EPT4

Question 1

What is the BEST description for radiant intensity?

Answer 1

The amount of energy PER second in a specific direction (or amount of space) produced by a light source)

Question 2

Where is the location of mitosis in the adult crystalline lens?

Answer 2

Pre-equatorial lens epithelium

NOTE: mitosis ONLY within the germinative zone of the anterior lens epithelium. New cells will migrate, elongate, and lose organelles to become lens fibers. Lens fibers are inactive and thus do NOT undergo mitosis.

Question 3

What is the % of pts who present with hyphema from blunt trauma exhibit angle recession in the affected eye?

Answer 3

60%

Question 4

What is true about proparacaine?

Answer 4

1. Prevents depolarization of neuron cell membrane
2. Prevents generation and conduction of nerve impulses
3. Effects are reversible
4. Blocks Na+ voltage gated channels

Question 5

What is the Fechner’s law assume?

Answer 5

That the Weber’s law will hold true for stimuli above a given brightness threshold (i.e. the perceived brightness of a stimulus is equal to Weber’s constant times the log of the stimulus intensity)

Question 6

Which lenses would complete correct for radial astigmatism?

Answer 6

Point focal lens

NOTE: radial astig and curvature of field are related. Attempts to eliminate one will worsen the other. Lenses are typically designed to balance the 2 aberrations. Point focal lenses completely correct for radial astig, at the cost of offering no correction for curvature of field. Percival form lenses completely correct for COF, at the cost of offering no correction for radial astig.

Question 7

Which muscles are part of the orbicularis oculi, which is responsible of closing the eyelids?

Answer 7

Riolan and Horner

Question 8

What would be the ideal index of an anti-flare coating for a polycarb lens?

Answer 8

1.26

nf=square root of n1 x nL
n1=index of surrounding medium
nL=index of lens material

npoly=1.586
nair=1.00
Thus square root (1*1.586)

Question 9

Which fat-soluble vitamin is LEAST toxic?

Answer 9

Vitamin E

NOTE: antioxidant and protects RBC from hemolysis

Question 10

Describe Donder’s law.

Answer 10

For any position of gaze, the eye has a unique orientation in 3D space

Question 11

Describe Listing’s law.

Answer 11

Eye must rotate around axes in order to achieve a specific direction of gaze

Question 12

What effects does parasympathetic activation do?

Answer 12

1. DEC diameter of ciliary body ring
2. Reduction in ciliary muscle tone
3. Dilation of pupil
4. Contraction of Muller’s tarsal muscle to slightly widen the palpebral fissure

Question 13

Which uveal layer is composed of myoepithelium?

Answer 13

Anterior iris epithelium

NOTE: the anterior border layer, the suprachoroid, and the supraciliaris are ALL composed of CT and thus are neither epithelium NOR muscle tissue. The sphincter muscle is smooth muscle and has no associated epithelial component

Question 14

Free sterols, including cholesterol, are a component of the secretions of?

Answer 14

Meibomian glands

Question 15

What are the clinical signs of pigment dispersion syndrome?

Answer 15

1. Kruckenberg spindle (pigment on corneal endo)
2. Scheie line (pig on post lens capsule)
3. Sampaolesi line (pig on schwalbe’s line)
4. Peripheral TIDs

Question 16

True or false. Brinzolamide is a suspension that must be shaken prior to instillation.

Answer 16

TRUE

Question 17

What is the oblique axises?

Answer 17

120-150