Basic science and investigations Flashcards
(131 cards)
1
Q
4 ocular structures derived from surface ectoderm
A
conjunctival and corneal epithelium nasolacrimal duct lens lacrimal gland eyelids
2
Q
4 ocular structures derived from neuroectoderm
A
neurosensory retina
pigment epithelium of retina, iris and ciliary body
pupillary sphincter and dilator muscles
optic nerve
3
Q
7 ocular structures derived from neural crest
A
corneal endothelium trabecular meshwork stroma of cornea, iris and ciliary body ciliary muscle choroid sclera orbital cartilage and bone
4
Q
4 ocular structures derived from mesoderm
A
extraocular muscles
blood vessels
Schlemm’s canal endothelium
sclera (temporal portion)
5
Q
congenital cataracts is inherited
A
AD
6
Q
Fuchs’ corneal dystrophy is inherited
A
AD
7
Q
Best disease is inherited
A
AD
8
Q
granular and lattice corneal dystrophies are inherited
A
AD
9
Q
Marfan syndrome is inherited
A
AD
10
Q
neurofibromatosis is inherited
A
AD
11
Q
retinitis pigmentosa is inherited
A
AD
12
Q
retinoblastoma is inherited
A
AD
13
Q
stickler syndrome is inherited
A
AD
14
Q
tuberous sclerosis is inherited
A
AD
15
Q
vHL is inherited
A
AD
16
Q
congenital glaucoma is inherited
A
AR
17
Q
oculucutaneous albinism is inherited
A
AR
18
Q
stargardt disease is inherited
A
AR
19
Q
fabry disease is inherited
A
XLR
20
Q
lowe syndrome is inherited q
A
XLR
21
Q
ocular albinism is inherited
A
XLR
22
Q
retinoschisis is inherited
A
XLR
23
Q
alport syndorme is inherited
A
XLD
24
Q
kearns-sayre syndrome is inherited
A
mitochondrial
25
leber hereditary optic neuropathy is inherited
mitochondrial
26
how does an XLD disease pass on to the female (same as XLR for male)
XLD female = can express condition from father alone even if mother is unaffected
27
most common cause of endogenous endophthalmitis presenting with white fluffy retinal lesions
candida - usually in immunocompromised patients
28
cause of fungal keratitis
aspergillus and fusarium (both filamentous fungi)
common in warm climates, usually following ocular trauma
29
cause of presumed ocular histoplasmosis syndrome (POHS)
histoplasma capsulatum (dimorphic - properties of both yeasts and filamentous fungi)
endemic in Mississippi and Ohio river valleys
30
cause of congenital/adult toxoplasmosis
toxoplasma gondii (protozoa)
cats, faecal-oral, vertical
31
cause of severe keratitis
acanthamoeba (protozoa)
32
cause of toxocariasis presenting with endophthalmitis in children
toxocara (helminth nematode - roundworm)
cats and dogs, faecal
33
most common helminth-related ocular condition
onchocerca volvulus - vector = simulium blackflies
34
what does onchocerca volvulus cause
onchocerciasis ('river blindness') endemic in Africa
35
what is MHC also called in humans
human leucocyte antigen (HLA) - found on short arm of chromosome 6
36
HLA subtype associated with birdshot choroidopathy
HLA-A29
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HLA associated with sympathetic ophthalmia
HLA-A11
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HLA associated with POHS
HLA-B7
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HLA associated with vogt-koyanagi-harada syndrome (VKH)
HLA-B22
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HLA associated with psoriatic arthritis, ankylosing spondylitis, reactive arthritis and enteropathic arthritis
HLA-B27
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HLA associated with behçet disease
HLA-B51
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HLA associated with posner-schlossman syndrome
HLA-BW5
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HLA associated with pars planitis, POHS, multiple sclerosis
HLA-DR2
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HLA associated with sympathetic ophthalmia, rheumatoid arthritis and VKH
HLA-DR2
45
HLA associated with juvenile idiopathic arthritis
HLA-DR5
46
HLA associated with multiple sclerosis
HLA-DR15
47
4 types of cytokines
TNF
interleukins
chemokines
interferons
48
normal IOP values
within +/-2 standard deviations of mean IOP values (10-21mmHg)
49
2 things causing IOP to increase
```
age
circadian rhythm (highest in morning)
```
50
average diurnal fluctuation of IOP
2-6mmHg (>10mmHg in glaucoma patients)
51
3 IOP-raising agents
steroids
tropicamide (close-angle glaucoma)
ketamine
52
6 drugs that can lower IOP (usually used for treating glaucoma)
beta blockers
prostaglandin analogues (e.g. latanoprost)
alpha-2 agonists (e.g. apraclonidine)
topical or systemic carbonic anhyrase inhibitors (CAI) (e.g. dorzolamide, acetazolamide)
miotics (e.g. pilocarpine)
osmotic agents (e.g. mannitol)
53
3 lowering IOP drugs that work by decreasing aqueous production
beta blockers
alpha2 agonists
topical and systemic CAIs
54
2 lowering IOP drugs that work by increasing uveoscleral outflow
prostaglandin analogues
| alpha2 agonists
55
how do miotics work
parasympathomimetics - increase aqueous drainage via trabecular meshwork by causing contraction of ciliary muscles
56
how do osmotic agents work
lower IOP by decreasing vitreous volume
57
2 uncommon drugs that can lower IOP
cannabinoids
| alcohol
58
5 drugs causing lens opacification and cataracts
```
steroids
amiodarone
allopurinol
chlorpromazine
tobacco smoke
```
59
4 drugs that can cause cystoid macular oedema
latanoprost
epinephrine
rosiglitazone
nicotinic acid
60
2 drugs that can cause bulls-eye maculopathy
hydroxychloroquine
| chloroquine
61
drug that can cause crystalline maculopathy
tamoxifen
62
5 drugs that can cause optic neuropathy
```
ethambutol
chloramphenicol
amiodarone
vigabatrin (causes binasal visual field defects)
isoniazid
```
63
what is vortex keratopathy (corneal verticillata)
deposition of asymptomatic grey opacities in a vortex pattern on the corneal epithelium
64
2 causes of vortex keratopathy
```
drugs (amiodarone, chloroquines, indomethacin and phenothiazines)
fabry disease (XLR condition - deficiency of alpha-galactosidase A)
```
65
5 features of fabry disease
```
burning pain in extremities
angiokeratomas
renal failure
posterior subcapsular cataracts
vortex keratopathy
```
66
what is keratometry
measures anterior corneal surface curvature
67
what is corneal topography
measures and quantifies curvature of whole cornea and provides info on its shape - uses placido-disc systems which project concentric rings of light on anterior corneal surface
68
4 indications of corneal topography
keratoconus
astigmatism
laser eye surgery
contact lens fitting
69
what is ultrasonic pachymetry
measures central corneal thickness (CCT) using an ultrasonic probe
70
normal central corneal thickness (CCT)
530-545 um
71
how does OCT work
uses near-infrared waves through the pupil to the retina = cross section and 3D image of retina
72
how does fluorescence angiography (FA) work
sodium fluorescence absorbs blue light (465-490nm) and emits a yellow-green light (530nm) - injected into peripheral vein to circulate to eye - passes through short posterior ciliary artery into choriocapillaris about 8-12 seconds post injection and then enters retinal circulation a second later
73
4 side effects of FA
urine discoloration
nausea
vasovagal syncope
anaphylaxis (rare)
74
what is FA contraindicated in
shellfish allergy
75
difference between indocyanine green (ICG) angiography and FA
uses near-infrared light and has little leakage (low permeability) while passing through the choroid = can visualise choroid vasculature better
76
2 contraindications of ICG angiography
pregnancy
| seafood and iodine allergies
77
how does fundus autofluorescence work
no dye - detects lipofuscin already present within retinal pigment epithelium (RPE)
78
when is fundus autofluorescence used
Best disease
| monitoring geographic atrophy
79
what does an electroretinogram (ERG) do
tests electrical activity of retina in response to a light stimulation
80
what does an electro-oculogram (EOG) do
reflects activity of photoreceptors and RPE - therefore retinal diseases proximal to the photoreceptors give normal EOG readings
81
when are ERG and EOG useful
aiding diagnosis in Best disease and retinitis pigmentosa
82
4 investigations for glaucoma
measure IOP
assess iridocorneal angle
measuring CCT
evaluating optic nerve head and visual fields
83
what is tonometry
procedure to measure IOP - Goldmann applanation tonometry most widely used
84
how does tonometry work
follows Imbert-Fick law to establish amount of force required to flatten a corneal area of 3.06mm diameted assuming a CCT of 520um
85
4 factors leading to incorrect tonometry measurements
excessive fluorescein (overestimates IOP)
low or high CCT (underestimates or overestimates IOP respectively)
astigmatism
calibration errors
86
what is gonioscopy used for
to determine whether the iridocorneal angle is open or closed - visualisation of all angle structures = wide-open angle, inability to visualise any structures = closed angle
87
5 angle structures (anteriorly to posteriorly)
schwalbe line
nonpigmented trabecular meshwork
pigmented trabecular meshwork (not present at birth, increases following puberty)
scleral spur (marks attachments of ciliary body's longitudinal fibres)
ciliary body
88
what is perimetry used for
to detect visual field defects - commonly used in glaucoma and neuro-ophthalmic conditions
89
3 types of perimetry
Humphrey visual field analysis
| Goldmann visual field testing
90
5 types of glaucomatous field defects
nasal step
paracentral depression (most commonly superonasally)
superior arcuate defect
ring scotoma (superior and inferior arcuate defects)
tunnel vision with temporal sparing
91
how is MRI useful in ophthalmologgy
diagnosis of intracranial lesions affecting visual pathway
92
4 indications for CT
orbital fractures
orbital cellulitis
thyroid eye disease
cerebral haemorrhages
93
2 indications for CT angiography
```
investigate for subarachnoid haemorrhage
intracranial aneurysms (e.g. third nerve palsy)
```
94
3 fundamental properties of light beams emitted by different types of lasers
coherency (all emitted photons are in same phase)
monochromacity (single wavelength)
collimation (narrow with minimal divergence)
95
3 principal parts to construct lasers
source of energy (light/electrical)
medium (e.g. gas, liquid (dyes), solid)
optical resonator that uses mirrors to amplify light
96
3 examples of gas mediums in lasers
argon
krypton
carbon dioxide
97
example of solid medium in lasers
neodymium-doped yttrium aluminium garned (Nd:YAG) crystals
98
how can UV lasers damage the eye
photochemical injuries to lens and cornea
99
4 main groups of lasers according to their hazardous effects on body
1 = harmless, 4 = most harmful
most used in ophthalmology = 3B and 4
100
where is melanin found in the eye
mainly RPE and choroid - absorbs most of visible spectrum and infrared wavelengths
101
where is xanthophyll found in the eye
macula - absorbs blue light (450-495nm)
102
type of light absorbed by haemoglobin
blue, green (495-570nm) and yellow (570-590nm)
103
3 main types of laser-tissue interaction
photothermal
photochemical
photo-ionizing
104
2 types of photothermal interaction
photovaporization - vaporization of water from tissues (e.g. CO2 lasers)
photocoagulation - absorption of laser emissions by tissues = rise in temp = protein denaturation
105
when is photocoagulation often used
in panretinal photocoagulation (PRP) in diabetic retinopathy
106
4 types of photocoagulative lasers
argon blue-green - absorbed by melanin, Hb and xanthophyll
krypton red (647nm) - absorbed by melanin
frequency-doubled Nd:YAG (532nm) - absorbed by melanin and Hb in RPE and trabecular meshwork
diode (810nm) - emits near-infrared radiation and is absorbed by melanin
107
why type of photocoagulative laser is not used on the macula
argon blue-greed (because absorbed by xanthophyll)
108
how does photochemical laser-tissue interaction work
breaking chemical bonds that hold tissue together using UV light = photoablation
109
what is an excimer laser
laser that causes photoablation
110
3 things an excimer laser is used for
photorefractive keratectomy (PRK)
laser-assisted in situ keratomileusis (LASIK)
laser epithelial keratomileusis (LASEK)
111
how does PRK work
corneal epithelium removed then laser ablation used to reshape the cornea
112
how does LASIK work
corneal flap created then stroma ablated to reshape cornea then flap is replaced
113
how does LASEK work
corneal epithelium peeled using 20% ethanol laser ablation is performed and epithelium is replaced
114
how does photo-ionizing laser work
causes destruction of tissues by altering stable state between photons and electrons
115
example of photo-ionizing laser
Nd:YAG (1064nm)
116
2 uses of Nd:YAG
posterior capsulotomy for treating posterior capsular opacification (PCO)
peripheral iridotomy used in managing angle-closure glaucoma
117
3 definitions of severe sight impairment (blindness)
VA <3/60 Snellen
VA 3/60-6/60 with reduction in VF
VA >6/60 with significantly reduced VF
118
3 definitions of sight impairment
VA 3/60-6/60 with full VF
VA 6/60-6/24 with moderate reduction in VF
VA >6/18 with significant reduction of VF (e.g. homonymous hemianopia)
119
3 DVLA criteria for car and motorcycle drivers
- ability to read car registration plate (post sep 2001) at 20m distance
- VA >6/12 with both eyes open or 1 if monocular
- VF of at least 120 degrees on horizontal with extension of at least 50 degrees to right and left, no significant defect encroaching 20 degrees of fixation above or below the horizontal meridian should be present
120
4 specific cases that must be notified to DVLA
- diplopia (can resume if controlled)
- VF defects e.g. RP, bilateral glaucoma, bilateral hemianopia
- nyctalopia
- blepharospasm (mild cases may be licenced)
121
2 types of absorbable suture
```
polyglactin 910 (VICRYL)
polyglycolic acid (DEXON)
```
122
3 types of nonabsorbable suture
silk
nylon
polypropylene (PROLENE)
123
suture used for eyelids and sclera
silk
124
suture used for conjunctiva, muscles and cornea
polyglactin 910
125
suture used for cornea, sclera and limbus
nylon
126
suture used for iris
polypropylene
127
suture used for limbus
polyglycolic acid
128
5 conditions included in Vision 2020
```
cataract
trachoma
onchocerciasis
refractive errors
childhood blindness
```
129
most common cause of infectious blindness
trachoma (onchocerciasis second)
130
most common cause of VI
uRE (cataracts is most common cause of blindness)
131
4 causes of childhood blindness
vit A deficiency
measles
ROP
cataract
