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Duke Elder: Finals Ophthalmology (Alice) > Introduction to Ophthalmology > Flashcards

Introduction to Ophthalmology Flashcards

1
Q

How is transparency of the cornea maintained?

A

relative dehydration of the stroma is maintained by impermeable epithelial barrier and active pumping mechanisms of corneal endothelium. regular spacing of individual stromal collagen fibrils

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2
Q

What is the sclera? Describe it.

A

Outer coat of the eye; opaque, mechanically tough. forms posterior 5/6 of the outer coat of the eye. consists of irregularly arranged collagen fibres

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3
Q

How can you visually differentiate between the retinal arterioles and retinal veins?

A

retinal arterioles are thinner and lighter in colour than the veins

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4
Q

What forms the aqueous humour and where is it located?

A

Active secretion by epithelium of the ciliary body in the anterior and posterior chambers; anterior is between the cornea and iris and posterior is between the iris and lens

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5
Q

What are three functions of the sclera?

A
  1. maintains the eye shape
  2. maintains intraocular pressure
  3. barrier to infection and trauma
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6
Q

What are the two routes of drainage of the eye? What are the relative proportions of each?

A
  1. Conventional route 85%: drains through the trabecular meshwork into the canal of Schlemm in the anterior chamber angle
  2. Uvoscleral route 15%: drains through ciliary body and into ciliary circulation
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7
Q

Where is the ciliary body located?

A

Behind the iris (continuous with it anteriorly, posteriorly continuous with choroid) and encircling the lens, forms part of the uveal tract; divides the posterior chamber from the vitreous

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8
Q

Where is the trabecular meshwork located?

A

Anterior chamber drainage angle; in front of the iris, in angle between iris and cornea

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9
Q

What is the range of normal intraocular pressure?

A

10-21mmHg

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10
Q

What maintains the intraocular pressure?

A

dynamic balance between secretion and drainage of aqueous humour

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11
Q

What is the general name of the condition in which there is high intraocular pressure?

A

Glaucoma

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12
Q

What can glaucoma lead to if untreated?

A

Loss of visual field and eventual blindness

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13
Q

What are 3 things that help ensure the lens is transparent?

A
  1. orderly arrangement of the lens fibres
  2. small difference in refractive index between the various components
  3. absence of blood vessels
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14
Q

What are 3 important roles of the vitreous humour?

A
  1. transparent
  2. protects the ocular structures
  3. passive “transport and removal” of metabolites
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15
Q

where is the vitreous humour located?

A

between lens and retina

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16
Q

What are the two key structures present in the retina?

A
  1. Rods/ photoreceptors: 120 million (monochromatic)

2. Cones: 6 million (colour and fine vision)

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17
Q

What are the two key structures present in the retina?

A
  1. Rods: 120 million (monochromatic)
  2. Cones: 6 million (colour and fine vision)
    (both types of photoreceptors)
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18
Q

What are 3 structures present in between the photoreceptors (rods and cones) and optic nerve fibres?

A

bipolar cells, synapse, ganglion cells

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19
Q

What is the macula?

A

Central vision area of the retina

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20
Q

Where is the macula located?

A

Lies lateral (temporal) to the optic disc: 3-3.5 mm temporal to temporal edge

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21
Q

How can the macula be identified/ what does it look like?

A

Slightly darker than the rest of the retina due to yellow luteal pigment

22
Q

What is the centre of the macula and how is it different?

A

Fovea; rod free, highest visual acuity

23
Q

What part of the optic nerve fibres are demyelinated?

A

Nerve fibres are only demyelinated after leaving the eye

24
Q

What is the course of the optic nerve fibres? Include the 6 components

A

nasal fibres decussate at the optic chiasm (but not temporal fibres). optic nerves –> optic chiasm –> optic tracts –> lateral geniculate nuclei (thalamus)–> optic radiations –> visual cortex (occipital lobe)

25
Q

What is the optic disc?

A

entry of the optic nerve into the eye, approximately 1.5x1.5mm

26
Q

What are 7 general symptoms and 4 visual symptoms to ask about in an ophthalmological history?

A 
General:
1. unilateral/ bilateral
2. onset
3. duration
4. pain
5. photophobia 
6. redness
7. discharge
Visual:
1. visual loss or distortion
2. field defect, where
3. flashers/floaters
4. diplopia - horizontal/vertical/binocular/monocular
27
Q

What is key (in addition to general and visual symptoms) that should be included in an ophthalmological history?

A

Past ocular history, including refractive (spectacles, contact lenses)

28
Q

Which part of the eye will a red eye be associated with?

A

Front of eye

29
Q

Which part of the eye will painless loss of vision be associated with?

A

Back of eye

30
Q

Which part of the eye will distortion of vision/central scotoma be associated with?

A

Macula

31
Q

Which part of the eye will flashes and floaters be associated with?

A

Vitreous or retina

32
Q

What are two classes of refractive error?

A

Emmetropia (no refractive error) and ametropia

33
Q

What are the 3 types of ametropia?

A

myopia, hypermetropia, astigmatism

34
Q

What is myopia?

A

Short sightedness; light rays brought to focus in front of the retina as the eye is too long OR the lens is too strong

35
Q

What is an example of when the lens is too strong, causing myopia, and what is this called?

A

Nuclear sclerotic cataract; index myopia

36
Q

What is hypermetropia?

A

Long-sightedness; light rays brought to a focus behind the retina as the eye is too short OR converging power of the cornea or lens is too weak

37
Q

What is astigmatism

A

the cornea is not spherical, i.e. is rugby ball shaped rather than football shaped

38
Q

What is accommodation?

A

Physiological mechanism that allows close objects to be focused on the retina

39
Q

What changes occur in the ciliary muscle to bring about accommodation?

A

in the non-accomodative state it is relaxed, allowing the suspensory ligaments to remain taught. in accommodation, the ciliary muscle contracts and suspensory ligaments become lax, causing the naturally elastic lens to assume a more globular (convex) shape

40
Q

What is presbyopia?

A

with age (usually over 45 years) the lens gradually hardens and is unable to accommodate (as in hypermetropia)

41
Q

How can presbyopia be corrected?

A

By a weak converging (plus) convex lens

42
Q

What are 5 things to examine in an eye exam

A
  1. Visual acuity
  2. visual fields
  3. colour vision
  4. pupil reflexes (light and accommodation),
  5. Ophthalmoscopy
    (AFRO+ colour vision)
43
Q

Why shouldn’t you ask a patient to look into the ophthalmoscope light?

A

They will accommodate so will constrict, and pupil will also constrict due to light

44
Q

How can you determine whether a patient is hypermetropic or myopic? 2 stages

A
  1. ask them - do you struggle with seeing things up close e.g. reading, or far away e.g. television
  2. look through their glasses; if things appear smaller–> myopic, if larger –> hypermetropic
45
Q

How should the ophthalmoscope be adjusted for hypermetropia and myopia?

A
  1. Hypermetropia –> positive i.e. black numbers
  2. Myopia –> negative i.e. red numbers
    (if thicker glasses, dial to a higher number)
46
Q

How should you decide which diaphragm level (Size of light beam) to use in ophthalmoscopy?

A

use small white beam for undilated pupil, large white beam for dilated pupil

47
Q

What are 4 things to look for/ comment on in opthalmoscopy?

A

colour of disc, cup:disc ratio, contour of disc, new vessels

48
Q

What is the difference between retinopathy and maculopathy?

A

haemorrhages and hard exudates etc. don’t affect macula in retinopathy but do in maculopathy, which is sight threatening

49
Q

How can pre-proliferative retinopathy be identified?

A

more than five cotton wool spots

50
Q

What 3 venous changes can occur in pre-proliferative retinopathy?

A

thickening, tortuosity or beading

51
Q

How can proliferative retinopathy be classified?

A

NVE - new vessels everywhere

NVD - new vessels of disc

Duke Elder: Finals Ophthalmology (Alice) (20 decks)

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