Week 2.03 CL & Presbyopia Flashcards
What is presbyopia
- Long sightedness caused by loss of elasticity of the lens of the eye, occurring typically in middle and old age
- Blurred vision is the first sign of ageing over which we have no control
Do myopias accommodate more with CLS or specs
CLs accommodate more
What happens to the pupil with age
Pupil size decreases
Minimises aberrations and scatter
Reduced retinal illumination
Can complicate multifocal lens fitting
Myope tend to have larger pupils
Eyelid changes with age
- reduced elasticity
- reduced muscle tone
- entropian
- ectropian
- increased Blepharitis
Ocular surface changes as you age
Yellowing of conj
Increased conj irregularity - folds, pingueculae, conjunctiva loose creates folds
Reduction in number of goblet cells - reduce mucin
Corneal changes as you age
Endothelial cell loss
Cornea less resistant to oedema
Exacerbated by long term lens wear
What are the CLs options for presbyopia
- Distance CLs with reading rx
- Monovision - distance eye corrected for distance, non dominated corrected for near
- Multifocal lenses
- Enhanced monovision, modified lens that has different focal points
Why does monovision work best for early presbyopia
Can adapt to add a lot more easy as they have lower add to begin with
What are monovision cls
• Dominant eye corrected for distance, non dominant eye for near
• Wearers must suppress the blurred img
• No longer the most popular form of presbyopia CL correction but:
o Cheapest and simplest option
o Single vision lenses
o Allows any toric – multifocal do not so if a px has high astig may need monovision
o In current wearers only one lens needs changing (NV)
What’s partial monovision
Low add, addition reading rx for prolonged reading
What is enhanced monovision
Single vision lens for dominant eye, multifocal for non dominant
What is modified monovision
Different multifocal lens design in each eye, biasing the dominant eye for distance
Monovision fitting routine
- refraction for distance eye corrected and near
- check for BV
- use trial frame
- determine dominant eye with DV correction in place
Which eye do u put dist rx and near rx
Distance in dominant eye
Distance + partial near add in non dominant eye
Do we refract monocularly or binocularity for presbyopia
BINOCULARLY!!!
What are the different multifocal lens options
Simultaneous vision:
1. Aspheric (centre dist, centre near)
2. Multi zone
3. Pupil independent zone design
Translating bifocal (mainly RGP)
Who can we use siumultaneous vision lenses for
- 1st choice in younger presbyopia
- ideal for those not wanting specs
- not for those requiring perfect vision at all distances
Aspheric simultaneous lenses
Design used by majority of soft and RGP multifocal lenses
Provides clear intermediate vision
Soft = centre near
Distance = centre distance
Centre distance front or back surface?
Centre distance is back surface aspheric
Centre near a front surface or back surface aspheric
Centre near is front surface aspheric
Which is most common centre near or distance
Centre near
What’s the issue with centre near and centre distance on bright sunny day
Issue is pupil changes. On a bright day if you have centre near your pupil is gonna get smaller and NV dominates poor distance vision
Centre distance = distance vision dominates, poor near vision as when sunlight the pupil will get smaller, and u see through that portion only.
Air optic aqua multifocal
Alcon
SiHi
33% water
Dk 83
Modulus 1.0 MPa
Three add options - CN design (LO, MED, HI)
Aspheric front and back surface
Pure vision multifocal
SiHI
36% water
Dk 68
Only two add options
Centre near aspheric
Coopervision biofinity multifocal
Sihi
48% water
Modified monovision
4 diff add powers - +1, +1.50, +2.00, +2.50
Modified monovision
Sihi
48% water
Modified monovision
4 diff add powers - +1, +1.50, +2.00, +2.50§§§§§
Multifocal fitting routine
Refraction dist and near
Determine dom eye
Determine pupil size
Select trial lens
Allow lenses to settle 20 mins before assessing
