Eyedocs answers Flashcards
What are the side effects of 5-FU during glaucoma filtration surgery?
Ischaemic blebs
Hypotony
Suprachoroidal haemorrahge
What is the difference between lentigo maligna and melanoma?
both show proliferation of atypical spindle shaped melanocytes, but melanoma has dermal involvement, and lentigo only has involvement of the epidermis
What type of cell is in a Kaposi sarcoma? Which layer does it involve?
Proliferation of spindle shaped cells and vessels in the dermis layer
What stain is used to identify fungi? (5)
- Gomori-methamine silver - stains black
- Grocott hexamine silver - fungi + acanthomoeba stains black
- Periodic acid schiff - stains purple
- Calcufluor - stains white
- haematoxylin and eosin stains pink
What stain is used to identify calcium (2)
Alizarin Red
Von Kossa
What are the stains involved in dystrophies?
1) Reis-Bucklers
2) Granular Dystrophy
3) Macular dystrophy of cornea
1) Masson Trichome stains new collagen blue
2) Masson Trichome stains hyaline material red
3) Alician blue stains mucopolysaccharides
What are the differences in substance concentrations between aqueous humor and plasma? (3)
- AH has 15 x more ascorbate than plasma
- AH has 35 x less protein than plasma (0.2%)
- AH is more hypertonic and acidic than plasma
- What are granulomatous keratic precipitates made out of ?
- What are non-granulomatous KPs made out of
- Granulomatous KPs - macrophages
- Non-granulomatous KPs - lymphocytes and polymorphonuclear leukocytes
What are the effects of atropine - cholinergic antagonist (2 ocular, 3 systemic)
Ocular
1. mydriasis via iris sphincter muscle paralysis
2. cycloplegia via ciliary body paralysis
Systemic
3. Sedatory effect
4. Delays gastric emptying
5. Reduces sweating
What are the most frequent side effects for prostaglandin analogues? (7)
- Increased iris pigmentation
- Iris cyst formation
- Increased peri-ocular skin pigmentation
- Peri-orbital fat atrophy
- Eyelash hypertrichosis
- Iritis
- CMO
HLA Associations
1. Birdshot choroidoretinitis
2. Presumed Ocular histoplasmosis syndrome / MS
3. Sarcoidosis/Intermediate uveitis
4. Idiopathic ant uveitis, psoriatic, ank spond, Reiter’s, IBD
5. Retinal vasculitis
6. Behcet’s disease
7. Juvenile RA, VKH syndrome, sympathetic ophthalmia
- Birdshot - HLA-A29
- POHS - B7, DR2. MS - B7, DR2, DR15
- Sarcoidosis / IU - HLA-B8
- Idopathic AU, psoriatic, AS, Reiter’s, IBD - HLAB27
- Retinal vasculitis - B44
- Behcet’s - B51
- JRA, VKH, SO - DR4
- What are the main HIV medications?
- What are their main side effects?
- Ritonavir - nausea and diarrhoea
- Zidovudine - cytopaenia
- Zalcitabine - peripheral neuropathy
- Didanosine - pancreatitis
What is the flicker fusion threshold for rods vs cones?
Rods is 20Hz, Cones is 60Hz
Which immunoglobulin passes through the placenta to assist foetal immunity?
IgG
What is the main immunoglobulin in human tears?
IgA
Which sinuses drain into…
1. the superior meatus
2. middle meatus
3. inferior meatus
- superior - sphenoid and posterior ethmoid
- middle - maxillary, anterior ethmoid, frontal
- inferior - opening of nasolacrimal duct
What is the route of the cavernous sinus?
1. Extends from the …. to the ….
2. Opens posteriorly into the ….
3. What structures are on the lateral wall?
4. What structure runs medially?
5. What structure runs in between?
- Extends from SOF to apex of temporal bone
- Opens posteriorly into petrosal sinuses
- Lateral wall - CN 3, CN 4, CN V1, V2
- Medially - internal carotid artery
- In between - CN 6 (abducens)
What is the most appropriate treatment for peripheral CMV retinitis?
oral ganciclovir
Ribosomes are inhibited by which drug?
Chloramphenicol
inositol triphosphate is activated by what? what is its pathway?
activated by alpha one adrenoceptors. Binds to endoplasmic reticulum membrane, increases concentration of intracellular calcium –> smooth muscle contraction –> ++ exocrine secretion and force/rate of cardiac contractions
What is the optimal length for primers in PCR?
17-20 base pairs
What is the optimal temperature for DNA polymerase?
70 degrees
What is ciclosporin’s main side effect?
nephrotoxicity, does not cause bone marrow suppression
What is the difference between the acute inflammatory response and the acute immune response?
INFLAMMATORY:
- vascular phase (histamine, kinins and prostaglandins) causing increased vascular permeability followed by cellular phase (recruitment of macrophages and neutrophils
- it is adaptive and specific
IMMUNE:
- non-specific, non-adaptive and does not exhibit memory
What are the main differences between duction, version and vergence eye movements?
Duction: single uniocular eye movements (adduction, abduction etc)
Version: binocular eye movements - conjugate , synchronous and symmetric movements in same direction
Vergence: binocular eye movements - disconjugate movement of eyes in opposite directions
What are the main characteristics of vergence eye movement -
It is a tracking movement slower than pursuit movement.
It is voluntary and stimulated by blurred images on the retina
It is limited by near and far point of accommodation
Which immunoglobulin is the first antibody to appear in infection?
IgM
What pathway does IgA activate?
Activates the alternative complement pathway (unlike other antibodies that activate the classical pathway)
The posterior pigmented iris epithelium is a continuation of?
The anterior pigmented iris epithelium is a continuation of?
posterior - non-pigmented epithelium of ciliary body
anterior - pigmented epithelium of ciliary body
What is the zonuluae occludantes and where are they located?
- tight junctions between cells
- between RPE cells of retina (blood-retinal barrier) and between non-pigmented ciliary epithelium (blood aqueous barrier)
What receptors do macrophages have? (3)
- pattern recognition receptors which recognise microbial components
- surface receptors that recognise Fc portion of immunoglobulin and complement components. Binding of these receptors to their ligands enhances phagocytosis of antigen (opsonisation)
- MHC class II molecules on surface when activated - present antigen to helper T-cells. Secrete IL-12 which directs T-cell differentiation to Th1 subset.
What pro-inflammatory cytokines do macrophages produce?
IL-1, IL-6, and TNF
What is transcription? What enzyme is involved?
DNA code is read in nucleus and complementary messenger RNA is produced, which leaves for the cytoplasm for protein synthesis.
RNA polymerase in a 5 prime to 3 prime direction
What type of hypersensitivty reaction is Myaesthenia Gravis and Grave’s disease?
Type V (antibody dependent cell mediated cytotoxicity)
What is the function of the iris capillaries?
Form the major site of blood-aqueous barrier.
What is the structure of iris capillaries (3)
1) Non-fenestrated
2) connected by tight junctions
3) have thickened basal lamina strengthened by perivascular collagenous hyalinised layers
What is the mechanism of action of fluoroquinolones?
Inhibit DNA replication by action on bacterial DNA gyrase
What is choroidal thickness? Thickest at ….
Choroidal thickness is 100-200um
Thickest at posterior pole
The activity of NK cells is enhanced by which immunomodulators? (3)
IFN-gamma, IFN-beta, IL-12
NK cells kill viral or bacterial cells?
viral
what is the antibody-independent NK response to viruses? (3 steps)
(1) Normal cells express MHC-1 and activation ligand receptors, which NK cells have receptors for - MHC-1 receptor inhibits NK cell activation
(2) In Virus infected cells, MHC-1 receptors are downregulated, and so NK receptors are activated
(3) NK cells release perforin and granzymes which lyse target cells and induce apoptosis
What is the pathway of antibody-mediated NK cell response? (3)
1) NK cells express receptors for the Fc region of IgG (CD16 and CD56 receptors)
2) When antigen is attached to IgG, the Fc portion goes towards CD16 receptor of NK cell and NK cell becomes activated
3) NK cell induces destruction of antibody - antibody dependent cell mediated cytotoxicity
Which complements are involved in the terminal pathway (membrane attack complex) and its deficiency predisposes to Neisserial infections?
C5-C9 (C3 is also associated)
Which imaging sequence of MRI is most likely coorelate with active orbital inflammation?
STIR sequence MRI
Red-Green defects are in which disease?
acquired optic nerve disease (except glaucoma and autosomal dominant optic atrophy)
Blue-yellow defects are in which disease
Acquired retina disease (except cone dystrophy and Stargardt’s)
IL-2 is produced by what cells?
CD4+ cell
What drugs can cause corneal verticillata or vortex keratopathy? (5 + 1)
(1) Chloroquine
(2) Hydroxychloroquine
(3) Amiodarone
(4) Indomethacin
(5) Phenothiazines
(+1) Fabry’s disease
What are the different serotypes of chlamydia ? what are they responsible for?
A B C - trachoma
D E F G H I J K - genital chlamydia and adult inclusion conjunctivitis
L1 - L3 : lymphogranuloma venereum
what is the mechanism of action of the imidazole antimicrobial?
inhibit cell membrane synthesis by inhibiting synthesis of sterols (important constiutent of fungal cell membranes)
What is the mechanism of action of aciclovir?
aciclovir inhibits DNA polymerase
What are the main examples of trinucleotide repeat disorders? (7)
- Fragile X syndrome
- Friedrich’s ataxia
- Machado-Joseph ataxia
- Spinocerebellar ataxia
- Spinobulbar muscular atrophy
- Myotonic dystrophy
- Huntington chorea
What do MacConkey agar and McCoy agar grow?
- MacConkey agar - lactose fermenting G-ves
- McCoy agar - obligate intracellular bacteria (chlamydia
What does Thayer-Martin medium and Thioglycate agar grow?
- Thayter martin - G-ve cocci (Neisseria)
- Thioglycate: aerobes on surface, anaerobes inside
What does Lowenstein-Jenson medium grow?
Mycobacteria tuberculosis
What does chocolate agar, blood agar and cooked meat both medium grow?
- Chocolate - haemophilus, neisseria, moraxella
- Blood agar - all bacteria except H, N, M above
- Cooked meat broth - anaerobes and fastiduous organisms
What does non-nutrient agar with E.coli grow and Sabouraud agar grow?
- Non-nutrient - Acanthomaeba
- Sabouraud - Fungi
What chromosome codes HLA antigen?
Chromosome 6
HLA Class I Antigens vs
HLA Class II Antigens
Class I : all nucleated cells, allows CD8+ cytotoxic T cells to recognise and eliminate virus infected cells
Class II: macrophages, dendritic cells, B cells, endothelial cells, allows initiation of immune response by interaction with T-helper CD4+ cells
- Whats the difference between staph and strep?
- Whats the difference bewteen staph aureus and staph epidermis?
- staph - clusters, strep - chains/pairs
- staph aureus - clusters and coagulase +ve
staph epidermis - clusters and coagulase -ve
What cytokines do TH1 produce?
What cytokines do TH2 produce?
- TH1 : IFN-gamma, IL2 –> B cells, NK cell and macrophage activation
- TH2: IL3, IL4, IL5, IL6 –> mast cell and eosinophil activation
What are the DNA viruses (7)
- Adenovirus
- Herpes SIMPLEX virus
- Varicella ZOSTER virus
- Epistein Barr virus
- Cytomegalovirus
- Molluscum contagiosum virus
- Vaccinia and variola virus
What are RNA viruses? (5)
- Picorna virus
- Paramyxo virus
- Toga virus
- Flavi virus
- Filo virus
Which virus is the most common cause of conjunctivitis? Which subtype?
Adenovirus (DNA) –> mostly belong to subgroup D (A-F classification) –> usually type 8, 19 and 37 –> type 8 is classic cause of EKC
What are the 3 types of conjunctiva? Subtypes?
- Palpebral (inner eyelid) - marginal, tarsal, orbital
- Bulbar (anterior eyeball) - scleral, limbal
- Forniceal (in between both)
Where is the conjunctiva firmly adherent to? Where is the conjunctiva loosly attached to?
- Adherent to lids over tarsal plates
- Loosely attached to fornices and over globe (except limbus)
- What is the sulcus subtarsalis?
- How far is it away from lid margin?
- When is the subtarsalis scarred?
- Groove 2mm away from lid margin
- 2mm - common site for foreign body lodging
- Trachoma - Arlt’s line
Where are psammoma bodies found?
In meningiomas
What are the ocular manifestations of chloroquine use? (3)
- Corneal deposition
- Anterior subcapsular cataract
- Bull’s eye maculopathy
What is the outcome of glycolysis?
conversion of glucose in cytoplasm to
- two molcules of pyruvate
- two molcules of NADH (–> 2 ATP each)
- two molecules of ATP
What are the main functions of interferon?
- activation of NK cells and macrophages
- directive antiproliferative action on tumour and virus infected cells
- increased expression of Class 1 HLA on infected/tumour cells
What cells produce interferon?
T lymphocytes & macrophages
What conditions can affect the first order neurons in the sympathetic pathway in Horner’s syndrome (hypothalamus to spinal centre of budge)
- CVA
- Lateral medullary syndrome
- Multiple sclerosis
- Neurological disorders and infections
What conditions can affect the second order (preganglionic neurons) from ciliospinal centre of budge to superior cervical ganglion in sympahetic pathway (Horner’s syndrome)
Any disease affecting mediastinum and neck
1. Apex lung lesions - Pancoast
2. Subclavian artery injury
3. Brachial plexus injury
4. Mediastinal lymphadenopathy
5. Dental abscess involving mandibular region
What diseases can affect the third order (Superior cervical ganglion to long ciliary nerves) in Horner’s syndrome
- Carotid cavernous fistula
- Carotid artery dissection/aneurysm
- Raeder paratrigeminal system
- Herpes zoster infection
- Temporal arteritis
- Cluster headaches or migraines
What is the reason for partial ptosis or reverse/inverse ptosis in Horner’s syndrome?
- Symphathetic chain supplies superior tarsal plate, responsible for partial elevation of eyelid
- Sympathetic chain supplies lower eyelid - lesions leads to upward movement of lower eyelid
What happens to the pupil in Horner’s syndrome?
Smaller than other side
Pupillary and accomodation reflex is intact as they are not reliant on sympathetic nerve supply
Which layer do flame haemorrhages occur?
Which layer do dot blot haemorrhages occur?
Which layer do hard exudates and CMO occur?
- flame - nerve fibre layer
- dot/blot - inner/outer plexiform layers
- exudates/cmo - outer plexiform layer
What are the 3 main features of malignant tumours?
- Cellular and nuclear pleomorphism
- Nuclear hyperchromatism
- Decreased cytoplasmic:nuclear ratio
What is the difference between type 1 HIV and type 2 HIV?
Type 1 - urban centre areas, homosexuals and IVDUs
Type 2 - Africa, heterosexually transmitted
