Miscellaneous Flashcards
(22 cards)
what are the causes of ocular trauma?
work related (often minor) assault accidents around the home sports associated eye injury other causes
what are the mechanisms of injury?
Blunt trauma
Penetrating trauma - large/small objects
Burns - chemical/physical
how do you asses ocular trauma?
good history of the incident
visual acuities
examination of the eye - lids, conjunctiva, cornea, anterior segment, pupil, fundus
use fluorescein drops - to identify area of epithelial loss
what is hyphaema?
blood in the anterior chamber
what is sympathetic ophthalmia?
when a traumatic injury in one eye causes inflammation in both eyes - resulting in bilateral blindness even though it was a unilateral injury
what is caused by alkali burns?
i. Easy, rapid penetration
ii. Cicatrising changes to conjunctiva and cornea
iii. Penetrates the intra-ocular structures
iv. ischaemia
v. corneal scarring and vascularisation
vi. end-stage scarring
what is caused by acid burns?
i. Coagulates proteins
ii. Little penetration
how to manage chemical injuries?
Assessment of chemical injury occurs after thorough irrigation
Quick history
Nature of chemical, when, irrigation at event…
Beware Lime / Cement
Check Toxbase if available
Check pH
Irrigate +++ (minimum of 2l saline, or until pH normal)
Then assess at slit lamp
how to prevent ocular trauma?
Prevention of ocular trauma:
a. More than 90% of all eye injuries are preventable
b. Ensure safe practices - training, up to date machinery
c. Protective eye wear
d. Clear rules - sport and work
e. Education - to ensure awareness
what are the golden rules for ocular trauma?
- History is key
- Always record visual acuity
- Don’t forget fluorescein
- Handle suspected globe rupture with care
- X-ray orbits if suspicion of intra-ocular foreign body (IOFB)
- Immediate irrigation of chemical injuries (the solution to pollution is dilution)
what is papilloedema?
swelling of the optic disc due to raised ICP
in which patients should you suspect papilloedema?
bilateral optic disc swelling, should be suspected of raised ICP due to space occupying lesion unless pro ved otherwise
what is mandatory to detect optic disc swelling?
ophthalmoscopy
what is part of the CNII examination?
i. Visual acuity
ii. Pupil exam
iii. Visual field assessment
iv. Colour vision
what is the pathophysiology of papilloedema?
The optic nerve is an extension of the brain with meningeal sheaths
Subarachnoid space around the optic nerve is continuous with subarachnoid space surrounding the brain, when the intracranial pressure increases, this is transmitted to the SAS then to the ON. This causes interruption of axoplasmic flow and venous congestion = swollen discs
what is ICP made of?
Sum of three components
1 Brain 80%
2 Blood 10%
3 Cerebrospinal fluid(CSF) 10%
what is the monroe-kellie hypothesis?
the sum must be constant.
an increase in one variable will result in a decrease of one/both other variables (Monro- Kellie hypothesis), as cranium is rigid and cannot expand
what are the functions of CSF?
Maintains stable extracellular environment for the brain Buoyancy Provides mechanical protectio Waste removal Nutrition
where is CSF produced?
Most produced in lateral ventricles by choroid plexus*
CSF travels through 3rd and 4th ventricles into subarachnoid space
*Choroid plexus is network of capillaries which filter blood to form CSF
what causes an increase in ICP?
Obstruction to CSF circulation
Overproduction of CSF
Inadequate absorption
what causes IIH?
A common cause of papilloedema - mechanism not understood fully
1. Stenosis of transverse cerebral sinuses and increased abdominal pressure (patients often obese) - obstructs CSF circulation therefore causing increased ICP 2. Role of vitamin A microemboli in sagittal sinus blocks CSF absorption - impairing CSF absorption (increased ICP)
what happens when there is chronic disc swelling?
- Disc swelling subsides, discs become atrophic and pale
2. Loss of visual function occurs and blindness might result
