Lecture 20: Eye Histology

Question 1

What is the function of the eyelid?

Answer 1

Protects the eye

Question 2

What is the function of tarsal glands?

Answer 2

Special sebaceous glands that produce meibum to prevent evaporation of of tears

Question 3

What can blocked tarsal glands lead to?

Answer 3

Chalazion

Lump on eyelid

Question 4

What can blocked sebaceous glands in the eyelashes lead to?

Answer 4

Stye

Near eyelash follicles

Question 5

What do lacrimal glands do?

Answer 5

Produce tears

Question 6

What is the conjunctiva that lines the outermost part of the eyeball?

Answer 6

Bulbar (ocular) Conjunctiva

Question 7

What is the conjunctiva that lines the innermost part of the eyelids?

Answer 7

Palpebral Conjunctiva

Question 8

What is the anterior chamber between?

Answer 8

Between Cornea and Iris

Filled with aqueous humor

Question 9

What is the posterior chamber between?

Answer 9

Between Iris/Pupil and Lens (small)

Question 10

What is vitreous chamber between?

Answer 10

Lens and neural retina

Filled with vitreous humor to maintain shape

Question 11

What structures compose the fibrous (external) layer of the eye?

Answer 11

• Sclera: supports eye and protects internal structure
• Cornea: protects anterior surface of eye and refracts light

Question 12

What are the five layers of the cornea, anterior to posterior?

Answer 12

1. Corneal Epithelium: nonkeratinized statified squamous
2. Bowman’s Membrane: anterior basement membrane
3. Corneal Stroma: avuscular and 60 layers thick
4. Descemet’s Membrane: posterior basement membrane
5. Corneal Endothelium: faces anterior chamber

Question 13

What is found in between the basement membrane and corneal epithelium?

Answer 13

Free Nerve Endings

Question 14

What structures compose the vascular (middle) layer of the eye?

Answer 14

• Choroid: supplies nourishment to retina
• Ciliary Body
  
  • ​Ciliary Muscle: manages accomodation
  • Ciliary Processes: secretes aqueous humor and and forms suspensory ligaments oflens
• Iris: controls light entering eye

Question 15

What are the layers of the lens?

Answer 15

• Capsule
• Subcapsular Lens Epithelium
• Lens Fibers

Question 16

What is accommodation?

How is this accomplished?

Answer 16

Ciliary muscles adjust eyes to see objects at various distances

• Distant objects: flatten lens
• Neaby objects: rounded lens

Zonular fibers help lens change its shape

Question 17

What is presbyopia?

Answer 17

Loss of lens elasticity with age

Question 18

What structures compose the internal layer of the eye?

Answer 18

• Pigmented layer: absorbs light and serves as a blood-neural retinal barrier
• Neural layer: where light is converted in nerve signals

Question 19

What is the optic disk?

Answer 19

Blind spot in retina where optic nerves from ganglion layer exit eye

Question 20

What are the layers of the retina?

Answer 20

• Retinal Pigmented Layer (most posterior)
• Photoreceptor Layer: Rods and Cones
• Outer Limiting Layer
• Outer Nuclear Layer
• Outer Plexiform Layer
• Inner Nuclear Layer
• Inner Plexiform Layer
• Ganglion Layer
• Optic Nerve Fiber Layer
• Inner Limiting Membrane: Muller Cells

Question 21

What is fovea centralis?

Answer 21

Highest concentration of cones with the sharpest visual acuity

Question 22

What is the macula lutea?

Answer 22

Surrounds fovea and protects cone

Question 23

What does the optic nerve penetrate to travel to the brain?

Answer 23

Choroid and sclera