CL Fitting For Presbyopia

Question 1

What are monovision lenses

Answer 1

• one eye distance, the 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 the smallest visible line
- add +1.00 to the right lens, then left
- ask which is clearer
- if RE clearer then left is dominant, as less blurring effect
- dominant eye for distance
- non dominant for near

Question 3

Monovision advantages and disadvantages

Answer 3

Advantages
- good for early presbyopia
- easy to fit
- reduced chair time
- reduced cost

Disadvantages
- reduced stereopsis
- glare when driving at night
- adaptation time
- unsuitable for monocular Px

Question 4

Modified 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 and potential challenges

Answer 5

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

Challenges
- lower lid must be no 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 and near are both in front of the pupil
• one zone produces clear image and the other a blurred image
• reduced image quality compared to SV correction SV correction

Biconcentric
Multizone concentric
Aspheric designs

Question 8

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

Multizone concentric

Answer 9

• should favour distance vision in bright conditions And extreme low light
• more qual distributions in normal light

Question 10

Extended depth of focus lens

Answer 10

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