Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
57 Cards in this Set
- Front
- Back
Why would you need an opthalmic injection?
|
To deliver faster and higher ocular drug levels.
|
|
The conjunctiva/sclera and cornea are in which layer of the eye?
A. Outermost B. Middle C. Innermost |
A. Outmost
|
|
The uveal tract (choroid, ciliary body, and iris) is in which layer of the eye?
A. Outermost B. Middle C. Innermost |
B. Middle
|
|
The retina is in which layer of the eye?
A. Outermost B. Middle C. Innermost |
C. Innermost
|
|
What divides the aqueous and vitreous humors?
|
The Lens.
|
|
True/False
The aqueous humor is anterior to the lens. |
True
|
|
True/False
The Vitreous humors is posterior to the lens. |
True
|
|
What divides the aqueous humor into the anterior and posterior chambers?
|
Iris
|
|
What continously generates the aqueous humor?
|
Ciliary body
|
|
Where does the aqueous humor flow?
|
From the posterior chamber thru the pupil.
|
|
A thin, transparent, vascularized mucous membrane that extends fromt he edge of the cornea, across a portion of the sclera, then extends to the internal surface of the eyelids to form conjunctival sacs (cul-de-sacs)
|
Conjunctiva
|
|
How does the aqueous humor exit to the systemic circulation?
|
Mainly thru Schlemm's canal.
|
|
Name a gland responsible for tear production.
|
Lacrimal Gland
|
|
Name a function of tears.
|
The removal of foreign material thru the puncta.
|
|
The Puncta is a small opening to the __________________.
|
lacrimal canaliculi
|
|
What's the drainage system for the lacrimal fluid?
|
Nasolacrimal Apparatus
|
|
Tears drain thru the ___________ to the __________ ______ then to the nasal cavity via the _____________ duct.
|
canaliculi
lacrimal sac lacrimal duct |
|
From the nasal cavity where do tears flow?
|
Nasopharynx
|
|
Tears drain by what two processes?
|
gravity and thru the active process employing a pumping mechanish.
|
|
Pumping mechism for tears.
|
Blink of an eye.
|
|
Major pathways for topical opthalamics to reach intraocular tissues:
|
#1 Cornea
#2 Sclera |
|
True/False
The cornea is a simple, optically transparent tissue and is covered by a tear film. |
False
It's complex |
|
Layer of tear film involved in adhesion of the aqueous tear fluid.
|
Mucoid: keeps cornea wettable
|
|
Layer of tear film w/ aqueous soln of inorganic electrolytes, proteins, and glucose.
|
tear fluid
|
|
Proteins in ther tear fluid include:
|
enzymes and immunoglobulins
|
|
Layer of the tear fluid containing a layer of wax and cholesterol esters adsorbed to the tear fluid.
|
Lipid film: reduces evaporation of the tear fluid.
|
|
The concentration of drug in the tear film provides the driving force for ___________.
|
passive diffusion thru the cornea.
|
|
True/False
Facilitated Diffusion dominates corneal permeation. |
False
It's passive diffusion. |
|
Name the layers of the cornea outer to inner:
|
Epithelium, Stroma, Endothelium
These are the most important layers for drug absorption. |
|
True/False
Epithelium = lipophilic |
True
|
|
T/F
stroma = hydrophilic |
True
|
|
T/F
Endothelium = lipophilic |
true
|
|
t/f
the corneal epithlium is continous w/the conjunctiva, but w/ different thickness. |
true
|
|
t/f
the corneal epithelium is stratified. |
true
|
|
The squamous cells on the surface are surrounded by tight junctions and have microvilli. What do the microvilli do?
|
increase surface area
|
|
The main barrier for drug passage thru the cornea is the:
|
Epithelium
|
|
What type of drugs permeate well thru the epithelium?
|
Lipophilic
|
|
t/f
ionized = more lipophilic |
false
unionized = more lipophilic, thus permeates epithelium better |
|
Are enzymes present in the corneal epithelium?
|
yes and they can metabolize some drugs.
|
|
What type of drugs find it hard to cross the stroma?
|
lipophilic
|
|
t/f
the stroma: about 60 thin lamella, each composed of collagen fibers. |
true
|
|
t/f
The endothelium is a multicell layer that provides metablic exchange between the cornea and the aqueous humor. |
false
It's a single cell layer. |
|
t/f
the endothelium is more permeable than the epithelium. |
false
The endothelium is 200 times more permeable than the epithelium. |
|
t/f
drugs w/ moderate water/octanol partition at physiological pH are best absorbed. |
False
w/ moderated octanol/water. they're best absorbed due to the diverse barriers. |
|
t/f
the greater the concentation in the tear film, the faster the penetration. |
true
|
|
t/f
Absorption cannot occur thru damaged epithlium. |
false.
There's greater absorption thru damaged epithelium. |
|
The time to peak aqueous humor concentrations often range between _____ to ______.
|
20 - 60 min
|
|
Normally, less than ____% of the dose (instilled as drops) will cross the cornea.
|
5%
|
|
Applied drug can be lost before crossing the cornea by:
|
spillage and by the nasolacrimal drainage.
|
|
1. normal tear vol:
2. an eyedrop range: |
1. 7 ul
2. 25 - 56 ul (avg: 39 ul) |
|
Vol of drug that can be momentarily accomadated inthe lower cul-de-sac w/o spillage =
|
30ul
Thus, instilling more is immediately lost. |
|
_______ increases the spillage and facilitates removal by the nasolacrimal apparatus.
|
Blinking.
Leads to a residual vol of about 10 ul. |
|
What forces fluid to the nasal cavity?
|
blink pumping
|
|
T/F
Sources of loss of drug before reaching cornea are thru spillage, nasolacrimal drainage, enzymatic degration and conjunctival permeation followed by systemic absorption. |
True
|
|
Greatest concentration of drug are achieved w/in _______ region of the eye.
|
anterior
|
|
The concentation w/in the anterior chamber will be less than in the applied prouct by what magnitude?
|
often 2 orders of magnitude
|
|
What is treating the posterior region typically not achievable w/ a topical product?
|
the amount of drug reaching the posterior region is usually insignificant.
|