Paper 2 CRQ Flashcards

(65 cards)

1
Q

Structures of the iridocorneal angle from anterior to posterior

A

Schwalbe Line
Trabecular meshwork
Scleral spur
Ciliary body
Peripheral iris

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2
Q

How does aqueous humour drain from the trabecular meshwork

A

Pass from the AC into the trabecular meshwork (uveal, corneoscleral, juxtacannalicular) and into Schlemm canal.
From Schlemm canal drains into collector channels and the aqueous veins of Ascher into venous plexuses and conjunctival and episcleral veins

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3
Q

Impact of the rise in pressure on the uveoscleral outflow

A

No impact- this pathway is not pressure sensitive

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4
Q

How do alpha agonists work to reduce IOP

A

Decreased aqueous production and increased outflow at least partially via the uveoscleral pathway

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5
Q

How do carbonic anhydrase inhibitors work?

A

Decreased aqueous production eg Dorzolamide, Brinzolamide

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6
Q

How do Parasympathetomimetics work?

A

Increased outflow via conventional pathway eg Pilocarpine

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7
Q

How does hyperosmotic agents like Mannitol work?

A

Decreased vitreous volume

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8
Q

What GPCR is found in the eye

A

Rhodopsin found in the outer segments of rod photoreceptors.

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9
Q

Which drugs target GPCR in Glaucoma

A
  • Beta-blockers/β adrenoreceptor antagonists
  • α2 adrenoreceptor agonists
  • Muscarinic ACh receptor agonists/cholinergics
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10
Q

What is static perimetry

A

Static’ refers to the presentation of visual stimuli: these are stationary, but presented at differing intensities and at different points throughout the potential visual field to determine the sensitivity of the eye at each point.

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11
Q

What is kinetic perimetry

A

where the stimulus is a moving target of a set luminance.

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12
Q

What is manual perimetry

A

an operator choosing when and where to present each stimulus.

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13
Q

Example of static automated perimetry

A

Humphrey is a commonly-used static, automated perimeter

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14
Q

Example of kinetic perimetry

A

Goldmann perimetry is a good example of a kinetic perimeter, which can be manual or automated (it is classically a kinetic test, but may also be used as a static test for the central field).

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15
Q

Normal percentage of acceptable false negatives or fixation losses

A

<20%

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16
Q

Normal percentage of acceptable false positives

A

<10%

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17
Q

What is the definition of pattern standard deviation

A

a measure of the patient’s overall deviation that is adjusted for generalised depression in the visual field (i.e. the deviation of a given area relative to the rest of the patient’s field)

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18
Q

What is the mean deviation in a visual field

A

measures the patient’s values for each data point in the field compared to age-matched norms, the PSD is useful as it is adjusted for generalised depression of the field.This represents diffuse visual loss throughout the field, commonly due to cataract.

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19
Q

Is PSD or MD better at measuring glaucomatous field loss in the presence of a cataract

A

PSD would be more useful for detecting glaucomatous field loss in a patient with cataract than the MD.

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20
Q

What are the units of background luminance in visual field testing

A

apostilbs (asb).

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21
Q

Equivalence of 1 apostilbs in lumen per square metre

A

One apostilb is equivalent to 1 lumen per square metre (or 1/π candela per square metre)

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22
Q

What is the background luminance and maximal luminance of Humphrey perimeter

A

background luminance of 31.5 asb, and a stimulus light with a maximal luminance of 10,000 asb.

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23
Q

What does a 0dB point of stimulus on the visual field tell us

A

the stimulus was maximal intensity (10,000 asb)

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24
Q

What is the dimmest stimulus that a patient can detect in dB

A

33 dB.

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25
Causes of a unilateral arcuate or altitudinal field defect
* Glaucoma * Ischaemic optic neuropathy * Hemiretinal artery or vein occlusion * Optic neuritis * Optic nerve coloboma * Compressive optic nerve lesion
26
Which antibodies are found in SLE
Anti double-stranded DNA (ds DNA) ANA (Not specific to SLE)
27
How is myeloma identified on protein electrophoresis
If the rise in immunoglobulins was monoclonal, a paraprotein band would be seen on protein electrophoresis suggesting myeloma or other monoclonal gammopathy
28
What does a paraprotein band on protein electrophoresis tell us
Monoclonal gammopathy
29
Causes of polyclonal rise in immunoglobulins
infections chronic liver disease autoimmune diseases such as systemic lupus erythematosus and rheumatoid arthritis.
30
Why does CNVI palsy suggest raised ICP
due to the stretching of the nerve during its long intracranial course where it is relatively tethered in Dorello’s canal.
31
What is the purpose of the Amsler grid with black squares and a large Cross across it
To guide the patient’s gaze to the fixation point useful in patients with a significant central scotoma
32
How is a Gram stain performed
Crystal violet dye is applied to the specimen to visualise bacterial cell wall. Iodine is then applied, which fixes crystal violet to the cells. Specimen is then washed with either acetone or ethanol to remove the remaining crystal violet and iodine. A counterstain is applied (usually safranin, although sometimes fuchsine is used) which allows visualisation of Gram negative bacteria.
33
What colour do Gram positive organisms stain
Blue
34
What colour do Gram negative organisms stain
Red/Pink
35
Principal type of immune cell seen during acute inflammation
Neutrophils
36
Antibiotics used for Endophthalmitis
Amikacin IVT. Peripherally through circulation poor ocular uptake Gentamicin can be used but risk of retinal toxicity
37
What is the underlying principle of ultrasound
acoustic impedence
38
How does ultrasound work
A piezoelectric crystal transducer converts electrical energy into high-frequency sound waves which travel through the tissues. The reflected signal (echo) from the target tissue is detected by the transducer and its magnitude measured. Echoes are generated from the interface of tissues with different acoustic impedance. Higher frequencies give greater resolution but less depth of penetration.
39
How does A- scan work
A-scan ultrasound plots the intensity of the echo versus time delay, which can be converted into distance based on the speed of sound in the tissue.
40
What is the frequency of ultrasound and why cant humans hear it
Ultrasound waves have a frequency higher than the audible range for humans (>20,000 Hz, or 20 kHz). The frequencies used in medical ultrasound are typically 8–100 MHz.
41
What is the 'gain' in ultrasound
The degree of amplification of the sound wave
42
Features of a choroidal melanoma on USS
large, solid lesion at the posterior pole of the eye that seems to be arising from the choroid and is collar-stud or mushroom-shaped in appearance. There is an associated retinal detachment. The lesion has low internal reflectivity on A-scan ultrasound
43
Why is the choroidal melanoma mushroom shaped
occurs in 20% of cases due to rupture through Bruch’s membrane.
44
Features of choroidal melanoma associated with a poor prognosis
* Large size * Extrascleral extension * Epithelioid cell type * High mitotic count * Monosomy 3 * Duplication of 8q
45
In immunihistochemistry staining of choroidal melanoma what do epitheloid tumours stain positive for
S100 melan-A HMB45.
46
When looking at a cross through a lens, what movement tells us the lens is concave
Concave lenses cause the image of the cross to move in the same direction as the lens (a ‘with’ movement)
47
When looking at a cross through a lens, what movement tells us the lens is convex
convex (plus) lenses cause the image of the cross to move in the opposite direction (an ‘against’ movement).
48
What are some of the pathophysiological changes observed in AMD
* Degeneration of the retinal pigment epithelium * Loss of photoreceptors * Accumulation of lipofuscin * Drusen formation * Thickening of Bruch’s membrane * Thinning of the outer plexiform layer and choriocapillaris
49
How do magnifiers create an enlarged retinal image
increasing the angle subtended by the object at the eye
50
What does LASER stand for
Light Amplification by the Stimulated Emission of Radiation
51
What are 3 features of laser beams
coherent, collimated and monochromatic Another way of phrasing this is that the rays of light are in phase, parallel and all of the same wavelength
52
What is the active medium of argon laser
argon blue green gas
53
What are the uses of argon laser
panretinal photocoagulation (PRP), focal/grid macular laser and laser trabeculoplasty
54
What is the active medium of Nd-Yag laser
neodymium–yttrium–aluminium–garnet;
55
What is NdYAG laser used for
posterior capsulotomy, peripheral iridotomy selective laser trabeculoplasty (SLT)
56
What is frequency doubled NdYAG laser used for
similar photocoagulation effect and indications as the argon laser panretinal photocoagulation (PRP), focal/grid macular laser and laser trabeculoplasty
57
What is frequency doubled NdYAG laser used for
similar photocoagulation effect and indications as the argon laser panretinal photocoagulation (PRP), focal/grid macular laser and laser trabeculoplastyw
58
What is the active medium for cyclodiode laser
a diode chip
59
What is cyclodiode laser used for
used trans-scerally to destroy the ciliary body to reduce intraocular pressure
59
What is cyclodiode laser used for
used trans-scerally to destroy the ciliary body to reduce intraocular pressure
60
What is the formula for calculating sensitivity
TP/ (TP + FN)
61
What is the formula for calculating specificity
TN/ (TN + FP)
62
What is the formula for calculating PPV
TP/ (TP + FP)
63
What is the formula for calculating NPV
TN/ (TN + FN)
64
What ophthalmology screening programmes are there in the UK
* Diabetic retinopathy * Retinopathy of prematurity * Amblyopia, strabismus and refractive errors in children