External Eye and Cornea Flashcards

1
Q

What is the refractive power of the cornea?

A

43D

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2
Q

What is the diameter of the cornea in a) an adult b) a newborn?

A

a) 10-13mm

b) 9.5-10.5mm

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3
Q

What is the thickness of the cornea a) centrally b) peripherally?

A

a) 535mcm b) 660mcm

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4
Q

Is the cornea vascular?

A

no

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5
Q

Where does the cornea get nutrition from?

A

aqueous humour and tear film

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6
Q

Which nerves supply the cornea?

A

Long ciliary nerves - from V1

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7
Q

How many layers does the cornea have?

A

5

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8
Q

Name the layers of the cornea from outermost to innermost.

A
epithelium
Bowman's layer
Stroma
Descemet's membrane
endothelium
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9
Q

Which corneal layer is the principal barrier to topical eye drops?

A

Epithelium

Lipid soluble drugs pass easily

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10
Q

Does the epithelium have regenerative potential?

A

yes- contains limbal stem cells

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11
Q

Which layer of the cornea is this:
thickest layer
contains keratinocytes and collagen fibrils
no regenerative power
increased pH increases absorption across this layer

A

stroma

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12
Q

Do acids or alkaline chemicals cause more damage to the eye?

A

alkaline- increasing pH causes increased absorption of chemicals across the stroma

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13
Q

Which elastic layer of the cornea contains type 4 collagen fibres?

A

Descemet’s membrane

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14
Q

What is the function of the corneal endothelium?

A

pumps fluid out of the stroma to maintain its transparency

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15
Q

contact lens wearer, unilateral acute pain, redness, photophobia and decreased VA with circumcorneal injection and discharge

A

bacterial keratitis

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16
Q

which bugs most commonly cause bacterial keratitis?

A

pseudomonas, staph aureus

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17
Q

which organisms cause a bacterial keratitis that is more likely to spread and infect the whole globe?

A

Neisseria gonorrhoea

Haemophilus influenzae

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18
Q

Which class of abx should be used in bacterial keratitis?

A

fluoroquinolones (-floxacin)

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19
Q

patient ran into a tree branch, feathery branching infiltrate on cornea, aspergillus cultured

A

filamentous fungal keratitis

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20
Q

immunocompromised patient,small ulcer with expanding infiltrate in collar stud formation

A

candida fungal keratitis

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21
Q

What treatment is given for filamentous fungal keratitis?

A

natamycin drops

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22
Q

What treatment is given for candida keratitis?

A

amphotericin B or voriconazole

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23
Q

Patient been swimming with contact lenses in. Eye pain out of proportion with clinical signs, photophobia and blurred vision. Ring shaped stromal infiltrates and perineural infiltrates.

A

Acathamoeba keratitis

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24
Q

What is the management for acanthamoeba keratitis?

A

stop contact lens wear

topical polyhexamethylene biguanide or chlorhexadine

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25
Blepharo conjunctivitis, pain, blurred vision, lacrimation, foreign body sensation, photophobia. Dendritic ulcer seen with fluorescein. Dendrite margins stain well with rose Bengal.
Herpes simplex keratitis
26
Which HSV is the most common cause of viral keratitis?
HSV 1
27
What is the treatment for herpes simplex keratitis?
topical acyclovir
28
Dermatomal rash, Hutchinson's sign. Keratitis with psuedodendrites- stain well with rose Bengal.
herpes zoster ophthalmicus
29
What is the treatment for herpes zoster ophthalmicus?
oral acyclovir 800mg 5 times/day | topical lubricants
30
Pain, photophobia, decreased VA, feathery midstromal scarring and neovascularisation.
interstitial keratitis
31
Causes of interstitial keratitis?
``` syphilis lyme disease HSV HZV Cogan syndrome ```
32
Interstitial keratitis, notched teeth and sensorineural deafness
Hutchinson's triad of congenital syphilis
33
interstitial keratitis, sensorineural hearing loss, vertigo and tinnitus
Cogan Syndrome
34
degeneration of corneal epithelium, foreign body sensation, mobile comma shaped epithelial strands
filamentory keratitis due to tear film changes
35
conditions associated with filamentary keratitis
sicca syndrome Sjogren's syndrome contact lenses
36
Peripheral corneal inflammation. Subepithelial infiltrates separated from the limbus by the clear zone. Staph infection
marginal keratitis
37
what type of hypersensitivity reaction is seen in marginal keratitis?
type III
38
Patient with RA. Peripheral corneal thinning and epithelial defect. Episcleritis and scleritis
peripheral ulcerative keratitis
39
Older patient with hypercalcaemia. Calcium deposition in Bowman's area. Band like chalky plaques containing haloes.
band keratopathy
40
What is the treatment for band keratopathy?
chelation with EDTA
41
Which layer of the cornea is thinned in keratoconus?
stroma
42
Patient with Down's syndrome. Irregular astigmatism, Munson's sign (lower eyelid protrusion on downward gaze), cone shaped protrusion of central cornea. Acute hydrops. Vogt's striae and fleischer ring. Oil drop and scissoring reflexes. Corneal topography shows bow tie pattern progressing to steep central cone.
Keratoconus
43
Which layer of the cornea tears in acute hydrops, leading to corneal oedema?
Descemet's membrane
44
what is the treatment for keratoconus?
mild- glasses mod- contact lenses or corneal collagen crosslinking using riboflavin and UVA sev- penetrating or deep anterior lamellar keratoplasty
45
Autsomal recessive disorder. Copper deposits in Descemet's membrane (Kayser-Fleischer ring). Anterior subcapsular sunflower cataract.
Wilson's disease
46
Drug causing vortex keratopathy
amiodarone
47
vortex keratopathy, burning pain in extremities, angiokeratomas and renal failure
Fabry's disease
48
Small eye by at least two standard deviations
microphthalmia
49
Older lady. Blurry vision worse in the morning. Corneal guttata (beaten metal appearance)
Fuchs endothelial dystrophy descemet's membrane affected
50
what sort of cells make up the conjunctiva?
stratified columnar epithelium
51
Which nerves supply the conjunctiva?
``` mainly CNV1 inferiorly CNV2 (infraorbital nerve) ```
52
lymphatic drainage of medial conunctiva
preauricular nodes
53
lymphatic drainage of lateral conjunctiva
submandibular nodes
54
what is the main function of the conjunctiva?
secrete mucin
55
Which bugs commonly cause bacterial conjunctivitis?
strep pneumo, staph aureus haemophillus influenzae
56
Redness, grittiness and mucopurulent discharge with conjunctival injection. Starts unilateral then spreads to both eyes.
Acute bacterial conjunctivitis
57
what is the treatment for acute bacterial conjunctivitis?
topical chloramphenicol
58
Unilateral red eye with mucopurulent discharge. Preauricular lymphadenopathy. Follicles in inferior fornix. Giemsa stain shows basophilic intracytoplasmic inclusion bodies. Immunofluorescent staining shows free elementary bodies.
Adult inclusion (chlamydial) conjunctivitis
59
Which serological variants of chlamydia trachomatis cause inclusion conjunctivitis?
D-K
60
Conjunctival inflammation developing in the first 30 days of life. Most commonly caused by chlamydia.
ophthalmia neonatorum
61
Baby aged 1-3 weeks, mucopurulent discharge. Organism and management?
chlamydia trachomatis | oral erythromycin
62
Baby aged 1-2 weeks. Watery discharge, periauricular skin vesicles, dendritic corneal ulcer. Organism and management
HSV | High dose IV acyclovir
63
Baby first week of life. Purulent discharge with sticky eyes. Organism and management.
Staphylococcus | topical chloramphenicol
64
Watery discharge in first few days of life. Chemical cause and management
silver nitrate | artificial tears
65
Baby first week of life. Hyperpurulent discharge, swollen eyelids, rapidly progressing corneal ulcer. Organism and management
gonococcus | systemic ceftriaxone and chloramphenicol
66
Unilateral red, itchy gritty eye with watery discharge, spreads to other eye. Pre-auricular lymph adenopathy.
Acute non-specific follicular conjunctivitis
67
Fever, pharyngitis, conjunctivitis and lymphadenopathy.
pharyngoconjunctival fever
68
Which serotypes of adenovirus cause pharyngoconjunctival fever?
3, 4 and 7
69
Red, itchy gritty eye with watery discharge and keratitis.
epidemic keratoconjunctivitis
70
Which serotypes of adenovirus cause epidemic keratoconjunctivitis?
8, 19 and 37
71
Which virus is the most common causative agent in viral conjunctivitis?
adenovirus
72
Red, watery, itchy eye with rhinitis. Conjunctival hyperaemia and papillary conjunctivitis.
Allergic conjunctivitis
73
What type of hypersensitivity reaction seen in allergic conjunctivitis?
Type 1
74
Contact lens wearer. Increased ocular tiredness while wearing lenses. Pruritis, red eye and mucous secretion worse after removing lenses. Superior tarsal hyperaemia and papillae.
giant papillary conjunctivitis
75
what sort of hypersensitivity is seen in giant papillary conjunctivitis?
Type 4
76
Elderly female. Bilateral conjunctivitis with conjunctival hyperaemia, swelling and subepithelial fibrosis. Dry eyes, trichiasis and chronic blepharitis. Symblepharon. Subepidermal oral mucosal involvement. Direct conjunctival immunofluoresence shows linear bands of IgG and IgA deposits at the basement membrane.
Ocular mucous membrane pemphigoid
77
What sort of hypersensitivity is seen in ocular mucous membrane pemphigoid?
Type 2- autoantibodies attack basement membrane
78
What is the treatment of ocular mucous membrane pemphigoid?
mild- dapsone | sev- systemic steroids
79
Female with deranged TFTs. Gradual onset foreign body sensation with itching and photophobia. Localised conjunctival hyperaemia and papillary reaction superiorly. Cornea has superior punctate epithelia
Superior limbic keratoconjunctivitis
80
Patient scratched by cat. Granulomatous unilateral conjunctivitis with ipsilateral pre-auicular lymphadenopathy and low grade fever.
Parinaud Oculoglandular syndrome
81
Which organism causes cat scratch disease?
bartonella henselae
82
Pink fleshy triangle shaped fibrovascular wedge arising on nasal limbus and growing over the cornea. Stocker's line (iron deposits). Fuch's islets. Ocular dryness, astigmatism and reduced vision.
pterygium
83
What is the management for pterygium?
conservative
84
Yellow white raised lesion at the nasal limbus. Doesn't extend over cornea. Associated with UV light exposure and increasing age.
pinguecula
85
Acute onset red eye with discomfort. Peaks at 12-24 hours and slowly fades over a few days.
simple episcleritis
86
Insidious onset red eye and discomfort. Tender vascular nodule at interpalpebral fissure.
Nodular episcleritis
87
Which chemical can aid diagnosis of episcleritis by blanching the episclera?
phenylephrine
88
Dull pain radiating to forehead or jaw. Gradual onset of localised or diffuse redness. Oedematous sclera resolves leaving a blue hue. Associated with joint pain
Diffuse anterior scleritis
89
Gradual onset pain followed by a red eye with erythematous tender nodules.
Nodular anterior scleritis
90
Severe pain radiating to forehead or jaw, redness and lacrimation. Scleral necrosis and blue/purple hue. Loss of vision.
Necrotising scleritis with inflammation
91
Elderly patient with advanced rheumatoid. Necrosis of sclera without inflammation. Asymptomatic gradual onset of necrotic patches and exposure of underlying uvea.
Scleromalacia perforans
92
Severe pain not correlating to appearance of eye. Diplopia, mild proptosis, optic disc swelling, vision loss, choroidal folds. USS shows increased scleral thickness and T sign. Can lead to retinal detachment.
posterior scleritis
93
What is the treatment for posterior scleritis?
topical steroids | oral NSAIDs