Physiology Flashcards
CSF
Cerebrospinal Fluid
CSF: Composed mainly of what?
Water
CSF: Produced from where?
Secretory epithelium of the chorioid plexus
CSF: In the CNS what is the volume of CSF present?
150ml
CSF: Function
Supplies water, amino acids and ions whilst removing metabolites
CSF: 3 functions
Mechanical Protection - shock-absorbing medium that protects brain tissue so that the brain floats within the cranial cavity
Homeostatic Function - pH of the CSF affects pulmonary ventilation and cerebral blood flow to transport hormones
Circulation - medium for minor exchange of nutrients and waste products between the blood and brain tissue
Embryology of the Brain and Ventricular System: At 3 weeks what has developed?
The neural canal gives rise to the adult brain and ventricles and the spinal cord central canal
Embryology of the Brain and Ventricular System: The chorioid plexus develops from what?
Cells in the walls of the ventricles
Embryology of the Brain and Ventricular System: How is the chorioid fissure formed?
Developing arteries invaginate the roof of the ventricle
Embryology of the Brain and Ventricular System: How is the chorioid plexus formed?
Involuted ependymal cells along the vessels enlarge into the villi
Embryology of the Brain and Ventricular System: Chorioid plexus in the adult brain is found within what?
3rd, 4th and lateral ventricles
Chorioid Plexus
Network of capillaries in the walls of the ventricles
CSF Production: Secretion involves the transport of what to where?
Ions - Sodium, Chloride and Bicarbonate
Across the epithelium from the blood to the CSF
CSF Production: Secretion is dependent on what?
Sodium transport across the cells into the CSF
CSF Production: Electrical gradient with Sodium allows the synchronised transport of what?
Cl-
CSF Production: CSF has a lower what (3) than blood plasma?
K+
Glucose
Protein
CSF Production: CSF has a higher what (2) than blood plasma?
Sodium
Chloride
The Ventricular System: What are the ventricles names?
Lateral ventricles
Third Ventricle
Fourth Ventricle
The Ventricular System: CSF Flow - Intraventricular Foramen of Monroe
Allows flow from the lateral ventricles to the third ventricle
The Ventricular System: CSF Flow - Cerebral Aqueduct of Sylvius
Allows flow from the Third Ventricle to the Fourth Ventricle
The Ventricular System: CSF Flow - Foramen of Magendie
Median aperture that allows flow from the Fourth Ventricle to the Subarachnoid Space
The Ventricular System: CSF Flow - Foramina of Luschka
Lateral aperture that allows flow from the Fourth Ventricle to the Subarachnoid Space
CSF Circulation: The CSF is originally formed where?
Chorioid Plexus of each lateral ventricle
CSF Circulation: Flows from the lateral ventricles to the third ventricle how?
Through two narrow openings in the interventricular foramina
CSF Circulation: Where is CSF added in third ventricle?
Roof
CSF Circulation: CSF flows from the third ventricle to where and how?
Into the fourth ventricle through the cerebral aqueduct of the midbrain
CSF Circulation: CSF enters the subarachnoid space how?
Through 3 openings in the roof of the fourth ventricle - single median aperture and paired lateral apertures
CSF Circulation: After the subarachnoid space the CSF circulates into what?
Central canal of the spinal cord
CSF Circulation: Where does CSF flow through the subarachnoid space and ventricular system?
Between the Pia and Dura Mater
CSF Circulation: CSF returns to venous blood via what?
Arachnoid granulations into the superior sagittal sinus
CSF Circulation: Interstitial fluid of the brain is composed mostly of what?
Circulating CSF
CSF Circulation: Interstitial fluid of the brain drains to the CSF via what?
Perivascular space
Blood Brain Barrier: Structure
Highly selective barrier between the systemic circulation and the brains extracellular fluid formed by endothelial cells
Blood Brain Barrier: BBB consists of what three structures?
Capillary endothelium
Basal membrane
Perivascular astrocytes
Blood Brain Barrier: Tight junctions between the brain endothelial cells function
Prevent paracellular movement of undesirable molecules
Blood Brain Barrier: What cells prevent the crossing of CSF into the blood?
End foot of the astrocytes
Blood Brain Barrier: What parts of the brain do not have a BBB?
Circumventricular organs
Pineal gland
Blood Brain Barrier: Main function
Protect the brain from harmful neurotoxins and helps prevent infection from spreading to the brain
Pathologies of the Ventricles, Chorioid Plexus and CSF: Examples of Tumours (3)
Colloid Cyst
Ependymomas
Choroid Plexus Tumours
Pathologies of the Ventricles, Chorioid Plexus and CSF: Colloid Cysts are often found where?
At the interventricular foramen
Pathologies of the Ventricles, Chorioid Plexus and CSF: Ependymomas arise from where?
Ependymal cells lining the ventricles
Ventricular Haemorrhage
Accumulation of blood within the ventricles
Ventricular Haemorrhage: Epidural Haematoma
Arterial bleed between the skull and dura mater
Ventricular Haemorrhage: Subdural Haematoma
Venous bleed between the dura mater and arachnoid
Hydrocephalus
Accumulation of the CSF in the ventricular system or around the brain causing ventricular enlargement and increased CSF pressure
Hydrocephalus: Aetiologies (2)
Obstruction of drainage
Overproduction of CSF
Idiopathic Intracranial Hypertension and Pseudotumour Cerebri: What type of condition is this?
Enigmatic
Idiopathic Intracranial Hypertension and Pseudotumour Cerebri: Clinical Presentation (2)
Headache
Visual disturbances
Idiopathic Intracranial Hypertension and Pseudotumour Cerebri: Why do visual disturbances develop?
Papilloedema
Papilloedema
Optic disc swelling due to increased intracranial pressure transmitted to the subarachnoid space surrounding the optic nerve
Papilloedema: Clinical Presentation (4)
Enlarged blind spot
Blurring of vision
Visual obscurations
Loss of vision
Aqueous Humor
Specialised fluid that bathes the structures within the eye
Aqueous Humor: Function
Provides oxygen and metabolites
Aqueous Humor: Ascorbate has what function?
Powerful antioxidant
Aqueous Humor: What is the function of bicarbonate in this?
Buffers the H+ produced in the cornea and lens by anaerobic glycolysis
Aqueous Humor: Produced in an … dependent process?
Energy
Aqueous Humor: Produced from what?
Epithelial layer of the ciliary body
Aqueous Humor: Secreted into where from the ciliary body?
Posterior chamber of the eye then flows to the anterior chamber
Aqueous Humor: Drained into what and how?
Into the scleral venous sinus via a trabecular meshwork and the canal of Schlemm
Aqueous Humor: Where is the canal of Schlemm located?
In the angle between the iris and cornea iridocorneal angle
Aqueous Humor: Small amount diffuses through what to where?
Vitreous to be absorbed across the retinal pigment epithelium
Aqueous Humor: Ionic Composition - Function of Carbonic Anhydrase
Hydration of Carbon Dioxide to form Bicarbonate and H+
Aqueous Humor: Ionic Composition - What happens to Bicarbonate and H+?
Transported across the basolateral membranes of pigmented epithelial cells into the interstitial fluid in exchange for Chloride and Sodium
Aqueous Humor: Ionic Composition - Cl- and Na+ Ions that enter cells undergo what?
Diffusion via gap junctions between pigmented and non-pigmented cells
Aqueous Humor: Ionic Composition - Cl- and Na+ are transported out of non-pigmented cells into aqueous humor how?
Na+/K+/2Cl- Transporters
Aqueous Humor: Ionic Composition - K+ ions leaving the cell are recycled how?
Na+/K+ pump and Cl- channels
Aqueous Humor: How does water move?
AQP1 aquaporins of non-pigmented cells and via the paracellular cell pathway
Glaucoma: Occurs due to what?
Increased intra-ocular pressure due to imbalance between the rates of secretion and removal of aqueous humor
Glaucoma: How can we treat this?
Carbonic Anhydrase Inhibitors
Glaucoma: How do Carbonic Anhydrase Inhibitors work?
Reduce the production of aqueous humor to reduce ocular pressure
Glaucoma: Examples of Carbonic Anhydrase Inhibitors (2)
Dorzolamide
Acetazolomide
Ciliary Epithelium: The ciliary body and posterior surface of the iris is covered by what?
Two juxtaposed layers of epithelial cells:
1. Forward continuation of the pigment epithelium of the retina
2. Inner non-pigmented epithelial layer
Microbiology: Bacterial Conjunctivitis - Causative organisms in neonates (3)
Staphylococcus aureus
Neisseria gonorrhoea
Chlamydia trachomatis
Microbiology: Bacterial Conjunctivitis - Causative Organisms in patients that are not neonates (3)
Staphylococcus aureus
Streptococcus pneumoniae
Haemophilus influenzae
Microbiology: Bacterial Conjunctivitis - Management options (3)
Topical Antibiotics - Chloramphenicol, Fusidic Acid and Gentamicin
Microbiology: Bacterial Conjunctivitis - Chloramphenicol does not manage what bacteria?
Pseudomonas aeruginosa
Microbiology: Bacterial Conjunctivitis - Chloramphenicol is avoided in what cases? (2)
Allergy
Aplastic anaemia
Microbiology: Bacterial Conjunctivitis - Chloramphenicol Effective against what bacteria? (3)
Streptococcus
Staphylococcus
Haemophilus influenza
Microbiology: Bacterial Conjunctivitis - Chloramphenicol has a risk of what side effect?
Gray Baby if the dose is too high
Microbiology: Bacterial Conjunctivitis - Chloramphenicol why does this present with Gray Baby?
Neonata cannot process the drug as the liver is immature and can cause hypotension
Microbiology: Bacterial Conjunctivitis - Fusidic Acid treats what bacteria?
Staphylococcus aureus
Microbiology: Bacterial Conjunctivitis - Gentamicin treats what bacteria?
Coliforms
Pseudomonas aeruginosa
Microbiology: Viral Conjunctivitis - Causative organisms (3)
Adenovirus
Herpes simplex
Herpes zoster
Microbiology: Viral Conjunctivitis - Management
Ganciclovir
Microbiology: Viral Conjunctivitis - Ganciclovir Mechanism of Action
Inhibits viral DNA synthesis as base analogue mimics Guanine
Microbiology: Viral Conjunctivitis - Ganciclovir application
Used for dendritic ulcers of the cornea
Microbiology: Chlamydial Conjunctivitis - Management
Topical Oxytetracycline
Microbiology: Chlamydial Conjunctivitis - Suspect in what cases?
Bilateral conjunctivitis in young children
Microbiology: Chlamydial Conjunctivitis - May have what complication?
Subtarsal scarring
Microbial Keratitis: Bacterial Keratitis - Why is admission required?
For hourly drops
Microbial Keratitis: Bacterial Keratitis - Usually associated with what? (2)
Corneal pathology
Contact lens wearing
Microbial Keratitis: Bacterial Keratitis - Management options (2)
4-Quinolone e.g Ofloxacin
Gentamicin + Cefuroxime
Microbial Keratitis: Bacterial Keratitis - 4-Quinolones does not treat what bacteria?
Streptococcus pneumoniae
Microbial Keratitis: Herpetic Keratitis - If recurrent can result in what?
Reduced corneal sensation
Microbial Keratitis: Herpetic Keratitis - Management
Topical Antiviral Ganciclovir
Microbial Keratitis: Herpetic Keratitis - Risk of Ganciclovir management
Can cause corneal melt and perforation of the cornea
Microbial Keratitis: Adenoviral Keratitis - Usually follows what? (2)
URTI
Conjunctivitis
Microbial Keratitis: Adenoviral Keratitis - Management
May require steroids to speed up recovery if chronic
Microbial Keratitis: Fungal Keratitis - Seen in what patients? (2)
Those who work outside
Ocular surface disease
Microbial Keratitis: Fungal Keratitis - Management
Topical Anti-fungals - Natamycin or Amphotericin
Keratitis: Causative amoebic organism
Acanthomoeba
Keratitis: Management if Acanthomoeba causative organism (3)
Polyhexamethylene Biguanide
Propamide Brolene
Chlorhexadine
Pre-Septal Cellulitis: Often associated with what structures?
Paranasal snuses
Pre-Septal Cellulitis: Diagnostic test
CT scan to identify orbital abscesses
Pre-Septal Cellulitis: Clinical Presentation (4)
Painful
Proptosis - bulging of one or both eyes
Pyrexial
Sight Threatening
Orbital Cellulitis: Direct extension from what?
The sinus or focal orbital infection
Orbital Cellulitis: When is a scan required?
Any suggestion of restriction of the muscles or optic nerve dysfunction
Orbital Cellulitis: Management
Broad spectrum antibiotics - if an abscess is present this requires drainage
Endophthalmitis
Infection of the inside of the eye
Endophthalmitis: Clinical Presentation (3)
Painful
Decreasing vision
Incredibly red eye
Endophthalmitis: Management
Intraviteal - Amikacin or Ceftazidime or Vancomycin
Topical antibiotics
Endophthalmitis: Most common Causative Organism
Staphylococcus epidermidis
Chorioretinitis: When does Cytomegalovirus Retinitis present?
During AIDS
Chorioretinitis: Viral aetiologies (2)
Herpes Simplex Virus
Herpes Zoster Virus
Chorioretinitis: Fungal aetiologies
Candida
Chorioretinitis: Parasitic aetiologies (2)
Toxoplasma gondii
Toxocara canis
HSK-HSV Chorioetinitis: Alternate Name
Acute Retinal Necrosis
Chorioetinitis: Endogenous Type is caused by what?
Candida and Aspergillus
Chorioetinitis: Endogenous Type - Associated with what? (2)
Bacterial endocarditis
Indwelling catheters
Chorioetinitis: Endogenous Type - How is this diagnosed?
Imaging shows Roth spots with disseminated embolic bacterial abscesses
Chorioetinitis: Toxoplasmosis - Causative organism
Toxoplasmosis gondii
Chorioetinitis: Toxoplasmosis - Aetiologies (2)
Contaminated soil
Undercooked meat
Chorioetinitis: Toxoplasmosis - Clinical presentation
Mild Flu-like illness followed by cyst formation in the latent phase
Chorioetinitis: Toxoplasmosis - Management when sight threatening (2)
Clindamycin
Azithromycin
Chorioetinitis: Toxocara Canis - Description of the organism
Parasitic nemotode that affects cats and dogs
Chorioetinitis: Toxocara Canis - Unable to do what in humans?
Replicate
Chorioetinitis: Toxocara Canis - How does this cause irreversible vision loss?
Forms granulomas
Chorioetinitis: Toxocara Canis - Diagnostic test
ELISA test on the serum
Antibiotics: Chloramphenicol - Mechanism of action
Inhibits Peptidyl Transferase Enzyme
Antibiotics: Chloramphenicol - Bacteriocidal action on what bacteria? (2)
Streptococcus
Haemophilus influenzae
Antibiotics: Chloramphenicol - Bacteriostatic action on what bacteria?
Staphylococcus
Antibiotics: Chloramphenicol - Side effects (3)
Allergy
Irreversible Aplastic Anaemia
Gray baby syndrome
Antibiotics: Inhibition of Cell Wall Synthesis - Two Types
Penicillins
Cephalosporins
Antibiotics: Inhibition of Cell Wall Synthesis - Used for what bacteria in Dacrocystitis? (2)
Streptococcus pyogenes
Staphylococcus aureus
Antibiotics: Inhibition of Nucleic Acid Synthesis - Example of type of drug
Quinolones - Ofloxacin
Vision: The pattern of the object must fall onto what?
The vision receptors - rods and cones
Vision: The pattern of the object must fall onto the vision receptors to enable what?
Accomodation
The Visual Field: How is binocular visual field generated?
Monocular visual fields (+/- 45 degrees) are overlapped
The Visual Field: The retina is divided in half relative to what?
The fovea
The Visual Field: Two halves of the visual field retina
Nasal hemiretina
Temporal hemiretina
The Visual Field: What happens to the nerve fibres of the nasal hemiretina?
Crosses at the optic chiasma
Visual Field: Visual Field Mapping involves what structures? (4)
Retina
Lateral Geniculate Nucleus
Superior Colliculus
Cortex
Visual Field: Why is the central field over-represented?
As the magnification factor is not constant
Visual Field: Primary Visual Cortex - In this the eye-specific inputs are segregated where?
Layer 4
Visual Field: Primary Visual Cortex - At the primary visual area vision is largely segregated into what?
Ocular dominance columns
Visual Field: Primary Visual Cortex - Each column in the primary visual area is dominated by what?
Input from one of the two eyes
Visual Field: Primary Visual Cortex - Cells outside of layer 4 receive input from where?
Both eyes
Visual Perception: Ambylopia can be caused by what from infancy?
Strabismus - wandering eye
Hebb’s Postulate
When the axon of cell A is near enough to excite cell B and is repeatedly fired, growth and metabolic changes cause increased efficiency in cell A
Retina: Direct Pathway Stages (3)
- Photoreceptors
- Bipolar Cells
- Ganglion Cells
Retina: Function of horizontal cells
Receive input from photoreceptors and project to other photoreceptors and bipolar cells
Retina: Function of amacrine cells
Receive input from bipolar cells and project to ganglion cells, bipolar cells and other amacrine cells
Photoreceptors: Two types
Rods
Cones
Photoreceptors: Function
Converts electromagnetic radiation to neural signals via transduction
Photoreceptors: Four regions
Outer segment
Inner segment
Cell body
Synaptic terminal
Photoreceptors: Phototransduction - The resting membrane potential is …
Depolarised
Photoreceptors: Phototransduction - Resting Membrane Potential (mV)
-20 mV
Photoreceptors: Phototransduction - On light exposure what happens to Vm?
Hyperpolarises
Photoreceptors: Phototransduction - In the dark what happens to Vm?
It is positive
Photoreceptors: Phototransduction - Why is Vm positive when its dark?
cGMP-gated Na+ channel is open
Photoreceptors: Modulation of the Dark Current - In the Dark the Outer segment Sodium Potential is what?
Equal to the potassium potential - therefore Vm is between ENa and EK
Photoreceptors: Modulation of the Dark Current - In the Light the Outer Segment Sodium Potential is what?
Reduced - as the channels close on the outer segment so ENa<EK
Photoreceptors: Modulation of the Dark Current - In the light the Outer Segment is …
Hyperpolarised
Photoreceptors: Visual Pigment Molecules - What is present on Rods?
Rhodopsin
Photoreceptors: Visual Pigment Molecules - Rhodopsin is composed of what?
Retinal - Vitamin A derivative
Opsin - G-protein coupled receptor
Photoreceptors: Visual Pigment Molecules - Rhodopsin is present where?
In the membrane folds of the discs of the outer segment
Photoreceptors: Visual Pigment Molecules - Light enables what reaction in Rhodopsin?
11-cis-Retinal to All-Trans-Retinal (active form)
Phototransduction: Molecular mechanism (4 stages)
- All-trans-Retinal activates Transducin
- Molecular cascades causes reduced cGMP
- Closure of cGMP-gated Na+ Channels
- Lowered Na entry results in hyperpolarisation
Phototransduction: Dark Current Channel - What state is it in in the dark?
Open
Phototransduction: Dark Current Channel - What state is it in in the light?
Opened by cGMP
Phototransduction: Dark Current Channel - Permeable to what?
Sodium
Phototransduction: Dark Current Channel - Enables steady release of what?
Glutamate
Phototransduction: Dark Current Channel - Relationship between Glutamate and Light
Glutamate decreases with light
Visual Acuity
Ability to distinguish two nearby points
Visual Acuity: Determined by what two factors?
Photoreceptor spacing
Refractive power
Visual Acuity: Rod function
Enable vision in dim light
Visual Acuity: Cone function
Enable vision in day light
Visual Acuity: Why does the rod system decrease acuity?
More convergence
Colour Vision: Cannot see what light ranges?
Infrared
UV range
Rods: Does it detect colour?
No its achromatic
Rods: Convergence is (high/low)
High
Rods: Level of light sensitivity
High
Rods: Level of visual acuity
Low
Cones: Does it detect colour?
Yes - chromatic
Cones: High density where?
Fovea
Cones: Level of convergence
Low
Cones: Level of light sensitivity
Low
Cones: Level of visual acuity
High
Immunology: Basic Immune responses for the eye (3)
Blink reflex
Physical and chemical properties of the eye surface
Limit exposure and size of the eye
Immunology: Blink Reflex - Function
Tears enable flushing of the eye
Immunology: Blink Reflex - Mucous layer acts as a what?
Anti-adhesive
Immunology: Chemical Protection - 7 components of the tears
Lysozyme
Lactoferrin and Transferrin
Lipids
Angiogenin
Secretory IgA
Complement system
IL-6 -8 and MIP
Immunology: Chemical Protection - Function of Lysozyme
Protective against Gram Negative bacteria and Fungi
Immunology: Chemical Protection - Function of Lactoferrin and Transferrin
Protective against Gram positive bacteria
Immunology: Chemical Protection - Function of tear lipids
Anti-bacterial to cell membranes
Immunology: Chemical Protection - Function of Angiogenin
Anti-microbial effect within the tear film
Immunology: Chemical Protection - Function of IL-6 -8 and MIP
Anti-microbial products that recruit leukocytes
Immunology: Immune Cells - Function of Neutrophils
Attracted by chemotaxis to the site to release Free radicals and enzymes
Immunology: Immune Cells - Function of Macrophages
Phagocytosis of damaged cells to aid the activation of adaptive immune system
Immunology: Immune Cells - Function of Conjunctival Mast Cells
Vasoactive mediators
Immunology: What is the main Antigen Presenting Cell of the External Eye?
Langerhans Cells
Immunology: Langerhans Cells are rich in what molecules?
Class II MHC
Immunology: Langerhans Cells - Abundant in what location?
Corneo-scleral limbus
Immunology: Langerhans Cells - Absent from what location?
Central third of the cornea
Immunology: Conjunctiva - The only part of the eye with what?
Lymphatic drainage
Immunology: Conjunctiva - What is present within this area in conjunctival zones?
Diffuse lymphoid populations
Immunology: Conjunctiva - What Lymphocytes are present?
CD4+ T cells
CD8+ T cells
IgA-secreting plasma cells
Immunology: Conjunctiva - What cells acts as APCs here?
Dendritic cells
Immunology: Conjunctiva - What is present in the MALT?
Macrophages
Langerhans Cells
Mast cells
Neutrophils and Eosinophils - if recruited
Immunology: Cornea and Sclera - What is the structure here?
Tough collagen coat
Immunology: Cornea and Sclera - Is there a blood supply?
No
Immunology: Cornea and Sclera - Langerhans cells are only present where?
Peripheral cornea
Immunology: Lacrimal Gland - Has more of what compared to the conjunctiva?
Plasma cells and CD8+ T cells
Immunology: Lacrimal Drainage System - What is present here?
Diffuse lymphoid tissue and follicles in MALT
Immune Privilege: Advantage
Tolerate the introduction of antigens without eliciting an inflammatory immune response
Immune Privilege: Examples of sites with Immune Privilege (4)
Brain or CNS
Testes
Placenta and Foetus
Eyes
Immune Privilege: Sites in the Eye that are Immune Privileged (5)
Cornea
Anterior chamber
Lens
Vitreous chamber
Sub-retinal space
Immune Privilege: ACAID
Anterior Chamber Associated Immune Deviation
Hypersensitivity Reactions: Occular Example of Type I
Acute Allergic Conjunctivitis
Hypersensitivity Reactions: Occular Example of Type II
Ocular Cicatricial Pemphigoid
Hypersensitivity Reactions: Occular example of Type III
Autoimmune corneal melting
Hypersensitivity Reactions: Occular example of Type IV
Corneal Graft Rejection - vascularisation of the host cornea reaching the donor tissue results in graft rejection
Corneal Transplants: Factors that help maintain immune privilege - Why is the net antigenic load is reduced?
Reduced and impaired expression of MHC Class I and II
Corneal Transplants: Factors that help maintain immune privilege - The cornea lacks what two structures?
Blood
Lymph vessels
Corneal Transplants: Factors that help maintain immune privilege - Central cornea is deficient of what?
Langerhans Cells
Corneal Transplants: Factors that help maintain immune privilege - Secretion of what?
Immunosuppressive properties
Meninges
Protective coverings of the brain and spinal cord
Meninges: Dura Mater - Sensory supply
CN V
Meninges: Dura Mater - Function
Encloses the dural venous sinuses
Meninges: Sub-Arachnoid Space - What is present here? (2)
Circulating CSF
Blood vessels
Meninges: Pia Mater - Function
Adheres to the brain, nerves and vessels
Sub-Arachnoid Space: Location
Between the arachnoid and pia mater
Sub-Arachnoid Space: Contains what?
CSF
Sub-Arachnoid Space: CSF can be accessed where?
Lumbar puncture at L3/4 or L4/5 intervertebral disc
Sub-Arachnoid Space: Ends where?
S2
Raised Intra-Ocular Pressure: Increase in pressure within the cranial cavity due to what? (2)
Increased pressure in fluid surrounding the brain
Increase in pressure within the pressure
Raised Intra-Ocular Pressure: 3 components of the cranial cavity
Brain
Blood Volume
CSF
Raised Intra-Ocular Pressure: Monro-Kellie Hypothesis
Increasing the volume of one of the three components increases the volume of the other two must increase to maintain the equilibrium
The Optic Nerve: Raised Intra-cranial pressure is transmitted along what?
The sub-arachnoid space in the optic nerve sheath
The Optic Nerve: Compression of the optic nerve may also compress what? (2)
Central artery
Vein of the retina
The Optic Nerve: Compression of the optic nerve can lead to?
Papilloedema - leads to bulging or swollen optic discs when caused by raised ICP
The Optic Nerve: Symptoms of the Optic Nerve Compression (5)
Transient visual obscurations
Transient flickering
Blurring of vision
Constriction of the visual field
Decreased colour perceptio
The Oculomotor Nerve: Raised ICP can compress the oculomotor nerve when?
If the medial temporal lobe herniates through the tentorial notch
The Oculomotor Nerve: Compression causes what? (2)
Paralysis of somatic motor innervation to the 4 extra-ocular muscles and eye lid
Paralysis of parasympathetic innervation of the sphincter of the pupil
The Oculomotor Nerve: Clinical Presentation of compression (4)
Loss or slowing of pupillary light reflex
Dilated pupil
Ptosis
Eye turned inferolaterally - due to unopposed actions of lateral rectus and superior oblique
The Trochlear Nerve: Emerges from where?
Midbrain
The Trochlear Nerve: Supplies what meninges?
Dura mater
The Trochlear Nerve: Compression can result in what?
Paralysis of the superior oblique muscle
The Trochlear Nerve: Clinical Presentation
Diplopia when looking down - inferior oblique is unopposed so cannot move inferomedially
The Abducens Nerve: Susceptible to what type of damage?
Stretching
The Abducens Nerve: Complication of stretching
Paralysis of lateral rectus muscle
The Abducens Nerve: Clinical presentation of stretching
Eye cannot move laterally in the horizontal plane - medial deviation of the eye
Dural Septae
Folds of the dura mater that creates a septa in the cranial cavity
Dural Septae: Divides the cranial cavity into what four sections?
Falx Cerebri
Tentorium Cerebelli
Falx Cerebelli
Diaphragma Sellae
Mechanisms of Ocular Trauma (3)
Blunt trauma
Penetrating trauma
Burns - chemical, physical or thermal
Blunt Trauma: Blow Out Fractures - Mechanism
Fracture to one of the walls of the orbit but the orbital rim remains intact
Blunt Trauma: Blow Out Fractures - What type are most common?
Inferior blowout fractures
Blunt Trauma: Blow Out Fractures - In an inferior blowout fracture what happens?
Orbital fat prolapses into the maxillary sinus that may be joined by prolapse of the inferior rectus muscle
Blunt Trauma: Blow Out Fractures - How may inferior blow out affect vision?
Diplopia
Hyphaemia
Blood in the anterior chamber
Hyphaemia is a sign of what?
Intra-ocular trauma
Sub-conjunctival Haemorrhage: Mechanism
One of the small blood vessels within the conjunctiva ruptures to release blood into the space between the sclera and conjunctiva
Sub-conjunctival Haemorrhage: Management
Self resolving within 2 weeks
Penetrating Trauma
Injury that penetrates the cornea or the sclera
Penetrating Trauma: Types of injury caused by small objects? (5)
Sub-tarsal
Conjunctival
Corneal
Intra-ocular
Intra-orbital
Penetrating Trauma: What do intra-ocular injuries require?
X-ray for potential intra-ocular foreign bodies
Penetrating Trauma: Signs of a Penetrating Foreign Body (4)
Irregular pupil
Shallow anterior chamber
Localised cataract
Gross inflammation
Sympathetic Opthalmia
Penetrating injury to one eye that results in the exposure of intra-ocular antigens for auto-immune reactions in both eyes
Sympathetic Opthalmia: Complication
Bilateral blindness
Burns: Alkali - Pathological changes (2)
Cicatrising changes to the conjunctiva and cornea
Can change the pH of the entire eye
Burns: Alkali - Is penetration easy?
Yes
Burns: Acid - Is penetration easy?
No
Burns: Acid - Impact on proteins
Causes coagulation
Burns: Complications (4)
Limbal ischaemia
Corneal scarring
Corneal vascularisation
End stage scarring
Average diameter of the optic nerve
1.5 mm
The Optic Nerve: What are the 3 C’s?
Contour
Colour
Cup
The Optic Nerve: What happens to the disc in Disc Drusen?
Disc margin appears blurred
The Optic Nerve: Colour
Orange with a pale centre
The Optic Nerve: Aetiologies of changes in colour (5)
Glaucoma
Optic neuritis
Arteric ischaemic optic neuropathy
Non-arteritic ischaemic optic neuropathy
Compressive lesion
The Optic Nerve: Disc - why is it pale?
Devoid of neuroretinal tissue
The Optic Nerve: Normal Cup:Disc ration?
0.3
The Optic Nerve: What does an increase in cup:disc ratio suggest?
Decrease in the quantity of healthy neuroretinal tissue
Visual Pathologies: Homonymous
Same part of the field in each eye
Visual Pathologies: Hemianopic
Half of the field is affected
Visual Pathologies: Quadrantanopic
Quarter of the field is affected
Visual Pathologies: Most common cause of Quadrantanopic pathology
Occipital lobe stroke
Visual Pathologies: Inferior quadrantic defect due to what?
Parietal lobe defect
Visual Pathologies: Superior quadrantic defect due to what?
Temporal lobe defect
What is given after a foreign body is removed from the eye?
Chloramphenicol ointment
Systemic Disease: Myotonic Dystrophy
Difficulty in releasing grip
Systemic Disease: Myotonic Dystrophy - Genetics
Autosomal dominant mutation of the dystrophica myotonica protein kinase gene
Systemic Disease: Myotonic Dystrophy - Common ocular presentations (3)
Early onset cataracts
Ptosis
Hypermetropia
Systemic Disease: Myotonic Dystrophy - Uncommon Ocular Presentations (4)
Mild ophthalmoplegia
Pupillary light-near dissociation
Pigmentary retinopathy
Optic atrophy
Systemic Disease: Neurofibromatosis Type I - Ocular presentation (2)
Optic glioma - causes an afferent pupillary defect with globe proptosis
Two or more Lisch Nodules - bilateral yellow or brown shaped nodules
Systemic Disease: Thyroid Eye Disease - Pathophysiology
Inflammation. ofthe eye muscles and orbital fat causes fluid retention and swelling of the eye
Systemic Disease: Thyroid Eye Disease - Appearance (4)
Peri-orbital swelling
Prominent eyes - lid retraction with proptosis
Kocher Sign - frightened appearance of eyes
Conjunctival injection
Systemic Disease: Thyroid Eye Disease - Symptoms of soft tissue involvement (3)
Grittiness
Photophobia
Lacrimation
Systemic Disease: Thyroid Eye Disease - Signs of soft tissue involvement (3)
Hyperaemia
Chemosis
Periorbital swelling
Systemic Disease: Thyroid Eye Disease - Proptosis complications
Keratopathy causing corneal ulceration
Systemic Disease: Thyroid Eye Disease - Optic Neuropathy complications (2)
Reduced colour vision
Vision with RAPD
Systemic Disease: Dermatomyositis - Ocular presentation (3)
Bilateral lilac eyelid discolouration - heliotropic rash
Swelling of the eyelids and periorbital skin
Dry eyes and scleritis
Systemic Disease: Marfan Syndrome - Genetics
Autosomal dominant mutation of the fibrillin-1 gene
Systemic Disease: Marfan Syndrome - Ocular presentation
Dislocated Lens - ectopia lentis
Systemic Disease: Rheumatoid Arthritis - Corneal findings (2)
Scleromalacia perforans
Peripheral ulcerative keratitis
Systemic Disease: What diseases present with Mutton-Fat Keratic Precipitates (Granulomatous Anterior Uveitis) (3)
Sarcoidosis
TB
Syphillis
Systemic Disease: Infective Causes of Uveitis (6)
TB
Herpes Zoster
Toxoplasmosis
Candidiasis
Syphillis
Lyme Disease
Systemic Disease: Non-infective causes of Uveitis (4)
HLA-B27
Juvenile Arthritis
Sarcoidosis
Behcet’s Disease
Systemic Disease: Causes of Vortex Keratopathy (4)
Amiodarone
Hydroxychloroquine
Chloropromazine
Fabry Disease
Systemic Disease: Causes of Bulls Eye Maculopathy (2)
Hydroxychloroquine
Chloroquine
Systemic Disease: Causes of Symbelpharon (3)
SJS - Sulfa drugs and penicillin
Ocular cicatricial pemphigoid
Chemical injury
Systemic Disease: Impact on the eye with Steroid use
Raised intraocular pressure
The Retina: How many layers?
9
The Retina: Diabetic Retinopathy - 3 Types
Non-proliferative Diabetic Retinopathy
Proliferative Diabetic Retinopathy
Diabetic Macular Oedema
The Retina: Non-Proliferative Diabetic Retinopathy - 5 signs on examination
Micro-aneurysms
Hard exudates
Intra-retinal haemorrhages
Cotton wool spot
Venous beading
The Retina: Proliferative Diabetic Retinopathy - 2 signs on examination
Neovascularisation
Vitreous haemorrhage and traction
The Retina: Proliferative Diabetic Retinopathy - Clinical Presentation (2)
Floaters
Severe visual loss
The Retina: Proliferative Diabetic Retinopathy - Management
Immediate ophthalmologic consultation
The Retina: Diabetic Retinopathy - Management for CSME (Clinically-significant Macular Oedema)
Focal macular laser
The Retina: Diabetic Retinopathy - Management for Proliferative Diabetic Retinopathy
Panretinal Photocoagulation
The Retina: Diabetic Retinopathy - Management for Vitreous Haemorrhage or Retinal Detachment
Vitrectomy
The Retina: Diabetic Retinopathy - Management for Diabetic Macular Oedema
Anti-VEGF
who do i love
kirsten <3
Normal Axial Length
> 26 mm
Normal Spherical Equivalent
<8.00 D
Posterior Vitreous Detachment: 3 classifications
Break
Hole
Tear
Posterior Vitreous Detachment: Break
Full-thickness defect in the Sensory Retina
Posterior Vitreous Detachment: Hole occurs due to what?
Chronic Retinal Atrophy
Posterior Vitreous Detachment: Tear occurs due to what?
Dynamic vitreoretinal traction
Retinal Detachment
Separation of the sensory retina from the RPE by sub-retinal fluid
Retinal Detachment: Rhgmatogenous occurs due to what?
Retinal break
Retinal Detachment: Two components of retinal break formation
Acute posterior vitreous detachment
Predisposing peripheral retinal degeneration
Fresh Rhegmatogenous Retinal Detachment: Presentation (5)
Convex deep mobile elevation that extends to the ora serrata
Slightly opaque retina
Dark blood vessels
Loss of choroidal pattern
Retinal breaks
Exudative Retinal Detachment
Damage to the RPE by subretinal disease that allows the passage of fluid from the coroid into the subretinal space
Exudative Retinal Detachment: Aetiologies - Intraocular Inflammation (2)
Harada disease
Posterior scleritis
Exudative Retinal Detachment: Aetiologies - Systemic (2)
Toxoaemia of Pregnancy
Hypoproteinaemia
Exudative Retinal Detachment: Aetiologies - Iatrogenic (2)
RD surgery
Excess retinal photocoagulation
Exudative Retinal Detachment: Signs (3)
Convex with smooth elevation
Mobile and deep with shifting fluid
Subretinal pigment after flattening
Central Retinal Artery Occlusion: Impact
Severe vision loss
Central Retinal Artery Occlusion: Leading cause of death in these patients?
Cardiovascular disease
Central Serous Chorioretinopathy: Typical Patient
Healthy 30-50 year old male
Central Serous Chorioretinopathy: Most common angiographic finding
Small focal hyperfluorescent RPE leak with a smokestack
Epiretinal Membrane: Mainly associated with what disease?
PVD
Epiretinal Membrane: Two stages
Subretinal fluid
Cystic
Epiretinal Membrane: Features (3)
Metamorphopsia
Decreased acuity
Retinal striae
Vitreomacular Traction: Features (4)
Metamorphopsia
Decreased vision
Partial posterior vitreous detachment
Vitreous traction on the macula with subretinal fluid accumulation
Macular Hole: Ia Staging
Foveolar detachment
Macular Hole: II Staging
Full thickness defect less than 400 micrometers
Macular Hole: III Staging
Full thickness defect more than 400 micrometers with no PVD
Macular Hole: IV Staging
III with PVD
Cystoid Macular Oedema
Fluid collection in the outer plexiform
Emmetropia
No refractive error - the light is focused on to the retina
Ametropia
Refractive error is present - the light is focused behind or in front of the retina
Anisometropia
Significant difference between the right and left ametropia
Myopia
Light is focused in front of the retina
Myopia: Impact on distance targets?
Blurred
Myopia: Impact on close targets?
None
Myopia: What lenses are required?
Negative - image magnification required
Hypermetropia
Light is focused behind the retina
Hypermetropia: Impact on distant vision?
Nothing
Hypermetropia: Impact on near vision?
Blurred
Hypermetropia: Lenses
Positive - image magnification required
Astigmatism
Eye has unequal refractive powers at different meridia to cause a distorted vision
Astigmatism: Lenses required
Cylindrical lenses
Presbyopia
Reduction in the ability of the eye to accomodate for close-work with age
Presbyopia: Requires what lens?
Supplementary converging or positive lens to focus on light from a near object onto the retina
Vision
Smallest letter on a chart that a patient can read without the aid of spectacles or contact lenses
Visual acuity
Smallest letter on the chart a patient can read with the best spectacle or contact lens correction
Pinhole Acuity
The smallest letter visible when viewing through a pinhole
The appearance of the retina with an arterial occlusion
Pale
The appearance of the retina with a vein occlusion
Dark red/purple
ARMD
Age-related macular degeneration
Causes of Sudden Visual Loss (6)
Vascular occlusion - retinal artery, vein or optic nerve head circulation
Haemorrhage
Vitreous haemorrhage
Retinal detachment
Age Related Macular Degeneration - Wet Type
Closed angle glaucoma
Aetiologies of Gradual Vision Loss (5)
Cataract
Age Related Macular Degeneration - Dry Type
Refractive error
Glaucoma
Diabetic Retinopathy
VIth Nerve Palsy: Four main causes
Microvascular
Raised intracranial pressure
Tumour
Congenital
VIth Nerve Palsy: Pathophysiology
False localising sign and as the pressure increases the brain descends to push the sixth nerve over the edge of the petrous bone
VIth Nerve Palsy: Clinical Presentation (3)
Papilloedema
Lateral Rectus Palsy - the impacted eye cannot abduct as medial rectus
Double vision
IVth Nerve Palsy: Aetiologies (4)
Congenital Decompensated
Microvascular
Tumour
Bilateral - due to closed head trauma
IVth Nerve Palsy: Clinical Presentation (3)
Superior Oblique Muscle Plasy - causes intorsion and depression whilst in adduction of the eye and abduction is weak
Vertical double vision
Head Tilt due to incyclo-torsion to compensate vision (tilted to impacted eye)
IVth Nerve Palsy: Clinical Presentation due to blunt head trauma (3)
Torsion
Chin is depressed
Asthenopia
IIIrd Nerve Palsy: Two branches of the nerve
Superior
Inferior
IIIrd Nerve Palsy: Aetiologies (5)
Microvascular
Tumour
Aneurysm - causes a blown pupil
Multiple Sclerosis
Congenital
IIIrd Nerve Palsy: Impacts what muscles? (6)
Medial rectus
Inferior rectus
Superior rectus
Inferior oblique
Sphincter pupillae
Levator palpebrae superioris
IIIrd Nerve Palsy: Clinical Presentation (2)
Ocular depression and lateral eye movement
Blown pupil - dilation
IIIrd Nerve Palsy: Most common artery impacted by aneurysm?
Posterior communicating artery to press the superficial parasympathetic around the nerve
Macular sparing
Visual field loss thay preserves vision in the centre of the visual field
IIIrd Nerve Palsy: When does macular sensing appear?
Damage to one hemisphere of their visual cortex
Optic Nerve Defects: Aetiologies (3)
Ischaemic Optic Neuropathy
Optic neuritis
Tumours - Meninioma, Glioma or Hemiangioma
Optic Nerve Defects: Pathophysiology
Complete or abide the horizontal
Optic Neuritis
Progressive visual loss with pain behind the eye on movement
Optic Nerve Defects: Clinical Presentation (3)
Colour desaturation
Central Scotoma
Gradual recovery within weeks or months
Optic Nerve Defects: Signs on Examination (2)
Optic atrophy
Optic nerve haemangioma