vision in bright light conditions + extreme low light
• more equal distributions in ambient light

Question 10

3. Aspheric design

Answer 10

• gradual change between each zone

Question 11

Extended depth of focus lens

Answer 11

• range of near add in one lens
• solves decreased quality of vision, pupils, centration + reduced contrast sensitivity