weird questions Flashcards
describe what you assess when examining the eye
- Assess the disc appearance (1mark)
o Colour of the disc- (1mark)
o Assess Cup to disc ratio (1 mark) and compare with the other eye (1 mark)
o If Rim ISNT rule applies (1 mark)
o Disc margin- Clear and Well defined (1 mark). - Fundus appearance- Red-orange colour retina. There are no lesions, scars, or
pigmentary changes. (1 mark) - Assess macula (1 mark)
- Assess Fovea (1 mark)
- Assess arteries and veins (1 mark)
- Work along major vessel in the 4 quadrants (1 mark)
- Mr Patel, a 45 year-old bus driver, has not had an eye exam in 3 years. He reports his
mother has glaucoma. His intraocular pressure is 30mmHg in both eyes and the colour of his
irises is blue-green. You want to assess the optic disc of this patient but you decide not to
use the direct ophthalmoscope. What technique would you use to examine the patient’s
fundi? Describe the power of the lens you would use. Explain your rationale (5 marks)
Indirect biomicroscopy ( 1 mark) because it provides greater magnification than headset BIO
(1 mark) so better to assess the optic disc in detail ( 1mark)
Power of the lens +60D or +66D ( 1 mark). It has good mag so better to assess the optic
disc (1 mark)
What are the three basic elements that determine the eye’s ability to focus light?
Shape of cornea
Power of crystalline lens
The axial length of the eyeball
Miss Logan comes to you practice reporting poor visual acuity at distance. Her unaided
vision is 6/18 in each eye and you want to use a pinhole. Explain the principle behind this
test and the possible outcomes.
It reduces the effective pupil size reducing the diameter of the
retinal blur circle. Pinhole is placed in front of each eye. If VA improves, refine
subjectively if not then possibly pathology or amblyopia.
A retinoscope is described as having:
a) a 1D convergent beam
b) a 1D divergent beam
c) a plane mirror
Where is the apparent light source (i.e. where does the light appear to come from) in
each of these retinoscopes?
6.a) 1m in front of mirror, b)
1m behind mirror, c) infinity
Preferential looking is a method of
assessing vision in:
infants
Which of the following factors
could result in hyperopia?
1. Cornea too curved
2. Lens too weak
3. Eye too long
4. Cornea too thin
5. Lens too strong
lens too weak
If you are performing ophthalmoscopy on a
high myope, which adjustment to the normal
routine might make the examination easier?
Ask the patient to wear their glasses
.State where the far point for an emmetropic eye is: (1 mark)
2.State where the far point for a hyperopic eye is: (1 mark) and a myope
far point for an emmetrope is at infinity
far point for a hyperope- behind eye
far point for a myope- front of eye
Describe the possible errors you can make in measuring monocular distance visual acuity.
(2 marks)
If the patient leans forward – this will decrease the distance between the patient and the
visual acuity chart and so results will be inaccurate
* If the patient has both eyes open and you want to measure monocular visual acuity – this is a
monocular assessment so if the patient has both eyes open the results will not be accurate.
* If the patient squints their eyes – this will give the same effect as if a pinhole aperture was
placed in front of the eye which would improve the patient’s acuity (unless the patient has
amblyopia or an ocular pathology). This would give inaccurate results.
) In which patients might the duochrome test not work and why? (2 marks)
Duochrome may not work in those patients with visual acuity worse than 6/12, as the ring targets
are usually constructed of ring thicknesses equivalent to 6/9 (inner) and 6/12 (outer) Snellen
equivalent targets.
It will not work if prescription is significant incorrect because the The difference in focal position due
to chromatic aberration is 0.50DS.
Small pupil will reduce size of blur circles because the difference between the clarity of red and green
is reduced
why does duochrome work better with larger pupiols
bc the test relies on the chromatic aberration of the eye which is a tendency of the eye to focus different colours at different distances.
pupil is larger= blur circle is larger so makes it easier to accurately determine rx.
describe what happens to an image w diff types of ametropia
Myopia – image is magnified (m more than 15x)
* Hyperopia – image is minified (m less than15x)
* Astigmatism – different magnification in each meridian and it also depends on type of
astigmatism (hyperopic, myopic or mixed)
* Emmetropia- image magnification 15x
To examine the ret movement at an axis of 90, in which direction should the ret be
moved?
2. To examine the refractive error at axis 45, in what direction should the ret be
moved?
. To examine the axis of 90, turn the streak to horizontal direction
(180) and tilt the retinoscope up and down (along the vertical
meridian)
2. To examine the axis of 45, turn the streak to 135 and tilt the
retinoscope up and down (along 45)
A patient has a Rx of -1.25DS/-0.50DC x 180. You observe this patient using a ret
with no lenses in place from a distance of 2/3m. What movements are seen?
Along 180, -1.25DS, FP is at 80cm behind the examiner so with
movement at 180
Along 90 -1.75DS, FP 57cm so between patient and examiner so this is an against movement.
A retinoscope is described as having:
a) a 1D convergent beam
b) a 1D divergent beam
c) a plane mirror
Where is the apparent light source (i.e. where does the light appear to come from) in
each of these retinoscopes?
1m in front of mirror,
b)1m behind mirror,
c) infinity
How to do retinoscopy in keratoconus
conic shaped cornea
reflex swirls over cornea
split or scissors reflex
reflex moves simultaneously in opposite directions from pupil centre
use lens steps larger than 0.25DS and bracket technique
d) If your patient has astigmatism of 4D what would be the best strategy to view their fundus with a direct ophthalmoscope? (2 marks)
Start with a high power of the ophthalmoscope Adjust the power on the lens wheel until a clearer image of the fundus appears
. Name clinical features of the ophthalmoscope
aperture stops, red free diagnostic filters, graticules, range of lenses, fixation targets, slit beam
. Name clinical features of the ophthalmoscope (6)
List the components of the ophthalmoscope (4)
aperture stops, red free diagnostic filters, graticules, range of lenses, fixation targets, slit beam
sighthole lens, multi element condensing system, diaphragms, light bulb.
What are advantages of direct [3 marks]
7. What are disadvantages of direct [3 marks]
8. What are the requirements for a good ophthalmoscope [5
marks]
Easy to use, magnified image, real & erect image
7. Small FoV, monocular, close WD
8. Clear uniform light patch, minimised corneal reflections,
absence of sight hole flare, extra targets, range of target
apertures
What are factors affecting indirect [6 marks]
Ametropia, pupil size, diameter of condensing lens, lens
power, distance from px to lens, distance from lens to
examiner
When do you use headset [3 marks]
6. What is OCT [2marks]
7. What are advantages of indirect [3 marks]
8. What are disadvantages of indirect [3 marks]
To see stereoscopic, when there is poor opacity of lens,
in px’s who have RD, diabetes and are young
High resolution, cross sectional imaging of retina and optic nerve by measuring reflectance and relative delay of light through the ocular tissues
Large FoV, stereoscopic, and greater WD
8. Inverted & lateral reversed image, low magnification,
dilation needed
What is the focal point [1 mark]
what is emmetropisation
where parallel light rays converge or meet after passing through the lens
Rapid resolution towards emmetropia in the first few years of life
What is visual acuity [1 mark]
2. What is the unaided VA [1 mark]
Sharpness and clarity of vision which is measured by the
ability to discern letters or numbers at a given distance
2. Smallest line of letters that can be read by a person with
the naked eye
. What are the design problems of snells chart [3 marks]
6. Why is logMAR better than snellens? [2 marks]
What are some methods of testing near vision?
What can you use if patient can’t respond to the letters?
[2 marks]
9. What are 3 methods of grating acuity tests? [3 mark
Letters are more crowded down the bottom, visual
demand changes down the chart, patients with poor
acuity are required to read less letters
6. LogMAR has the same number of letters per line with
the spacing between each letter & row being related to
the width and height of the letters respectively
- Snellens, logMAR, N notation, Jaegar chart, M notation
- Landolt C or tumbling E notions
- Preferential looking, optokinetic nystagmus, visual
evoked potential tests
What is the definition of ret? [1 mark]
2. What movements would you get if its further away from
neutral? [3 marks]
3. What are the rules for ret? [3 marks]
4. Why is ret important? [5 marks]
5. What are the components of the retinscope? [4 marks]
Objective method that determines nature of patients
refractive error
2. Slower, duller and smaller
3. Both eyes open but fog other eye to reduce
accommodation, examiner’s right hand for patients RE,
examiner at set wd
4. Determines refractive error, can screen for ocular
diseases, can assess clarity of media, can assess
refractive error in children or patients who cannot
communicate, can measure accommodation
5. Sight holes, light source, collar, mirror
What is a spherocylindrical lens? [1 mark]
Lens that has sph power component with cyl power
component that’s twice the power of the sphere, and the
opposite sign
- Which patients will the duochrome not work in? [1
mark] - What are some limitations of the duochrome [4 marks]
- If the vision is better than 6/18 with the +1.00 check,
what does this indicate? [2 marks] - If the vision is worse than 6/18 with the +1.00 check,
what does this indicate? [2 marks]
Patients who’s VA is worst than 6/12
5. Lens acquires brunescence (yellows=cataracts) and
cannot do with cataracts, colour defectiveness, chromatic
aberration decreases with age
6. Blur circle smaller than expected so either under corrected positive or overcorrected negative
7. Blue circle bigger than expected so either overcorrected
positive or under corrected negative
. What are the two theories as to why presbyopia occurs
and what are they? [4 marks]
Helmholtz relaxation theory = contraction of ciliary
muscles causes relaxation of fibres but as age, the lens becomes less flexible
Schachars theory = when
accommodating, there’s increased tension on the lens by
equatorial zonular tension, so he suggests that as we age there is a less of tension in these zonular fibres making it harder for the lens to focus on close objects
What factors affect vision? [3 marks]
8. When is entropic phenomenon? [1 mark] why does it
happen? [3 marks]
Cataracts, forward light scatter, backward light scatter
8. Visual sensation which arises within the eye, originating
in the ocular media. Particles in the vitreous causes light
scattering`
What is an optometer? [1 mark]
2. What are pros and cons of a simple optometer? [2 marks]
3. What are pros and cons of the badal optometer? [2
marks]
- Instrument that measures refractive error
- Pro—cheap, quick
con—large depth of focus, non
linear scale, accommodation, size of target varies - Pros— reduced depth of focus, linear scale, target size is
constant
con—target can still stimulate
accommodation
What are three types of optometers? [3 marks]
5. What are the difficulties? [4 marks]
Retinoscopic principle, scheiners disc, image size principle
- Small pupils, children, irregular media/opacities, eye
movement disorders, retinal changes, squint
What does a white reflex and dark reflex mean with
photorefraction? [2 marks]
8. What are prods and cons of Phoropters? [2 marks]
. White means ametropic, dark means emmetropic
Pros— quicker, more comfortable, no lens smear, high tech, computerised & cons— cannot do larger rx’s, can
only do small lens change steps
advantages and disadvantages indirect vs direct
direct- easy to use, magnified view, erect image. dis- small field of view, dim image, monocular= not stereoscopic, close working distance
indirect- large field of view, usually stereoscopic view, greater wd, inverted image, low magnification, usually need to dilate pupil
Q List the names of 3 tests you can use to assess near vision in an adult. (3 marks)
Answer:
Snellen chart for near, LogMAR chart for near, N notation Jaeger chart, M notation
. List 5 posterior ocular components that you can observe when you perform a fundus
eye examination (5 marks)
Retina, retinal vessels, optic disc, optic cup, neuroretinal rim, macula, fovea
