18. Cranial Nerves and Ophthalmology Flashcards
Conditions affecting any cranial nerve
Diabetes mellitus - can also dmg cranial nerves
MS - can dmg optic nerve as it is myelinated
Tumours - compression
Sarcoid
Vasculitis - temporal arteritis perhaps key one to remember as ophthalmic artery can be affected leading to blindness
Systemic lupus erythematosus
Syphilis
How can you formally test CN1
Strong smells like lemons and vinegar, or with standardised University of Pennsylvania smell identification kit
CN1 pathology
Ageing (M>F) - may notice taste change Traumatic Brain Injury (Cribiform plate) Parkinson’s (a synuclein in olfactory bulb; prodromal anosmia) Alzheimer’s Tumour - frontal lobe (YA) Kallmann's
Inheritance pattern of red-green colourblindness
Common X linked genetic disorder
Acuity disturbance hints
Bilateral = age related macular degeneration
Sudden = infarct
Hours = inflammatory attack in MS (+pain)
conditions, but most others painless
YA = MS
Old = ischaemia or diabetes
Consider risk factors for stroke, diabetes etc
What if they can’t see the Snellen’s chart?
Count fingers
hand movements
Light perception
What does acuity involve?
Focusing an image on the retina and then passing the action potential this creates onto the occipital and temporal cortices
Patho can be any of these points
Whats the pitfall of Snellen’s charts?
Tells us something about the very small retinal area onto which the letter seen is projected. When the image of that letter is blurred due to optical factors (opacities, refractive error) the surrounding image will be equally blurred. But when visual acuity loss is due to retinal factors, Schnellen chart acuity tells us nothing about how the surrounding retina functions.
Acuity DDx
Refractive issues (most common) – glasses - Gradual loss of this in 40s and 50s of acuity at short distances. Can also happen transiently in diabetes
Ocular media: opacification can occur like in cataracts/diabetes (steroids, radiation, trauma)
Retinal blood vessels haemorrhage into vitreous then creates opacity, mostly following neovascularisation in diabetes
Macular degeneration = bilateral, affects central acuity
Diabetic neuropathy -microvasculature to retina are abnormally leaky so oedema can decrease acuity
- Glaucoma sees loss of acuity only late on
- Nerve: MS – retrobulbar neuritis.
Conjunctivitis Definitions and Symptoms
Inflammation on the conjunctiva, the membranes lining the inside of the eyelid and sclera.
Causes: Bacterial, Viral or Allergic
Symptoms Conjunctival Hyperaemia – “pink eye” Chemosis (oedema of eyelid) Crust and Discharge “Foreign body sensation” Photophobia
Bacterial vs Viral conjunctivitis
Bacterial = thick yellow discharge/pus (dead neutrophils), reduced vision, urethritis, vaginal discharge, unilateral Viral = watery clear discharge, bilateral, fever/lymphadenopathy
Allergic Conjunctivitis
Young adults
Type 1 Hypersensitivity (IgE)
- pollen, dust, chemical scents
Conjunctivitis plus:
Itching
Sneezing
Red, watery and oedematous eye
Cataracts definition, symptoms and signs
Clouding of the lens of the eye, reducing visual acuity
This can also lead to glare, and patients may see halos around lights
Reduced red reflex
Cataracts causes
90% is age related
Congenital (1%), metabolic conditions like diabetes, drug induced like steroids, trauma to the eye.
Glaucoma definition
Vision loss resulting from optic nerve damage - Damage to optic disc leads to progressive peripheral visual loss
Normally due to increased intraocular pressure
2nd leading cause of blindness worldwide
