Examining the Eye Flashcards
What questions should you always ask in opthalmology histories?
History – always important to find out what normal vision is for them and questions regarding eye tests, glasses and contact lenses (especially whether they are hard or soft lenses). Ask about • Visual loss • Discomfort • Double vision of diplopia • Flashing lights (photopsia)
When examining the eyes what is the key thing to remember?
ALWAYS EXAMINE ONE EYE AT A TIME
Describe how a snellen chart is used to measure acuity?
Assess wearing glasses if glasses wearer
Snellen Chart (actually not used anymore) Standing at 6 metres from the board read out the lowest line you can read. Top line is 6/60 meaning they can read at 6metres what someone with perfect vision can read at 60metres. Bottom line is usually 6/6 meaning they are normal.
Describe how a logmar chart is used to measure acuity?
Logmar chart is more modern and a better test of acuity. It is a logarithmic scale going from 0.00 meaning normal vision to 1.00 which is equivalent to 6/60.
- If the patient is struggling to read either of these top lines, then you move them closer e.g. 5/60, 4/60, 3/60, 2/60 and 1/60
- If they can’t then ask them to count how many fingers you are holding up at 50cm (indicated in examination by FC)
- If they can’t them ask them to say when you are moving your fingers (HM)
- If they can’t ask for perception of light (PL)
- If they can’t they are NPL – no perception of light
If less than 6/6 examine with a pinhole – if this improves it is likely there is a refractive error.
How are visual fields assessed?
Finger confrontation
Tested by patient covering their eye – move finger in each visual field testing one eye at a time. Test each peripheral field individually
Neuro-tip confrontation
You and the patient stand or sit 1m away from each and cover the opposite eyes. You then move in a red (central) or white (peripheral) neuro tip to map out any field defects. Also, important to determine the position and size of the blind spot.
What is a scotoma?
Scotoma – visual field defect
How does the shape of a scotoma suggest the cause of the defect?
An Arcuate scotoma looks like an eyebrow and is caused by Glaucoma
Unilateral defect of superior or inferior field – arterial occlusion, branch retinal vein thrombosis or inferior retinal detachment
Central scotoma – macula degeneration or macula oedema
What is an Amsler grid?
Amsler Grid – grid of straight intersecting lines used to test macula function. If macula dysfunction then some lines may appear wavy or incomplete
Describe how you should examine using an opthalmoscope?
Done using a direct ophthalmoscope – first check for a red light reflex then with the patient looking straight into the distance move in closer to find the disc.
Examine the disc using the 3 Cs
Contour – well defined borders
Colour – should be pink yellow with a pale centre (will be paler in atrophy)
Cup – cup should lie centrally and occupy 1/3rd of the disc diameter
Examine radiating vessels and then the macula by asking them to look straight at the light.
How should you assess colour vision?
This is done simply by checking against Ishihara plates to get a score out of how many plates were tested.
How are pupils examined?
First look at the pupils – are they equal?
Next test direct and consensual pathways to look at the efferent (CNIII) and afferent (CNII) pathways.
Accommodation test – as eyes accommodate inwards they pupils should constrict
Finally do the swinging light test – move from one eye to the other with the pen torch fairly swiftly multiple times. There is a relative afference pupillary defect if one of the eyes dilates when the light comes to it.
What is the slit lamp used for?
Fluorescein drops can be used to highlight epithelia that’s exposed or damaged. Can also measure IOP using a tanometric attachment
What common investigations can we use in opthalmology?
- Visual fields – officially tested with a perimeter – also gives an indication for the reliability of the results
- Fluorescein angiography – IV infection of fluorescein which allows visualisation of retinal vessels. A later photo is taken to look for leakage
- Orthoptic assessment – angle of deviation of the eyes in different gazes and binocular function and acuity
- US, MRI and CT are used to visualise the orbit
How do ointments and drops differ in their uses?
The eye retains ointments longer than it does drops so frequent application may be required. Ointments are well suited for use at night. Allow 5 mins between doses of drops to prevent overspill. Make sure you consider manual dexterity of patient before prescribing. There are special applicators if required – speak to the pharmacist.
What antibiotics are often used in opthalmology?
Antibiotics – chloramphenicol, fusidic acid and neomycin
