presbyopic fitting and afterare

Question 1

What happens to eyelids in presbyopia px?

Answer 1

Reduced elasticity, due to atrophy of the orbital fat. This will change the position of the eyelids

Question 2

How does the anterior eye change over time?

Answer 2

• reduced corneal sensitivity
• age related corneal degenerations e.g. guttata
• pupil gets smaller
• lens gets thicker and yellow

Question 3

how does the tear film change over time?

Answer 3

• less tear production
• tear stability
• goblet cell density decreases
• change in Meibomian gland secretion
• lid changes
• epiphora due o blocked lacrimal duct

Question 4

What happens to Conjunctiva with age?

Answer 4

pinguecula
pterygium

Question 5

what is more common, pinguecula or pterygium?

Answer 5

pinguecula

Question 6

if a px has pinguecula, what happens when they wear CLs?

Answer 6

can still wear them, lens edge may start rubbing against it which will make it more red and affects dynamic lens wear

Question 7

what are the MOTOR method of identifying ocular dominance?

Answer 7

• sighting test

Question 8

how do you do the sighting test?

Answer 8

ask px to make a triangle at arms lenght
px fixates on a distant target and bring hand closer to eye keeping the target in the centre

Question 9

what is the SENSORY method of identifying dominance?

Answer 9

defocussing lens

Question 10

how do you use the defocussing lens theory to identify ocular dominance?

Answer 10

use distance rx
present +ve lens (according to fitting guide) on one eye at a time
ask px when the letters are worse
most blurred eye = dominant eye

Question 11

which way of identifying dominance is better?

Answer 11

defocussing lens

Question 12

what are the 3 different presbyopic CL options?

Answer 12

over specs
multifocals
monovision

Question 13

how do you use CL over spectacles?

Answer 13

CLs are dist corrected
use reading specs when reading

Question 14

advantages of over specs method?

Answer 14

• no diff to cost (px can use existing brand of CL)
• allows stable distance vision
• simple, inexpensive, easy to use

Question 15

disadvantages of over specs method?

Answer 15

• still need specs to see - inconvenient
• negates cosmetic benefits provided by CL wear

Question 16

how does monovision work?

Answer 16

• dominant eye is fully corrected for the distance
• non-dominant eye is fully corrected for reading

Question 17

who is monovision good for?

Answer 17

low adds

Question 18

what is the limit to the ADD allowed for monovision?

Answer 18

+2.50D

Question 19

advantages for monovision?

Answer 19

• no increase in cost
• no change in lens type
• wider range of lens material options as using single vision lenses
• useful for existing wearers
• easy for practitioners to fit

Question 20

disadvantages for monovision?

Answer 20

• loss of stereopsis and contrast
• adaptation required (all multifocal options)
• cannot be used with px who are monocular
• px must have strong ocular dominance (cannot be amblyopic)
• not suitable for a px with strong near visual task demands

Question 21

what is the alternating design ?

Answer 21

2 distinct sectors - basically like a bifocal
on down gaze upper eyelid holds the lens in place and px looks out of the lower portion for reading/near vision

Question 22

what do you need for an alternating design?

Answer 22

good tension in lower eyelid
lower eyelid no lower than the inferior limbus

Question 23

what is the rule of thumb for an alternating design?

Answer 23

approx ¾ of pupil region must be covered by the correct section of lens for successful wear – for them to be able to ignore this line

Question 24

advantages of alternating designs

Answer 24

• binocularity
• good visual quality
• stereopsis shouldn’t be affected

Question 25

disadvantages of alternating designs

Answer 25

- lens stability relies on lens-eyelid interaction - px who read at eye level or higher - adaptation required

Question 26

with an alternating design, how much should the lens lift by on downward gaze?

Answer 26

2mm

Question 27

what are some examples of different alternating designs?

Answer 27

- fused segmented bifocal - solid segmented bifocal

Question 28

how does a simultaneous design CL work?

Answer 28

2 images placed simultaneously on the retina

Question 29

what are the subcategories of simultaneous design?

Answer 29

- aspheric - multizone - zonal aspheric

Question 30

who cannot use a simultaneous design lens?

Answer 30

amblyopes - need equal contribution

Question 31

how does a centre near lens work?

Answer 31

low illumination = larger pupil = dis VA favoured high illumination = smaller pupil = near VA favoured

Question 32

advantages of aspheric lenses?

Answer 32

- does not rely on lens movement - stereoacuity

Question 33

diadvantages of aspheric lenses?

Answer 33

- dependence on pupil size - adaptation required - lens centration critical otherwise px can experience ghosting - loss of contrast sensitivity due to light scatter (exaggerated by lens)

Question 34

how does the multi-zone design work??

Answer 34

concentric zones of distance and near power

Question 35

which lens type has reduced reliance on pupil size?

Answer 35

multi-zone

Question 36

how do zonal aspherics work?

Answer 36

uses principles of aspheric and multi zone lenses zone distribution for each add power (high, med, low) is optimised for the normal physiological change in pupil size that occurs with age

Question 37

what is enhanced monovision?

Answer 37

monovision with DV corrected in dominant eye and a bifocal lens in the non-dominant eye

Question 38

what is partial monovision?

Answer 38

When full near correction isn't incorporated into the non-dominant eye, only a partial correction used

Question 39

what is modified monovision?

Answer 39

Dominant eye = C-D design Non-dominant eye = C-N design

Question 40

which part of h&s do you need to pay most attention to?

Answer 40

occupation and hobbies how is the px going to use the lenses?

Question 41

what are some considerations for fitting?

Answer 41

- px expectations - refractive error - ocular conditions - pupil size - occupation and hobbies

Question 42

how do you manage expectations?

Answer 42

- be positive - explain adaptation is part of the process - concentrate on real world activities - vision may not be as good as specs but still good - will remove the need for specs for majority of things

Question 43

key points for successful multifocal fitting

Answer 43

- FOLLOW THE FITTING GUIDE - identify visual needs - set expectations about adaptation - avoid fitting to highly critical visual situations - have good centration without excessive movement (0.6-0.7mm)

Question 44

what is the difference for presbyopic aftercares when checking vision?

Answer 44

binocular real world tasks (consider size of print N8)

Question 45

what is the difference for presbyopic aftercares when over refracting?

Answer 45

FOLLOW FITTING GUIDE when changing rx -consider the impact on the other D or N no +1.00 Blur, duochrome limited, no PH