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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.