Green 3 Flashcards by Azeem Siddique

Where is the stromal nerve plexus desnsenst in the cornea

Peripherally
Decreases in density and complexity towards the central cornea

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What is the structure of the trabecular meshwork

Uveal meshwork is first layer which has large intercellular spaces and low resistance to aqueous flow

Corneoscleral meshwork has lamellar structure of CT covered by endothelium like cells

Juxtacanalicular meshwork embedded in extracellular matrix composed of collagen, elastic fibres and proteoglycans

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What does contraction of ciliary msucle cause

Expansion of trabecular meshwork,
Enlargement of intertrabecular spaces
Reduced resistance to aqueous flow

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What collagen for conjunctival epithelial basement membrane

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What does ST elevation in leads V1-V4 suggest? ARtery?

II, III, aVF

Reciprocal changes in V1, V2, V3

I aVL, V5, V6

V1-V4 anteroseptal - left anterior descending artery

II, III, aVF - inferior - right coronary artery

Reciprocal changes in V1, V2, V3 - posterior - right coronary artery

I aVL, V5, V6 - lateral - circumflex artery

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Layers of primary visual cortex

2/3 - project to secondary visual cortex
4 - receive optic radiations from LGN
5 - projects to superior colliculus
6 projects back to LGN

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What is noradenaline synthesised from?

Tyrosine
Immediate precursor is dopamine
Dopamine hydroxylase converts dopamine to noradrenaline

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What enzymes metabolise NA

COMT
MAO

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What is the total refracting power of eye with -10D myopia?

Around 70D

Therefore magnification by direct ophthalmoscope 70/4 = 17.5x

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What is lens epithelium

Simple cuboidal epithelium on anterior lens surface

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What is the difference between vitiligo and albinism

IN vitiligo, melanocytes are absent

In albinism, melanocytes present but melanin production is impaired

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What is melanin synthesised from

Phenylalanine
Tyrosine
DOPA
Melanin

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How much CSF produced per day?

550ml/day

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What is total CSF volume

150ml
CSF turnover 4x per day

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When does conjugate fixation rflex develop?
Fix and follow?
Smooth pursuit
Accomodation?
Convergence

Conjugate fixation 2-3 weeks
Fix and follow 6-8 weeks
Smooth pursuit and accommodation - 2 months
Convergence 6 months

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What is the prevalance of robertsonian translocation?

1 in 1000 - most common chormosomal rearrangement

Two long arms of acrocentric chormosomes fuse to form single chormosome
Short arms are non essential and can be lost
Complete data and normal phenotype but only 45 chromosomes

Subsequent risk of trisomy in offspring

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What are MHC class I HLAs

HLA A B and C

HLA D is MHC type 2

What stains for fungi

Calcofluor white - binds to chitin and cellulose in cells wall bluish white under high frequency light

H+E - pink eoisin
PAS - purple
Gomorri methaenamine - black
Gtocott hexamine - black

Which is limited to west africa HIV 1 or 2

HIV 1 - first HIV subtype spread globally
HIV2 - less prevalent and less pathogenic

Does corneal neovascularisation contribute to the immune privilege of the eye

No, allows blood to contract grafts

What are connexins

Gap junctions

Hemichannnels between the cytoplasm of two cells
Found at gap junctions and each cell will provide connexin so complete channel is formed

What tear lens if K reading is > base curve of CL?

K reading is greater - cornea flatter than base curve - convex tear lens

K reading less - steeper - concave tear lens

What inhertiance of Gorlin Goltz

Autosomal dominant

How do sclerosing BCC spread

INvade dermis, spread outwards

What structures are continuous with Tenon's capsule

Fascial sleeve of the EOM tendons Medial and lateral check ligaments which are expansions fo the fascial sleeves of the medial and lateral recti Suspensory ligament of Lockwood inferiorly

What lasers cause photodisruption? Photocoagulation? Photoablation?

Disruption ND YaG Photocoagulation - argon, cyclodiode Photoablation - excimer

Gallilean telescope vs compound microscope

Galiliean - convex objective, concave eyepiece Compound - 2 convex lenses

What are stages of trachoma

I - conj red, oedema II - follicles and papillae, corneal pannus III - inflammatory tissue is replaced by fibrous material IV - contraction of palpebral conj stroma - entropion, trichiasis and cornealdamage

What is metastatic calcifcation?

OCcurs in normal tissues in the presence of hypercalcaemia e.g. chronic renal failure leads to secondary hyperparathyroidism resulting in hypercalcaemia and metastatic calcification

What is dystrophic calcification

Occurs in normocalcaemia in necrotic or hyalinised tissue E.g. phthisical eye

What is forster fuchs spot?

Pigmented macular scar associated with pathological myopia

How do corticosteroids work?

Bind to specific cytoplasmic receptors which translocate to nuecleu and affect gene transcription Reduce transription of COX2 - reduced prostanoid production

What are SE of systemic chloramphenicol

Bone marrow suppression Aplastic anaemia

How does aciclovir work?

REquires phosphorylation to become active Inhibits viral DNA polymerase Specific for HSV and VZV

What are trinucleotide repeat disorders

Fragile X Hunitingtons Myotonic dystrophy Spniocerebellar atrophy Friedereichs ataxia Autosomal dominant Increases severity with increased size of expansion Genetic anticipations

What does full field ERG do

Measures electrical response of retina as a whole when stimulated by a bright flash of light

What do VEPs do

MEasure electrical response of visual cortex to chanding visual stimulus

Rate of aqueous prodiuction

2.5uL/min

What factors shift oxygen-Hb dissociation curve to right

Reduced oxygen binding affinity Increased acidity Increased pCO2 - Bohr effect Increased temperature Increased 2,3 DPG

Nerves of pharygneal arches

1 - V 2 - VII 3 - IX 4 - X SLN 6- X RLN

What percentage of ocular circulation passes through uveal tract

98%

What do intrinsically photosensitive retinal ganglion cells contain

Melanopsin Modulate circadian rhythm (suprachiasmatic nuclei) Sleep regulation cycle Pupillary light reflex