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IDK Flashcards

1
Q

TYPES OF RETINAL HAEMORRHAGES AND LAYER OF RETINA AFFECTED

A

Flame haemorrhages - NFL
Dot and blot haemorrhages - inner and outer plexiform layers.
Hard exudates and CMO (epinephrine, latanoprost and nicotinic acid are recognized causes) - outer plexiform layer.

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2
Q

% of pt w/ acute symptomatic PVD w/ vitreous haemorrhage that have a retinal tear?

A

75%
Haemorrhage or vitreous cells (tobacco dust) are highly suggestive of retinal breaks.

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3
Q

Most common cause of hyper acute purulent conjunctivitis
B - what culture medium to grow it
C- complications

A

Neisseria gonorrhoea - use Chocolate agar/Thaymer Martin

If untreated-> corneal ulceration, perforation and endophthalmitis as N.g can progress through intact corneal epithelium

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4
Q

Retinal capillary endothelial cells are surrounded by what 3 things:

A

Thick basal lamina
Pericytes
Astrocyte foot processes

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5
Q

Coat’s disease

A

Retinal telangiectasia
EXUDATIVE RETINAL DETACHMENT W/ ASSOC VASCULAR ABNORMALITIES

Not hereditary and not assoc w/ systemic vascular abnormalities
Men predominantly affected.
Children predominantly effected

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6
Q

Where are the axons of cells in the retinal layer

A

Horizontal cells - inner nuclear layer.

Amacrine cells and bipolar cells - inner plexiform layer

Ganglion cells - nerve fibre layer of the retina

CHECK

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7
Q

TROCHLEAR N

A

nucleus - anterior part of the periaqueductal grey matter in the inferior colliculus

supplies only somatic efferent innervation to the superior oblique

emerges from the posterior aspect of the brain stem, just inferior to the inferior colliculus

The trochlear nerve is unusual in that it decussates before leaving the brainstem

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8
Q

CULTURE MEDIUMS

Thaymer-Martin =

MacConkey =

Blood agar =

Chocolate agar =

Cooked meat broth =

Thioglycate agar =

Lowstein-Jensen =

McCoy =

Non-nutrient agar w/ E.coli =

Sabouraud agar =

A

Thaymer-Martin = Gram neg cocci e.g. Neisseria

MacConkey = Lactose fermenting gram negative

Blood agar = MOST But Haemophilus, Neisseria, Moraxella

Chocolate agar = MOST incl (Con) Haemophilus, Neisseria, Moraxella

Cooked meat broth = Anaerobes, fastidious organisms

Thioglycate agar = Aerobes on surface, anaerobes inside

Lowstein-Jensen = Mycobacteria TB

McCoy = Obligate intracellular bacteria

Non-nutrient agar w/ E.coli = Acanthomoeba

Sabouraud agar = Fungi

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9
Q

DEFINE

Pharmacokinetics

Pharmacodynamics

A

Pharmacokinetics = drug absorption, distribution, elimination

Pharmacodynamics = biochemical and physiological effect of drug and their mechanisms of action at organ/subcellular/macrocellular level.

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10
Q

Sclera vs Cornea

  1. Water content
  2. CT arrangement
A
  1. 68% in sclera
    75-80% in cornea
  2. Sclera
    - dense irregular CT - type 1 collagen
    - Less proteoglycans and glycosaminoglycans in its matrix than cornea
    Cornea
    - regular CT arrangement - type 1 (also 4,5,7)
    - More proteoglycans and glycosaminoglycans in its matrix
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11
Q

Ficks law

A

Rate of diffusion

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12
Q

MOA OF ANTIFUNGALS

A

ECHINOCANDIN E.G. MICAFUNGIN
- interferes w/ glucan synthesis, which is an essential component of fungal cell walls

POLYENE E.G. AMPHOTERICIN, NYSTATIN, PIMARICIN
- interact w. sterols in fungal cell membrane to form channels causing leakage

AZOLE E.G. FLUCONOZOLE, KETOCONAZOLE, ITRACONOZOLE
- inhibits p450 dependent enzymes involved in biosynthesis of ergosterol, required for fungal cell membrane structure and function

GRISAN E.G. GRISEOFLUVIN
- binds to tubular, preventing microtubule assembly

GLUTARAMIDE E.G. CYCLOHEXIMIDE
- inhibits protein synthesis at ribosomal level

ANTIMETABOLITES E.G. 5-FLUROCYTOSINE
- inhibits both DNA/RNA synthesis via intracytoplasmic conversion of 5-fluorocytosine to 5-flurouracil

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13
Q

ROD/CONE TO GANGLION CELL RATIO

A

Cone:GC in fovea is 1:1
—> mainly parvocellular pathway to lamellae 3-6 in LGN
Rod:GC in periphery is 10,000:1
——>mainly magnocellular pathway to lamella 1 and 2 in LGN

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14
Q

STANDARD ERROR

A

STANDARD ERROR OF MEAN = S.D/sqrt of n

standard error of the mean is a measure of this scatter, i.e. how accurate is the sample mean as an estimate of the true population mean.

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15
Q

Blood supply of LGN

A

DUAL supply
1. ANTERIOR CHOROIDAL ARTERY (branch of ICA)
2. LATERAL POSTERIOR CHOROIDAL ARTERY (branch of post. CEREBRAL artery)

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16
Q

EPINEPHRINE causes

A
  • cortisol release
  • anxiety and sweating
  • glycogenolysis and glycolysis
  • reduced appetite
  • lowering of IOP
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17
Q

lattice CORNEAL DYSTROPHY

A

AD

Corneal stromal dystophy
- fine criss-crossing lines in stroma

Microscopy - amyloid deposition (also present in Avellino dystrophy)

Test with congo red - green birefringence

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18
Q

EMBRYOLOGICAL ORIGIN OF OCULAR TISSUE

A

SURFACE ECTODERM
- LENS
- LACRIMAL GLAND AND NASOLACRIMAL SYSTEM
- EPITHELIUM OF CORNEA
- EPITHELIUM OF CONJUNCTIVA
- MEIOBIAN GLANDS

NEUROECTODERM
- RETINA
- OPTIC NERVE
- SPHINCTER PUPILLAE AND DILATOR PUPILLAE
- EPITHELIUM OF IRIS
- EPITHELIUM OF CILIARY BODY

MESODERM
- EOM
- BLOOD VESSEL ENDOTHELIUM AND IN SCLERA AND CHOROID
- SUSPENSORY FIBRES
- ANGLE OUTFLOW APPARATUS

NEURAL CREST
- IRIS STROMA
- CORNEAL STROMA AND ENDOTHELIUM
- TM and SCHLEMM’S CANAL
- CILIARY MUSCLE
- CONNECTIVE TISSUE
- BONY STRUCTURE OF ORBIT

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19
Q

CAVERNOUS SINUS

Location in relation to other structures

A

Either side of sella turcica
Lateral and superior to sphenoid sinus
Immediately posterior to optic chiasm

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20
Q

CAVERNOUS SINUS

receives blood from which veins

A

Facial veins (via sup and inferior ophthalmic veins)
Sphenoid veins
Middle cerebral veins

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21
Q

CAVERNOUS SINUS

Empties into..

A

Inferior petrosal sinus -> Internal jugular vein
Superior petrosal sinus ->Sigmoid sinus -> IJV

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22
Q

Most common cause of CL associated corneal ulcers

A

Pseudomonas

sensitive to aminoglycoside (neomycin, gentamicin) and quinolone (ciprofloxacin) antibiotics.

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23
Q

MITOSIS

A

INTERPHASE - chromosomes prepare to divide

PROPHASE - chromosomes condense

METAPHASE - chromosomes line up on equator of cell

ANAPHASE - chromosomes begin to seperate

TELOPHASE - chromosomes have segregated to the poles and the nuclear membranes reform

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24
Q

SYMPATHETIC OPHTHALMITIS

A

B/l granulomatous pan-uveitis - can occur after traumatic injury to 1 eye, where uveal tissue is incarcerated in sclera

Dalen - Fuch’s nodules are an accumulation of macrophages in the RPE

Condition can lead to exudative retinal detachment secondary to severe inflammation, with consequent hypotony and phthisis bulbi.

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25
Q

Oxybuprocaine

A

Local anaesthetic - toxic if used systemically

Bacteriostatic so proxymethocaine preferred for corneal scrapes

Tetracaine has longer anaesthetic effect that oxybuprocaine

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26
Q

Muscles of facial expression

A

The muscles of facial expression are innervated by the facial nerve and include:

procerus
frontalis
corrugator supercilii
orbicularis oculi
zygomaticus major and minor
levator labii
nasalis
depressor supercilii
occipitofrontalis
buccinator

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27
Q

THYROID HORMONES

A

Peptides
T3>T4
99% bound to thyroxine binding globulin
Thyroxine sensitises myocardium to NA

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28
Q

HYPERSENSITIVITY REACTIONS W/ EXAMPLES

A

ACID

T1 - ALLERGIC
IgE mediated - quick onset after exposure
E.g. bee sting, latex, drug allergy

T2 - CYTOTOXIC/ANTIBODY-MEDIATED
E.g Haemolytic reactions, Good pasture syndrome, Hyperacute graft rejection, blood transfusion reaction

T3 - IMMUNE COMPLEX/IGG/IGM MEDIATED
Immune complex deposition
E.g Hypersensitivity pneumonitis, SLE, PAN, RA, glomerulonephritis

T4 - DELAYED/CELL-MEDIATED
E.g. chronic graft reactions, contact dermatitis.

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29
Q

HORNER’S SYNDROME

A

Miosis - reacts normally to light
Partial ptosis - disappears w/ topical phenylephrine
Conjunctival injection
Updrawing of lower eyelid which looks like enophthalmos
Decreased sweating of face

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30
Q

DOWN’S SCREENING TEST

A

At 12wks, together the

Nuchal scan (Thickened)
bHCG (Elevated)
PAP (Reduced)

identifies those at high risk of a Down syndrome pregnancy in greater than 80% of cases.

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31
Q

Primary metabolic substrate of the cornea is

A

Glucose

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32
Q

synaptic terminals of the cones/rods

A

cones - pedicles
rod - spherules

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33
Q

CHOROID LAYER comprising large arteries and veins

A

Haller’s layer comprises large arteries and veins.

Sattler’s layer, which lies above Haller’s layer, is composed of arterioles and venules which supply the choriocapillaris directly above.

Above layers are not fenestrated unlike the capillaries in the choriocapillaris which lie above both layers -> Fluoroscein leakage is seen in the choriocapillaris.

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34
Q

Clinical and anatomic terms for the regions of the fundus:

A

CLINICAL
posterior pole -> macular lutea ->fovea centralis

ANATOMICAL
area centralis -> fovea -> foveola

posterior pole: area centralis
(the area between the vascular arcades)

macula lutea: fovea
(1.5 mm diameter area, yellow from xanthophyll)

fovea centralis: foveola
(0.35mm central depression with thickened margins)

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35
Q

MOA of botox

A

Botox binds irreversibly
to presynaptic receptors on the nerve terminal of the neuromuscular junction,
inhibiting the release of acetylcholine following an action potential.

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36
Q

Dimensions of CORNEA

A

Form ant 1/6th of eyeball

LENGTH
10.6mm vertically
11.7mm horizontally (10mm at birth)
Post diameter circular 11.7mm

THICKNESS
Centre is thinnest 0.5-0.6mm
Peripherally 0.7mm

RAD OF CURVATURE
Ant surface - 7.7mm
Post surface - 6.9mm
More curved in vertical than horizontal plane (regular astigmatism)

n=1.37

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37
Q

LAYERS OF CORNEA

A

FRONT TO BACK

EPITHELIUM
BOWMAN’S LAYER
SUBSTANTIA PROPRIA
DESCEMET’S MEMBRANE
ENDOTHELIUM

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38
Q

Diploë

A

Diploë is the name of the spongy bone that separates tables of compact bone.

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39
Q

WALLS OF ORBIT

A

MEDIAL (post to anterior)
- Body of sphenoid
- Ethmoid
- Lacrimal
- Maxilla

FLOOR
- Maxilla
- Palantine
- Zygoma

LATERAL WALL
- Zygoma
- Great wing of sphenoid

ROOF
- Frontal
-Lesser wing of sphenoid

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40
Q

MEIOBIAN GLAND

A

tarsal glands embedded in the tarsal plates.

openings, 20–25 in each lid

posterior to both the lash line and the grey line

modified sebaceous glands - oily substance forms outer layer of the precorneal tear film

Meibomian gland dysfunction/posterior blepharitis
Anterior blepharitis involves crusting/debris and inflammation around the lash line, and the two often coexist.

A chalazion is a lipogranulomatous inflammatory cyst resulting from a blocked Meibomian gland.

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41
Q

INNERVATION OF LACRIMAL GLAND

A

Parasympathetic supply

lacrimatory nucleus OF FACIAL CN7
-> nervus intermedius
-> pterygopalatine ganglion
-> via the maxillary nerve to its zygomatic and zygomaticotemporal branches
->via the lacrimal nerve to the gland.

Sympathetic supply,
superior cervical ganglion
->nerve plexus surrounding ICA
-> deep petrosal nerve to its zygomatic and zygomaticotemporal branches
->via the lacrimal nerve to the gland.

Sensory supply
- From lacrimal nerve, which is a branch of the trigeminal nerve (V1).

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42
Q

FORAMEN SPINOSUM

A

Connects middle cranial fossa with inferotemporal fossa

Transmits
-meningeal n of mandibular n
middle meningeal artery and vein

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43
Q

EOM VS SKELETAL MUSCLES

A

Thin, delicate CT including epimysium sheath
Loosely packed muscle fibres
Larger fibres in centre, small in periphery
Long muscle spindles 1mm in length
More vascular

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44
Q

BRANCHES OF FACIAL CN7 N

A

Two Zebras Bit My Coccyx
-Temporal
-Zygomatic
-Buccal
-Mandibular
-Cervical

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45
Q

Lens Capsule Dimensions

A

posterior pole 2–3 μm
anterior pole 9–14 μm
peri-zonular region the capsule is 17–28 μm

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46
Q

site of attachment of the vitreous base?

A

Peripheral retina and pars plana

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47
Q

PARS PLICATA and PARS PLANA

A

pars plicata forms the anterior portion and is contiguous to the posterior surface of the iris. It represents approximately one quarter of the whole CB.

The pars plana, the posterior portion of the CB, is contiguous to the choroid at the ora serrata

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48
Q

LAYERS OF CHOROID

A

Outer to inner

VESSEL LAYER
-loose CT w/ melanocytes
- embedded w/ large-medium vessels (branches of short posterior ciliary arteries)

CAPILLARY LAYER
- wide-bore capillaries w/ sac like dilatations
- again supported by CT and melanocytes
- lined by continuous layer of fenestrated endothelial cells
- capillary density and bore greatest at macula

BRUSCH’S MEMBRANE
2-4micrometers thick
1. BM of choriocapillaris
2. Outer collagenous layer
3. Elastin layer
4. Inner collagenous layer
5. BM of RPE

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49
Q

CILIARY BODY

A

AP length temporal (5.6-6.3mm) >nasal (4.6-5.2mm)

Blood supply - via the
- anterior ciliary arteries
- long posterior ciliary arteries

The ciliary body stroma lies between the ciliary muscle and the ciliary epithelium.

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50
Q

Layers of ciliary body muscles

A

outer longitudinal layer - attaches to the scleral spur

middle radial layer - continuous w/ corneoscleral meshwork

third (innermost) - composed of circular fibres

CONTRACTION OF CILIARY MUSCLES ESP 1 AND 3 -> used in convergence, accomodation

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51
Q

IRIS BLOOD SUPPLY

A

Iris capillaries are non-fenestrated - tight junctions and pericytes contribute to the blood ocular barrier.

Most of the anastomoses between the major and minor arterial circles run through the IRIS STOMA in a radial manner. (Anterior border layer - significant vascularisation here suggests ischaemic insult.)

The MAJOR arterial circle of the iris receives blood from
- anterior ciliary arteries (which travel anteriorly with the extraocular muscles before piercing the sclera)
- long posterior ciliary arteries (which pierce the sclera near the optic nerve and run anteriorly between the sclera and choroid to the ciliary body).

The MINOR arterial circle of the iris is at the level of the collarette

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52
Q

LYMPHATIC DRAINAGE

A

Right lymphatic duct (empties into right subclavian vein) - drains right head, neck, arm

Thoracic duct (empties into left into left subclavian vein) - drains rest of body

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53
Q

GCA - what part of artery affected

A

Internal elastic lamina (part of intima) is fragmented in giant cell arteritis.

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54
Q

Compared to plasma, aqueous contains:

A
  • Higher levels of
  • lactate
  • ascorbate;
  • Similar concentrations of
  • Na
  • K
  • Mg
  • Lower levels
  • bicarbonate;
  • glucose
  • calcium (about half that of plasma),
  • much lower levels of albumin.
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55
Q

COLLAGEN SYNTHESIS

A

Stage of collagen synthesis

Transcription
DNA → RNA

TRANSLATION
RNA → peptide formation
The basic amino acid sequence is repeating triplets
(Glycine-X-Y )n
where X is often proline, Y is often hydroxyproline Polypeptides (primary structure) twist into a left-handed helix (secondary structure; ≠ α-helix)

POST-TRANSLATIONAL MODIFICATION (ENDOPLASMIC RETICULUM)
- Vitamin C-dependent HYDROXYLATION of the Y-position amino acid
- GLYCOSYLATION
- TRIPLE HELIX FORMATION (tertiary structure) linked by covalent S–S bonds

EXCRETION FROM CELL
Cleavage of terminal peptide chains, making it insoluble

(EXTRACELLULAR MODIFICATION)
Lysine oxidation
Formation of crosslinks

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56
Q

matrix metalloproteinases (MMPs)

A

zinc and calcium-dependent endopeptidases

act as an enzyme cascade to degrade extracellular matrix.

required for normal tissue growth (make room)
regulated by Endogenous inhibitors called TIMPs are present in normal tissues

released mainly by neutrophils in acute inflammation
___
MMPs in the cornea,

  • maintenance of normal framework (principally MMP-2)
  • remodelling following injury: MMPs:
    - MMP-1 (a collagenase),
    - MMP-2 (a gelatinase)
    - MMP-3 (a stromelysin),
    all produced primarily by the stroma, along with MMP-9 (a gelatinase) produced primarily by the epithelium.
    MMP-9 is involved in corneal epithelial remodelling.
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57
Q

LENS PROTEIN

A

Cytoplasmic interdigitations between lens fibres contain channels formed by MIP26 (aquaporin-0)

FIBROBLAST growth factor stimulates the differentiation of lens epithelial cells into lens fibres

genes encoding α-crystallin are found on chromosomes 21 and 11

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58
Q

Glycosaminoglycans

A
  • composed of long chains of repeating disaccharides
    -relatively inflexible molecules
    -strongly hydrophilic - form a gel resistant to compression
    -high negative charge
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59
Q

corneal endothelial cell pump

A

moves sodium and bicarbonate from the stroma to the aqueous by active transport.

mediated by a sodium/potassium-dependent ATPase and a bicarbonate-dependent ATPase,

facilitated by co-transporters.

Potassium and chloride move to the aqueous predominantly by passive diffusion.

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60
Q

PERICYTE COVERAGE

A

frequency of 1:1 pericytes to endothelial cells

meticulous metabolic demands of the retina and the requirement to maintain the blood–retinal barrier.

Conversely choroid — less dense coverage of pericytes, facilitating exchange of metabolites.

61
Q

ROLE OF PERICYTES

A

contractile cells embedded in the BM of vessels

regulatory functions
- communicating w/ endothelial cells
by paracrine signalling and direct contact.
-maintaining the blood–brain barrier - regulate permeability.
?role in controlling cerebral blood flow.

62
Q

VEGF

A

Aflibercept - decoy VEGF receptor molecule

Bevacizumab VEGF mab

Ranubizumab VEGF man-fragment

VEGF synthesis is upregulated by
TNFα, TNF-β, IL-1α, IL-6, prostaglandin
E2, epidermal growth factor, fibroblast growth factor, insulin-like growth factor-1, keratinocyte growth factor and platelet-derived growth factor.

All three identified VEGF receptors act via intracellular tyrosine kinase activity.

ROLE - promote the division and survival of vascular endothelial cells, VEGF promotes vascular dilatation and permeability to macromolecules. It also has functions in regulating gene expression, cell migration and nitric oxide production.

63
Q

CONE/ROD PHAGOCYTOSIS

A

About 10% of the rod outer segment is phagocytosed daily, and it takes 9–10 days for the renewal cycle to be complete.

Melatonin is synthesized by photoreceptors in conditions of darkness and suppresses dopamine production. Conversely, local dopamine production increases during conditions of light and suppresses melatonin production. These mechanisms are involved in modulating the circadian rhythm of photoreceptor renewal, with rod disc shedding and phagocytosis occurring at first light.

Cone outer segments are predominantly shed at the onset of darkness.

Rod discs are phagocytosed in groups of approximately 200. It is hard to measure cone segment phagocytosis experimentally.

63
Q

STRUCTURE OF MRNA

A

introns are removed before it leaves the nucleus as mature mRNA

a poly-adenine tail provides stability to mature mRNA leaving the nucleus and helps to prevent degradation before translation

a cap of ATP/GTP is added to the 5’ end which facilitates binding to the ribosome

the start codon is AUG which codes for methionine

it is synthesised from a single strand of DNA by RNA polymerase II enzyme

64
Q

The inner capillary plexus of the retina is contained in the

A

ganglion cell layer.

65
Q

Collagen type that forms an integral part of hemidesmosomes and the anchoring fibril architecture of the corneal epithelium to the Bowman’s.

A

TYPE VII 7

66
Q

SIGMOID SINUS

A

continuation of the transverse sinus

ends below the jugular foramen.

groove of the sigmoid sinus is on the mastoid process of the temporal bone; and runs along the border of the temporal and occipital bones.

receives blood from the cavernous sinus via the superior and inferior petrosal sinuses

close proximity to the mastoid air cells, infection in this region can cause thrombosis.

67
Q

Compared to plasma, CSF has:

A

Increased
-pH
-Chloride
- magnesium

Lower everything but
- (low o2 as low pH)
- (almost absent protein)
- (glucose is 2/3rd that of blood)

68
Q

Main GAG or corneal stroma

A

keratan sulphate (most common) and dermatan sulphate

69
Q

Staph aureus:

A
  • grows well on blood agar
  • main commensal of the outer eye
  • aerobic
  • non-motile
  • it is a Gram positive bacteria
  • it can produce exotoxins
70
Q

Rx for corneal ulcer caused by filamentous fungi

A

Topical natamycin

Causative organisms include
Fusarium,
Aspergillus
Penicillium

71
Q

Cyclosphosphamide MOA, SEs

A

alkylating agent - interferes with DNA replication by forming intrastrand and interstrand DNA cross-links.

SE: most commonly bone-marrow suppression, particularly granulopoiesis and lymphopoiesis, which is almost universal.

Haemorrhagic cystitis is also common, occurring in up to 10% of patients. Other side-effects include bladder cancer, hepatic toxicity, amenorrhoea and azoospermia (usually reversible).

72
Q

Yoked muscles ??

A

Yoked muscles receive equal and simultaneous innervation in accordance with the Hering ‘s law. The right inferior rectus is yolked with the left superior oblique (as the eyes look right and downwards). Other options supplied are true.

73
Q

The Purkinje effect

A

The Purkinje effect describes the shift in spectral sensitivity from 555nm (yellow) to 505nm (blue-green) with dark adaptation as rod function overtakes cone function. This results in an enhanced sensitivity to short (blue-green) wavelengths at dusk.

74
Q

Reis–Buckler Corneal dystrophy

A

-aD
-characterised by granular deposits in the epithelial basement membrane.
-stain with Masson’s trichrome.
-manifests clinically as recurrent corneal erosion and corneal opacification which may require corneal grafting.

NB: All corneal dystrophy is autosomal dominant apart from Macular Corneal Dystrophy (aR).

75
Q

Gene Therapy

A

-aims to treat a genetic condition by replacing the abnormal gene with a healthy one or by manipulating its expression.

Viral vectors include adenoviruses, retroviruses, adeno-associated viruses and herpes simplex viruses.

Non-viral vectors include liposomes and naked DNA in the form of plasmids.

Ribozymes (RNA that catalyses reactions) are also a tool in gene therapy but they are not vectors: they are used to cut mRNA of the target gene to block transcription.

76
Q

Antigen presenting cells:

A

Antigen presenting cells (APCs) include:

monocytes,
macrophages,
dendritic cells,
some B cells,
activated endothelial cells.

They constitutively express MHC class II molecules.

APCs do not include T cells; the main function of APCs is to allow T cells to recognise antigens.

77
Q

Minimum sterilisation times for dry and moist heat

A

Moist Heat Temperature (oC)
121–124 - 15mins
126–129 - 10mins
134–138 - 5mins

Dry Heat Temperature (oC)
160 - 180mins
170 - 60mins
180 - 30mins

78
Q

BOTOX

A

Botulinum toxin A is a protein

of Clostridium botulinum - gram +ve

internalised by cholinergic nerve terminals and inhibits the exocytosis of acetylcholine.

79
Q

Toxocariasis

A

nematodal infection

typically affects children.

posterior uveitis

part of the differential diagnosis of leukocoria.

Both toxocara and toxoplasma can be transmitted to humans via ingestion of animal faeces. Toxocara canis ova are shed in dog faeces; Toxocara cati ova and Toxoplasma gondii cysts are shed in cat faeces.

Both toxocara and toxoplasma cause white chorioretinal lesions and, in some cases, vitritis.

Infection may be asymptomatic.

80
Q

Haemophilus influenzae

A

aerobic, Gram-negative bacillus

The descriptor coccobacillus is often applied, as the rods are very small and can give the appearance of cocci.

Haemophilus influenzae is best cultured on chocolate agar with added X and V factors.

common cause of respiratory tract infections and sinusitis, the latter becoming orbital cellulitis if spread through the orbital wall occurs.

encapsulated serotypes being more virulent and invasive.

81
Q

IOL placement moved anteriorly

A

Adjust by -1D
(if 17.5-28)

If >28D, -1.5

If <17.5D –0.5

If IOL< 9.5 dioptres - keep same

82
Q

Uveal tract melanomas - percent of locations

A

8% iris,
12% ciliary body
80% choroid

83
Q

Retinal detachment causes

A

Accumulation of sub retinal fluid in all types

RHEGMATOGENOUS
Most common
Liquefaction of vitreous, vitreous traction, retinal tear/break
COMMON CAISES
- PVD causing retinal tear or hole
- Dehiscence of the anterior retina at the ora serrata causing retinal dialysis (usually due to trauma)

EXUDATIVE/SEROUS
Compromised outer blood-retinal barrier
COMMON CAUSES
- Vascular e.g ARMD
- Inflammatory e.g posterior scleritis
- Neoplastic e.g. choroidal melanoma

TRACTIONAL
Contracting proliferative retinal membranes, abnormal vitreoretinal adhesions
COMMON CAUSES
- Proliferative DM retinopathy
- Proliferative viteoretinopathy
- ROP

84
Q

Proliferative vitreoretinopathy

A
  • common cause of failure following retinal detachment surgery
  • more common with
    -large breaks,
    -multiple operations
    -duration of retinal detachment.
    -may also occur in untreated retinal detachment.

Following the break in the retina, RPE cells migrate into the subretinal space and vitreous.

The blood–retinal barrier is broken and inflammatory cells are recruited.

Fibrosis and collagen production occur, contributing to the formation of retinal membranes.

Contraction of these can lead to retinal detachment and, if untreated, ocular hypotony (not raised intraocular pressure) and ultimately phthisis bulbi.

85
Q

Phases of healing of a full-thickness corneal laceration

A

MINS
- Retraction of Descemet’s and stromal collagen
- Fibrin plug formation
- Stromal oedema
- Invasion of leukocytes from aqueous and limbal vessels

HOURS
- Transformation of leukocytes and of stromal keratocytes into fibroblasts
- Collagen formation
- Start of epithelial regeneration

DAYS
- Endothelial sliding, filling in gaps in endothelium and Descemet’s

WEEKS
- Replacement of stroma and Bowman’s layer with scar tissue

86
Q

Ciclosporin
DRUG CLASS
MOA
OTHER EXAMPLE W/IN CLASS
SEs

A

calcineurin inhibitor

inhibits transcription of IL2 and other cytokines

TACROLIMUS, CICLOSPORIN

SEs:
nephrotoxicity
tremor
hirsutism
gingival hypertrophy

87
Q

HORNERS TESTS

effects of
COCAINE 4%
HYDROXYAMPHETAMINE 1%
APRACLONIDINE 0.5%/1%
PHENYLEPHRINE 1%

A

COCAINE
Fails to dilate pupil as NA reuptake inhibitor but no NA released

HYDROXYAPHETAMINE
ONLY fails to dilate in 3RD ORDER LESIONS as causes release of NA

APRACLONIDINE (ALPHA 2 AGONIST W/ WEAK ALPHA1 ACTIVITY)
Denervation hypersensitivity to apraclonidine occurs due to up regulation of iris alpha-1 after a few days
Pupil dilates in all cases

PHENYLEPHRINE (A1 AGONIST) - SAME AS APRACLONIDINE

88
Q

BRIMONIDINE

A

α2 adrenoreceptor agonist

lowers aqueous production
AND
increases uveoscleral outflow.

α2 agonists such as brimonidine carry more risk of allergy (approximately 10%).

However, they are considered safer than the others in pregnancy,
and
not contraindicated in asthma (unlike BBs).

89
Q

MOA OF THROMBOXANE A2

A

Vasoconstriction
Platelet aggregation

90
Q

EICOSANOIDS

A

Eicosanoids are an important group of signalling molecules and inflammatory mediators that include prostaglandins and thromboxanes (together termed prostanoids), and leukotrienes. They can be generated as required in response to stimuli. The inflammatory response always involves prostanoid generation.
The precise stimuli vary depending on cell type and include cell damage, thrombin (platelets), complement-derived C5a (neutrophils) and bradykinin (fibroblasts). They are derived from arachidonic acid, which is liberated from cell membrane phospholipids in a rate-limiting step catalysed primarily by phospholipase A2.The enzymes cyclooxygenase (COX-1 and COX-2 isoforms) and lipoxygenase then catalyse the production of different eicosanoids from free arachidonic acid.
Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce inflammation by inhibiting cyclooxygenase and therefore the biosynthesis of prostaglandins, but subsequently have no effect on their actions on target tissue. Prostaglandins exert their effects by acting on G-protein coupled receptors.
Thromboxane A2 is an eicosanoid which causes vasoconstriction and platelet aggregation.

91
Q

HISTAMINE EFFECTS

A

H1
Intracellular
- phospholipase C activation
- increase Ca2+

Extracellular
- increased vasc permeability
- vasodilation
- CNS depressant

H2
Intracellular
-Activation of adenylate cyclase
- increase in cAMP

Extracellular
- Increase gastric acid production
- Increase cardiac stroke volume

__
3 histamine receptors - g-protein coupled.

92
Q

WHAT IS CHROMATICITY

A

nature of the reflected light determines the object’s colour.

‘Colour’ = chromaticity

Depends on:
* Hue
* Saturation
* Luminance

Hue is not independent of luminance (which in this context could also be referred to as luminosity or brightness): with increasing brightness, eventually all hues appear yellow-white (the Bezold–Brücke effect), whilst with very low luminosity all hues appear achromatic.
The perceived colours of objects around us are a product of both the light source and the surface properties of the objects, which determine the composition of the reflected light.
The maximal spectral sensitivity of green cones is 535–550 nm.

93
Q

LIGHT/DARK ADAPTATION

A

Dark adaptation is the process by which the retina increases in sensitivity to light in response to decreasing background illumination.

The dark adaptation curve plots the light intensity required to perceive a spot of light versus time. It is bipartite, with an initial rapid (5–10 minutes) increase in cone sensitivity and then a slower period (15–30 minutes) where rods reach their maximum sensitivity. Thus dark adaptation is complete in 30 minutes in normal subjects.

Fully dark adapted rods allow perception of a spot of light at least 100 times dimmer than cones.

Light adaptation occurs more rapidly than dark adaptation.

94
Q

AQUEOUS HUMOUR PRODUCTION

A

INHIBITED BY ONCOTIC PRESSURE

Oncotic pressure is generated by plasma proteins and works against aqueous humour production. Recall that the aqueous is virtually free of protein in the healthy state.

PRODUCTION MAINTAINED BY
- active secretion in the double- layered ciliary epithelium,
- passive diffusion of ions down their concentration and charge gradients and
- ultrafiltration of water and solutes secondary to the CAPILLARY HYDROSTATIC PRESSURE.

Of these processes active secretion is thought to account for 80–90% of aqueous humour production.

95
Q

Regarding hearing

A

Regarding hearing

Depolarisation of the hair cell in the cochlea occurs due to the influx of
POTASSIUM

Higher frequencies are detected by hair cells near the base of the cochlea

Sound is audible to humans between 20 and 20,000 Hz

Sound is converted by the organ of Corti into action potentials in the auditory nerves

96
Q

Mechanism of OPTICAL COHERENCE TOMOGRAPHY

A

A broadband, low coherence light source is directed at the desired target

A beam splitter is used to simultaneously direct the same light source at
a reference mirror

The reflected light from both the desired target and the reference mirror are directed onto a detector, and the interference pattern is analysed using low coherence interferometry to construct an image of the desired target.

97
Q

Lacrimal gland - how many ducts

A

12 excretory ducts.

orbital portion of the gland contains fine interlobular ducts that unite to form 3-5 main excretory ducts,

joining 5-7 ducts in palpebral portion

98
Q

RETINITIS PIGMENTOSUM

A

can be caused by a host of mutations, some of which code for rhodopsin.

peripheral retinal atrophy with streaks of pigmentation (bone-spicule appearance—> fine and course strands of pigmentation)

microscopy reveals evidence of retinal vessel attenuation and hyalinization.

it causes night blindness

it can lead to tunnel vision

individuals are typically affected in early adult life

99
Q

Shifting the hemoglobin-oxygen dissociation curve to the right

increases the release of O2 to the tissues. This shift occurs in

A

acidosis,
raised temperature
increased 2,3 DPG.

100
Q

The volume of the eye is

A

6.5ml.

101
Q

Where do junctional scotoma and binasal defects lie?

What causes them

A

Junctional scotoma
Anterior to chiasm at the junction of the optic nerve
Sphenoid meningioma

Binasal
Lateral to chiasm
Dilatation of 3rd ventricle in hydrocephalus

Superior bitemporal
Inferior to chiasm
Pituitary adenoma

Inferior bitemporal
Superior to chiasm
Craniopharyngioma; suprasellar or olfactory groove meningioma

102
Q

Name
Location

of

Lacrimal Accessory Glands

A

Krause -> around the conjunctival fornix.

Wolfring -> at the border of the tarsal plate.

103
Q

Branches of EXTERNAL CAROTID ARTERY

A

Some Anatomists Like Freaking Out Poor Medical Students:

S – superior thyroid artery
A – ascending pharyngeal artery
L – lingual artery
F – facial artery
O – occipital artery
P – posterior auricular artery
M – maxillary artery
S – superficial temporal artery

104
Q

The most vulnerable sites to globe rupture are:

A

*at or just posterior to the insertion of the rectus muscles;
* At the corneoscleral junction (limbus);
* At the site of previous surgical incisions.

ie. Where the sclera is thinnest. Ie usually anterior to the equator

Globe ruptures occur more often in the left eye, as a significant proportion are due to assault by a right-handed assailant.

105
Q

Volumes of chambers

A

Anterior chamber = 250micro litres

Posterior chamber = 60 micro litres

Vitreous body = 4ml

Intraocular volume = 6.5ml

106
Q

Enzyme-linked immunosorbent assay (ELISA)

A

plate-based assay

both qualitative and quantitative

used to detect
- antigen
- antibody
- peptides,
- proteins
- hormones.

HIV

It is highly sensitive and specific, although it may not detect a mutated antigen.

Unlike radioimmunoassay, ELISA does not require the use of radioisotopes. Instead the antibodies (or antigens) are labelled with an enzyme (such as horseradish peroxidase) which induces a colour change in a substrate when present.

107
Q

major neurotransmitter at the synapse between photoreceptors and
bipolar cells

A

GLUTAMATE

108
Q

VISUAL CYCLE

A

The human visual cycle involves phototransduction and the subsequent regeneration of visual pigment. 11-cis retinal (a chromophore) is covalently bound to opsins via a lysine residue on one of the transmembrane domains. Upon photon absorption, it undergoes photoisomerisation from 11-cis retinal to all-trans retinal, triggering the phototransduction cascade. All-trans retinal is converted to all-trans retinol in the photoreceptor outer segment before being transported to the retinal pigment epithelial cells, where it is reconstituted into the 11-cis retinal isoform (an isoform of vitamin A derived from carotenoids).

109
Q

actin

A

Actin is an important component of the cytoskeleton. It is a protein in the form of a microfilament, 7 nm in diameter, and can exist in monomeric and polymeric forms. Unlike microtubules, which are larger and rigid, actin is flexible.
As well as providing structural support, actin is involved in cell motility, cell division, cell–cell interactions, contractility and the interaction of transmembrane and cytoplasmic proteins.

110
Q

PHARYNGEAL ARCHES

A

1
Muscles of mastication (masseter, pterygoids, temporalis);
mylohyoid;
tensor tympani;
tensor veli palatini;
anterior belly of digastric

2
Muscles of facial expression (surrounding the eye these include orbicularis oculi; corrugator supercilii; depressor supercilii; procerus and occipitofrontalis);
stylohyoid;
stapedius;
posterior belly of digastric

3
Stylopharyngeus

4
Pharyngeal constrictors,
levator veli palatini,
cricothyroid

5
Intrinsic muscles of the larynx except cricothyroid

111
Q

SINUSES PRESENT @

A

The sphenoid sinus normally develops two to three years after birth and reaches
its adult size around age 14. The ethmoid and maxillary sinuses are usually present at birth, while the frontal sinuses, although occasionally present at birth, usually appear at around two years after birth. They continue to develop well into and even following puberty. The maxillary sinuses are the first sinuses to appear (usually at 3–4 months’ gestation) and are also the largest paranasal sinuses.

112
Q

HYALOID ARTERY

A

The hyaloid vasculature develops between the 3rd and 8th week along with the primary vitreous.

From 18 weeks, the hyaloid vessels, the tunica vasculosa lentis and the primary vitreous begin to atrophy. As they regress, Cloquet’s canal is formed.

Blood flow in the hyaloid artery stops at around 30 weeks, and by this point it has ceased to be visible on ultrasound.

By 34–35 weeks it has lost its connection to the optic nerve and has essentially disappeared, though fragments can take longer to resorb entirely.

113
Q

CORNEAL DYSTROPHY INHERITENCE

A

Macular dystrophy - aR disorder.

Granular, lattice and Reis– Buckler dystrophies are all aD, resulting from mutations in the TGF-β-induced gene on chromosome 5q31 (as are Avellino dystrophy and Thiel–Behnke dystrophy).

114
Q

ANIRIDIA

A

b/l disease

congenital - mutation at PAX6 on chromosome 11
a DOMINANT

Ocular features include nystagmus, cataracts and foveal/optic nerve hypoplasia, with later complications including keratopathy and glaucoma.

The commonest variant (approximately 70% of aniridia cases) is inherited in an autosomal dominant pattern, with no systemic associations.

Of the smaller number of non-familial (sporadic) cases, 30%–50% are associated with nephroblastoma (Wilm’s tumour) due to deletion of the WT1 locus adjacent to PAX-6. Genitourinary malformations and mental retardation may also occur; this is sometimes referred to as WAGR syndrome (Wilm’s tumour–Aniridia–Genital anomalies–Retardation).
A rare form of aniridia is Gillespie syndrome, which is usually autosomal recessive and associated with cerebellar ataxia.

115
Q

HARDY WEINBERG EQUILIBRIUM

A

The Hardy–Weinberg equilibrium describes the constancy of gene frequencies in a population from one generation to the next. For a gene with two alleles, it is expressed as:
p2 + 2pq + q2 = 1
where p and q are the frequencies of the two alleles of a gene (i.e. p + q = 1).
It only applies in randomly-breeding populations, in the absence of mutation, genetic drift and natural selection.

116
Q

VON HIPPEL LINDAU

A

autosomal DOMINANT cancer syndrome

mutation in the VHL gene on chromosome 3.

Retinal angiomata (also known as capillary haemangiomata) are the cardinal ocular feature. These are visible on dilated fundoscopy, progressing from a small dot to a vascular mass. These can be treated with laser or cryotherapy and can cause retinal detachment.

Cerebellar haemangioblastoma is also a cardinal feature of VHL but not an ocular one.

Other non-ocular features include renal cell carcinomas and phaeochromocytomas.

117
Q

Chromosomes

A

Metacentric
Submetacentric
Acrocentric
Holocentric
Telocentric

118
Q

COMPLEMENT

A

account for 15% of serum proteins

form an important immunological effector mechanism.

most complement is produced by the liver, extrahepatic synthesis occurs in mononuclear phagocytes. The complement system functions as an enzyme cascade or series of zymogens.

The classical cascade is triggered by antibody–antigen binding, and by acute phase proteins such as CRP.

The alternative pathway is initiated by binding of C3b to factorB on the surface of an organism or foreign material.

There are several regulatory mechanisms preventing inappropriate complement activity, including factor H and factor I (but not factor B), C1 inhibitor and sialic acid.

119
Q

COAGULASE PROMOSTES BACTERIAL SPREAD

A

Coagulase indirectly promotes the conversion of fibrinogen to fibrin, which coats the surface of the bacterium and helps to isolate it from host defence mechanisms, including phagocytosis.

The following promote bacterial spread.

Streptokinase activates fibrinolysin and dissolves fibrin clots;

hyaluronidase breaks down the extracellular matrix constituent hyaluronate;

collagenase dismantles collagen.

120
Q

RISK REDUCTIONS

A

The relative risk reduction (RRR) = (5/10) x 100 = 50%

The absolute risk reduction (ARR) = 10% - 5% = 5%

121
Q

INCLUSION BODIES

A

Owl’s eye inclusion = CMV

Cowdry type A inclusion bodies are nuclear = HSV, VZV

Inclusion bodies can be detected on light microscopy in haematoxylin and eosin (H&E) stained preparations, and may be present in the cytoplasm (predominantly RNA viruses), the nucleus (generally DNA viruses) or both (as in cytomegalovirus).

122
Q

PRISMS

A

Porro prisms
-deviated 180degrees AND inverted
-not transposed

DOVE
- inverted
- not deviated or transposed

Wollaston prisms
- split an incident beam of light into two polarised emergent beams at a fixed angle without dispersion.

Fresnel prisms
- series of parallel small prisms of equal refracting angle which cause an equivalent prismatic effect to a single large prism of the same angle.

123
Q

MAGNIFICATION OF LENSES

A

60 = 1.15
66 = 1.00
78 = 0.93
90 = 0.76

124
Q

REFRACTIVE INDICES

A

Air = 1
Aqueous/Vitreous humour/Water = 1.33
Cornea = 1.37
Lens = 1.38-1.41
Crown glass = 1.52

125
Q

Hruby Lens

A

planoconcave lens

used with the concave surface towards the patient.

It has a power of –58.6 D

forms a virtual, erect
and diminished retinal image that lies within the eye of the patient but within the focal range of the slit lamp (usually in the pupillary plane when the lens is positioned close to the patient’s eye).

126
Q

Deposition material and location in

Fleischer rings

Kayser Fleischer rings

A

Fleischer rings = iron deposition in the basal epithelial layers at the base of the cone

Kayser–Fleischer rings = copper deposition in Descemet’s membrane caused by Wilson’s disease and certain other hepatobiliary pathologies

127
Q

Malignant vs Benign

A

mesenchymal cells
Malignant tumours originating from have the suffix -SARCOMA, whereas benign mesenchymal tumours have the suffix -oma (compare liposarcoma: malignant with lipoma: benign).

Similarly malignant tumours originating from
the epithelial cells of surface tissues are denoted CARCINOMA (e.g. squamous cell carcinoma) and benign tumours are denoted papillomas (e.g. basal cell papilloma).

Glandular epithelial cell tumours are called ADENOCARCINOMA if malignant and adenoma if benign.

Tumours derived from neuroectodermal cells are generally malignant, with the notable exceptions of neurofibromas, ganglioneuromas and some meningiomas.

128
Q

POOR PROGNOSTIC FACTORS IN

CHOROIDAL MELANOMAS

A

Epitheliod cells
Monosomy 3
Partial duplication of 8q
Old
Large tumour size
Extrascleral extension

129
Q

Following separation of the neurosensory retina from the retinal pigment epithelium…..

A
  • Degeneration of photoreceptors
  • Proliferation and migration of the retinal pigment epithelium
  • Subretinal recruitment of macrophage
130
Q

Corneal graft rejection

RISK FACTORS

A

type IV hypersensitivity reaction.

Risk factors include:
* Young age
* Repeat grafts
* Large grafts
* Preoperative stromal vascularisation
* Loose or broken sutures
* Active inflammation

131
Q

Muscarinic anatogonist

Examples

EFFECTS

A

Atropine, cyclopentolate and ipratropium

SE: dry mouth, tachycardia, palpitations, and urinary retention.

The first two agents are common topical mydriatics and cycloplegics, whereas ipratropium is used as an inhaled bronchodilator.

//Pyridostigmine is an inhibitor of acetylcholinesterase, used in the treatment of myasthenia gravis. It enhances rather than blocks acetylcholine activity at parasympathetic synapses.

132
Q

AQUEOUS FLOW

A

CONVENTIONAL - via TM (pressure dependent)
* trabecular meshwork to Schlemm’s canal;
* Schlemm’s canal to collector channels and aqueous veins of Ascher;
* collector channels and aqueous veins of Ascher to venous plexuses and conjunctival veins)

e.g muscarinic agonist pilocarpine causes miosis and ciliary body contraction to open TM channels

UNCONVENTIONAL - uveo-scleral flow
e.g prostaglandin analogue e.g lantoprost

BBlocker/Carbonic anhydrase inhibitors (e.g. dorzolamide)
- reduce aqueous production

AAgonist (e.g. brimonidine) - reduce aqueous production and increase aqueous outflow

133
Q

Drusen LOCATED WHERE

A

Drusen is situated between the basement membrane of the RPE and the Bruch’s membrane.

134
Q

The parasympathetic nerves travel along the

A

inferior division of the oculomotor (third) nerve

—> nerve supplying the inferior oblique muscle

ciliary ganglion;

short ciliary nerve to innervate the sphincter pupillae.

135
Q
A

Squamous cell carcinoma consists of squamous cells with prominent nuclei and abundant eosiophilic cytoplasm.

BCC exhibits the pathognomonic palisading of cells at the periphery of the tumour.

136
Q

NF Type 1 and 2

Autosomal DOMINANT

A

NF Type 1 occurs from a mutation in the NF-1 gene on chromosome 17. It is characterised by:

cafe-au-lait spots
Lisch nodules
goniodysgenesis
retinal hamartomas
optic nerve glioma
phaeochromocytoma (nf1 and vhl)

NOTE: B/L acoustic neuroma is associated with NF Type 2 but can also occur in NF1

________

NF2 - chromosome 22

nearly all patients with NF2 will develop b/l acoustic neuromas before 30

meningioma

137
Q

EOG

A

The EOG is an indirect measure of the standing potential of the eye. It depends on a normal retinal pigment epithelium. It requires co-operation of the patient who moves the eyes back and forth over a specific distance. The light response is higher than dark response. The result is given as a ratio between light to dark response. The normal ratio is more than 180%.

138
Q
A

Luminous flux is the total light (or perceived light power) emitted from a source. It is measured in lumen (lm).

Luminous intensity is the light emitted per unit solid angle; it is measured in candelas.

Illumination/illuminance is a measure of the amount of light arriving at a surface. It is measured in lux, which measures luminous flux per unit area.

Luminance is a measure of the amount of light emitted, reflected, or transmitted from a surface; luminance is measured in lamberts.

139
Q

Stickler’s syndrome

A

most common inherited cause of retinal detachment,

most common cause of rhegmatogenous retinal detachment in childhood.

140
Q

AMINOGLYCOSIDES

e.g. GENTAMYCIN
NEOMYCIN
STREPTOMYCIN

A

they are not as effective against systemic infection if given orally

bind 30s subunit on ribosomes -> inhibits protein synthesis
they act on messenger RNA

they are NOT effective against streptococci or anaerobes as

they require aerobic transport mechanisms to enter the bacterial wall

141
Q

what is the power of the study

A

(1 - beta) is also called the power of a study.

It is the probability of not accepting (i.e. rejecting) the null hypothesis when the alternative hypothesis is true.

Put another way, it is the probability that if there is indeed a difference, that this difference will be found statistically.

142
Q
A

The circle of least confusion in Sturm’s conoid coincides with the focal point of the spherical equivalent of the toric lens.

143
Q

A patient with a history of keratoconus presents with a 1-day history of painful reduction in vision as shown in the image above. What is the initial treatment of choice?

A

This patient has hydrops caused by a rupture of Descemet’s membrane with resultant corneal oedema and opacification. The initial therapy includes topical steroids, cycloplegics, and hypertonic saline drops. Once the condition has settled, scarring may occur and corneal transplantation may then be considered. Corneal transplantation should not be considered in the acute stage while the eye is inflamed.

144
Q
A

120 million rods
6 million cones in the retina.

145
Q
A

The chorda tympani is a branch of the nervus intermedius which in turn is a sensory component of the facial nerve. It contains: the parasympathetic nerve fibres that supply the salivary glands and the sensory nerve fibres that innervate the anterior two-third of the tongue. Anatomically, it passes between the internal jugular vein and internal carotid artery as it travels anteriorly. The greater petrosal nerve that contains parasympathetic nerve fibres to the lacrimal nerve exits the nervus intermedius at the geniculate body and therefore is not part of the chorda tympani.

146
Q

TRIALS

A

I = SAFETY AND SE

II = DOSING AND EFFICACY

III= EFFICACY VS GOLD STANDARD

IV = SURVEILLANCE - EFFECTIVITY AND SIDE EFFECTS

147
Q

CORNEAL ENDOTHEILIAL COUNT

A

KIDS - 3500/mm2

ADULTS = 2500/mm2

ELDERLY = 2000/mm2

148
Q

BCC

A
  1. NODULAR
    well circumscribed
    clear peripheral palisading
    easily excised;
  2. SUPERFICIAL
    appear as lobules localised to the dermal–epidermal junction;

3.INFILTRATIVE
grow aggressively in strands with reduced peripheral palisading
indistinct border;

  1. MUTLINODULAR multiple small nodular aggregates of tumour.

Both infiltrative BCCs and micronodular BCCs have an increased tendency for subclinical spread and caution should be taken to ensure clear margins.

EYEDOCS (2 decks)

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