Ocular Fluids

Question 1

blood (ocular functions)

Answer 1

• nourishment and ridding of waste components for ocular cells
• source for the formation of aqueous fluid/generation of IOP
• homeostasis of retinal functions

Question 2

aqueous fluid (ocular functions)

Answer 2

• filter blood produced by the ciliary body
• nourishes cells of posterior cornea, the iris, lens, and trabecular meshwork
• provides transparent refractive index
• shape/protection
• eliminates waste, inflammatory products, & blood

Question 3

composition of the aqueous

Answer 3

protein, AAs, ions, glucose, lactate, hydrogen peroxide, Vit C

Question 4

aqueous fluid characteristics

Answer 4

decreased proteins/lipids= decreased buffering capacity, but enhances ability to transmit light
increased Vit C= enhanced reservoir of antioxidants

Question 5

Aqueous humor flow

Answer 5

• aqueous is filtered by blood from the major arterial circle of iris in the ciliary body
• H2O and solutes transport through epithelium into posterior chamber easily due to gap junctions, and then into anterior chamber

Question 6

aqueous production (3 processes)

Answer 6

ultrafiltration, diffusion, and active secretion

Question 7

ultrafiltration

Answer 7

passive flow of fluid from blood plasma to CB stroma, through fenestrated capillaries
- dependent on BP

Question 8

diffusion

Answer 8

passive movement of CO2 from CB stroma into the CB epithelium
- dependent on charge and conc. gradients

Question 9

active secretion

Answer 9

Na-K ATPase pump & carbonic anhydrase move Na+ & Cl- across the epithelial layers into the posterior chamber (pulling water with it)

Question 10

vitreous body makeup

Answer 10

depends on patient age
- starts 80% gel/ 20% fluid
- changes to 40 % gel/ 60 fluid

Question 11

vitreous body structure

Answer 11

1. type II collagen (gel-like property, majority)
2. type IX collagen (links type II & GAG)
3. Hyaluronate (GAG)
   - stabilizes collagen
   -associates w/ water molecules not gel

Question 12

vitreous compared to blood

Answer 12

• increased ascorbate
• increased protein
• very few cells

Question 13

stickler syndrome

Answer 13

• abnormalities in production of collagen types II, IX & XI
• leads to vitreal syneresis (breakdown) and lead to RD

Question 14

age-related liquefaction

Answer 14

breakdown of the spacing mechanisms in vitreal collagen
- allows for formation of non-collagenous, liquid volumes

Question 15

synchisis

Answer 15

increase in the fluid-filled spaces (liquefaction) w/ age

Question 16

syneresis

Answer 16

formation of aggregated collagen fibrils over time (floaters)

Question 17

precorneal tears layers

Answer 17

1. lipid layer (outermost)
   - fatty acids, cholesterol, and esters
2. aqueous layer
   - H2O, immune defense proteins
3. mucin layer
   - mucins, electrolytes, & water

Question 18

precorneal tears functions (5 of them)

Answer 18

1. lubricate eyelids
2. forms a smooth layer over irregular corneal surface
3. immune component for ocular surface
4. nourishes corneal epithelium
5. washes away toxin irritants from ocular surface

Question 19

precorneal tear proteins

Answer 19

lysozyme & lactoferrin, both have antimicrobial activity