EYE Flashcards
1
Q
The orbit and its content
A
2
Q
Layers of the orbit
A
3
Q
Content of the orbit
A
4
Q
Fascia which surrounds the eyeball around the sclera
A
BULBAR FASCIA (TENON’S CAPSULE)
5
Q
The … and the … are transparent and do not have blood vessels
A
Lens, cornea
6
Q
The … travels from ciliary body to the cornea so as to nourish it.
A
Aqueous humour
7
Q
The ciliary muscle is attached to the …., so as to relax and contract the lens capsule and the lens.
A
fibers of ciliary zonule
8
Q
What might happen if pressure increases in the SINUS VENOSUS SCLERAE (Schlemm’s canal)?
A
Glaucoma
9
Q
LAYERS OF THE EYEBALL
A
10
Q
The retina originates from an evagination of the secondary prosencephalon (hypothalamus):
A
The optic vesicle, and later, the optic cup
11
Q
DEVELOPMENT OF THE EYE
• inner layer of the optic cup – …
• outer layer of the optic cup – … (pigmentary epithelium)
• invaginating lens placode – …
• optic stalk – …
A
- neural retina
- non‐ neural retina
- lens of the eye
- optic nerve
12
Q
The optic cup has 2 layers: internal and external, separated by an INTRARETINAL SPACE.
EXTERNAL LAYER gives rise to layer … of the retina.
INTERNAL LAYER to layers …
If internal and external layers separate (with a problem in intraretinal space), … could happen.
A
1
2 to 10
RETINAL DETACHMENT
13
Q
Transformation of the optic stalk in the optic nerve
A
14
Q
Embryonic origin of the extrinsic muscles of the eye.
Where do they insert?
A
Somitomeres (non‐segmented paraaxial mesoderm).
These muscles insert into the sclera, except for the levator palpebrae (which inserts in the superior lid to elevate it).
15
Q
Extrinsic muscles of the eye
A
16
Q
Origin of the four rectus muscles
A
common tendinous ring: thickening of periorbita around the optic canal and SOF
17
Q
A
18
Q
Which muscles insert in the anterior quadrant of the sclera and pull the eyeball backwards?
A
Rectus muscles
19
Q
Which muscles insert in the posterior quadrant of the sclera and pull the eyeball slightly forwards?
A
The obliques
20
Q
1st nerve that becomes affected with an aneurysm
A
VI CN (Abducens). The patient might present diplopia.
21
Q
A
22
Q
Which nerve is this one? What does it innervate?
A
TROCHLEAR nerve (IV), it innervates the superior oblique muscle
23
Q
Which nerves are these ones? What do they innervate?
A
24
Q
… muscles pull eyeball lateral & medially, respectively
A
Lateral & medial rectus
25
Because of different axis of orbit & eyeball, … muscles pull the eyeball medially as well as elevate and depress it
superior & inferior rectus
26
Because of their oblique course, the … muscles pull the eyeball laterally as well as down and up
superior & inferior oblique
27
Pure elevation is produced by the … mhuscles acting together
superior rectus & inferior oblique
28
Pure depression is produced by … muscles
IR & SO
29
Name the intrinsic muscles of the eye, their function and their origin
Origin: neural crest cells
1. constrictor m of the pupil – contracts the pupil
2. ciliary muscle – relaxes the lens for accommodation
3. dilator m of the pupil – dilates the pupil
30
Innervation of intrinsic muscles of the eye
AUTONOMIC INNERVATION
- Contrisctor m of the pupil: PS with III
- Ciliary muscle: PS with III
- Dilator m of the pupil: sympathetic fibers
31
INTRINSIC MUSCLES OF THE EYE INNERVATION
32
The eye is supplied by branches of the … that accompany the …
Ophthalmic artery, sensory nerves
33
The … provides supply for the layers 2 to 10 of the retina
Central artery of the retina
*IMPORTANT*: it is a terminal branch, if there is an aneurysm, the retina will become prived of blood flow.
34
The cornea is supplied by blood vessels (T/F)
False: THERE ARE NO BLOOD VESSELS IN THE CORNEA
It is supplied by aqueous humour
35
36
37
central artery of the retina supplies …
ant and posterior ciliary aa supply …
- layers 2 to 10 of the retina
– layer I, vascular and fibrous layers
38
Branches of the central artery and vein of retina…
Enter/exit at the optic disc or papilla and are absent at the fovea centralis
The branches of the central artery of the retina have NO ANASTOMOSES.
39
Venous drainage of the eyeball
40
41
42
Syndrome in which sympathetic fibers are lesioned on one side of the face.
- Palpebral ptosis: no basal sympathetic tone (the superior tarsus lacks of innervation)
• Miosis: pupil is contracted by the PS system
• Lack of sweating (anhydrosis)
HORNER’S SYNDROME
43
Lacrimal system
44
Lacrimal system is under … control
PS
45
46
The contraction of the … compresses the lacrimal sac and produces nasolacrimal drainage
orbicularis oculi m
47
A person wearing glasses with a correction of -3 diopters, suffers from…
MYOPIA (we need a negative power correction because myopia presents to much power, so we need to reduce it)
48
A woman reads a book in a dark room, and then she leans out of the window in a sunny day. The expected result is that:
The crystalline lens flattens/becomes rounder and the depth of field decreases/increases.
Flattens, increases.
49
For myopic people, corrective lenses, glasses or contact lenses, create an image
Upright and virtual
50
One person with normal vision, another one with myopia, and a third with hyperopia are looking at a candle. Indicate how far away the candle must be for the situation in the figure to be feasible.
None, it is impossible.
Normal eye can create an image from 25 cm to infinity, but the others have other behaviours.
A myopic eye can create a good image for close objects and a little far away. So as the image is created in the retina (para que coincida en retina), it should be far away.
In a hyperopic eye, the accommodation range might be from 1m to infinity. So as the image is created in the retina, it should be closer to the eye.
51
A myopic person with a correction of -2.5 diopters reads a book placed at a distance of 35cm from the eye. This lens forms an image that is then the object perceived by the eye. How will the image be, bigger, smaller or same size compared to the original object?
Smaller
52
A woman presents a large floater on her left eye and she experienced an episode of “light flashes” 5 days ago. What does the patient present?
The patient has a detachment of the retina
53
How can we divide the eye?
The eyeball & the retina: two distinct yet interconnected systems
54
The cornea … the light to the retina
Redirects
55
56
57
Cornea
- The … layer of the eye
- Transparent, clear, convex and …
- … innervated
- To provide the … of the eye
- outermost
- avascular
- Highly
- refractive power
58
Name the structure
Corneoscleral limbus: the transitional zone between the cornea and sclera
59
SCLERA
- A thick … containing flat collagen bundles that pass in various directions and in planes parallel to its surface
- Interspersed between the … are fine networks of … and a moderate amount of ground substance
- fibrous layer
- collagen bundles, elastic fibres
60
Why is The Cornea Clear and The Sclera Not?
Connective tissue is formed by fibroblast, collagen and ground substance.
The collagen fibers are highly organized in the cornea (in parallel), in the sclera they are disorganised. They light can pass freely through the cornea.
61
What can we see in this image?
What is the brownish colour?
CILIARY BODY: they look like fingers that go to posterior chamber.
The brownish color is melanin, it helps to protect against radiation.
THE MOST COMMON TUMOUR IN THE EYE IS MELANOMA!
62
Functions of ciliary body
1. Protection against radiation (with pigmented cells that have melanin)
2. Aqueous humour production.
3. Accommodation of the lens.
4. Responsible for the intraocular pressure.
63
64
GLAUCOMA can be caused because of…
An increase of collagen fibers in trabecular outflow pathway (which causes an increase in intraocular pressure). There is less space for water to pass.
65
What structure can be seen?
IRIS
66
The retina is located in the ….
Posterior chamber
67
The retina converts light energy into … that travel out the optic nerve into the brain
membrane potentials (through changes in polarity and the secretion of neurotransmitters - it is part of the CNS)
The more light, the more action potential.
68
What does light do when it enters the eye?
Light will reach the retina, light will hyperpolarise photoreceptor cells, neurotransmitters will be released and the electrical impulse will be generated.
69
What can we appreciate in this image?
Photoreceptors and the Adjacent Retinal Pigment Epithelium (RPE)
70
The RPE serves the Photoreceptors in several distinct ways:
- …. of the photoreceptor outer segments, which are damaged by the impact of millions of photons every day
Each morning, the distal 10% of photoreceptor outer segments are … by the RPE and degraded inside …
Degradation and recycling (DURING SLEEP), engulfed (phagocytosed), lysosomes
71
A 76 year old woman underwent mastectomy for a primary breast malignancy: low grade ductal adenocarcinoma (stage T1 N0)
- Three months after surgery: visual deterioration in her right eye.
In the fundus we can see an elevated mass, mainly yellow in color with some intrinsic pigmentation
What does the patient have?
She has a melanoma: BRAF mutation. There is a drug which can act against it: BRAF inhibitor.
72
The retina is where the … wave is transformed into an electrical signal.
EM
73
The visible spectrum ranges from …
750 to 400 nm
74
On a very sunny day, the pupil of our eye…
Reduces its diameter to the minimum, meaning the behaviour of the eye will be the same as that of the camera obscura.
75
On a cloudy day, the pupil of our eye would…
Increase its diameter: as much less energy is coming in a single ray, we need more rays so as to create an image.
76
On a sunny day, the lens in our eye…
PLAY NO ROLE (more similar to camera obscura)
77
The main role of the lens is…
To recover sharp images when the diameter of the pupil is large.
78
Snell’s law explains…
The behaviour of an EM wave when it reaches the interface between 2 different materials
79
WATER REFRACTIVE INDEX
1.33
80
AIR REFRACTIVE INDEX
1
81
The refractive index of a material is defined as…
The velocity of light in vacuum, divided by the velocity of light in the given material.
82
REFRACTIVE INDEX IN CORNEA
1.4
83
SNELL’S LAW says…
We can characterise the incoming ray by using the angle this ray forms with the perpendicular line (NORMAL AXIS) to the interface
84
When the refractive index in the 2nd material is higher than in the previous, then the trajectory of the ray … the normal axis
approaches
85
When the refractive index in the 2nd material is smaller than the previous, then the trajectory will … the normal axis
move away from
THE REFLECTED ANGLE WILL INCREASE
86
We can only deviate light rays by…
Using an interface (LENS)
87
If the rays incide perpendicularly to the interface…
THERE IS NO DEVIATION
88
Device with a refractive index that is different from the surrounding materials, and whose interface is curved.
LENS
89
Device able to focus/concentrate a set of rays that are coming perpendicular to the lens, into a single point (point known as focus)
CONVERGING LENS
90
The distance between the position of the focus and the lens is called …, denominated "f" and measured in metres
focal length
91
Capacity of a lens to deviate the incoming light rays is known as…
POWER
92
P=
1/f
93
… lens = they separate the incoming light rays. They diverge, meaning their trajectories will not be able to cross in any real point.
However, once again we can derive a "focal length", but in this case it's virtual.
DIVERGING
94
CONVERGING LENS= … distance
Positive (f>0)
95
DIVERGING LENS= … distance
NEGATIVE (f<0)
96
CRYSTALINE LENS and CORNEA are …(converging/diverging) lenses
CONVERGING
97
Lens which are concave on both side are used to correct …
HYPEROPIA (convergent)
98
Lens which are convex on both sides are used to correct…
MYOPIA (divergent)
99
Crystalline lens is…, it can be deformed
ELASTIC
100
When we need a high power (studying) , the crystalline lens will …
Increase its curvature (ciliary muscles contract)
101
When we need lower powers (looking at a landscape), the crystalline lens will…
Relax and be less curved (ciliary muscles relax)
This is why they recommend that we look into the distance every x time, if we're studying for a long period of time and forcing our eyes to concentrate (be contracted) for many hours. It allows the ciliary muscle to relax and rest for a while.
102
NEAR POINT OR CLOSE POINT
Maximum power: the closest the object can be in order to recover a cleat sharp image
103
For normal eye sight, NEAR/CLOSE POINT has to be …
Lower than +25cm
104
FAR POINT:
Minimum power: defines the greatest distance at which we can still see a sharp image
105
The property of being able to recover a sharp image for whatever is the distance of the object is known as…
DEPTH of FIELD
106
When looking at a landscape, iris is more… and the depth of field…
Closed, increases
107
When looking at a portrait, the iris is more … but the depth of field…
Opened, decreases
108
The more … the iris, the larger the depth of field
Closed
109
Presbyopia is caused because of…
Loss of elasticity of the crystalline lens
110
- P which is too large
- Maximum distance is lower than infinity
- Minimum distance is closer than +25cm
MYOPIA
111
Occurs when the power of the combined crystalline lens and cornea is not high enough to create a sharp image
HYPEROPIA
112
In presbyopia, the problem resides in …
In hyperopia, in the…
Elasticity of the lens
Ciliary muscle
113
A person who needs a lens which reduces the power, a negative power (DIVERGING SYSTEM) has…
MYOPIA
114
A person who needs a lens which increases the power, a positive power (CONVERGING LENS) has …
HYPEROPIA
115
Un ojo con miopía e hipermetropía pueden crear una imagen enfocada (T/F)
True: but with a different range
116
MYOPIC LENSES create…
Upright and virtual images
117
FÓRMULAS BIOFÍSICA
