Prescribing for different refractive states (near vision) Flashcards Preview

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Flashcards in Prescribing for different refractive states (near vision) Deck (24):
1

which 3 refractive groups of patients will you consider prescribing for near vision

- Non-presbyopic Hyperopes

- Presbyopes in general

- Myopic presbyopes

2

for this non-presbyopic hyperope:

35 year old
Symptoms: Headaches towards the end of the day associated with near vision. No problems with distance vision.

Vision: 6/5 R & L No previous Rx

Final subj: +1.50DS R + L = 6/5

Amplitude of accommodation (AOA) = 5D R + L (measured with px wearing the +1.50DS final subjective)

will you prescribe for this px? How and why

- Prescribe the DV Rx of +1.50 R + L, but prescribe it for NV
Because:
It is the answer to the patient’s symptoms
Without the distance Rx this patient is using +1.50D accommodation for D/V.
AOA = 5D, which leaves 5D – 1.5D = 3.5D accommodation available for NV
It is when their accommodation is reduced to approximately 3.50D that patients often first need help for near vision tasks
So this patient presents with typical symptoms of presbyopia
When wearing the glasses, this restores the available accommodation to 5D and the patient’s symptoms should disappear

3

list 3 main aims when prescribing for presbyopia in general

- Give comfortable N5 at preferred working distance (PWD)
Crucial to establish PWD

- Give a useful range of clear vision
Good guide is if you can move in x cm from PWD and move out 2x cm from PWD then patient is likely to be comfortable

- Not too much change from current prescription for near vision

4

what does it mean for the patient when your reducing the positive power or increasing the negative power for near and when is the ONLY time you will do this for a near

- the patient has to exert more accommodation

- if the patient complains that they have to hold the material too close

5

how much should a positive power for near vision be increased for:
Emmetrope. Complaining of difficulties reading
small print with current glasses.
Current Rx for near vision R + L +2.00
Refraction DV = Plano R and L = 6/5 R+L

explain why

- +2.50 R + L

Because just increasing it to +2.25D won't make enough difference and +2.50D is enough for the patient to make a difference and not too much to cause intolerance problems

6

give 2 reasons as to why if the positive power is increased too much, the patient may not tolerate the new Rx

- The established relationship between accommodation and convergence is upset

- The range of distinct vision may be reduced to an unacceptable extent


Most “intolerances” in practice are related to increasing the positive power for near by too much

7

what happens to the near vision range for a emmetropic patient:

Old Rx:
Plano with Add +2.00 R + L
Patient is looking through +2.00DS when reading
New Rx:
Plano with Add +3.00 R + L
Patient is looking through +3.00DS when reading

explain the outcome and why
what can you do to avoid over plussing the patient

- The range for near vision is reduced
Px will be happy with the +2.00DS add as their range = 50cm, so will be relatively blurred 50cm away from the eyes

Px will be unhappy with the +3.00DS ass as their range = 33cm, so will be relatively blurred 33cm away from the eyes (which is too small of a range)

- Must ask patient questions about their working distance to avoid over plussing the px

8

for this myopic presbyope:

Patient aged 50. Asymptomatic. Takes glasses off to read. Wants bifocals or PPLs for convenience.
Wearing –2.50DS R + L = 6/5
Final subj: -2.50DS R & L Add +1.00 = N5

Patient returns complaining that glasses are not good enough for reading (as it was better when they took their glasses off to read)

explain why this patient cannot tolerate their new rx
give 3 options for this patient

Reason:
- When patient removed old glasses:
She was looking through Plano, or
through an effective Add of +2.50D

- With the perfectly correct Rx of -2.50 and a +1.00D Add
She is looking through -1.50D for near work
Compared with her previous situation (taking glasses off), the prescriber has reduced the positive power for N/V by 1.50D

Options:
- Continue with single vision DV Rx and remove for near work

- Prescribe an Add less than but close to that which patient is accustomed, e.g. Add +2.00D
Too high for patient’s age, but closer to usual situation
Patient may benefit from greater range of clear vision and from holding material a bit further away
Show the px the difference from having a +2.00D and a +2.50D

- Prescribe a +2.50D Add to leave the patient in exactly the same visual situation as before for near vision

9

what must you always do before prescribing/changing rx for near vision

Demonstrate to the patient the difference in acuity between previous and new prescriptions (Rx), and hence show the patient the improvement in VA with the new Rx

10

list 4 main symptoms of a px with a nuclear sclerosis cataract

- Patient complains of gradual painless progressive loss of vision

- Visual acuity may remain reasonable for years (as can correct with specs)

- VA tends to be worse in bright light as pupil shuts down and cataract is central

- “Second sight”

11

explain what causes this "second sight" in patients with a nuclear sclerosis cataract, what the outcome is and how its managed

- Increase of refractive index produces an increase in myopia (second sight)
- Increase in myopia may be quite rapid in advanced cases, could be 1D in three months
- VA may remain reasonable for years
- Management of second sight in optometric practice – need for regular eye exams etc
- Distance vision affected more than near

12

other than due to reduced range of near vision, name one other time when you will consider reducing the positive power for near

for a patient with a nuclear sclerosis cataract

13

for this patient:

65 year old, with healthy eyes apart from nuclear sclerosis cataract in both eyes.
No binocular vision problems
Symptoms:
Distance vision blur with latest glasses (bifocals), steadily getting worse.
Prefers reading with an old pair of bifocals because he is now having to hold reading material too close with latest glasses

Wearing (latest Rx):
DV R + L Plano = 6/12 R + L
NV R + L Add +2.50 = N5 at 25cm
Old Rx preferred for reading:
DV R + L +0.75DS = 6/24 R + L
NV R + L Add +0.75 = N5 at 40cm
Final subj:
DV R + L -1.00DS = 6/6 R + L
NV R + L Add +2.50 = N5 at 40cm

Old Rx (preferred) and Final subj Rx both = looking through a +1.50D add for reading

give 4 possible prescribing options for this px, naming the best and most expensive option out of the 4

- New DV Rx only

- To continue to use old bifocals for reading

- New DV and NV Rx as bifocal

- New DV and NV Rx
Do not prescribe and refer for cataract surgery

Best option:
New DV Rx only

Most expensive option:
New DV and NV Rx as bifocal - as rx will continue to change

14

when do most optoms in the UK prescribe a first add of +0.75D

if symptoms are present

15

when do most optoms in the UK prescribe a first add of +1.50D

if no symptoms are present

16

how many over 85 year old's were in the UK in 1985

700,000

17

how many over 85 year old's were in the UK in 2010

1,400,000

18

how many over 85 year old's were in the UK in 2035

3,500,000

19

as well as eye disease, what is there also an increased prevalence of in the ageing population

dementia

20

how many people in the UK does dementia affect

around 750,000

21

what 3 parts of an eye examination did optoms find is possible to do on 90% of patients with dementia

- retinoscopy
- tonometry
- ophthalmoscopy

22

what 2 parts of an eye examination did optoms find is possible to do on 80% of patients with dementia

- VAs
- subjective

23

what is recommended when doing history and symptoms on a patient with dementia

ask the carer

24

list 4 things that need to be considered when testing and dispensing a patient with dementia

- “If it ain’t broke don’t fix it” applies to everything!
Try to use same frame style and colour
Not the patients for first time PPLs! Keep type of lens the same

- Allow more time for examination (as they respond slow and less reliable)

- Advise carer on labelling glasses

- Try to make the practice “dementia friendly”