Opthalmology Online And SDL Flashcards
Lecture 1/4: Cell struc and innervation of eye
what part of eye described by:
epithelium, stroma, accessory lacrimal glands?
conjuctiva (outer skin of eye)
what is the role of accessory lacrimal glands in conjuctiva?
secrete aq component of tears alongside lacrimal gland
The conjunctival epithelium has 2-5 layers of keratinised or non keratinised epithelium?
non keratinised
what are the two cell types that compose the non keratinised epithelial layers of the conjunctival epithelium of the eye?
stratified squamous and stratified columnar
are stratified squamous or stratified columnar cells known as palpebral/limbal?
stratified squamous
true or false, the term bulbar is associated with stratified columnar cells?
true
What is the role of microvilli in the conjunctival epithelium?
secrete glycoproteins, forms glycocalyx which stabilises tear film
what cell type is responsible for producing the mucin layer of tear film?
goblet
what is the main type of collagen that is found on the basement membrane of the conjunctival epithelium which anchors fibrils and hemidesmosomes?
4
what are the two layers of the conjunctival stroma?
superficial lymphoid and deeper fibrous
the superficial lymphoid layer of the conjunctival stroma contains lymphoid tissue, what is its purpose?
attaches to epithelium via basement membrane
which layer of the conjunctival stroma attaches to the episclera aka tenons layer?
deeper fibrous
what are the 2 different types of tissue that make up the deeper fibrous layer of the conjunctival stroma?
collagenous elastic and neurovascular
what are the functions of the tear film
protect, lubricate, reduces infection risk, washes away foreign particles
why does tear film reduce infection risk?
has antimicrobial protective substances
what are the 3 layers of the tear film going in order of proximity to the cornea
mucin, aqueous and phospholipid
The mucin layer of the tear film is made of goblet cells, why does it stabilise aq substances against the hydrophobic corneal epithelium?
hydrophilic surface
what different things would you expect to find in the aq layer of the tear film?
lacrimal and accessory lacrimal glands
water
growth factors
lactoferrin
lysozyme
immunoglobulins
cytokines
what is the name of the sebaceous glands on the eyelids that are present in and secrete the phospholipid layer of the tear film?
meibomian
what is the role of the phospholipid layer of the tear film?
reduces evaporation of aq layer, increases surface tension of tear film, makes it more stable
what is the maximal volume of the conj sac/ tear volume in microlitres?
7-30
what is the volume of an eye drop in microlitres
25-70
how many drops can the conj sac of the eye roughly support?
1
list some of the different factors that can affect the rate and extent of ocular absorption of eye drops ?
tear volume
tear turnover time
spontaneous blink rate
corneal thickness
lipophilic hydrophilic lipophilic nature of cornea
tear turnover time is 0.5-2.2 microlitres/min roughly, what effect would an irritating drug have on tear turnover time potentially?
increase
how long does a drug remain in the conj sac on average?
3-5 mins
do ointments have better or worse penetration than drops and why
better because they stay longer in the sac
what is the rate of ocular absorption?
1 to 7%
what is the function of the cornea?
clear view and protection from infection, trauma
how many layers does the cornea have ?
5
describe the epithelial layer of the cornea
5-7 layers of non keratinised squamous cells
hemidesmosomes to basement membrane
flatter wing cells superficially
microvilli
limbus junction between cornea and sclera
describe the cellular structure of the bowmans layer of the cornea
superficial strong layer of stromal collagen
beneath epithelial basement membrane
avascular unable to regenerate
heals by scarring
describe the cellular structure of the stroma layer of cornea
75% water
collagen type 1,2,3 and 4
fibres arranged in regular way to confer transparency and allow light through
proteoglycan around substance
made of modified fibroblasts called keratocytes - remodelling after injury
describe the cellular structure of the descements membrane of the cornea
basement membrane of endothelium
produced and repaired by endothelial cells
cornea endothelium cornea is made from monolayer of hexagonal cells but cant regenerate due to damage/ cell loss, how does it compensate for this?
enlargement and migration
the cornea gets nutrition from aq, limbus (+ tera film), transparency is dependant on what? 2
correct water amount in stroma
regular orientation and spacing of collagen fibres
water amount in stroma is dependant/ derived from the water + nutrients flowing passively from aq –> stroma.
how does the endothelium control water vol and prevent overhydration?
actively pumps Na+ back into aq (Na/K ATPase), water follows Na passively
what is the episclera?
loose connective tissue overlying the sclera
that provides the nutrition to sclera
also providing low friction to allow free movement of the eye
what is the episclera composed of? 3 layers
inner layer
intermediate loose connective tissue
outer layer - muscle sheaths fused & conjuctiva at limbus
and heavily vascularised
- anterior and posterior plexus
what are the main functions of the sclera?
protect
maintain shape
tolerance of intraocular pressure fluctuations
blocking of light
name of the tough outer coat of the eye?
sclera
continuous w cornea and optic nerve
T/F sclera has own blood vessels
false
avascular but pierced by vessels
what does the sclera consist of?
collagen (1,2,5, also 4,6,8)
proteoglycans
glycoproteins
elastin
2 main layers of the sclera?
outer stroma: criss cross of collagen
inner lamina fusca: blends w uveal tract, separated by suprachoroidal space
what are the three components of the uveal tract?
iris
choroid
ciliary body
what is the iris composed of?
Anterior surface - Connective tissue, incomplete border layer overlying
stroma
Stroma
Contains vessels, nerves Sphincter pupillae(circular)
Smooth muscle (short ciliary nerves – CNIII – parasympathetic)
Dilator pupillae (radial)
Smooth muscle (sympathetic supply, carried by long ciliary
nerves (Va))
Posterior epithelium
Cuboidal, pigmented
what is the function of the iris?
control pupil size to regulate light, depth of focus, minimising optical aberrations
blood-aqueous barrier due to tight junctions between iris and endothelium cells
what is the ciliary body composed of?
- Ciliary epithelium
* Cuboidal bilayer, apex to apex, gap junctions
- Inner layer – nonpigmented, high metabolic activity
- Outer layer – pigmented - Ciliary muscle
whats the function of the ciliary body?
- Blood aqueous barrier (tight junctions between inner nonpigmented cells)
- Aqueous humour production (both epithelial layers)
- Accommodation (ciliary muscle)
*Contracts => zonules relax => lens fattens =>
enables focus on near objects
*Parasympathetic (short ciliary nerves CNIII)
whats the structure of the choroid? in order
bruchs membrane
choriocapillaries
stroma - larger blood vessels
most vascular layer of eye?
choroid
choroid functions?
Vascular supply:
1. Nutrition
2. Waste removal
3. Heat dissipation
4. Ocular immunity
what structure of the eye is:
80% ocular volume
99% water
Transparent “gel”
Hyaluronic acid
Collagen (II, IX, V/XI hybrid)
vitreous
4 parts of the lens?
capsule (BM)
epithelium
fibres
zonules
what % refractive power of eye from lens and cornea?
30% lens
70% cornea
what is the epithelium of the lens like
a) centrally
b) peripherally
a) cuboidal and non-mitotic
b) columnar and mitotic
stretch
what do lens cells lose when they become FIBRES?
elongate and lose organelles
in the lens, where are the a) older fibres
b) newer formed fibres found?
nucleus
cortex
in lens, name for sheets of suspensory fibres, made of fibrililin, and attach ciliary body to lens at and around equator?
zonules
what strutcure helps hold lens in place?
zonules
what % of lens is water andprotein?
low water 65%
high protein 35%
relatively hypoxic
the clarity of lens maintained by what?
narrow lens fibre membs
small interfibre spaces
tightly packed contents (crystallin)
no blood cells
loss of organelles from cells when they -> fibres
what is the structure of RPE (pigment epithelium) like in retina?
- Hexagonal monolayer epithelial cells
- Microvilli – envelop photoreceptor outer segments
- Tight juncs – outer blood-retinal barrier
- Rich in mitochondria
- BM – forms part of Bruchs membrane
4 cell types as integrators in retina?
bipolar cells
horizontal cells
amacrine …
ganglion …
what cells support retina?
muller cells
(R also is neural and photoreceptors: rods and cones involved)
the X in the retina is area of highest acuity, multilayered ganglion cell layer and has Fovea struct in centre of it.
macula
where is maximal density of cones in retina?
in fovea (centre of macula)
where does blood supply of retina come from?
retinal circ (supplies inner 2/3)
from: central retinal artery
choroidal circ (supplies outer 1/3)
from: post ciliary arteries
what struc maintains outer blood-retina barrier
stores metabolites and Vit A
supply nutrition for photorecs
absorb scattered light
make and recycle photopigments
phagocytosis of photorec discs
RPE
rods and cones are the 2 parts of photoreceptors, describe each
rods - low light and peripheral vision
cones - bright/normal, colour
Light perception by outer segments of photoreceptors
- G proteins – “opsins”
- Vitamin A derived molecules (chromophores)
role of chromophores in photoreceptors?
vit a derived molecules
they alter light signal -> electrical, to brain
rods and cones synapse with what cells?
bipolar, which synapse w ganglion
negative feedback, moderation
horizontal between photorecs
amacrine between bipolar and ganglion
describe the ganglion cells (2)
Optic nerve - produced a Light signal => brain
- Parvocellular - Fine vision, colour,
Mainly in fovea - Magnocellular - Motion, coarse vision,
Peripheral
what nerves are important to the eye?
optic 2
oculomotor trochlear adbucent 3,4,6
trigeminal 5
facial 7
parasymps 3,7
symps T1 pupil dilation
optic nerve and visual pathways, learn detail?
?
extraocular muscles, covered in prev CN lec.. inferior oblique, medial rectus, eye movement
nerve supply of extraocular muscles?
slide 46
autonomic innervation?
A
A
A
Lecture 2/3: Retinopathy
what is meant by retinopathy
disease of retina that -> vision impairment or loss
list some different causes of retinopathies
diabetes
htn
radiation
trauma
retinal vasc disease
…
diabetic retinopathy causes microangiopathy, what does this mean
affects small vessels
what small vessels are affected in diabetic retinopathy due to microangiopathy
precapillary arteries
capillaries
post capillary venules
pathology of diabetic retinopathy
thickening of basement membranes, capillary non-perfusion and ischaemia
what are microaneurysms in the context of diabetic retinopathy
weakening and bulging of vessel wall
what are the 3 different types of haemorrhage that can occur in the retina
dot
blot
flame
which type of retinal haemorrhage is due to a rupture of capillaries in outer plexiform layer
dot
how are blot haemorrhages different to dot haemorrhages
larger
bleeding from capillaries
tracks between photoreceptors and RPE
in flame haemorrhages you get a rupture of the small arterioles which leads to leakage into the
nerve fibre layer
hard exudates in the retina are caused by endothelial damage which lead to plasma leakage into the
outer plexiform layer
what is the term given to the swollen ends of interrupted axons in nerve fibre layer due to microinfarction
cotton wool spots
in venous beading veins have a beaded appearance in the retina, this reflects
retinal ischaemia
intraretinal microvascular abnormalities (IRMA) are vascular abnormalities in the venous side of the capillary bed and do not leak. What are they precursors of
neovascularisation
what is neovascularisation
new vessels grow from venous side of capillary bed in area of non perfusion
what releases vasoproliferative factors that can cause neovascularisation
ischaemic retina
new vessels can bleed into vitreous and cause retinal detachment leading to what condition
glaucoma
how many disease severity levels are there for retinopathy
4
what is meant by diabetic macular oedema DMO
leakage into macula often with exudates and surrounding a microaneurysm
what is the criteria for macular laser
clinically significant macular oedema CSMO
involves
- retinal thickening 500 microm of mac centre
- hard exudates
- retinal thickening of >1 disc area
how might a diabetic retinopathic retina differ from an image of a normal retina
cotton wool spots
microaneurysms
oedema
exudates
neovascularisation
what systemic management is involved in the management for retinopathy
glycaemic control
bp control
cholesterol control (statins, fibrates)
support renal function
smoking cessation
weight control
exercise
what is the bp aim for someone with diabetic retinopathy
130/80
for diabetic patients with no retinopathy or background/mild non proliferative diabetic retinopathy how often should patients be monitored for screening
annually
pre proliferative to moderate to severe NPDR should be monitored in
hospital
what can be used for the management of proliferative retinopathy
laser - panretinal photocoagulation
what anti VEGF drug can be used off licence for the treatment of proliferative diabetic retinopathy
bevacizumab
what can be used for the management of non central macular oedema
macular laser
what 2 drug classes can be used for the management of centre involving macula oedema
intravitreal therapy
anti vegf and corticosteroids
what laser is used for panretinal photocoagulation PRP
argon green 514nm laser
how does PRP (panretinal photocoagulation) help treat retinopathy
laser absorbed by rpe pigment
converted to thermal energy -> outer retinal cell death + coagulative necrosis
reduces stimulus for neovascularisation
list some different complications/ risks of PRP
pain
loss of peripheral field
decreased acuity
retinal detachment
haemorrhage
macular laser is similar to PRP but is used to treat macular oedema, how does it work
gentle burns to macula
release of anti angiogenic factors
inhibition of angiogenic factors
how can hyperglycaemia lead to DME (diabetic macula edema)
hyperglycaemia -> retinal capillary damage
release of inflammatory cytokines and vegf
disrupts blood retinal barrier
vascular leakage
dme
what 2 drugs are licensed as intravitreal anti vegf therapies to treat diabetic macular oedema
afilbercept
ranibizumab
what procedure uses infrared light to capture images of layers of the retina to investigate for things like DMO/AMD
optical coherence tomography
true or false, optical coherence tomography cannot measure central retinal thickness
false
in DMO >400 at any point in centre = NICE Tx recomm
in DMO afilbercept is given every month for x consecutive months
5
after 5 consecutive months of afilbercept therapy for DMO patients are given 1 injection every x months
2
after the first 12 months of aflibercept therapy for DMO the treatment interval may be extended based on what 2 things
visual and anatomic outcomes
true or false, aflibercept should be discontinued if the patient is not benefitting from continued treatment
true
what drug is recommended as an option for treating visual impairment due to diabetic macula oedema if the eye has a central retinal thickness of 400 micrometers or more at the start of treatment
ranibizumab
ranibizumab should be given monthly and continued until maximum visual acuity has been reached, how would you know when to determine this
visual acuity has been stable for 3 consecutive months
after visual acuity has stabilised following treatment with ranibizumab visual acuity should be monitored at what intervals
monthly
treatment with ranibizumab may have to continue if monitoring indicates a loss of visual acuity caused by diabetic macular oedema until 3 consecutive months of stable visual acuity. However, the interval between doses should not be shorter than x month
1
intravitreal corticosteroids suppress inflammation to reduce oedema, give some examples of preparations for this use
triamcinolone acetate
dexamethasone implant
flucinolone acetonide implant
how long does a dexamethasone implant last
6 months
how long does a flucinolone implant last
3 years
list some different risks of intravitreal corticosteroids
endophthalmitis
haemorrhage
retinal detachment
increased IOP
cataract
true or false steroid drugs themselves can increase IOP
true
true or false steroid drugs can themselves cause cataract
true
dexamethasone implants should be used as second line treatments if what other methods have failed
anti vegf or macular laser
intravitreal implants deliver dexamethasone for 6 months and may be repeated after 6 months if the patient experiences decreased vision or increase in retinal thickness with recurrent or worsening diabetic macular oedema
how much drug is delivered by the implant in this 6 month period
700 micrograms
give one important side effect it is important to check for with intravitreal dexamethasone implants
increased IOP
hypertensive retinopathy also exists, what is the best and only treatment option
bp control
what are the different treatment options for retinal vein occlusion
risk factor modification
treat underlying condition
PRP
control iop
intravitreal therapy
would you treat retinal vein occlusion with PRP if associated with ischaemia or oedema
ischaemia
would you treat retinal vein occlusion with PRP or intravitreal therapies like corticosteroids or anti vegf if associated with ischaemia or oedema
oedema
list some different treatment options for retinal artery occlusion
modify risk factors
treat underlying cause
lower iop
give 3 ways that iop may be lowered
iv acetazolamide
ocular massage
rebreathing into paper bag(?)
Lecture 3/4: Glaucoma
what is glaucoma
progressive optic neuropathy
glaucoma is characterised by optic nerve head (disc) changes and corresponds with loss of
visual field
what is the most important treatable risk factor
raised intraocular pressure (glaucoma)
what is the name of angle between the cornea and iris known as
anterior chamber angle
what is contained within the anterior chamber angle
trabecular meshwork
the ciliary body produces aqueous, how does it get to the anterior chamber of the eye
goes into post chamber behind the iris and then through the pupil
what structure in the eye is a circumferential structure that drains aqueous into collector channels
schlemms canal
from the collector channels where does the aqueous drain into
episcleral veins
name of the fibrocellular structure through which aqueous drains into schlemms canal
trabecular meshwork
what are the 2 aqueous humour outflows in the eyes
uvoscleral and trabecular
if the aqueous humour is drained via uveoscleral outflow where does it drain into
choroidal circulation
when the aqueous humours drains via trabecular outflow, where does it drain into
episcleral circulation
what is the term given to the inflow and outflow of aqueous in the eye
IOP
true or false, the range for IOP in the general population is 11-21 mmHg with values over 21 associated with increased risk of glaucoma
true
true or false, you cannot get glaucoma with an IOP value below 21 mmhg
false
IOP can fluctuate between individuals, list some different causative factors
time of day
heartbeat
blood pressure
respiration
what are the 4 different types of glaucoma
primary open angle
primary angle closure
secondary open angle
secondary angle closure
which type of glaucoma is most common
primary open angle
what is the cause of primary open angle glaucoma
abnormal resistance to outflow of aqueous mainly in trabecular meshwork
primary open angle glaucoma causes pressure induced ischaemia of the x
optic nerve capillary bed
in primary open angle glaucoma there is mechanical pressure on the optic nerve head, what does this lead to
reduced axoplasmic flow
different risk factors for developing primary open angle glaucoma
smoking
diabetes
htn
high cholesterol
myopia
primary angle closure glaucoma may be acute in nature i.e. sudden rise in IOP or
chronic
what is the cause of primary angle closure glaucoma
drainage angle becomes narrow
fluid cannot exit through trabecular meshwork/ schlemms canal
secondary open angle glaucoma is caused by blockage of the trabecular meshwork, list some different things that can cause this
cells
proteins
blood
tumour cells
drugs
give a type of drug that could cause secondary open angle glaucoma
steroids
what might be the cause of cells/protein in the trabecular meshwork that eventually block it and give rise to secondary open angle glaucoma
inflammation
what is the cause of secondary closed angle glaucoma
narrowing of angle
list some different factors that can cause angle narrowing in secondary closed angle glaucoma
tumours pushing iris or lens forward
iris sticking to angle
new blood vessels
how can diagrams of visual fields show defects that would be indicative of glaucoma and its progression
dark spots represent areas missed by patients on testing
3 Tx options for glaucoma/ visual field defect
- medical: drops, systemic
- laser: iridotomy/ trabech/ cyclophotocoag
- surgery
topical medical therapy for glaucoma commonly involves eye drops, list some different drug classes that would be used to treat this disease
prostaglandin analogues
beta blockers
carbonic anhydrase inhibitors
alpha 2 agonists
miotics
alpha 2 agonists aka
sympathomimetics
miotics aka
parasympathomimetics
what classes of drug can be used for systemic medical therapy for the treatment of glaucoma
carbonic anhydrase inhibitors
osmotics
what drug class is often used as first line in the treatment of glaucoma
prostaglandin inhibitors
what is the moa of prostaglandin inhibitors in the treatment of glaucoma
increase uveoscleral outflow
side effects of prostaglandin inhibitors
red eye
pigmentation
inflammation
bronchospasm
list some areas where pigmentation can occur as a side effect of prostaglandin inhibitor use
iris
skin
lash
true or false, prostaglandin inhibitors can cause eyelash thickening and lengthening
true
give some examples of prostaglandin inhibitors which may be used in the treatment of glaucoma
latanoprost
bimatoprost
travoprost
what is the moa of bb in the treatment of glaucoma
reduce aq production the ciliary body
list 2 respiratory Contra Indications for the use of bb to treat glaucoma
asthma, COPD
list 3 cardiac CI for the use of bb to treat glaucoma
heart failure
heart block
bradycardia
list some different side effects of beta blockers when used in the treatment of glaucoma
allergic conjunctivitis
bronchospasm
bradycardia
hypotension
lethargy
glucose intolerance
impotence
most common bb used for topical eye drops to treat glaucoma
timolol,
levobunolol and cartelol also used
what is the moa of carbonic anhydrase inhibitors when used in the treatment of glaucoma
decrease aq production in ciliary body
list some CI for carbonic anhydrase inhibitors
sulphonamide sensitivity
renal failure
liver failure
true or false, the use of acetazolamide is only contraindicated in liver/renal failure when the drug is given systemically
true
carbonic anhydrase inhibitors topical/ local SEs
burning
watery eyes
metallic taste
allergic conjunctivitis
list some different systemic side effects that are associated with the use of carbonic anhydrase inhibitors
lethargy
depression
metallic taste
hypokalemia
dorzolamide and brinzolamide are examples of what class of drugs that are used to treat glaucoma
carbonic anhydrase inhibitors
are dorzolamide/brinzolamide used topically or systemically
topically
acetazolamide is a drug that is used systemically in the treatment of glaucoma either PO or IV, list some different side effects
lethargy
depression
metallic taste
hypokalemia
renal calculi
blood dyscrasia
what class of drugs does acetazolamide interact with to cause profound hypokalemia
thiazide diuretics
alpha 2 agonists have a dual mechanism when used in the treatment of glaucoma, what is this
decrease aq production
increase uveoscleral outflow
what ocular side effect could occur as a result of alpha 2 agonist use
allergic conjunctivitis
what systemic side effects could occur due to use of alpha 2 agonists
bradycardia
hypotension
insomnia
irritability
GI disturbance
name 2 alpha 2 agonists that may be used in the treatment of glaucoma
brimonidine
apraclonidine
how do miotics work to treat glaucoma
muscarinic agonists
ciliary muscle contraction
opens trabecular meshwork
increases trabecular outflow
why are miotics commonly used in angle closed glaucoma
iris constriction may pull iris away from angle
list some different side effects of miotics
sweating
salivation
nausea
headache
bradycardia
name one example of a miotic drug
pilocarpine
give an example of an osmotic agent that is used iv
mannitol
under what circumstances would you give IV mannitol to patients with glaucoma
acute angle closure where temporary drop in IOP is required that cannot be achieved by other means
moa of mannitol when used in the treatment of glaucoma
water drawn out of vitreous into blood
by osmotic gradient
decrease in vitreous volume
so IOP decreases
list 2 side effects of mannitol when used in this way
urinary retention and fluid overload
CI for the use of mannitol in the treatment of glaucoma
cardiac disease /
heart failure
Lecture 4/4: age related macular degeneration ARMD
what is ARMD
age related deterioration in the macula
what effect does armd have on central vision
reduction
list some different risk factors for developing armd
age
smoking
female
white
dietary
cv risk
hypermetropia
is hypermetropia more of a risk factor for glaucoma or armd
armd
is myopia more of a risk factor for glaucoma or armd
glaucoma
2 types of ARMD?
dry (non-neovascular)
wet (neovascular)
what is meant by dry armd
non neovascular age related macular degradation
there are 4 categories of armd and they are ranked by severity, what ARED classification does no amd fall under
1
what category is advanced/late amd
4
is the majority of amd dry or wet
dry
true or false, dry AMD is associated with a gradual but potentially significant reduction in central vision
true
list 4 different features of dry amd
drusen
rpe changes
geographic atrophy
basement membrane deposit
in dry amd what is meant by drusen and where does it occur
PAS positive amorphous deposit between RPE basement membrane and inner collagenous layer of bruchs membrane
what RPE changes can be observed in dry amd
focal hyperpigmentation seen as clumps of pigment cells
geographic atrophy occurs in the later stages of dry amd and results in the loss of what 2 things
rpe and photoreceptors
in dry amd where does basement membrane deposit/ basal linear deposit occur
between RPE basement membrane and RPE cells
give 2 symptoms of dry amd
Dec vision
Distortion
what supportive treatment exists for dry amd
counselling
support groups
visual aids
what does refraction involve when used as a treatment method for dry amd
best spectacle correction
magnification
what grid allows for the self monitoring of distortion in dry amd
Amsler
what lifestyle changes can you recommend to patient with dry amd
smoking cessation and dietary changes
true or false, vitamin supplementation may help in the treatment of dry amd
true
supplements are shown to reduce the progression of dry AMD, what is the current recommended daily amount of vitamin c
500mg
how many international units of vitamin E are recommended for dry amd
400
is wet or dry amd associated with rapid and severe loss of vision
wet
give 3 features of wet amd
new capillary growth
proliferation
sequelae
in wet amd new capillaries grown from x through bruchs membrane and is known as choroidal neovascularisation
choriocapillaris
where does proliferation occur in wet amd
beneath rpe or retina
give 3 causes of sequelae as seen in wet amd
haemorrhage
leakage
scarring
what might cause scarring and fibrosis in the eye
activation of macrophages and endothelial cells
list some different clinical features of amd
decreased vision
distortion
scotoma
grey haemorrhage
fluid
subretinal fibrosis
what does scotoma mean
missing patches
what imaging technique is important in investigating and monitoring the following features:
subretinal fluid
intraretinal fluid
cystoid macular oedema
pigment epithelial detachment
fibrosis/ scarring
OCT
what is injected iv to allow for fundus fluorescein angiograms
fluorescein
fluorescein absorbs blue light in what wavelength
465-490nm
fluorescein emits light with a longer wavelength at 520-530nm which corresponds to what colour in the spectrum
yellow-green
for fundus fluorescein angiogram a camera used with a filter, which only lets x through to take images of circulation
light of wavelength emitted by fluorescein
as well as supportive therapies for wet amd what 2 other therapies exist
intravitreal anti vegf and photodynamic
rationale behind using intravitreal therapy to inhibit vegf-a
induces angiogenesis
increases vascular permeability
induces inflammation
4 anti vegf therapies that may be used for the treatment of wet amd
ranibizumab
afilbercept
pegaptinib
bevacizumab
name the anti vegf therapy
humanised mab fragment
binds to all vegf isoforms
prevents binding to its receptors vegfr1 and vegfr2
ranibizumab
name the anti vegf therapy
fusion protein
binds to vegf a
afilbercept
name the anti vegf therapy
oligonucleotide with polyethylene glycol attached
binds to vegf-165
not recommended by nice
pegaptinib
name an anti vegf therapy that is derived from the same antibody as ranibizumab
bevacizumab
name the 2 licensed anti veg f therapies
ranibizumab
aflibercept
list some different risks/ complications of anti vegf therapy in the treatment of wet amd
endophthalmitis (infection)
retinal detachment
lens damage
cataract
raised iop
haemorrhage
inflammation
pain
visual loss
floaters
why do most centres advise caution with anti vegf therapies in patients who have had a stroke/mi/heart failure in the last 3 months
possible risk of stroke/ MI
what is the recommended dose of ranibizumab
0.5mg
what is the treatment regimen of ranibizumab in the loading phase
1 injection per month for 3 consecutive months
during the maintenance phase of ranibizumab what are patients monitored for monthly
visual acuity
during the maintenance phase if patients experience a loss greater then x letters on a snellen chart or one snellen line equivalent a further dose of ranibizumab should be administered
5
the interval between doses of ranibizumab should not be shorter than x months
1
what is the recommended dose of afilbercept
2mg
wet armd
when starting afilbercept treatment should be given monthly for x consecutive months
3
after the initial 3 month period on afilbercept, 1 injection should be given every x months
2
true or false, afilbercept solution for injection must only be admin by a qualified doctor experienced in admin intravitreal injections
true
is there a need for monitoring in between injections of aflibercept yes or no
no
after the first 12 months of aflibercept treatment the treatment interval may be extended based on what 2 outcomes
visual and anatomic
if treatment on aflibercept is prolonged monitoring schedules should be determined by who
treating doctor
photodynamic therapy or PDT is no longer widely used since the introduction of anti vegf therapies, however what drug does it use
verteporfin
verteporfin is given at a dose of 6mg/m2 of BSA over 10 mins via what route
IV
15 mins after the start of the verteporfin infusion what is applied over a circular area slightly larger than the lesion
low powered laser at 689nm
how does PDT help to manage wet amd
laser light absorbed by drug
becomes activated
forms cytotoxic free radicals
damage new blood vessels
leading to closure
recommendation of PDT depends on the type of wet PDT and this is determined by the
appearance on fundus fluorescein angiogram
name 3 different types of wet amd
classic cnv
occult cnv
mixed picture
which type of wet amd
well demarcated lacy hyperfluorescence and progressive leakage
classic cnv
which type of wet amd
fibrovascular PED, irregular elevation, stippled hyperfluorescence
occult cnv
PDT is recommended for people with a confirmed diagnosis of
classic with no occult subfoveal choroidal neovascularisation
Opthalmology SDL
What are the four main types of conjunctivitis?
- Allergic
- Bacterial
- Adenoviral
- Chlamydial
What questions should you ask a px with suspected conjunctivitis?
Check if need referral
Onset and duration.
Pain in or around the eye?
Photophobia?
Any associates systemic symptoms - headaches, sickness
Discharge from eyes - colour, how much
Itching
Changes in vision such as blurring
Eyelid changes such as swelling, flaking and vesicles
what are the red flags for suspected conjuctivitis?
Severe pain in eye
Swelling/ pain around
Visual acuity.
Red sticky eye in neonates.
Lots of discharge.
Upper resp infections.
Enlarged tender lymph nodes.
Contact lens.
Recurrent infections.
Ophthalmic surgery.
Drug Hx - anticholinergics and anticoagulants.
How should you manage complaints of conjunctivitis in patients who wear contact lenses?
Refer to specialist.
Advise to stop wearing contact lenses immediately.
advice for contact lens wearers when using chloramphenicol/ conjuctivitis Tx?
- Do not wear contacts during treatment
- Avoid contacts until 24 hours after treatment stopped
- Do not reuse old contact lenses reinfection
restrictions on prescribing ranibizumab for diabetic macular oedema (DMO) in the NHS?
Recommended for treating visual impairment due to DMO if:
Eye has central retinal thickness of 400 microM or more at start of treatment
… and manufacturer provides drug with discount agreed in px access scheme revised in context of this appraisal
Mechanism of action of ranibizumab?
When a patient has DMO, the body produced too much VEGF which causes blood vessel to grow too thickly and too quickly.
Ranibizumab is a human recombinant monoclonal antibody and it inhibits VEGF. Therefore it reduces oedema and improves vision.
What are barriers to drug like ranibizumab being administered systemically?
Drug delivery to the back of the eye by systemic administration is restricted by the tight junctions of the blood brain barrier.
Why is ranibizumab administered as an injection and not a topical eye drop solution?
site of action: post segment of eye
bypass ocular barriers
o high tier turnover, the nasal drainage, reflex blinking
o or things like poor interocular penetration.
direction of penetration opposite to direction of intraocular liquid circ
How can drug delivery to the posterior segment of the eye be improved?
prodrugs and nanoparticles
why us aflibercept better than bevacizumab
binds VEGf A with higher affinity
complications of intravitreal therapy
cataract, inflammation, pain, raised IOP, visual loss, floaters
do the DVLA need to be notified of a diagnosis of diabetic macular oedema
yes
What is Sjogren’s syndrome?
systemic autoimmune disease that affects exocrine galnds - causes a deficiency in saliva, tears, skin lubrication, and other exocrine secretions -
What types of medications cause dryness? Make symptoms of dryness worse? E.g.dry mouth
anticholinergics
what meds also exacerbate dryness symptoms?
o Antihistamines
o Some antidepressants: tricyclics, amitriptyline
o Some antipsychotics
o Antimuscarinics: hyoscine butylbromide/ hydrobromide
Sjogren’s syndrome treatnent
Good eyelid hygiene
eye ointments more effective at adhering to eye for long time
- Immunosuppressive meds hydroxychloroquine
- Lozenges/ gels (saliva substitutes)
- Pain relief
why may the parotid gland be swollen in SJS?
B lymphocytes overactive, cause inflammation.
build up in salivary glands etc, damage
B cell lymphoma likely. Must exclude - ultrasound
