Eye Flashcards
(165 cards)
1
Q
A
2
Q
A
3
Q
What is the general shape of the eyeball?
A
Globe-shaped
4
Q
How many layers make up the wall of the eyeball?
A
Three layers
5
Q
What term refers to the three-layered wall structure enclosing the contents of the eyeball?
A
The wall of the eyeball
6
Q
What is enclosed within the layers of the eyeball?
A
The refractive components of the eye
7
Q
Enumerate the refractive components of the eye.
A
Cornea, aqueous humor, lens, vitreous body, retina
8
Q
What structures are responsible for focusing light in the eye?
A
Refractive components (cornea, aqueous humor, lens, vitreous body, retina)
9
Q
How is the eye divided anatomically in terms of compartments?
A
Into anterior and posterior compartments
10
Q
What are the two subdivisions of the anterior compartment of the eye?
A
Anterior chamber and posterior chamber
11
Q
What structures bound the anterior chamber of the eye?
A
Cornea (front) and iris (back)
12
Q
What is the filtration angle in the eye?
A
The point where the cornea and iris meet
13
Q
Where is the posterior chamber located?
A
Between the lens and the iris
14
Q
How does the posterior chamber communicate with the anterior chamber?
A
Through the pupil
15
Q
What occupies the posterior compartment of the eye?
A
Vitreous body
16
Q
What tunic of the eye includes the sclera and cornea?
A
Fibrous tunic
17
Q
What connective tissue composes the sclera?
A
Dense white fibrous connective tissue (DWFCT) rich in elastic fibers
18
Q
What are the three layers of the sclera?
A
Episclera, sclera proper, lamina fusca
19
Q
What is the outermost layer of the sclera?
A
Episclera
20
Q
What type of tissue is the episclera?
A
Transparent fibroelastic connective tissue
21
Q
What structure lies between the episclera and Tenon’s capsule?
A
Tenon’s space
22
Q
What fibrous covering of the eyeball lies peripheral to Tenon’s space?
A
Tenon’s capsule
23
Q
What is the middle portion of the sclera called?
A
Sclera proper
24
Q
What connective tissue is the sclera proper made of?
A
DWFCT rich in inelastic fibers
25
Is the sclera proper highly vascularized?
No, it has minimal vascularization
26
Into what structure does the sclera continue rostrally?
Cornea
27
What is the transition zone between sclera and cornea?
Corneoscleral junction
28
What is the name of the corneal edge at the corneoscleral junction?
Limbus
29
What is the innermost layer of the sclera?
Lamina fusca
30
What tissue composes the lamina fusca?
DWFCT rich in elastic fibers
31
What gives the lamina fusca its brown color?
Presence of pigments
32
What are the five layers of the cornea?
Epithelium, Bowman’s membrane, substantia propria, Descemet’s membrane, endothelium
33
What type of epithelium covers the cornea?
Nonkeratinized stratified squamous epithelium
34
What conjunctiva is the corneal epithelium continuous with?
Bulbar conjunctiva
35
Name the progression of conjunctival layers starting from bulbar.
Bulbar conjunctiva → fornix conjunctiva → palpebral conjunctiva
36
What kind of nerve supply is abundant in the corneal epithelium?
Naked (free) nerve endings
37
What corneal layer is a rostral limiting membrane made of BM and fine collagen?
Bowman’s membrane
38
In which species is Bowman’s membrane most distinct?
Primates
39
Which layer forms the bulk of the cornea?
Substantia propria
40
Describe the fiber arrangement in the substantia propria.
Collagen fibers arranged in a platelike manner
41
Does the substantia propria contain blood vessels?
No, it is avascular
42
What structure does Descemet’s membrane separate?
Substantia propria from the endothelium
43
What does Descemet’s membrane resemble under light microscopy?
A basement membrane
44
What is Descemet’s membrane composed of, ultrastructurally?
Atypical collagen array
45
What type of cells make up the corneal endothelium?
Large squamous or low cuboidal cells
46
What does the corneal endothelium separate?
Cornea proper from the aqueous humor of the anterior chamber
47
In which type of animals is the cornea relatively larger?
Nocturnal animals
48
How does the cornea respond to superficial wounds?
Heals rapidly
49
How does the cornea respond to deep wounds?
Heals slowly
50
Compare species differences in corneal healing:
Ruminants: Least sensitive, rapid healing
Felines: Slow healing, minimal scarring, limited neovascularization
Canines: Extensive neovascularization
Equines: Most sensitive, slow healing, severe scarring (cicatrization)
51
Why is corneal transplantation often successful?
Lack of blood vessels prevents immune rejection
52
What tunic includes the choroid, ciliary body, and iris?
Vascular tunic or uveal tract
53
What are the 5 layers of the choroid?
Epichoroid, lamina vasculosa, tapetum lucidum (if present), choriocapillaris, Bruch’s membrane
54
What is another name for the epichoroid?
Subarachnoid layer
55
What separates the epichoroid from lamina fusca?
Perichoroidal or suprachoroidal space
56
Is the epichoroid vascularized?
No, it is avascular
57
What components are found in the epichoroid?
Loose collagenous fibers, chromatophores, fibroblasts
58
What does the lamina vasculosa contain?
Large blood vessels in loose connective tissue with some chromatophores
59
What is the layer of the choroid located between the lamina vasculosa and choriocapillary layers?
Tapetum
60
What is the primary function of the tapetum in the eye?
Reflects light back to photoreceptors to enhance dark-adapted (scotopic) vision
61
What type of vision does the tapetum enhance, and under what conditions?
Scotopic vision; under poor illumination (dark-adapted conditions)
62
What is the term for vision that occurs under poor illumination conditions?
Scotopic vision
63
What are the two types of tapetum based on structure and species?
Fibrous tapetum and cellular tapetum
64
Which animals typically have a fibrous tapetum and what is it composed of?
Ungulates; composed of collagenous fibers and fibroblasts
65
Which animals typically have a cellular tapetum and what are its components?
Carnivores; composed of fibroblasts with crystalline zinc structures
66
What metal is found in the crystalline structures of carnivore tapetum?
Zinc
67
In which species is the tapetum absent?
Swine and humans
68
What anatomical structure is responsible for 'eyeshine' seen at night in animals?
Tapetum
69
Which layer of the choroid is rich in capillaries?
Choriocapillary layer
70
What layer is adjacent to the basal lamina of the pigmented epithelium in the choroid?
Elastic membrane (Bruch’s membrane)
71
What is another name for the elastic membrane in the choroid?
Bruch’s membrane
72
What is the anterior continuation of the choroid?
Ciliary body
73
Where does the ciliary body begin?
Ciliaris retinae (where the nervous portion of the retina stops)
74
What two cell types cover the ciliary body?
Pigmented epithelium and non-nervous columnar cells
75
What connective tissue type comprises the bulk of the ciliary body?
Areolar connective tissue rich in elastic fibers
76
What muscle is found in the ciliary body, and how is it developed in domestic animals?
Ciliary muscle; poorly developed in domestic animals
77
What is the functional consequence of poorly developed ciliary muscles in domestic animals?
Poor accommodation potential
78
What bounds the ciliary body's vasculature and connective tissue mass?
An elastic lamina (anterior continuation of Bruch’s membrane)
79
What layer internal to the elastic lamina of the ciliary body forms part of the retina?
Ciliary epithelium (pars ciliaris retinae)
80
What is the rostral continuation of non-nervous and non-pigmented retinal cells?
Pars ciliaris retinae
81
What structure covers the retina and ciliary body and blends with suspensory fibers of the lens?
Internal limiting membrane (a fibrillar condensation of vitreous body)
82
What is the most rostral extension of the ciliary body?
Ciliary processes
83
What fibrous structures extend from the ciliary processes to the lens?
Zonular fibers (suspensory ligament of the lens)
84
Which part of the eye is responsible for producing aqueous humor into the posterior chamber?
Capillaries of the ciliary processes
85
What is the extension of the choroid into the anterior compartment of the eye?
Iris
86
How is the iris oriented, and what anatomical structure does its margin define?
Radially oriented; defines the pupil
87
What type of epithelium covers the rostral border of the iris?
Endothelium reflected from posterior lining of cornea
88
What connective tissue type forms the stroma of the iris?
Areolar connective tissue
89
What components are found in the stroma of the iris?
Areolar C.T., blood vessels, chromatophores, sphincter pupillae, and dilator pupillae
90
Where is the sphincter pupillae muscle located?
Along the caudal border of the iris
91
What cells cover the caudal border of the iris and form a part of the retina?
Cells forming the pars iridica retinae
92
What cyst-like structures are found on the pupillary margin of the iris in horses and ruminants?
Corpora nigra (iridial granules)
93
In which animals are corpora nigra found, and where are they most prominent?
Horses and ruminants; prominent dorsally, may occlude pupil during sphincter pupillae contraction
94
What is the function of the retina in the eye?
Reception and transduction of light, and transmission of nerve impulses to the brain
95
What is the transition point from photosensitive to non-photosensitive retina in domestic animals?
Ora ciliaris retinae
96
What is the human equivalent of the ora ciliaris retinae?
Ora serrata
97
What forms a bistratified layer at the transition zone of retina?
Epithelial and pigment cells
98
What is the rostral continuation of the bistratified retinal layer with the ciliary body?
Pars ciliaris retinae
99
What part of the bistratified layer is associated with the caudal iridial surface?
Pars iridica retinae
100
Enumerate the 10 layers of the retina.
1. Pigmented epithelium
2. Photoreceptor layer
3. Outer nuclear layer
4. Outer plexiform layer
5. Inner nuclear layer
6. Inner plexiform layer
7. Ganglion cell layer
8. Optic nerve fiber layer
9. Inner limiting membrane *(not detailed above)*
10. Outer limiting membrane *(not detailed above)*
101
Which layer of the retina lies adjacent to Bruch’s membrane and consists of cuboidal cells?
Pigmented epithelium
102
What are two functions of the pigmented epithelium in the retina?
Vitamin A storage and phagocytosis of shed rods and cones
103
Which layer contains the processes of rods and cones?
Photoreceptor layer
104
Which layer contains the nuclei of rods and cones?
Outer nuclear layer
105
What is found in the outer plexiform layer of the retina?
Axons of photoreceptors, dendrites of bipolar neurons, and fibers from associated neurons
106
Which layer contains the cell bodies of bipolar and associated neurons?
Inner nuclear layer
107
What composes the inner plexiform layer?
Axons of bipolar neurons, dendrites of ganglion cells, and processes of associated neurons
108
What does the ganglion cell layer consist of?
Cell bodies of ganglion cells
109
What fibers compose the optic nerve fiber layer?
Axonal processes of ganglion cells
110
What is the optic papilla and why is it called the 'blind spot'?
Exit point of the optic nerve; lacks photoreceptors, thus no vision is possible there
111
112
What are the two types of limiting membranes of the retina?
Internal limiting membrane and external limiting membrane.
113
What structure forms the internal limiting membrane?
Fibrillar material (basal lamina) and conjoined processes of supporting Müller cells.
114
Where are the cell bodies of Müller cells located?
Inner nuclear layer of the retina.
115
What forms the external limiting membrane?
Peripheral processes of the Müller cells.
116
A retinal membrane composed of the basal lamina and Müller cell processes.
Internal limiting membrane.
117
A retinal membrane formed solely by Müller cell peripheral processes.
External limiting membrane.
118
What is the region of most acute vision in domestic animals?
Area centralis retinae.
119
Which cells are increased in number in the area centralis retinae?
Cone cells, bipolar neurons, and ganglion cells.
120
What human eye structure is the area centralis retinae comparable to?
Macula (specifically the fovea centralis).
121
Do domestic animals have a fovea centralis?
No, they do not.
122
Retinal region with a high concentration of cones, bipolar neurons, and ganglion cells, corresponding to the macula in humans.
Area centralis retinae.
123
What are the two chambers of the anterior compartment of the eye?
Anterior chamber and posterior chamber.
124
What bounds the anterior chamber?
Iris and cornea.
125
What structure must aqueous humor pass through before reentering circulation?
Anterior chamber.
126
What bounds the posterior chamber?
Iris rostrally, lens and associated structures caudally.
127
How does the posterior chamber communicate with the anterior chamber?
Through the pupil.
128
Chamber of the anterior eye bounded by the iris and cornea.
Anterior chamber.
129
Eye chamber located between iris and lens; receives aqueous humor.
Posterior chamber.
130
Where is the filtration angle located?
At the limbus, between the base of the ciliary body and iris, and the initial caudal cornea.
131
What structure fills the iridial angle?
Meshwork of the iridial angle (triangular spongy tissue).
132
What comprises the meshwork of the iridial angle?
Solid trabeculae and fluid spaces (Spaces of Fontana).
133
What is the name of the modified vein in the iridial angle responsible for aqueous humor outflow?
Canal of Schlemm.
134
In which species is the canal of Schlemm found?
Ox and man.
135
What condition can result from debris plugging the meshwork of the iridial angle?
Glaucoma.
136
Enumerate the components of the filtration angle.
Meshwork of solid trabeculae, Spaces of Fontana, Canal of Schlemm.
137
Where is aqueous humor formed?
Ciliary body.
138
What is the nature and composition of aqueous humor?
Clear, watery, slightly alkaline ultrafiltrate of blood, similar to cerebrospinal fluid.
139
How is intraocular pressure regulated in relation to aqueous humor?
Balanced formation and drainage at the filtration angle.
140
What happens if the drainage of aqueous humor is impaired?
Intraocular pressure increases, causing glaucoma.
141
What occupies the space between the lens and the retina?
Vitreous body.
142
What is the consistency and composition of the vitreous body?
Gelatinous; water, hyaluronic acid, collagen fibers.
143
Where does the vitreous body adhere tightly?
Optic papillae, ora ciliaris retinae, orbicularis ciliaris, posterior lens capsule.
144
What is the function of the lens?
Dioptic/refractive medium of the eye.
145
What encloses the lens?
A capsule composed of basement membrane and fine reticular fibers.
146
Where is the lens thickest?
Near the equator.
147
What are the components of the lens aside from the capsule?
Lens epithelium and lens fibers.
148
What epithelium covers the external surface of eyelids?
Stratified squamous epithelium.
149
Which glands are especially well-developed in pigs?
Sweat and sebaceous glands.
150
What membrane continues from the skin at the eyelid margin?
Palpebral conjunctiva.
151
What cells are found in the palpebral conjunctiva?
Goblet cells.
152
What gland openings are found at the eyelid margin?
Tarsal (Meibomian) glands.
153
What do the glands of Moll secrete and associate with?
Sweat; associated with hairs.
154
What are glands of Zeis?
Sebaceous glands associated with hairs.
155
What type of cartilage is in the third eyelid of dogs and ruminants?
Hyaline cartilage.
156
What type of cartilage is in the third eyelid of horses, pigs, and cats?
Elastic cartilage.
157
What types of superficial gland secretions occur in the third eyelid across species?
Serous in horse/cat, mixed in dog/ruminants, mucous in pig.
158
What animals have a deep gland in the third eyelid?
Pig and ox.
159
What type of secretion does the deep gland of the third eyelid have?
Mixed secretion.
160
What are the components of the lacrimal apparatus?
Lacrimal glands, conjunctival sac, lacrimal passages.
161
Where are lacrimal glands located?
Dorsolateral margins of the orbit.
162
What type of secretion do lacrimal glands have in pigs?
Mucoid.
163
What prevents evaporation of water on the eye surface?
Mucoid secretion of palpebral glands and oily secretion of Meibomian glands.
164
What is the name of the fluid-collecting area in the conjunctival sac?
Lacus lacrimalis (lacrimal lake).
165
Trace the flow of tears from the eye to the nasal cavity.
Lacus lacrimalis → puncta lacrimalia → lacrimal canaliculi → lacrimal sac → nasolacrimal duct.
