Basic Anatomy and Fundamentals

Question 1

Anterior Segment Contains

Answer 1

Anterior & Posterior Chambers w/ Cornea, aqueous humor, iris/ciliary body, lens

Question 2

Posterior Segment Contains

Answer 2

Sclera, Choroid, Retina, Vitreous humor

Question 3

Uveal Tract contains

Answer 3

Iris, Ciliary Body, Choroid

Question 4

Meibomian glands

Answer 4

produce oil to mix with tears

Question 5

Aqueous Humor Production

Answer 5

Continually being produced by cilary body (2-3 microliters/minute)

Question 6

Intraocular Pressure (IOP)

Answer 6

Balance between formation and reabsorption of aqueous humor determines volume & pressure of IOP. Amount leaving usually = amount formed so pressure usually remains constant.
Elevated = Glaucoma

Question 7

Aqueous Humor Outflow

Answer 7

Pupil –> anterior chamber –> trabeculae meshwork –> Canal of Schlemm –> Empties into extraocular veins & systemic circulation

Question 8

Normal IOP

Answer 8

12-20mm Hg

Question 9

Main determiner of IOP

Answer 9

Resistance to outflow of aqueous humor

Question 10

Rods

Answer 10

Retinal receptors associated w/ peripheral vision and vision in low light (less concentrated in macula)

Question 11

Cones

Answer 11

Retinal receptors associated w/ central vision and color vision

Question 12

5 Corneal Layers

Answer 12

External to Internal:
Epithelium (5-6 layers)
Bowman's Layer
Stroma (90% of corneal thickness)
Descement's membrane
Endothelium

Question 13

Corneal Stroma

Answer 13

90% of corneal thickness
Composed of collagen fibrils
Stromal edema causes decreased corneal clarity

Question 14

Descemet’s membrane

Answer 14

Specialized basement membraine for endothelial layer

Question 15

Endothelium

Answer 15

Maintains desiccatio of the stroma by actively removing water

Question 16

Anterior cornea provides how much refractive power of eye?

Answer 16

2/3

Question 17

Lens provides how much refractive power of eye?

Answer 17

1/3

Question 18

Accomodation

Answer 18

lens increases curvature in response to nervous signals from brain

Question 19

Anterior suface of cornea can be modified to overcome refractive errors how?

Answer 19

Various types of surgeries

Question 20

Myopia

Answer 20

Nearsightedness
EYEBALL is too LONG so FOCAL POINT is in FRONT of retina

(can’t relax ciliary muscle any more to extend focal point back further BUT when object comes ear, gets close enough that image can be focused onto retina)

Question 21

Hyperopia

Answer 21

Farsightedness
EYEBALL is too SHORT so FOCAL POINT is BEHIND retina

(lens can focus distant objects on the retina initially by accommodation. Accomodative power of the lens is eventually maxed out & lens can’t focus on close objects)

Question 22

Errors of Refraction

Answer 22

Emmetropia (20/20)
Hyperopia (Farsighted)
Myopia (Nearsighted)

Question 23

Myopia Correction

Answer 23

“Minus” concave numbers (e.g. -3.75 diopters)

Question 24

Hyperopia Correction

Answer 24

“Plus” convex numbers (e.g. +2.75 diopters)

Question 25

Presbyopia

Answer 25

Elasticity of lens declines w/ age Lens loses ability to change shape to accommodate for near objects Corrected w/ cheaters or bifocals

Question 26

Astigmatism

Answer 26

Non-spherical cornea Corneal images focus at different distances Accomodation manipulates the entire lens, so can't correct for astigmatic refractive error in the cornea

Question 27

How the lens works

Answer 27

W/out tension, eye would assume spherical shape Suspensory ligaments (zonules) attach radially around lens, pulling edges outward to flatten lens Constant tension causes the lens to remain relatively flat in the normal state Ciliary muscle attaches to zonules (lens ligaments) & causes contraction and relaxation of lens

Question 28

Ciliary muscle contraction

Answer 28

Zonules & Lens relax Lens becomes more spherical to focus on NEAR OBJECT

Question 29

Ciliary muscle relaxation

Answer 29

Tension on zonules & lens increase Lens flattens to focus on DISTANT OBJECTS

Question 30

Ciliary muscle control

Answer 30

Primarily Parasympathetic under CN III Sympathetic --> minimal effect/almost no role in accomodation

Question 31

Pupillary Response

Answer 31

Direct & consensual pupillary light reflex Sensory --> CN II Motor --> CN III Consensual response via Edinger-Westphal nucleus

Question 32

Parasympathetic pupillary response

Answer 32

stimulation causes pupillary muscle contraction & decreases in size

Question 33

Miosis

Answer 33

Decreasing pupil size

Question 34

Sympathetic pupillary response

Answer 34

dilates the pupil

Question 35

Mydriasis

Answer 35

Increasing pupil size

Question 36

Horner's Syndrome

Answer 36

Lesion of sympathetic pathway | Miosis, ptosis, absence of sweating on ipsilateral face/neck if preganglionic (sweating preserved if post-ganglionic)

Question 37

Marcus Gunn

Answer 37

Decreased direct reaction to light Consensual response intact RAPD with "swinging flashlight test"

Question 38

Argyll Robertson

Answer 38

Pupillary constriction w/ near accomodation but NOT to light stimulation

Question 39

Hx in pt w/ eye sx

Answer 39

1. Any change in VA? 2. Any Hx of trauma? OLDCARTS PMH: Comorbidities, Meds FH Pt. Profile: Occupation, Hobbies

Question 40

PE in pt w/ eye sx

Answer 40

``` VA (best corrected) VF/confrontation Inspect: lids, lashes, brows, conjunctiva, sclera EOMS PERRLS Ispect cornea/iris Anterior Chamber Depth (IOP) Lens clarity Fundoscopic Exam - disc, vessels, retina, macula *IOP if indicated ```

Question 41

Ocular Vital Signs

Answer 41

``` VA VF EOMs Pupillary Response IOP ```

Question 42

Red Reflex

Answer 42

Cornea/aqueous/lens/vitreous must be clear

Question 43

Eye arteries

Answer 43

lighter in color than veins, 2/3 size of veins, have brighter light reflex

Question 44

Eye veins

Answer 44

larger, darker w/ less bright light reflex

Question 45

Disc Margins

Answer 45

sharp or blurred, elevated? | Cup/Disc ratio: normal is <1:2

Question 46

Retinal Background

Answer 46

Normal is uniform | Abnormal? Hemorrhages, "drusen," "cotton wool spots"

Question 47

Macula

Answer 47

Temporal to disc; NO VESSELS = macular degeneration