Anatomy and Physiology Flashcards
1
Q
What are 4 functions of the eyelid?
A
- Blinking keeps the eye moist
- Distributes nutrients, tears, and oxygen
- Flushes debris towards inner canthus
- Protect the globe from injury or light
2
Q
Canthi
A
Where the upper and lower eyelid meet
3
Q
Caruncle
A
Mound of skin inside the medial canthus that contains sebaceous and sweat glands
4
Q
What is our vestige third eyelid called?
A
Semilunar Fold
5
Q
What are the 4 layers of the eyelid?
A
Skin, orbicularis oculi muscle, a multipurpose layer, and the palpebral conjunctiva
6
Q
Eyelid Layers:
Skin
A
The first layer of the eyelid, thinnest and outermost layer
7
Q
Eyelid Layers:
Orbicularis Oculi Muscle
A
The orbicularis oculi muscle surrounds the palpebral fissure and is responsible for lid closure, aids in tear function by spreading tears
8
Q
Eyelid Layers:
Multipurpose Later
A
The multipurpose layer is composed of the orbital septum, various muscles, and the tarsal plates.
9
Q
Orbital Septum
A
The orbital septum seperates the lid from the fat around the bony orbit
10
Q
Palpebrae Superioris Muscle
A
Palpebrae superioris muscle raises the upper lid and and the retractor muscle in the lower eyelid
11
Q
Mullers Muscle
A
Mullers muscle is smooth and gives the lid tone
12
Q
The Tarsal Plate
A
The tarsal plate is a strong , firm connective tissue that gives the lid support and shape; it contains the meibomian glands
13
Q
Palpebral Conjunctiva
A
The palpebral conjunctiva is a thin, mucus membrane that lines the inner portion of the lid. It runs continuously with the bulbar conjunctiva.
14
Q
Fornix
A
The point where the palpebrae and bulbar conjunctiva meet. The fornix prevents anything from being lost behind the globe
15
Q
What types of glands are located in the tarsal plate?
A
Meibomian glands and tarsal glands They are sebaceous so they secrete oil and lipid secretions.
16
Q
Define Blepharitis
A
An inflammation of the lid margins
17
Q
Define Chalazion
A
A blockage or inflammation of the mebomian gland
18
Q
Define Ectropion
A
Outward turning of the eyelid
19
Q
Define Entropion
A
Inward turning of the eyelid
20
Q
Define Lagophthalmos
A
Incomplete lid closure
21
Q
Define Ptosis
A
Also called blepharoptosis, it is a drooping of the upper eyelid
22
Q
Define Stye
A
Technically known as a hordeolum, is an inflammation of a zeis gland
23
Q
Define Trichiasis
A
Inward turning of the eyelashes so they rub against the globe
24
Q
What are the four causes of conjunctivitis?
A
Bacterial, viral, allergic and chemical
25
Name the symptoms of conjunctivitis
Pain, decrease in vision, photophobia and discharge
26
What color would bacterial conjunctivitis discharge be?
Green-Yellow
27
What would viral conjunctivitis discharge look like?
Watery
28
What would allergic conjunctivitis discharge look like?
White and Stringy
29
What is GPC?
Giant Papillary Conjunctivitis, is most commonly associated with improper contact lens wear. It is believed to be caused by dirty lenses with excessive proteins that the body no longer recognizes as its own.
30
What are patient symptoms of GPC?
Bumps underneath the eyelid, foreign body sensation and mucus secretions
31
Define Eye Freckle (Nevus)
Small, colored growth that may be raised. This can be an issue in contact lens fit depending on the size and type of contact lens needed
32
Define Pinguecula
A thickening of the conjunctiva that results in a raised, yellow bump on the eyeball. Typically occurs in older adults who spend a lot of time outside. Can me asymptomatic and feels primarily like dry eye
33
Define Pterygium
A triangular growth of pink fleshy tissue on the conjunctiva that typically starts nasally and grows towards the temple. Most common symptom is foreign body sensation
34
Define Subconjunctival Hemmorage
Broken conjunctival blood vessels . Causes are not always known but can be related to poorly cleaned or maintained contact lenses
35
What is the bony orbit?
A protective socket that is composed of seven bones and divided into four main parts
36
What are the 4 main parts of the bony orbit?
The roof, medial wall, floor, and lateral wall
37
What are the bones that compose the bony orbit?
Maxilla, Palate, Frontal, Sphenoid, Zygomatic, Ethmoid, and Lacrimal
38
What is the main function of the bony orbit?
Holds connective tissues, muscles, optic nerve, and opthalmic vessels that cushion and nourish the globe of the eye
39
How many extraocular muscles are there?
Six
40
Define Lateral Rectus
Moves the eye outward, away from the nose
41
Define Medial Rectus
Moves the eye inward towards the nose
42
Define Superior Rectus
Moves the eye upward and slightly outward
43
Define Inferior Rectus
Moves the eye downward and slightly inward
44
Define Superior Oblique
Moves the eye outward and downward
45
Define Inferior Oblique
Moves the eye outward and upward
46
Define Supraversion
The movement of both eyes upward
47
Define Infraversion
The movement of both eyes downward
48
Define Dextroversion
The movement of both eyes to the right
49
Define Levoversion
The movement of both eyes to the left
50
Define Convergence
The movement of both eyes inward towards the nose
51
Define Divergence
The movement of both eyes outward towards the temples
52
What does stereopsis mean?
That an image has height, weight and depth
53
What are some ways that monocular patients can still achieve stereopsis?
Shading, size of objects in relation to things, motion parallax and linear perspectives
54
What is a phoria?
When the eye has a tendency to turn from its normal position
55
What is a tropia?
When there is a definite or obvious turning of one or both eyes away from their normal positions
56
What is another name for a tropia?
Strabismus
57
Define Exo-
meaning turning outward or in a temporal direction
58
Define Eso-
meaning turning inward or in the nasal direction
59
Define Hyper-
meaning upward
60
Define Hypo-
meaning downward
61
What are the two basic types of tear secretions?
Reflex tears and basal tears
62
How do basal tears differ from reflex tears?
Reflex tears require a stimulus but do not lubricate the eye very well, basal tears provide lubrication and protection
63
What is referred to as the first refractive medium of the eye?
Tears
64
What are the three layers of the tear body?
A lipid or oily layer, aqueous or water layer, and a mucin or mucous layer
65
What is the lipid layer of the tear film composed of?
Waxes, Cholesterols, and triglycerides so it can slow the rate of tear evaporation and maintain tension on the aqueous layer so that tears will not spill over onto the cheeks
66
What is the thickest layer of the tear film?
The aqueous layer at 7 microns thick
67
What composes the aqueous layer of the tear film?
water, salts, glucose, proteins, lysozymes and immunoglobulins so it is the most crossfunctional layer of the tear film
68
What is the purpose of the Mucin Layer?
The mucin layer is the stablilizing layer of the tear film due to the stickiness of the glycoproteins and mucopolysaccharides that reduce the tension of the aqueous layer. It is produced by goblet cells.
69
Explain the kinetics of tears
Formed by glands, moves across the globs, creates a tear prism at the lower lid, picked up again by lid across the globe, drains out of the eye through lacrimal puncta, drains down nose and throat.
70
How are tear secretion issues usually detected?
By looking at tear production rate and break up time (BUT)
Normal BUT is longer than blink time with no corneal drying, 15-30 seconds
71
What is the Schirmer Test?
Measures tear production by inserting 5mm of no 41 Whatman filter paper into the lower conjunctival sac. It is reviewed over 5 min and the amount of wetness on the paper is noted.
72
Explain how Break Up Time is measured.
Fluroescein is placed into the conjunctival sac and then viewed with cobalt blue illumination. You would look at how quickly the flurescien pattern changes due to lack of moisture. A BUT of less than 10 seconds indicates a mucin deficiency.
73
What is the difference between Rose bengal or lissamine green dye?
Both of these dyes adhere to degenerated cells to make them more visible. Green is becoming the preferred color because it makes the vascularization easier to see, and the Rose Bengal has a high irritation rate.
74
Define Dacryoadenitis
Inflammation of the lacrimal gland
75
Define Dacryocystitis
Inflammation of the lacrimal sac
76
Define Keratitis Sicca
Inflammation of the ocular surface due to dryness
77
What is the purpose of the Outer Tunic?
A tough fibrous structure that gives the globe its structure, restricts light and provides protection.
78
What does the outer tunic consist of?
The sclera, a transitional zone called the limbus, and the cornea.
79
What is the purpose of the sclera?
It is the largest portion of the globe, In addition to providing protection, the thickness of the sclera prevents light from scattering within the globe.
80
What is the purpose of the Limbus?
It is a transitional zone that connects the thick and opaque sclera to the clear corneal tissue. It contains blood vessels that supply the periphery of the cornea with nutrients.
81
Define Neovascularizaion
When the limbal blood vessels should loop away from the cornea and not enter into the clear surface. If it does, it is called neovascularization.
82
What is the refractive index of the cornea?
1.376, the most refractive component of the optical system
83
What are the five layers of the cornea?
Epithelium, Bowman's Membrane, Stroma, Descements Membrane, and Endothelium.
84
Describe the Epithelium (layer of the cornea)
Comprises 10% of the corneas thickness, The primary function of this layer is protection, enabling a smooth refracting surface and stablizing tear film. Because of its protective purpose, it repairs quickly with regeneration beginning within 24 hours. Receives nutrition from air and tears.
85
Describe Bowman's Membrane (layer of the cornea)
A very tough barrier membrane that acts as a basement membrane for the epithelium layer. It is comprised of collagen fibers attached to the limbus. Because this layer scars, it is important to minimize damage to this structure.
86
Describe the Stroma (layer of the cornea)
It is 90% of the thickness of the cornea, and is one of the main layers to maintain corneal transparency. Finally stacked collagen lamellae running parallel to the surface allow the light to pass unobstructed through the layer. Takes weeks to heal.
87
Define Deturgescence
The dehydration of the stroma is maintained by deturgescence.
88
Describe the Descement's Membrane (layer of the cornea)
A true basement membrane, it is loosely attached to the stroma via fibrils. The banded layer is developed in utero and the non banded layer is developed througout life by the endothelium. The membrane is resistant to protection and damage to it causes temporary folds.
89
Describe the Endothelium (layer of the cornea)
A special layer of hexagon shaped cells that is comprised of 400,000 cells at birth with no more cells developed through life. If there is any damage, it can only be repaired via corneal transplant.
90
Define Arcus Senilis
Fat deposits that settle along the edge of the cornea giving it a white ring; commonly found in those over the age of 60
91
Define Bulbous Keratopathy
Corneal swelling caused by the dysfunctional endothelial cells; the sacs of fluid called bullae can rupture causing severe pain
92
Define Corneal Guttata
Breakdown of the lining of the cornea. Primarily seen in females, it is characterized by bumps and in the primary form there is no edema. In the Fuchs Dystrophy form, there is corneal edema present
93
Define Infiltrates
White blood cells in the cornea in the cornea, usually see in dirty contact lens wearers
94
Define Keratoconus
Cone shaped protrusion of the cornea due to corneal thinning, usually presents between the ages of 10-20.
95
Define Leukoma
White, dense opacity in the cornea. Caused by a traumatic, inflammatory, or ulcerative process. If it is a medium opacity it is called a Macula and if it is a small opacity it is called a Nebula.
96
Define Recurent Corneal Erosion
Reoccuring loss of corneal tissue after an injury
97
Define Corneal Ulcer
Erosion of corneal tissue from trauma, burns, or inflammation or infection
98
What is the purpose of the Middle Tunic?
Also called the uveal tract and is the vascular body of the globe. Its primary function is to provide nourishment to the eye.
99
What does the middle tunic consist of?
The Choroid, Cilliary Body, and Iris.
100
Describe the Choroid
The Choroid is located between the sclera and the retina, extending from the optic disc in the back of the globe to the ora serrata in the front. Contains numerous arteries and veins to nourish many ocular structures.
101
Why is it important to the contact lens fitter to understand the correlation between the choroid and inflammation?
Many of the arteries and veins in the choroid terminate at the corneal limbus. This is important because it can point to where inflammation may be originating. If there is greater irritation at the outer portion of the globe, then the inflammation is likely conjunctival in nature. However if the irritation is closer to the limbus, the inflammation may be corneal or intraocular.
102
Describe the Cilliary Body
The cilliary body contains the cilliary muscles and processes. The Cilliary processes secrete aqueous humor and the muscles move the zonules of Zinn to allow for accomodation.
103
Define Accomodation
The process where the lens focuses light onto the retina by flexing, it adjusts its image based on its distance from the eye. The closer an object is to the eye, the more power is required to focus the image on the retina.
104
How is accomodation achieved?
When the cilliary body contracts, the zonules relax allowing the lens to thicken (adding power). When the eye wants to see at a distance, the cilliary body relaxes, allowing the zonules to contract which draws the lens outward.
105
Describe the Pupil
The point where light enters the eye. The amount of light is controlled by the iris. The iris has two muscles, the sphinctor muscle and the dilator muscle.
106
Define Mydriasis
When the dilator muscle in the iris opens the pupil to allow more light into the eye
107
Define Miosis
When the sphinctor muscle of the iris closes the pupil
108
Define Aniridia
Congenital absence of an iris, there is a loss of vision from too much light entering the eye
109
Define Anisocorea
Uneven pupil sizes, can result in blurred or double vision.
110
Define Heterochromia
iris's of two different colors
111
Define Iridectomy
Surgical removal of the iris, typically due to melanoma of the iris
112
Define Colobona
Congenital absence of a portion of the iris
113
Define Iridocyclitis
Inflammation of the iris and the ciliary body.
114
Define Iritis
Inflammation of the iris
115
Define Uveitis
Inflammation of the uvea tract
116
Define Rubeosis
Neovascularization of the iris, commonly caused by diabetes
117
What can potentially cause accommodation loss?
The ciliary muscles and the zonules of zinn losing their ability to tighten or relax or it can be due to the age of the lens itself. As the lens grows throughout our lifetime, the lens hardens (the cause of presbyopia)
118
What is the primary cause of blindness in those over 40?
Cataracts
119
What are the three types of cataracts?
Subcapsular, nuclear, and cortical
120
Define Subcapsular Cataracts
Form in the back of the crystalline lens and are primarily caused by diabetes and steroid use
121
Define Nuclear Cataracts
The primary type of cataracts which begin in the center of the lens and are caused by the aging process.
122
Define Cortical Cataracts
Much like nuclear cataracts but form in the periphery of the lens.
123
What is the inner tunic composed of?
A layer of photoreceptors and neurons (rods and cones)
124
Describe Rods
Very sensitive to light and very plentiful around the periphery of the retina. Ideally suited for night vision and peripheral vision
125
Describe Cones
Cones are used for detail and color detection. Cones are largely concentrated on the fovea (the center of the retina)
126
What is the fundus?
The posterior area of the retina viewed through the pupil, and it encompasses the fovea, macula , retina arteries and veins, and the optic disc
127
What is the optic disc?
The point where the optic nerve enters the brain, it has no photoreceptors so it is a technical "blind spot"
128
Define Monochromats
Have only one photopigment color receptor and therefore can only see shades of grey
129
Define Dichromats
Have two photopigment color receptors and can see color combinations based off of the two color receptors they posess
130
Define Anomalous Trichromats
Have all of the photopigment color receptors but has a lack of sensitivity to one of them, the most common form of color deficiency
131
What is Diabetic retinopathy?
premature aging of the blood vessels caused by diabetes and may result in hemorrhages, neovascularization, and fibrous tissue growth; can result in vision loss and retinal detachment
132
What is Macular Degeneration?
Loss of central vision due to damage to the macular region , affects ability to see fine detail
133
What is a retinal detachment?
When the retinal tunic seperates from the choroid tunic depriving it of blood, oxygen and nourishment
134
Define Retinis Pigmentosa
Hereditary loss of rods and cones
135
Where is the anterior chamber located?
Between the cornea and the iris
136
Where is the posterior chamber located?
Located directly behind the iris but in front of the crystalline lens
137
What is aqueous humor?
A watery fluid produced by the ciliary body. Its purpose is to maintain IOP and provide nutrients to the lens and cornea.
138
What is Glaucoma?
A condition in which increased intraocular pressure causes damage to the optic nerve and will lead to blindness if left untreated.
139
Describe open angle glaucoma
Symptoms do not normally present until vision is already lost. This is the most common form
140
Describe closed angle glaucoma
Is when the canal of schlemm abruptly closes and cuts off flow of fluid, is a medical emergency and presents with sharp pain, nausea and blurred vision
