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Sensory > Ophthalmology > Flashcards

Ophthalmology Flashcards

1
Q

Sclera

A

Hard, inflexible white of the eye made of collagen

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2
Q

Uvea

A

Inner vascular layer containing the iris, ciliary body and choroid

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3
Q

Retina

A

Further inner layer that converts information into images

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4
Q

Lens

A

Causes image to be inverted

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5
Q

What type of vision does a visual acuity test check?

A

Central vision

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6
Q

Visual field

A

The portion of the external environment of the observer wherein the steadily fixating eye can detect visual stimuli

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7
Q

Size of monocular visual field

A

Vertical axis: 135˚ –60˚ superior field (limited because of brow) and 75˚ inferior field
Horizontal axis: 160˚ – 60˚ nasal field (limited because of nose) and 100˚ temporal field

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8
Q

Size of binocular visual field

A

180˚ in total with 120˚ overlap between right and left eye, allowing depth perception

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9
Q

Fovea

A

Centre of macula (1.5 mm diameter)

Peak in number of cones, therefore responsible for visual acuity

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10
Q

Macula

A

5 mm ring around fovea in the temporal retina

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11
Q

Foveola

A

Centre of fovea

0.2 mm diameter

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12
Q

Vertical meridian

A

Imaginary line that goes through the fovea

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13
Q

Nasal and temporal retina

A

Nasal retina is medial, temporal retina is lateral
The left temporal retina and the right nasal retina pick up the left nasal and right temporal visual fields and project to the left hemisphere
The right temporal retina and the left nasal retina pick up the right nasal and left temporal visual fields and project to the right hemisphere

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14
Q

Where is the defect in a patient with central scotoma?

A

In the temporal retina of the affected eye

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15
Q

Where is the defect in a patient with bitemporal hemianopia?

A

At the optic chiasm where the optic nerves meet, affecting both nasal retina tracts and inhibiting the temporal visual field in both eyes

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16
Q

Where is the defect in a patient with homonymous hemianopia?

A

Anywhere in the optic tract downstream of the optic chiasm, causing visual field loss on same side of both eyes
E.g., if a lesion in the left optic tract occurred, both eyes would lose the left visual field (nasal retina affected in the right eye affecting the temporal visual field and temporal retina affected in the left eye affecting the nasal visualfiel)

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17
Q

Extra-ocular muscles

A

Superior, inferior, lateral and medial rectus

Super and inferior oblique

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18
Q

Nerves that supply extra-ocular muscles

A

All by oculomotor nerve, except:
Lateral rectus, which is supplied by abducent nerve
Superior oblique, which is supplied by trochlear nerve

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19
Q

7 bones that make up the orbit

A 
Frontal
Sphenoid
Lacrimal
Ethmoid
Maxillary
Zygomatic
Palatine
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20
Q

Obicularis oculi

A

Muscle that closes eyelid

Controlled by facial nerve

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21
Q

Levator palpebrae

A

Muscle that opens eyelid

Controlled by oculomotor nerve

22
Q

Assembly of the eye

A

Cornea: Contains ganglion cells attached to processing and connecting cells and further in these are connected to photoreceptor rods and cones
Rods at a higher concentration in the peripheral retina and cones at a higher concentration near the fovea
Rods and cones attach to the retinal pigment epithelium at the back of the eye

23
Q

Physiological blind spot

A

The optic nerve sits in the nasal retina but has no ability to detect light. This creates a blind spot normally filled in by the temporal retina of the other eye

24
Q

Tear film

A

About 10 mincrons think on front of eye
Consists of oil from tarsal gland (stops evaporation of fluid from eye surface), an aqueous component from the lacrimal gland and mucin

25
Q

Ptosis

A

Dysfunction of levator papebrae superiosus

Can be due to a multitude of reasons including congenital, mechanical, traumatic, neurogenic, etc.

26
Q

Oculomotor nerve palsy

A

Supplies LPS, therefore upper lid ptosis
Pupil dilated
Eye looks to left because only muscles working are now superior oblique and lateral rectus

27
Q

Horner’s syndrome

A

Damage to sympathetic nerves in the face causes ptosis, pupil constriction and anhydrosis

28
Q

Function of tears

A

Lubrication
Oxygen transmission
Vision clarity

29
Q

Function of conjunctiva

A

Oxygen transmission
Tear production
Defence and protection

30
Q

Function of eyelids

A

Protection
Tear film production and distribution
Tear flow and drainage

31
Q

Function of cornea

A

Refractive surface of fixed power
Oxygen transmission
Potection

32
Q

Function of sclera

A

Protection
Ocular rigidity
Attachment of extra-ocular muscles

33
Q

Function of lens

A

Refractive surface of variable power

34
Q

Function of iris/pupil

A

Restriction of light to retina

Reduction of light scatter

35
Q

Function of ciliary body

A

Attachment of lens

Production of aqeuous humour

36
Q

Aqueous humour

A

Transparent, watery fluid similar to plasma, but containing low protein concentrations
Secreted from ciliary epithelium in the eye for nutrient supply to lens and cornea

37
Q

Choroid

A

Provides oxygen and nutrition to outer retina

38
Q

Vitreous chamber

A

Storage of vitreous humour which maintains ocular shape and protects ocular structures during trauma

39
Q

Function of retina

A

Provides visual sensation and converts light images into nerve impulses

40
Q

Function of optic nerve

A

Transmits electrical signals to the brain via the optic nerve

41
Q

Pathway of visual signal

A

Light filtered by iris/pupil and image inverted by lens
Retina converts light image into a nerve impulse which travels through:
Optic nerve
Optic chiasm
Optic radiation
Lateral geniculate nucleus
Ending up at the occipital cortex

42
Q

Rods

A

Process signals within visual images seen at low light levels
Found more in the peripheral retina and are responsible for the detection of peripheral movement

43
Q

Cones

A

Responsible for the detection of colour and fine details, particularly in high levels of light
More concentrated in the central visual field

44
Q

Form/spatial vision

A

Clinically measured by visual acuity which varies with contrast, brightness, eccentricity and the testing procedure
Reflects rod/cone distribution

45
Q

Colour vision

A

Hue, saturation, brightness and colour interactions indicative of cone function and associated processing of visual signal
May be useful in early detection of disease

46
Q

Curvature of the cornea

A

Focuses light
Formed from collagen lamellae that run parallel to surface of eye and underneath collagen formed orthogonally to each other for strength
Needs to be kept in a state of relative dehydration because hyaluronic acid is hydrophilic

47
Q

Keratoconus

A

A physiological difference where the curvature of the eye looks more oblong
Can be genetic or environmental e.g. eye rubbing

48
Q

Types of cells in the retina

A 
Photoreceptors
Horizontal cells
Bipolar cells
Amacrine cells
Ganglion cells
Mueller cells
49
Q

Retinal blood supply

A

Consists of a dual supply: Choroidal to the outer retina and central retinal artery to the inner retina
No blood vessels around the fovea because they disturb visual acuity

50
Q

Accommodation

A

Focusing on something closer, which requires more refraction. Gets worse as we get older, causing presbyopia, a type of long-sightedness

51
Q

Cataracts

A

Lens clouding
Decreased visual acuity
Diagnosis by ophthalmoscope and slit lamp

Sensory (9 decks)

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