Anatomical basis of eye exams Flashcards
How do you test visual acuity
Snellen chart
How do you interpret snellen chart results
- Denominator is distance away in metres
- If you get 2 letters wrong on a line then you have failed, so your score becomes the line above
- Pt covers one eye and reads lowest line they can
causes of decreased visual acuity
optic neuritis, lesions in higher visual pathways, cataracts, macular degeneration
How do you inspect retina
Ophthalmoscope
What do you inspect using fundoscopy?
- Opthalmoscope to inspect retina
- Tells you about intracranial pressure
- Assess for red reflex - shine the light at pt eye at one arm’s length away - look for red reflection in pupil
- Use same hand as eye you are examining
- Identify blood vessel and follow to optic disc - assess the four retina quadrants
- Assess macula by asking pt to look into light
Papilloedema
Optic disc swelling secondary to raised ICP - disc is blurred and small haemorrhages seen
Pupillary light reflex
Afferent is optic nerve
Efferent is oculomotor nerve
Absence of red reflex in adults
cataracts, vitreous haemorrhage, retinal detachment
Absence of red reflex in children
congenital cataracts, retinoblastoma
Retinoscopy
- Pt who can’t obey demands
- Hand held retinoscope projects beam of light into eye
- Light is moved around back of the eye to give examiner info about pt - for example if they have refractive error and what type (short/long sighted)
How to correct hypermetropia
Convex lens
How to correct hyperopia
Concave lens
Astigmatism
Eye is shaped like rugby ball - light is focussed more in one place than another = headaches and vision loss
Can be long or short sighted
Keratometry test
- Measures shape and curve of cornea
- Pt looks into machine which gives reading of whether cornea is within normal range
Keratoconus
Cornea bulges out too far
