low vision assessment Flashcards
name 3 things that you observe about a patient in your lv clinic
- postural abnormalities
- mobility
- appearance
what is the most important part of a low vision assessment
history taking
how is a lv history taking different to a pcc history taking
more follow up questions are asked and more time is spent on it
list 9 things you will ask about in history taking of your lv assessment
- the duration of condition and onset
- stability of condition and differences between the eyes
- patients knowledge of the condition and prognosis
- ongoing hospital monitoring and or treatment
- registration status
- education and or employment
- present aids and spectacles
- general health and medications
- reason for making the appointment
why will you ask the patient about their knowledge of the condition and prognosis, during history taking
as the patient needs to understand the eye condition to know how to deal with it and they will know if the condition will deteriorate so they can adjust to it well
why will you need to know if a lv patient is on any ongoing hospital monitoring and or treatment
to know if you should prescribe glasses or not
and you dont want to dilate the patient unless they’re having a new symptom, because if they’re at the hospital then they are getting dilated already, but if they’re not then you must dilate
why will you want to know about a patients registration status during history taking
to know if they’re SI or SSI
and you want to know if they have access to any benefits e.g. social services
if not you may need to follow up with them or refer them to be registered
why will you want to know about a patients education status during history taking
if its a child, you want to know if they’re in an ordinary or a specialist school
why will you want to know about a patients employment status during history taking
incase you need to tell them about the access to work scheme
if they’re employed they can use lv aids at work
why will you want to know about present aids and spectacles during history taking
to know if the aids/spectacles have been working in order to avoid wasting your patients time
why will you want to know about a patients general health and medications during history taking
to know which aid to give e.g. patient may have arthritis or Parkinson’s therefore they cannot hold a magnifier and you will want to give glasses instead etc
why will you want to know about a patients reason for making the appointment during history taking
you don’t want to assume that the px made the appointment themselves
sometimes they don’t know why they have made the appointment, as in the UK, the patient will be referred by the ophthalmologist and they don’t know why they came to the clinic
why do you want to ask about distance vision to your lv patient during history taking
- difficulty seeing: faces, buildings, cars, street signs, road signals, bus numbers and steps
- vision fluctuates or not
- eccentric viewing status
- problems with glare: wears tinted glasses
- vision better outdoors/indoors
which type of eye conditions will a lv px have if they have difficulty seeing faces
AMD or stargart’s / any macula problem
why would you want to know if a patients distance vision fluctuates or not during history taking
because you want to be aware, incase you give the wrong lv aid or glasses
why would you want to know about a patients eccentric viewing status during history taking
because if they dont use this technique, then you can give advice on how to use it for e.g. AMD or stargart’s patient management
why would you want to know if vision is better outdoor or indoor during history taking
as this can cause a fluctuation in vision and this can impact on what LVA you give to the px
what do you want to know about a patients mobility in the lv clinic
does the patient walk alone, or accompanied in new/familiar environments
give an example of a px who will have problems with mobility in unfamiliar environments
px who’s had a stroke and got a hemianopia
list 4 things you want to ask about a patients home situations during history taking
- if the patient lives alone or with family
- if they have difficulty getting around the house
- if they have difficulty watching tv
- if they have difficulties with colours
why would you want to ask a lv patient is they live alone or with family in your history taking
- if lives alone, they may need additional help e.g. with reading letters etc
- if lives with family, you know that support is easier for them
what 3 things will you ask your lv px during history taking about reading, close work and hobbies
- do they have difficulties seeing books, newspapers, headlines, large print, own writing
- is vision better in dim light or bright light
- do they have difficulties with hobbies such as sewing, bingo etc
why would you want to ask your lv px about their reading during history taking
it is one of the main problems a lv px faces, especially the elderly as they tend to stay at home and read
why would you want to ask your lv px about their hobbies during history taking
to know how to best help the px
whats a good idea to do at the end of history taking
make a list of the patients priorities in order to know what help the patients wants
then summarise your findings to the patient and offer help by asking the patient
what is the next thing to do in your lv assessment after history taking
measure visual acuity
record visual acuity ____________ then ___________ ______ and ___________ aid
record visual acuity monocularly then binocularly with and without aid
where is it best to start testing va’s
a close distances and then modify
what must you never resort to when measuring va’s and why
contain fingers
because if the px can read 6/60 at 1m then they can definitely see counting fingers at 1m, so don’t resort to it
give an example of how precisely va should be recorded
3/60 instead of
if a lv patient does not have a previous va history, how must you start
start at 3 metres as this is a positive start and the patient is most likely to read
when measuring near vision on your lv px, what 2 things must you do/record
- distance at which near vision assessment was made
- measure reading speed if possible
why must you measure the distance at which near vision assessment was made
because for example, N40 at 40cm can be different to N40 at 20cm
so must record working distance
what must you make sure of when measuring near vision of your lv px
that field of illumination is uniform and glare free
reading charts should not be laminated
give an example of how you will record distance VA unaided
if px wears glasses then record their unaided va’s with glasses
RE: 3/60 LE: 2/60 BE: 3/60
give an example of how you will record distance VA with an lv aid
distance va with (Eschenbach telescope, 6x) used with RE
RE: 6/9
give an example of how you will record near VA unaided
Near va (reading glasses)/MNREAD charts RE: N36 LE: N36 BE: N36@ 40cm
give an example of how you will record near VA with an lv aid
near va with (Eschenbach HM, 6x)
N6 at 12cm
after measuring visual acuity, what is the next step to your lv assessment
determine refractive error
when may you observe a dull reflex on your lv px during retinoscopy and what will you need to do
if the px has cataract
you need to move closer
what can you do in difficult cases of retinoscopy when you can see the reflex at all
use old glasses as a guide, but be careful
why is it a good idea to use a trial frame and full aperture lenses when determining refractive correction on your lc px
it is easier to see their facial expressions while testing, which you can’t with a phoropter
what can you use for high refractive errors whilst determining your refractive correction
Harlberg clips
where you refract over the patients glasses
used if can’t see ret reflex and want an idea of px’s rx and then do subjective that way
what steps of spheres and cross cyls should you use when refining your rx when determining the refractive correction of your lv px
+/- 2DS spheres
+/-1DC JCC
px has low va’s so can’t appreciate small steps
how and when will you check the binocular status of your lv px when determining they refractive correction
- by doing CT or EOM if required
- only check if px has diplopia or you see a squint, as VI px will usually have one very bad eye
what must you remember to take into account when prescribing
the working distance used for subjective acceptance. it is important if the px’s working distance is 3m or less
what must be in place in order to determine near acuity on your lv px
distance correction and appropriate addition
what add should you always check with for what a px can read when determining a lv px’s near vision and at what distance should this be
+4.00D add at 25cm
what type of near chart us best to use on your lv px when checking their near acuity and why
a word chart
because the px can guess the next word in the sentence and this is not a good estimation of near va
as well as near acuity, what else must you record when measuring near vision
record what type of illumination was preferred
name 2 additional tests you can carry out after determining the refractive error of your lv px
- visual field test: area of distortion/defect
- contrast sensitivity: if you feel theres a need to that
which three things can you use to measure visual fields on your lv px
- amsler grid: for central vf
- arc perimeter
- tangent screen
what 2 things do 10-20% of lv patients only need
a good refraction and advice on lighting
so don’t need a full lv examination
what is required in va of an lv px to appreciate subjective improvement
an increase of at least 2 lines
so only change glasses if theres that much of an difference
what may not all lv px’s benefit with
an LVA
they may need sensory substitution e.g. braille or convert text to speech
what must you need to determine when prescribing magnification
whether monocular or binocular correction would be preferable
how is magnification for distance calculated
mag = required va/present va
e.g.
required va = 6/6 (to watch tv)
present va = 6/18
mag = (6/6) / (6/18) = 3x…..18/6 = 3x (dist lv aid)
how is magnification for distance calculated using a LogMAR chart
magnification = (1.25)n n = number of steps e.g. required va = 0.1 present va = 0.5
mag required = (1.25)4 = 2.5x
n = 4 steps
what is the rule of thumb when predicting near magnification from distance vision
always divide by 3
e.g.
if distance va = 6/18 then near va = 18/3 = N6
but it is better not to predict near vision from distance vision
what are three disadvantages to predicting near magnification from distance va
- crowding effects with words (as with distance va you’re measuring isolated letters on a chart)
- increased va with sentences (can guess whats coming up next)
- cataracts (e.g. nuclear sclerosis makes px more myopic, bad dv but good nv, so can’t use the divided by 3 rule)
at what distance should you measure patients current near va
25cm
how do you use the LogMAR chart to measure a patients near magnification
same as for distance mag
magnification = (1.25)n n = number of steps e.g. required va = 0.1 present va = 0.5 at 25cm
mag required = (1.25)4 = 2.5x
n = 4 steps
how do you use N notation to measure a patients near magnification
magnification = present va/required va
present va = N16 @ 25cm
required va = N8 @ 25cm
magnification = 16/8 = 2x
what are the 2 ways to calculate near magnification
- LogMAR chart
- N notation
what will a lv px require for each task that they wish to perform
a separate lv aid
what will a lv patients ability to read for leisure depend on
their acuity and contrast reserve
what type of magnifier is available for distance tasks
telescope: monocular or binocular
what 4 types of magnifiers are available for near tasks
- spectacle mounted magnifier
- hand magnifier
- stand magnifier
- near vision telescope
when trialling a predicted magnification, what should you assess
the patients visual acuity with the selected aid
what should you increase or decrease the magnification go the aid depending on
the acuity achieved and task requirement
always give minimal magnification that gives you best acuity
which rx does a distance telescope need to be used with
distance rx
which rx does a hand magnifier need to be used with and why
distance rx
as the rays of light leaving the HM are parallel so the patient does not accommodate when using this aid
which rx does a stand magnifier need to be used with and why
near rx
as the rays of light diverge, the px needs the rays of light to converge, whereas older patients can’t accommodate so they need a near rx
what can you do with a lv aid if its under the nhs
loan the aid for home trial
what must you mention when explaining to the patient how to use the lv aid
- which rx the aid should be used with
- how to clean the aid and charge the batteries if required
what is the next step after dispensing a lv aid
a follow up visit
after how long is a follow up visit after dispensing a lv aid
usually 3 weeks (to check that they know how to use the LVA)
after the first 3 weeks visit of dispensing a lv aid, how often should subsequent visits be
either yearly or whenever the patient experiences difficulties
name 3 reasons why an lv aid may not be successful at a follow up visit
- deterioration in va 9 (e.g. wet AMD)
- aid is used incorrectly e.g. too far away from the eye or inappropriate lighting
- using the aid for a different task than what is was intended for
what should you do with the LVA if it isn’t successful due to deterioration in va
select a different possible stronger aid
what should you do with the LVA if it isn’t successful due to the aid being used incorrectly
give appropriate training/advice
what should you do with the LVA if it isn’t successful due to using the aid for a different task than what it was intended for
explain the intended use of the aid
what 4 final things should you do upon completing the lv assessment visit
- give patient the contact details of the practice and encourage the patient to call if a problem arises
- encourage the patient to implement practical tips that were suggested e.g. the use of felt tip pens etc
- give the px useful contacts such as: RNIB, macular degeneration society, social services department
- report to the: GP/optometrist/ophthalmologist where appropriate
