Slam Dunk Course Flashcards
1
Q
What are the 3 layers of the eye?
A
Global structure of the eyeball is made up:
- Fibrous tunic (sclera + cornea) = Outermost layer
- Vascular tunic (uvea) = Middle layer
- Neurosensory tunic = Inner layer
2
Q
What are the components of the fibrous tunic layer of the eye?
A
Sclera - white part of the eye, provides attachment for rectus muscles, terminates at limbus.
Cornea - 5 layers in total, consisting of regular fibrous connective tissue.
3
Q
What are the components of the vascular tunic layer of the eye?
A
Choroid - vessels for retina
Ciliary body - lens accommodation & produces aqueous humour
Iris - dictates aperture of the eye
4
Q
Where in the eye does bilirubin accumuate?
A
Sclera is where bilirubin accumulatesespecially the dense connective tissue
5
Q
What are the layers of the sclera?
A
Episclera (dense CT)
Sclera proper (collagen)
Lannina fusca (pigmented)
6
Q
Which bones form the roof of the bony orbit?
A
Frontal
Lesser wing of sphenoid
7
Q
Which bones form the floor of the bony orbit?
A
Maxilla
Palatine
Zygomatic
8
Q
Which bones form the medial wall of the bony orbit?
A
Ethmoid
Maxilla
Sphenoid
9
Q
Which bones form the lateral wall of the bony orbit?
A
Zygomatic
Greater wing of sphenoid
10
Q
Which wall of the orbit is the thinnest?
A
The medial orbital wall is thinnest, followed by the bone of the floor of the orbit, but is strengthened by the ethmoid sinuses.
11
Q
Which wall of the orbit is the most vulnerable to fracture?
A
The floor of the orbit is most vulnerable to fracture when there is direct force exerted on the ocular globe because it is thin and unsupported.
12
Q
What is the shape of the walls of the orbit?
A
All the orbital walls are curvilinear in shape.
Their purpose is to maintain the projection of the ocular globe and to cushion it when subjected to blunt force.
13
Q
What are orbital blowout fractures?
A
Orbital blowout fractures: incarceration of rectus muscles (IR), oedema ecchymosis, orbital compartment syndrome, upgaze restriction
14
Q
What are the layers of the eyelid?
A
15
Q
What are the anatomical layers of eyeball?
A
Skin
Orbicularis oculi
Submuscular adipose tissue
Orbital septum
Tarsal planes (connective tissue)
Levator apparatus
Conjunctiva
16
Q
What is the role of the orbital septum?
A
DIvides the orbital content from lid content
17
Q
What are the 3 components of the levator apparatus?
A
LPS (skeletal)
Superior tarsal muscle (Muller’s, SNS)
Inferior tarsal muscle (Muller’s, SNS)
18
Q
What is the difference between a complete and partial ptosis?
A
Complete: Paralysis of LPS, due to CN Ill lesion (somatic nerves, skeletal muscle)
Partial: Paralysis of Muller’s muscle (found in the tarsal plate) due to Horner’s syndrome
19
Q
What is the difference between a stye and chalazion?
A
Stye - a focal infection of a hair follicle, (folliculitis) or Meibomian gland. Painful.
Chalazion - a focal cyst of a Meibomian gland. Painless.
20
Q
What are the three layers of the tear film?
A
Lipid layer - superficial, oily (MGs)
Aqueous layer - substrates, immune (lacrimal)
Mucinous layer - adhesion (epithelium)
21
Q
What is the name for a focal infection of the lacrimal sac?
A
Dacrocystitis
22
Q
What are the 5 layers of the cornea?
ABCDE
A
Tear film
Anterior corneal epithelium
Bowman’s capsule
Corneal stroma
Descement’s membrane
Endothelium
23
Q
What are the 3 distinct regions of the conjunctiva?
A
Bulbar - covers sclera
Palpebral - lines inside of eyelid
Fornices - edges
24
Q
What are the branches of the external carotid artery (ECA)?
‘Some Ancient Lovers Find Old Positions More Stimulating’
A
Superior thyroid
Ascending pharyngeal
Lingual Facial
Occipital
Posterior auricular
Maxillary
Superficial temporal
25
What is the anterior circulation of the brain?
Mainly ICA
## Footnote
ICA enters at carotid canal (petrous part of temporal bone)
Once in internal cavity, divides into: ACA, MCA
26
Through which bone does teh ICA enter the brain cavity?
Temporal bone
Specifically: carotid canal (petrous part)
27
Which arteries supply the posterior circulation of the brain?
Vertabral arteries
## Footnote
Vertebral arteries come off subclavian arteries
Travel posteriorly & ascend in transverse foramina of C1 - С6
Merge to form the basilar artery (located anterior of pons)
28
Where does the basilar artery form?
Anterior of the pons
Joining of the vertebral arteries
29
What are the 3 main mechanisms that can disrupt blood flow to the brain?
1. Thromosis
2. Embolism
3. Haemorrhage
Infarction (secondary to occlusion)
Ischaemia (secondary to infarction)
30
What is amaurosis fugax?
Transient loss of vision (monocular blindness) due to an interruption in retinal blood flow.
Associated with vascular thromboembolic event, usually arising from ICA.
Other pathology: hypoperfusion, vasospasm, coagulopathies (leukaemia, myeloma), atherosclerosis.
31
What are the symptoms of amourosis fugax?
1. Acute monocular, painless blindness
2. Lasts seconds to minutes (rarely hours)
3. Curtain coming down / generalised darkening
32
For a patient with amaurosis fugax, how should they be investigated?
Ophthalmic examination, vascular / stroke workup (carotid dopplers, echo, ECG), neuroimaging
33
For a patient with amaurosis fugax, how should they be managed?
1. Control underlying RF (smoking, lipids, HTN)
2. Aspirin, clopidogrel (anti-platelets)
3. Steroids (if GCA)
34
What is the 'stroke of the eye'?
Central retinal artery occlusion (CRAO)
35
What is central retinal vein occlusion?
Thrombosis of veins
36
Which parts of the eye are involved in refraction?
The cornea does 80% refraction, lens and vitreous does the other 20%, occurring due to convex lens.
37
Where does the retina terminate?
Ora serrata (sits behind the ciliary body)
38
What are the 2 major components of the retina?
Retinal pigmented epithelium (RPE) + Neurosensory retina
39
What is the blood supply to the retina?
Highly metabolic areas (RPE) from choroid
Low metabolic areas (inner retina) from retinal vessels & nutrition rom vitreous
40
What are the layers of the retina?
'In New Generation It Is Ophthalmologists Examining Patient's Retina'
41
What is phototransduction?
highly complicated process involving rhodopsin - a molecule that bleaches in light - and aims to convert light energy into neuronal impulse.
42
Is transduction a high or low metabolic process?
Odd arrangement, but transduction is a highly metabolic process, carried out by photoreceptors - turning light energy (photons- a type of quantum particle) into electrochemical energy.
## Footnote
Blood can be delivered more easily to the back of the eye than to the surface (choroidal > retinal vessels).
43
In the visual pathway, what is the 'relay' point?
LGN is a 'relay' point in the thalamus for filtering top-down & bottom-up information
44
What are the layers of the striate cortex?
Layer 1-5 - receives feedback from from LGN Layer 6 - provides feedback to LGN
45
Which part of the brain is involved in prosopagnosia?
Occipital facial area (OFA)
Face fusiform area (FFA)
46
Which part of the brain is involved in people recognition disorder?
Anterior temporal lobe (ATL)
47
What type of visual field defect is caused by a stroke?
Macular sparing homonymous hemianopia
## Footnote
Reason: The macula receives dual blood supply from the posterior cerebral arteries from both sides.
48
What are the extraocular muscles and their movements?
Each muscle has 3 movements
49
What is the major route of absorption of drugs given topically?
Cornea
50
What is the most common drug given intraocularly?
Intravitreal injections e.g. Anti-VEGF injections (ranibizumab) for proliferative diabetic neuropathy and wet AMD.
51
Which barriers do systemic drugs need to pass to reach the eye?
Blood-retinal barrier
Blood-aqueous barrier
52
What is the most common form of drug administration?
Topical administration into the inferior fornix represents the most common route of administration.
53
When giving drugs topically to the eye, what is important to remember?
The conjunctiva is an extremely vascular structure. Drugs can be lost through absorption into the systemic circulation.
Once the drug has been administered the amount available at the site of action (bioavailability) is affected by pre-corneal and corneal factors.
54
Pre-corneal factors affecting bioavailability of drugs: solution drainage?
Once in the fornix, the drugs enter the inferior meatus through the valve of Hasner, where high amounts of the drug are absorbed into the bloodstream.
## Footnote
Reduce by: pinching nose for 5 mins or giving gel/ointment (rather than drops)
55
What are some pre-corneal factors affecting the bioavailability of drugs?
1. Solution drainage (valve of Hasner)
2. Blink rate
3. Tear volume & tear turnover time
4. Disruption of the tear film
56
Pre-corneal factors affecting bioavailability of drugs: tear volume and turnover time?
Tear volume ranges from 7-8uL.
Transiently the fornix can hold 30uL.
Most applicators will deliver 50uL so a large volume is lost in over spill.
57
What is normal tear turnover time?
Normal tear turnover time is 0.5-2.2uL/minute
58
What are the three layers of the tear film?
59
How will disruption of the tear film affect bioavailability of drugs?
Anything that disrupts the integrity of the tear film e.g. meibomian gland dysfunction (MGD) will reduce drug residency time in the fornix.
The pH of the tear film 6.5-7.6. If the pH of the tear film is altered, drug ionisation and hence diffusion capacity is affected.
Some drugs will bind to tear film proteins such as albumin and lysozyme.
60
Which layer of the cornea is hydrophobic?
Epithelium is hydrophobic - will only allow lipid soluble drugs to pass through.
61
Outline corneal factors that affect bioavailability of drugs?
62
What does the blood-aqueous barrier consist of?
1. Vascular endothelium of the iris/ciliary vessels
2. The non-pigmented ciliary epithelium
## Footnote
Both cell layers express tight junctional complexes and prevent the entry of solutes into the anterior segment.
63
Which barrier prevents anything passing from the anterior segment of the eye?
Blood-aqueous barrier
64
Which barrier prevents anything passing to the anterior segment of the eye?
Blood-retinal barrier
65
What are the two cell types that make up the blood-retinal barrier?
The retinal capillary endothelial cells (inner BRB)
The retinal pigment epithelium cells (outer BRB)
66
What are the outer retinal layers of the blood-retinal barrier nourished by?
The choroid
67
What are the inner retinal layers of the blood-retinal barrier nourished by?
Retinal vessels
68
Which types of receptors does acetylcholine act on?
69
Where are acetylcholine receptors found in the eye? (6)
1. EOM
2. LPS
3. Iris sphincter
4. Ciliary body
5. Lacrimal gland
70
Where in the eye is choline acetyltransferase present?
1. Corneal epithelium
2. Ciliary body
3. Inner plexiform layer of the retina
71
What are two examples of Indirect parasympathomimetic drugs used in the eye?
Edrophonium, Physostigmine.
72
What are the actions of cholinergic agonists in the eye?
73
What is an example of a direct parasympathomimetic?
Pilocarpine
## Footnote
Used frequently in the treatment of glaucoma.
74
In which condition is edrophonium (indirect parasympathomimetic) used for diagnostic purposes?
Myasthenia Gravis
## Footnote
Ocular myasthenia can be made using the Tensilon Test. IV is edrophonium is administered. Any improvement in ptosis or diplopia confirms a positive diagnosis. Longer acting neostigmine can be used for treatment.
75
What are the side effects of cholinergic agonists/parasympathomimetics?
Systemic -salivation, bradycardia
Ocular - cataracts iris cysts, conjunctival toxicity
76
What are the actions of cholinergic antagonists?
77
In which condition is cholinergic antagonists often used in?
Used to prevent the formation of posterior synechiae in uveitis and iritis.
Posterior synechiae are adhesions between the posterior iris and anterior len surface.
78
In which examination are cholinergic antagonists used?
Routine funal exam
Also: provocation of glaucoma (test)
79
What are 3 examples of cholinergic antagonists?
Atropine
Cyclopentolate
Tropicamide
80
What are the actions to alpha agonists in the eye?
**Smooth muscle contraction**
Dilator pupillae muscle
Ciliary muscle
Constriction of conjunctival and episcleral vessels
81
What are 3 examples of topical alpha agonists?
Apraclonidine
Brimonidine
Clonidine
82
What are the side effects of alpha agonists?
Common: allergic conjunctivitis, conjunctival blanching
Systemic: hypotension, dry mouth
83
What drug can be used to differentiate between scleritis and episcleritis?
Instillation of **phenylephrine** drops can be used to differentiate between these 2 conditions.
The drug will cause constriction of the episcleral vessels in episcleritis but not in the deep plexus in scleritis.
84
What are some examples of topical beta blockers?
Timolol
Betaxolol
Levobunolol
85
What are some of the side effects of beta blockers?
Ocular: Conjunctivitis
Systemic: caution - heart block, heart failure, asthmatics
86
Where are beta-2 receptors found?
B2 receptors found on ciliary processes (this is different from the muscle) and trabecular meshwork
87
How do beta blockers affect aqueous?
Increase aqueous outflow
Decreased aqueous production
88
How do carbonic anhydrase inhibitors (CAIs) work?
Inhibit carbonic anhydrase which is found in ciliary body epithelium. It is a key enzyme in aqueous production.
89
What are some examples of topical carbonic anhydrase inhibitors?
90
What drugs are commonly given with carbonic anhydrase inhibitors for glaucoma treatment?
Generally combined with topical B antagonist (timolol) for glaucoma treatment
91
What are the side effects of carbonic anhydrase inhibitors (CAls)?
Systemic: renal stones, malaise, fatigue,
Ocular: stinging, allergic reactions
92
What are the 3 functions of the aqueous?
1. **To supply nutrition to the lens, corneal epithelium, corneal stroma** but NOT the corneal epithelium. The corneal epithelium derives nutrition from tears.
2. **To maintain IOP.** IOP is determined by the rate of aqueous secretion and rate of aqueous outflow. 10-21 mmHg.
3. **To remain transparent**
93
How is the aqueous produced?
The passive diffusion of water and ions from the ciliary body and the active transport of Na and Cl. It is an active secretory process that involves Na/K ATPase pump and carbonic anhydrase type Il activity.
94
Outline the flow of aqueous.
95
Where is aqueous drained out?
Aqueous can be drained through the trabecular outflow (90%) or uveoscleral outflow (10%)
## Footnote
Trabecular: trabecular meshwork, Schlemm's canal, episcleral veins
Uveoscleral: Drained by the venous circulation in the ciliary body, choroid and sclera
96
Outline the trabecular drainage of the aqueous.
Involves the trabecular meshwork, Schlemm's canal, episcleral veins
97
Outline the uveoscleral drainage of the aqueous.
Drained by the venous circulation in the ciliary body, choroid and sclera
98
How do alpha agonists and beta antagonists affect aqueous flow?
Alpha agonists and B antagonists will suppress aqueous flow
99
What is the role of the orbicularis oculi pump?
70% tears drained by the lower canaliculus. Remainder drained by the upper.
With each blink fibres of orbicularis shorten the canaliculi and move the puncta medially. The lacrimal sac expands creating negative pressure and drawing in the tears.
When the eyes open and the muscles relax, the sac collapses and tears drain down the ducts.
100
What does the accomodation reflex involve? (3)
1. Convergence of the eyes
2. Pupillary constriction
3. Increased biconvexity of the lens
101
How does accomodation change throughout life?
Accommodation begins to develop at 2 months and is well developed by 8 months. The ability to accommodate decreases with age and by 60 years accommodation is extremely poor (presbyopia) .
102
How does convergence of the visual axis occur in accomodation?
Contraction of the medial rectus via innervation of the oculomotor nerve
103
How does increased lens biconvexity occur in accomodation?
Circular ciliary muscle contracts, decreasing tension in zonular fibres, and allowing the lens capsule to contact and change the shape of he lens. The anterior pole moves forward, the axial width increases and the diameter of the lens decreases.
104
Stye/hordeolum
105
What is the difference between exteral and internal hordeolum?
**External (stye)**: Infection of the glands of Zeis or Moll
**Internal**: Infection of meibomian gland within the tarsal plate
## Footnote
'pus points TOWARDS you'
106
What are the symptoms of canaliculitis?
Unilateral red eye
Epiphora (watery eye)
Swollen lump on medical eyelid margin
Mucoid discharge when pressure applied over canaliculus
Granules at punctum
107
What pathogen is commonly implicated in canaliculitis?
Actinomyces israelii (anaerobic filamentous gram +ve)
108
What is dacrocystitis?
Infection of lacrimal sac secondary to obstruction in nasolacrimal duct causing stagnation of tears
109
What pathogens are commonly implicated in dacrocystitis?
Adults = Staph epidermidis Children = H influenzae
110
Which pathogens are commonly implicated in orbital cellulitis?
Strep pneumoniae
Staph aureus
H influenzae
110
What are some of the possible complicates of orbital cellulitis?
Orbital abscess, **cavernous sinus thrombosis**, brain abscess and meningitis, optic neuropathy, central retinal artery occlusion
110
What is cavernous sinus thrombosis?
A clot formed in the cavernous sinus usually as a result of a spreading infection from the paranasal sinuses, ear or orbital cellulitis
111
How does cavernous sinus thrombosis present?
Causes sudden onset headache, N&V, chemosis, proptosis
Can also cause diplopia due to CN 3, 4 or 6 compression
Lateral gaze palsy in CN 6 compression (first sign)
112
How is a cavernous sinus thrombosis diagnosed and managed?
Diagnosed with an MRA
Managed with IV abx/steroids + LMWH ( ± surgical invervention)
113
Which antibiotics are given in pre-septal cellulitis?
Co-amoxiclav
## Footnote
Important to treat as can progress into orbital cellulitis
114
What is orbital mucormycosis?
115
Bacterial keratitis
116
What investigations are done for bacterial keratitis?
Corneal scraping for microbiology (blood / chocolate agar)
Gram / Giemsa stain
117
Which pathogens are implicated in bacterial keratitis?
Contact lens wearers = Pseudomonas aeruginosa
Otherwise = Staph aureus
118
How does candidal fungal keratitis present?
Common in immunocompromised patients
Yellow-white infiltrate with 'mushroom'/'collar stud' morphology
## Footnote
Mx: Voriconazole drops
119
What investigations should be done for suspected fungal keratitis?
Gram & Giemsa staining, Sabouraud's agar
120
How does filamentous funal keratitis (e.g. aspergillus) present?
Ocular trauma (e.g. tree branch)
Branch like stromal infiltrate pattern
## Footnote
Mx: Natamycin drops
121
What investigations should be done for acanthamoeba keratitis?
Corneal scraping - E.coli plated over non-nutrient agar
122
What condition presents with ring shaped stromal infiltrates?
Acanthamoeba keratitis
123
How is acanthamoeba keratitis managed?
Topical biguanides or chlorhexidine
124
How does epithelial HSV keratitis present?
Decreased corneal sensation
Decreased VA
Lacrimation
Foreign body sensation
125
What are the signs of herpes simplex keratitis?
Superficial punctate keratitis causing stellate / 'star-shaped'/ 'terminal buttons'
Classic dendritic ulcer visualised under fluorescein + Rose Bengal stain
126
What must you avoid in herpes simplex keratitis?
AVOID STEROIDS - can lead to ulcer and corneal perforation
## Footnote
Managed with topical acyclovir for epithelial
127
What causes endothelial/disciform HSV keratitis?
HSV antigen hypersensitivity
128
How does endothelial/disciform HSV keratitis present?
Insidious onset painless loss of vision
Circular central stromal oedema Intact epithelium on fluorescein staining
Wessely ring
129
How is disciform keratitis managed?
PO acyclovir for disciform
130
What causes herpes zoster ophthalmicus
Latent virus in the trigeminal ganglion may reactivate leading to shingles over the dermatome supplied by CNV(1)
131
What is interstitial keratitis?
Stromal inflammation +/neovascularization (infective or immune reaction)
132
What condition presents with non-ulcerated stromal keratitis with feathery mid-stromal scarring?
Interstitial keratitis
133
What are the three main causes of interstitial keratitis?
**Syphilis**: Congenital = BL, acquired =unilateral - treat IM benpen + topical steroids
**Lyme disease**: Borrelia bacteria via tick bite causing erythema migrans
**Viral**: HSV & VZV, EBV
134
Which pathogens are implicated in bacterial conjunctivits?
Haemophilus influenzae most common in children
Staphylococcal species most common in adults
135
How is bacterial conjunctivitis treated?
Can treat with topical chloramphenicol if severe
Topical fusidic acid in pregnant women (due to risk of aplastic anaemia with chloramphenicol)
136
How is viral conjucntivitis distinguished from bacterial?
Viral will have preauricular lymph node swelling!
137
What is the most common pathogen in viral conjunctivitis?
Adenovirus
VERY infectious! Should avoid sharing towels etc.
## Footnote
Treat with steroids!
138
What are the 4 types of allergic conjunctivits?
1. Seasonal and perennial allergic conjunctivitis
2. Vernal keratoconjunctivitis (VKC)
3. Atopic keratoconjunctivitis (AKC)
4. Giant papillary conjunctivitis
139
What are the symptoms of chlamydial conjunctivitis?
Unilateral red eye
White follicles
Preauricular lymphadenopathy
Mucopurulent/ 'stringy' discharge
140
What is chlamydial conjunctivitis associated with?
Associated with Reiter's / reactive arthritis (urethritis, arthritis and conjunctivitis)
## Footnote
Can't see, pee or climb a tree
141
How is chlamydial conjunctivitis managed?
STAT 1g azithromycin **OR**
100mg doxycycline for 14/7
142
Trachoma
143
What is the leading cause of infectious blindness worldwide?
Trachoma
144
What is trachoma?
Type IV hypersensitivity reaction
145
Which pathogen is implicated in trachoma?
Chlamydia trachomatis
Transmitted by musca sorbens fly (bazaar fly)
146
What are the WHO stages of trachoma?
Inflammation follicular: 5+ follicles in upper tarsal conjunctiva
Inflammation intense: thickening of upper tarsal conj causing irritation
Scarring: repeated infections causing scaring and entropion
Trichiasis: ingrowing eyelashes towards cornea
Opacity: corneal inflammation leads to opacity
147
Endophthalmitis
148
What is endophthalmitis?
Infection of vitreous and aqueous humour
Post op complication (but can have endogenous causes too)
149
How is endophthalmitis investigated?
Vitreous tap for culture
150
Which pathogens are implicated in endophthalmitis?
Acute endophthalmitis within first week: **Staph epidermidis**
Delayed endophthalmitis (6 weeks +): **Propionibacterium acnes**
151
How is endophthalmitis managed?
URGENT intravitreal abx
Pars plana vitrectomy if severe
## Footnote
Prevention = povidone-iodine preop, intracameral ABx peri-op, postop topical ABx
152
What are the ocular features present in tuberculosis uveitis?
Conjunctivitis
Scleritis
Keratitis
Anterior uveitis: **Mutton fat KPs **
**Posterior uveitis **
Dacryoadenitis
153
What is teh 2nd leading cause of infectious blindness worldwide?
## Footnote
First = trachoma
Onchocerciasis African River Blindness)
154
What pathogen is implicated in african river blindness?
Onchocerca volvulus
Simulium black fly vector
## Footnote
Another name = Onchocerciasis
155
What is a classical systemic feature in Onchocerciasis (African River Blindness)?
Maculopapular rash
156
How is Onchocerciasis (African River Blindness) managed?
Ivermectin
157
Cat Scratch Neuroretinitis
158
What is cat scratch neuroretinitis?
Inflammation of optic nerve and neural retina causing oedema rom the nerve head to the macula
Caused by Bartonella henselae (gram -ve)
## Footnote
Commonly associated with cat-scratch disease (but noninfective causes too)
159
What is CMV retinitis?
Opportunistic infection caused by cytomegalovirus
Occurs in AIDS patients when CD4+ count <50
160
What are the possible complications of CMV retinitis?
Full thickness retinal infection that can lead to necrosis and retinal breaks and detachment
161
How is CMV retinitis treated?
IV ganciclovir
162
How is toxoplasmosis treated?
**Triple therapy **
1. Pyrimethamine
2. Sulfadiazine
3. Corticosteroid
163
How is toxoplasmosis diagnosed?
PCR (only needed if not clear from examination + fundoscopy)
164
Which conditions are included in the term 'uveitis'?
**Iritis** = iris, anterior chamber
**Cyclitis** = ciliary body
**Choroiditis** = posterior chamber
**Iridocyclitis** = anterior & posterior chamber
165
What is uveitis initiated by in developed nations (usually)?
An autoimmune process or dysregulated immune response
## Footnote
HLA-B27
166
In less developed countries, what is the leading cause of uveitis?
Infectious causes e.g. HHV 1-3, TB, syphilis, Lyme disease, delayed post-operative endophthalmitis
167
Which cell type is present in chronic and granulomatous uveitis?
Macrophages
168
Outline the adaptive immune response in uveitis
169
What doe sit mean that the eye is immune privileged?
A limit is placed on local ocular immune and inflammatory responses (to preserve vision) - driven by the eye-driven systemic regulatory process (ACAID system)
## Footnote
ACAID = there is a delayed immune response / ¿ hypersensitivity reaction (12-24 hours at minimum for inflammation to occur) in response to antigens
170
Which HLA is associatred with birdshot (chorioretinopathy)?
HLA-A29
171
Which HLA is associated with Behcet's?
HLA-B51
172
Which HLA is associated with anterior uveitis?
HLA-B27
173
Which HLA is associated with sympathetic ophthalmia?
HLA-DR4
174
Which HLA is associated with panuveitis?
HLA-DR4
175
Which HLA is associated with intermediate uveitis?
HLA-DR3
176
Which HLA is associated with chronic iridocyclitis (IJA)?
HLA-DR5
177
What are synechiae?
**adhesions** that are formed between adjacent structures within the eye usually as a result of inflammation
seen in **uveitis**
## Footnote
iris adheres to either the cornea (i.e. anterior synechia) or lens (i.e. posterior synechia)
178
What are keratic precipitates?
acute, white, round, PMNs - as they age become pigmented & irregular
179
What are mutton fat precipitates?
chronic, white-yellow, greasy, granulomatous, clumped-up cells macrophages +++
associated with sarcoidosis + syphilis
180
What are (a) peripheral anterior synechiae and (b) posterior synechiae?
(a) adhesions between peripheral iris and angle of drainage
(b) adhesions between iris and anterior capsule of lens)
## Footnote
Photophobia (due to adhesions, the iris is unable to regulate eye aperture & ciliary spasm)
181
What are koeppe nodules and bussaca nodules?
Koeppe nodules (inflammatory cell precipitates that lie at pupillary marginfound in both non & granulomatous)
Bussaca nodules (lie on the iris surface - pathognomonic for granulomatous uveitis)
182
How is uveitis managed?
1. Cycloplegics e.g. atropine 1% - prevent new synechiae and breaks existing adhesions
2. Anti-inflammatory e.g. topical steroids
183
What is intermediate uveitis and who does it affect?
Inflammation of vitreous body with minimal anterior / posterior signs.
Young, bilateral.
TO infiltrates in pars plana (pars planitis) and vitreous (vitritis).
184
What signs are seen in intermediate uveitis?
Epiretinal membrane, snow banking, snow balls, vitritis (hazy)
185
What is the pathophysiology of posterior uveitis?
Inflammation of choroid & retina (more often pan-uveitis). May target tissue (choroiditis) or vessels (choroidal vasculitis).
186
Which type of uveitis presents with dyschromatopsia?
Posterior uveitis
187
What does PORN stand for?
Progressive Outer Retinal Necrosis
187
Which type of uveitis is associated with infectious causes?
Posterior uveitis
188
Which parts of the eye are affected in uveitis?
Anterior (iris to ciliary body)
Intermediate (ciliary body to retina)
Posterior (choroid layer, retina, and retinal vessels) and panuveitis iris, ciliary body, and choroid layer)
189
Which conditions are associated with HLA-B27? (4)
190
HLA association in Behcet's?
HLA-B51
191
What are the A's of ankylosing spondylitis?
192
How does reactive arthritis present?
## Footnote
Reiter's syndrome (Can't see, can't pee or climb a tree)
193
How is thyroid eye disease managed?
194
3 complications of thyroid eye disease?
Exposure keratopathy
Corneal erosions
Optic nerve compression
195
What are the stages of diabetic retinopathy?
196
Outline the pathophysiology of diabetic retinopathy.
197
What are the 4 stages of hypertensive retinopathy?
197
What are some of the complications of hypertensive retinopathy?
Central & Branch Retinal Vein Occlusions Malignant HTN (acutely high BP >180/120 & could cause acute-onset papilloedema / I ICP)
197
Why does the consensual response occur?
Consensual response occurs as each pretectal nucleus is connected to BOTH EDW nuclei. Therefore, a unilocular light stimulus evokes a bilateral response.
198
What is the role of the pretectal nucleus?
involved in the control of pupillary reflexes and contains several nuclei, including the pretectal olivary nucleus, which is believed to be the main pupillary center in primates.
198
How does parasympathetic and sympathetic innervation affect the eye?
199
What are the steps (and main nuclei) involved in pupil dilation?
199
What causes RAPD?
Caused by incomplete optic nerve lesion or severe retinal disease
| NOT by cataract
199
What is an amourotic pupil?
Absolute Afferent Pupillary Defect
200
What are some optic nerve diseases that result in RAPD?
* Optic neuritis (Infectious, demyelinating)
* Orbital disease (TED, sarcoid, tumours)
* Drugs (ethambutol, methanol)
* Ischaemic optic neuropathy
* Glaucoma (unilateral; severe)
* Trauma e.g. surgery, head injury, radiation
* Congenital - Leber's optic neuropathy
200
What causes aniscoria?
Efferent lesions, iris(synechide) or pupillary muscles
201
What are some retinal diseases that result in RAPD?
* Ischaemic retinal disease - CRVO, CRAO
* Retinal detachment - if the macula is detached or if at least two quadrants of retina are detached.
* Severe macular degeneration - If unilateral and severe
* Tumours- melanoma, retinoblastoma, and metastatic lesion if severe.
* Retinal infection - CMV, HSV
202
What are some bilateral causes of light-near dissociation?
## Footnote
The light reflex is absent or sluggish but the near response (accommodation) is normal
203
What pharmacological test can be used to determine if a patient has Horner's syndrome?
Cocaine 4% into both eyes
## Footnote
Affected eye: pupil does NOT dilate; eye is not producing noradrenaline
Unaffected eye: pupil dilates (normal response); prevents noradrenaline reuptake
204
What are the 4 subdivisions of the optic nerve?
**Intraocular**: Optic disc, neve head: 1mm
**Intra-orbital**: 25-30 mm and extends from globe to optic foramen
**Intra-canalicular**: 6mm. Traverses the optic canal.
**Intracranial**: Joins the chiasm. 5mm-16mm. Longer nerve is more prone to damage.
205
What are 6 signs of optic nerve dysfunction?
206
How do you test contrast sensitivity?
Pelli-Robson Chart
207
What is optic neuritis?
Optic neuritis is an inflammatory, infective or demyelinating process affecting the optic nerve
208
What are the 4 major causes of optic neuritis?
Demyelinating - most common cause. Think MS!
Para-infectious - may follow viral infection or immunisation
Infectious- Lyme disease, meningitis, syphilis, cat-scratch fever
Autoimmune - associated with systemic autoimmune disorders (SLE, Sarcoid, thyroid eye disease)
209
What is non-arteritic optic neuropathy?
Total or partial infarction of the optic nerve head caused by occlusion of the short posterior ciliary arteries
210
What is arteritic optic neuropathy?
Usually referring to giant cell arteritis
211
What is papilloedema?
Swelling of the optic nerve head **secondary to raised intracranial pressure (RIP). **
Swelling of the optic nerve head in the absence of RIP is known as **disc swelling**.
212
What are the signs seen in papilloedmea?
Elevation of optic disc
Blurred disc margins
Swelling of optic nerve head Hyperaemia of optic disc
Flame haemorrhages
Exudated
213
What is idiopathic intracranial hypertension?
Presence of RIP in the absence of intracranial mass or enlargement of the ventricles due to hydrocephalus
DIAGNOSIS OF EXCLUSION
## Footnote
90% of patients are obese women of child bearing age; amenorhoeic
214
What drugs are associated with idiopathic intracranial hypertension?
tetracyclines, nalidixic acid
215
How is idiopathic intracranial hypertension treated?
IV acetazolamide
Optic nerve sheath fenestrations (tiny slits in the optic nerve to allow CSF to flow out and reduce pressure)
216
Why do you get a ptosis in CN III palsy?
**Weakness of levator palpabrae muscle** that causes a profound ptosis
**Unopposed action of abducens nerve** ('out' position in primary gaze) Normal abduction.
217
Why do patients with CN III palsy have limited adduction?
Weakness of medial rectus limiting adduction
218
Why do patients with CN III palsy have limited elevation?
Weakness of superior rectus and inferior oblique limiting elevation
219
Why do patients with CN III palsy have limited depression?
Weakness of inferior rectus limiting depression
219
Why do patients with CN III palsy have a dilated pupil?
Dilated pupil as PNS fibres travel along CN Ill in between brain stem and cavernous before reaching pupillary muscles
220
What is the primary, secondary and tertiary actions of each of the eye muscles?
221
What are some of the causes of a third nerve palsy?
222
Outline the anatomy of the cavernous sinus
223
What are the features of a CN 6 palsy?
Right esotropia
Failed abduction
Normal Adduction
224
Which nerve might also be affected in CN 6 palsy?
CN 7
225
What are some of the causes of CN 6 palsy?
226
How does a CN 4 palsy present in the primary gaze and on adduction?
**In the primary gaze (middle picture):** Hypertropia and hyperdeviation of the affected eye due to unopposed action of inferior oblique.
**On adduction (right picture):** Hypertropia worsens on adduction due to overaction of inferior oblique
227
In a CN 4 palsy, to which direction is the compensatory head tilt?
AWAY the lesion
228
What are the 5 branches of the facial nerve (CN7)?
229
What do signs involving both CN 6 and CN 7 suggest?
A lesion in the BRAIN
230
What are the two types of squints?
Split into tropias / manifest or phorias / latent
Tropia / manifest = constantly present
Phoria/ latent = only detected on dissociation with an alternate cover-uncover test
231
What is a concomitant vs incomitant squint?
Concomitant = deviation remains the same in all positions of gaze
Incomitant = angle / magnitude of deviated eye changes with position of the gaze
232
What is amblyopia and how common is it?
Lazy eye
2% of the population (+ most common cause of unilateral decrease in VA in children)
233
How is amblyopia treated?
If not fixed at a young age will become permanent
**Occlusion therapy**: good eye patched allowing visual connections to develop properly (can be pharmacological using atropine) - not tolerated very well
234
What is the name for allied health professionals who assess diplopia, strabismus and eye movement defects?
Orthoptists
235
What is binocular single vision (BSV)?
Use of both eyes together to achieve binocular depth perception - stereopsis
236
What is the result of binocular single vision not developing correctly?
esotropia
237
What is the AC/A ratio?
accommodative convergence to accommodation
238
What is hypertropia and hypotropia?
Hypertropia = eye deviated superiorly and moves inferiorly with cover testing to fixate
Hypotropia = eye deviated inferiorly and moves superiorly with cover testing to fixate
239
What is heterotropia and how common is it?
Manifest strabismus - One of the eyes is not directed towards a fixation point
5-8% of the population
240
What is esotropia and exotropia?
Esotropia = eye deviated nasally and moves temporally with cover testing to fixate (convergent squint)
Exotropia = eye deviated temporally and moves nasally with cover testing to fixate
241
What is accomodative esotropia?
Secondary to refractive errors or convergence excess
Associated with hypermetropia
242
What is the most common childhood squint in the UK and what are the 2 subtypes?
Esotropia
Either accommodative or non-accommodative
243
What is non-accomodative esotropia
Latent horizontal nystabmus
Normal refraction
SURGICAL management
244
What is exotropia associated with?
Myopia
## Footnote
Esotropia is associated with hypertropia
245
What is the most common type of exotropia?
Intermittent
246
What are the two types of intermittent exotropia?
Distance or near
247
How is constant exotropia managed?
SURGICAL
248
What are the two possibilities for strabismus surgery?
Resection or recession
249
In which patients are prisms used to treat strabismus?
Adults
250
Which extraocular muscle has the closest and furthest insertions in relation to teh limbus?
Medial rectus has closest insertion to the limbus (5.5mm)
Superior rectus has furthest insertion from the limbus (7.7mm)
251
What are antagonist-agonist and synergist muscles?
**Antagonist-agonist muscles**: Muscles in same eye that move the eye in different directions (e.g. right MR & right LR)
**Synergist muscles**: Muscles in the same eye that move the eye in the same direction (e.g. right IR & right SO)
252
What are yolk muscles?
Muscles in different eyes that cause movement in the same direction (e.g. right LR and left MR) - both cause right gaze
253
What is Hering's law?
Yolk muscles involved in a particular direction of gaze receive equal and simultaneous flow of innervations
254
What is Sherrington's Law?
An increase in innervation of a muscle is accompanied by a decrease in innervation of its antagonist
255
What is heterophoria?
Both eyes look straight but deviate on dissociation
Deviation of eye is normally hidden by the presence of fusion
It is revealed when fusion is broken e.g. during an alternating cover test
256
What is duane retraction syndrome?
Rare congenital condition
**Retraction** of the globe on **ADduction**
Due to innervation of the LR muscle by CN3 rather than CN6
Associated with **deafness and Goldenhar's syndrome**
257
What is Brown syndrome?
Congenital / post trauma
Unilateral mechanical **restriction of SO tendon**
Leads to limited elevation on ADduction
Patients can't look up and in
Some patients report a "click"
258
How do you test visual acuity in infants up to 3 years (pre-verbal)?
Cardiff Acuity test / Cardiff cards
259
How do you test visual acuity in children 18m to 4y (verbal)?
Kay Picture Tests
260
How do you test visual acuity in children 4-5 years?
Keeler Crowded LogMAR test
261
What is a retinoblastoma?
Malignant tumour of the retina - most common intraocular tumour of childhood + most sinister cause
262
What is the genetic basis for retinoblastoma?
Loss of function of retinoblastoma tumour suppressor gene on chromosome 13
263
How is retinoblastoma managed?
Mx: radioactive plaque or enucleation + adjuvant chemo
90-95% survival at 5 years with treatment
264
What infection is congenital cataract associated with?
Rubella
265
Which babies are most affected by retinopathy of prematurity?
Screen pre term babies (<30 weeks) + low birth weight (<1.5kg)
266
What is the pathophysiology of retinopathy of prematurity?
Incomplete retinal vascularisation causes hypoxia
267
What is seen in advanced case of retinopathy of prematurity?
**Leukocoria** seen in advanced cases due to a **retinal detachment**
268
What is the management of retinopathy of prematurity?
ablation of avascular retina + laser
269
How does a coloboma form?
Failure of choroidal fissure to close during embryological developmentmutation of **PAX2 gene** + also linked with foetal alcohol syndrome
Degree of visual impairment ranges from asymptomatic to significant loss of vision
White retinal reflex + severe amblyopia
270
How is ptosis treated in children?
Require urgent frontalis suspension surgery (within 2-4 weeks) - Take part of fascia lata and insert it onto tarsal plate and frontalis muscle
271
What is buphthalmos?
Buphthalmos is an enlargement of the eye and in children is a feature of congenital glaucoma
272
What is the name of a congenital glaucoma?
Buphthalmos
273
What is the definition of a congenital glaucoma / buphthalmos?
Corneal diameter > 12mm before 1 year
274
What investigation is used for chlamydial conjunctivitis?
Giemsa stain
275
What is the management of chlamydial conjunctivitis?
Erythromycin drops
276
What is the management of gonococcal conjunctivitis?
IM / IV ceftriaxone
277
What is the management of capillary haemangioma?
oral beta blockers
278
What is congenital naso-lacrimal duct obstruction (Valve of Hanser)?
Tearing +/- conjunctivitis
Normally opens spontaneously by one year of age
If it does not open, can syringe and probe
279
What is a limbal dermoid?
Benign congenital tumour often associated with eyelid coloboma or Goldenhar's syndrome
280
Why is a dermoid cyst?
Smooth round non-tender immobile lump on orbital rim
Gradually grows with risk of rupture
281
What is a retinal haemorrhage associated with?
Cerebral haemorrhage
282
What does higher pressures in the eye cause?
Higher pressures = mechanical damage (especially lamina cribosa). Local deformation results in axonal damage.
Remodelling & degeneration of neuronal glial cells (astrocytes, microglia) resulting in further atrophy of axons.
Disrupted axonal transport & atrophy of local cells results in rise in ROS and subsequent mitochondrial dysfunction.
283
What is the definition of ocular hypertension?
Raised IOP (>21 mmHg) Open angles BUT, no optic neuropathy and visual field defect
284
What is the cause of primary open angle glaucoma?
Progressive optic neuropathy with visual field loss.
Increased resistance to flow, resulting in an elevated lOP.
## Footnote
RF: M=F, age (>40), myopia, DM
3rd leading cause of blindness (worldwide).
285
How does IOP cause neuronal death? (2 theories)
1. Ischaemic (compromise in the microvasculature)
2. Direct mechanical (force leads to neuronal apoptosis)
286
What is Normal Tension Glaucoma (NTG)?
A variant of POAG - progressive optic neuropathy despite a **normal or low lOP.**
Systemic conditions (BP, migraines, vascular insult)
287
What are the classic signs in normal tension glaucoma?
* Optic disc cupping
* Visual field defects
* Peripapillary atrophy (usually focal - segments that are lighter)
* Focal notching and thinning (segmental)
* Drance haemorrhage
288
What is acute angle closure glaucoma?
An ophthalmic emergency where the iris blocks the TM (primary, secondary if inflammatory)
289
What is the pathophysiology of Acute Angle Closure Glaucoma (AACG)?
**Primary** due to physiological **pupil block** (e.g. stress, fatigue, change in room lighting)
This results in anterior lens surface **obscuring aqueous flow posteriorly** resulting in build up of pressure = iris bowing forward (bombé) = subsequent TM obstruction
**Secondary** = inflammatory
290
What is the management of Acute Angle Closure Glaucoma (AACG)?
EMERGENCY - Peripheral iridotomy (PI)
In the meantime:
1. IV acetazolamide (then oral switch)
2. Topical anti-hypertensives (timolol 0.5%, iodipine 1%)
3. Cycloplegia (pilocarpine 2%)
4. Steroids (dexamethasone 1%) - If IOP remains high: IV mannitol 20%
291
What is Inflammatory (uveitic) glaucoma?
Uveitis causes local inflammation (obstruction, cellular debris & trabeculitis) & leaky blood vessels (loss of blood-aqueous barrier).
292
What causes inflammatory (uveitic) glaucoma?
1. JIA
2. Seronegative arthropathies (AS, Psoriatic, Reiter's)
3. Infectious (TB, syphilis, herpetic)
4. Sarcoidosis
5. Lens-induced (aphakic)
5. Ocular disorders (Fuchs iridocyclitis)
293
What are the classic signs of inflammatory (uveitic) glaucoma?
* Synechiae (peripheral anterior)
* Bulky ciliary bodies
* Acute or chronic uveitis signs (nodules, perilimbal injections etc.)
* Systemic signs
294
How is Inflammatory (uveitic) glaucoma treated?
Treat the underlying cause of uveitis
Other treatments: oral anti-hypertensives, implantable steroids tenon corticosteroids
295
What is rubeotic glaucoma?
**Neovascularisation of the iris** (rubeosis iridis). Known as 100 day glaucoma.
Due to proliferative DR or ischaemic insult (CRVO, CRAO, sickle cell crisis, carotid disease).
296
What is the pathophysiology of rubeotic glaucoma?
Due to a process of neovascularisation, the iris starts to produce irregularlyshaped blood vessels. These are poorly formed and prone to leak. The AC may contain cells, flare or even hyphaema. The TM may contain irregular blood vessels as an extension from iris.
297
What are the classic signs of rubeotic glaucoma?
* Rubeosis iridis
* Retinal pathology (diabetic retinopathy)
* Neovascularisation of the trabecular meshwork
298
How does traumatic glaucoma occur?
Blunt trauma is often well tolerated by the eye due to the 2 x humours, however, the more delicate structures (e.g. TM) are less resilient.
Blunt trauma results in a **'coup-contrecoup injury'-like** injury. There is expansion of fluid in the opposite end of injury. This sudden volume expansion (+ transmitted force) results in damage to TM, ciliary body & zonules.
Early onset: obstruction due to blood / pupil block
Late onset: tears, synechiae
299
What are some possible signs seen in traumatic glaucoma?
300
What is pseudoexfoliation syndrome?
**Systemic** condition due to abnormal protein synthesis that affects BM structure.
Filamentous, proteoglycans & aminoglycans are shed from lens ED, iris pigmented ED & non-pigmented ciliary body ED.
Pathological debris found in TM, as well as systemically (myocardium, lung, liver, etc).
301
What are some of the classic signs seen in pseudoexfoliation syndrome?
Exfoliation flakes (AC)
Moth eaten (pupil, iris)
TM pigment
(Sampaolesi's line)
Transilluminat ion defects (loss of iris shape)
302
What is pigment dispersion syndrome?
Bilateral ocular condition when pigment rubs off the back of the iris (and ciliary body).
The classic triad consists of dense trabecular meshwork pigmentation, mid-peripheral iris transillumination defects, and pigment deposition on the posterior surface of the central cornea.
303
What are 2 rare causes of glaucoma?
Pseudoexfoliation syndrome
Pigment dispersion syndrome
304
Which type of glaucoma presents with NO iris bombe?
Malignant glaucoma
305
What is malignant glaucoma?
Characterised by a shallow anterior chamber plus raised IOP, all despite treatment (iridotomy, glaucoma surgery).
306
What is the normal range for cup:disc ratio (CDR)?
0-0.8
307
How does one assess the optic nerve in clausoma?
308
What are the two methods for measuring IOP?
Tonometry
Pachymetry
309
What are the two methods of perimetry for testing visual fields?
310
What is a gonioscope?
Gonioprisms are used to directly visualise the angle (Shaffer grading system).
Topical anaesthetic / topical lubricants required.
311
What is OCT?
OCT uses light waves & can measure retinal nerve fibre layer (RNFL), optic nerve head (ONH) - including parameters such as disc, cup, and rim area measurements & other aspects of the retina.
312
Which ocular anti-hypertensives decrease AQ vs. increase AQ outflow?
313
What are the steps in medical management of glaucoma?
314
What laser or surgical procedures can be used in management of glaucoma?
Selective laser trabeculoplasty (increased ciliary body drainage)
Trabeculectomy (small hole is created at sclera)
315
How do cataracts present?
**Change in vision**: reduced VA, glare (halos around lights), difficulty seeing in dim light, monocular diplopia. Patient might have multiple changes in prescription.
**Change in refraction**: typically myopic shift
**Change in fundal view**: may have difficulty looking in' before patient has difficulty 'looking out'
316
What is the structure of the lens?
317
What are the 3 most common types of cataracts?
318
How is a pre-operative cataract assessment done?
319
How is the power of a lens calculated?
320
Which drug can cause floppy eye syndrome, which can be a problem during cataract surgery?
Tamsulosin
Alpha-blocker
321
What do the following terms mean:
1. Phakia
2. Pseudophakia
3. Aphakia
1. Phakia: natural lens in situ
2. Pseudophakia: cataract removed and IOL implanted
3. Aphakia: cataract removed without IOL implanted
322
What is a monofocal lens?
Monofocal e.g. toric lenses: Vision will be in focus at just one distance - either near, far, or intermediate distance. Toric lenses are particularly useful for correcting astigmatism. Patients may need to still wear glasses for reading (occasionally distance vision also)
323
What is a significant intra-operative complication of cataract surgery?
Posterior capsule rupture
Mx: Vitrectomy
324
What is the most common ACUTE post-op complication of cataract surgery?
Endophthalmitis (4-5 days after surgery) s.epdidermis,
325
What is the most common SUB-ACUTE post-op complication of cataract surgery?
Cystoid macular oedema (6-8 weeks after)
Posterior capsule pacification (months to years) - image
Retinal Detachment (particularly if posterior capsule was breached)
## Footnote
Acute post-op complications:
Endophthalmitis (4-5 days after surgery) s.epdidermis,
326
What is the refractive ability of the eye determined by?
Refractive properties of the cornea (43D) and natural lens (15D) (also includes aqueous and vitreous) .
Total refractive power of an emmetropic eye: 58D
327
What may the refractive power in a myopic eye be?
Too great
More commonly due to a too long eyeball length
