Ophthalmology notes Flashcards
Name 4 ocular adnexa
Eyelids
Lacrimal glands
Naso-lacrimal duct
Lacrimal sac
What is emmetropia
Normal vision
What is the medical term for long sightedness
Hypermetropia
What is presbyopia and what causes it
Long-sightedness due to loss of elasticity of lens over time
Name a gram positive and gram negative coccus species
Gram + -> Staph/Strep
Gram - -> Neisseria
What is keratitis
Inflammation of the cornea
What is orbital cellulitis
Inflammation behind orbital septum
What is the most common cause of bacterial conjunctivitis
Staph Aureus
What investigation and treatment is done for suspected bacterial conjunctivitis
Swab -> topical chloramphenicol
When should chloramphenicol not be given
History of aplastic anaemia or allergy
What are 3 common causes of viral conjunctivitis
Herpes zoster
Adenovirus
Herpes Simplex
What kind of conjunctivitis shows sub tarsal scarring and follicle development
Chlamydial Conjunctivitis
What kind of keratitis can present with hypopyon
Bacterial
What kind of keratitis can present with a dendritic ulcer
Herpetic keratitis
Which steroid is given as treatment for herpetic keratitis
DONT GIVE STEROIDS
can cause corneal melt
What kind of keratitis presents with bilateral sub-epithelial infiltrates
Adenoviral Keratitis
Name 2 common causes of fungal keratitis
Pseudomonas
Acanthamoeba
Who tends to get fungal keratitis
Contact lens wearers
Which ENT pathology can lead to orbital cellulitis
Sinusitis
Which scan must be done in suspected orbital cellulitis
CT scan
What is CMV chorioretinitis
CMV infection of choroid and retina
Seen in HIV patients
Investigation for Bacterial Keratitis
Corneal scrape
Investigation for endophthalmitis
Aqueous/Vitreous culture
Mechanism of action of Chloramphenicol
Inhibits protein synthesis
Mechanism of action of Penicillin & Cephalosporin
Inhibit cell wall synthesis
Mechanism of action of Quinolones
Inhibits nucleic acid synthesis
What specifically does Chloramphenicol inhibit
Peptidyl Transferase
Name some side effects of Chloramphenicol
Irreversible aplastic anaemia
Grey-baby syndrome
Mechanism of action of Aciclovir
Base Analogue (mimics guanine)
Treatment for Chlamydial conjunctivitis
Topical oxytetracycline
Treatment for genital chlamydia
Oral Azithromycin
Treatment for bacterial keratitis
Gentamicin + Cefuroxime
Which ventricles contain the choroid plexus
3rd and 4th
Compare the chemical makeup of CSF to water with regards to NaCl, K+, Glucose & proteins
CSF has higher concentrations of NaCl
Water has higher concentrations of K+, glucose & protein
How does CSF return to venous blood
Via Arachnoid granulations in the Superior Sagittal Sinus
Where does CSF predominantly circulate
Subarachnoid space
Between pia and dura mater
What is pseudotumour cerebri
Idiopathic inter-cranial hypertension
Where does aqueous humour drain
To the scleral venous sinus via the trabecular meshwork and the canal of Schlemm
Which cells are responsible for lateral connections in the retina
Amacrine cells
Horizontal cells
What is the resting membrane potential in photoreceptor cells and why
-20mV due to a constant influx of Na+ in the dark
What is the dark current
cGMP gated Na+ channel open in the dark but closed in light
Which chemical conversion modulates the dark current
The conversion of 11-cis-retinal to all-trans-retinal
What are the three main immune cells in the eye
Mast cells
Macrophages
Neutrophils
What is the only part of the eye with lymphatic drainage
Conjunctiva
Are there Langerhans cells in the cornea or sclera
Langerhans cells are in the peripheral cornea
What is ACAID (Anterior Chamber Associated Immune Deviation)
Peripheral tolerance to ocular antigens
What can be described as bilateral granulomatous uveitis
Sympathetic Ophthalmia
Which eye is the exciting eye in Sympathetic Ophthalmia
The injured eye
the fellow eye is the sympathising eye
What is a Dalen-Fuchs nodule
An epithelial cell cluster in the retinal layers
Give an example of a Type 1 hypersensitivity of the eye
Acute allergic conjunctivitis
Give an example of a Type 2 hypersensitivity of the eye
Ocular cicatricial pemphigoid
Give an example of a Type 3 hypersensitivity of the eye
Autoimmune corneal melting
Give an example of a Type 4 hypersensitivity of the eye
Corneal graft rejection
What is the sensory supply to the Dura Mater
CN V
Which meningeal layer are the dural venous sinuses in
Dura Mater
Which meningeal layer are the arachnoid granulations in
Arachnoid mater
Where does the subarachnoid space stop with regards to the spinal cord
S2
Where is the 3rd ventricle
In midline with the diencephalon
Where is the 4th ventricle
Between the cerebellum and pons
What will the eye look like in a patient with 3rd nerve palsy
Ptosis (loss of eyelid muscle) Dilated pupil (loss of sphincter of the pupil) Eye down and out (LR & SO functioning)
When will a patient with 4th nerve palsy get diplopia
When looking down
eye can’t move inferomedially
What should you always do for suspected Intra-Ocular-Foreign-Body
X-ray orbits
Is an alkali or acid burn worse and why
Alkali is worse because it easily and rapidly penetrates
Acid coagulases protein so has little penetration
What does intracameral mean
Into the anterior chamber of the eye
What is the structure of the cornea in terms of lipid and water
lipid: water: lipid
epithelium: stroma: endothelium
What can be added to drugs to make them more hydrophobic
Alcohol or Acetate
What can be added to drugs to make them more hydrophilic
Phosphate
What kind of disease would Prednisolone Phosphate be used for and why
Corneal disease (phosphate makes it more hydrophilic so the drug does not penetrate and remains on cornea)
Name a preservative that is used and how it enhances corneal penetration
Benzalkonium
disrupts lipid layer of tear film
When is the intra-vitreal mode of administration used
To administer antibiotics in endophthalmitis
To administer anti-VEGF
What is the mechanism of action of anaesthetics used in tonometry/ corneal scrape
Block Na+ channels
impede nerve conduction
How do mydriatic drugs work
Cause pupil dilation by blocking parasympathetic supply to the iris
What visual field side effect can Vigabatrin have
Constriction of the visual field
What visual field side effect can Ethambutol have
Optic neuropathy
What visual field side effect can Chloroquine have
Maculopathy
What is the pathogenesis of diabetic retinopathy
Glycosylation of basement membranes
leads to loss of basement pericytes
What are the 3 classifications of new vessel growth in the eye
Growth on disc (NVD)
Growth in the periphery (NVE)
Growth on iris (Rubeosis iridis)
The central retinal artery supplies the inner 2/3rd’s of the retina, what supplies the outer 1/3rd
Choroid
Management of Central Retinal Artery Occlusion
If in 24 hours - Ocular massage to try and convert it to BRAO
Management of Central Retinal Vein Occlusion
Anti-VEGF
Which arteries, that supply the optic nerve head, become occluded in Ischaemic Optic Neuropathy
Posterior Ciliary Arteries
Ischaemic Optic Neuropathy can be arteritic or non-arteritic - Name a cause of each type
Arteritic - Giant Cell Arteritis
Non- Arteritic - Atherosclerosis
What could a loss of the red reflex suggest
Retinoblastoma
Vitreous haemorrhage
Retinal detachment
Cataract
What do flashes and floaters suggest
Retinal Detachment
What do haloes around lights suggest
Acute Angle Closure Glaucoma
Treatment of dry ARMD
Low vision aids (magnifiers)
What kind of visual field defect does open-angle glaucoma cause
Arcuate field defect
What should you assume is causing bilateral papilloedema until proven otherwise
Space-occupying lesion in the brain
What is the Monroe-Kellie hypothesis
States that if one component of inter-cranial pressure changes, the others must also change to compensate
What are the two causes of anterior blepharitis
Seborrhoeic (on eyelashes)
Staphylococcal (on hair follicle)
What is usually the cause of posterior blepharitis
Meibomian gland dysfunction
What derm condition is posterior blepharitis associated with
Acne Rosacea
Which derm condition can follicular conjunctivitis be secondary to
Molluscum Contagisoum
How can you differentiate between infective and autoimmune corneal ulcers
Infective ulcers tend to be central
Autoimmune ulcers tend to be peripheral
Treatment for bacterial corneal ulcers
Ofloxacin hourly
Which MSK pathologies are Episcleritis and Scleritis associated with
Episcleritis - Gout
Scleritis - Rheumatoid Arthritis
Which test is done for Scleritis
Phenylephrine test
What kind of vision puts you at a higher risk of retinal detachment
Myopia
short-sighted
What kind of vision puts you at a higher risk of Acute Angle Closure Glaucoma
Hypermetropia
long-sighted
What disease are Brushfield spots seen in
Down Syndrome
What disease are Kayser Fleischer rings seen in
Wilson’s disease
What disease are blue sclera seen in
Osteogenesis Imperfecta
CRVO can present with a relative afferent pupillary defect true or false
True
What is the normal range of intraocular pressure
10-21mmHg
Name a risk factor for ARMD
Smoking
If a patient presents complaining that straight lines are appearing wavy/curvy, what should you think of
ARMD
Which endocrine disease can cause vitreous haemorrhages
Diabetes
Flashes and Floaters suggest what pathology
Retinal detachment
When can contact lenses be worn in a patient with conjunctivitis
Should not be worn
What is the next course of action in a patient with ARMD and neovascularization
Fluorescein angiography
What is another name for a Marcus-Gunn pupil and what are the two possible causes
RAPD
Damage to optic nerve/ retina
What is a retinal cause of a relative afferent pupillary defect
Retinal detachment
What is an optic nerve cause of a relative afferent pupillary defect
Optic neuritis
Which biochemical abnormality can predispose to cataract formation
Hypocalcaemia
60 year old asthmatic presents with symptoms consistent with open-angle glaucoma. Tonometry confirms this with an intraocular pressure of 29mmHg. What is the management
Latanoprost (prostaglandin analogue)
b-blocker contraindicated due to asthma
A fractured zygoma tends to rotate in which direction and what can this disrupt
Medially
can disrupt suspensory eye ligament
Which tendon is attached to the superior tarsus
Levator Palpebrae Superioris
What is another name for Muller’s muscle
Superior tarsal muscle
What is the innervation of the lacrimal gland
CN VII (parasympathetic)
Where do all rectus muscles originate
Common Tendinous ring
Which nerve is responsible for conduction of afferent action potentials from the cornea in the blink reflex
CN V1 (long ciliary branch)
Which three things are being tested in the accommodation reflex and which structures are involved
Bilateral pupillary constriction (Spinchter pupillae)
Bilateral midline convergence (Medial rectus)
Bilateral lens relaxation (Ciliary muscle constriction)
Bilateral conjunctivitis in young adults can indicate what
Chlamydial Conjunctivitis
What kind of eye disease can result in sub tarsal scarring
Chlamydial Conjunctivitis
What is the most common cause of endophthalmitis and what is the treatment
Staph Epidermidis
Ceftazidime/ Vancomycin/ Intra-vitreal Amikacin
What do quinolones inhibit
DNA gyrase
thus inhibiting nucleic acid synthesis
What enzyme does chloramphenicol inhibit
Peptidyl transferase
Where on the cornea are Langerhan’s cells NOT found
Absent from central 1/3rd
Which two eye structures are known as the tough collagen coat and have no lymphatics or vasculature
Cornea + Sclera
Describe an Epidural Haematoma
Arterial bleed between skull and dura mater
Describe a Subdural Haematoma
Venous bleed between dura mater and arachnoid mater
What are the lateral and medial apertures of the 4th ventricle also known as and what space do they open to
Subarachnoid space
Lateral -> Foramen of Luschka
Medial -> Foramen of Magendie
What is the foramen of Monro
Connects 3rd and lateral ventricles
Define visual acuity
The ability to distinguish between 2 points
What colour of light do short medium and long wavelength cones allow us to see
Short -> Blue
Medium -> Green
Long -> Red
