Accommodation, Zonular, Uveal

Question 1

What is the only human accommodative factor?

Answer 1

changing surface curvatures and or refractive index of the lens

Question 2

What are the three components for human accommodation?

Answer 2

ciliary muscles, zonule apparatus, lens

Question 3

Lens Accommodation

Answer 3

Ciliary muscles contract, zonules relax, rounder/thicker

Question 4

Lens Distance Focus

Answer 4

ciliary muscles relax, zonules contract, thinner/flatter

Question 5

Fibrillin

Answer 5

a cysteine-rich glycoprotein, major component of the beaded fibrils of the zonular apparatus

Question 6

Marfan syndrome

Answer 6

mutated fibrillar protein, weakened zone and sublimation of the lens, fragile

Question 7

Pars plana

Answer 7

junction of vitreous and ciliary bodies

Question 8

Pars plicate

Answer 8

produces aqueous humor, holding the lens zonules

Question 9

Does the unaccommodated state or the accommodated state have a smaller van Herck angle?

Answer 9

accommodated state

Question 10

3 Parts of Helmholtz Accommodative Mechanism

Answer 10

A. increased lens thickness
B. increased lens convexity
C. reduced distance to the cornea

Question 11

Presbyopia

Answer 11

age-related loss of accommodative amplitude

Question 12

Presbyopia Physiology

Answer 12

lens thickness increases, lens anterior surface curvature increases, stiffness increases (lens nucleus), but ciliary muscles retain the ability to contract

Question 13

The Lens Paradox

Answer 13

the phenomenon in which the curvature of the human eye lens increases with age, yet human eyes do not become more powerful as they get older

Question 14

In younger lens, is the stiffness lowest or highest near the lens nucleus?

Answer 14

lowest

Question 15

In older lens, is the stiffness lowest or highest near the lens nucleus?

Answer 15

highest

Question 16

The Uveal Tract

Answer 16

iris, ciliary body, choroid (main vascular compartment of the eye

Question 17

Pigment-Bearing Melanocytes

Answer 17

not identifiable in the iris stoma until late in development, around brith or later

Question 18

Sphincter Pupillae Muscles

Answer 18

run circular around the pupil, above the dilator pupillae muscles

Question 19

Iris Color

Answer 19

thickness of the stroma, degree of melanogenesis

Question 20

Blue Irides

Answer 20

interference and reflection of light from storm and collagen

Question 21

Brown Irides

Answer 21

result of heavily pigmented melanocytes within the stroma

Question 22

Mydriasis

Answer 22

iris is thrown into a number of ridges and folds, extremely dilated pupils

Question 23

Miosis

Answer 23

anterior surface appears relatively smooth, extremely constricted pupil

Question 24

Sphincter pupillae are controlled by what pathway?

Answer 24

parasympathetic

Question 25

Dilator pupillae are controlled by what pathway?

Answer 25

sympathetic

Question 26

Cyclopentolate/Tropicamide

Answer 26

block parasympathetic pathway, compete with acetylcholine at the effector cells of the sphincter

Question 27

Epinephrine (phenylephrine)

Answer 27

directly stimulate the receptor sites of the dilator muscles

Question 28

Pupillary Light Reflex

Answer 28

reflex that controls the diameter of the pupil, constriction is caused in both pupils even when only when is stimulated