LACRIMAL SYSTEM EVAL Flashcards
what comprises the afferent lacrimal system
secretory lacrimal system
basal tears are a part of which lacrimal system?
afferent / secretory
the secretory lacrimal system is responsible for what
tear production
the afferent lacrimal system has what two types of tears
basal tears and reflex trears
what are reflex tears
produced in response to ocular surface irriation or emotions
T/F there is 100x more basal tears than reflex tears
false
what system is responsible for tear drainage
excretory efferent lacrimal system
what is the efferent lacrimal system responsible for
tear drainage
T/F 90% of tears are drained by the nasepharynx and 10% evaporate
true
what percentage of tears evaporate?
10%
what percent of tears are drained by the naseopharynx
90%
what nerve innervates the lacrimal system?
lacrimal nerve, a branch of the opthalmic division of the trigeminal nerve (CN V)
the lacrimal nerve is a branch of what nerve
ophthalmic division of the trigemnial nerve (CN V)
T/F reflex tearing occurs with stimulation of branches of the opthalmic nerve or in response to external stimuli such as intense light
true
what are functions of the tear film
surface moist
lubricant
trap debris
remove epithelial cells
oxygen source
smooth refractive surface
antimicrobial
corneal hydration
ocular surface wound healing
what are the three layers of the tear film
lipid layer
aqueous layer
mucin layer
what produces the lipid layer of the tear film
meibomian glands, zeiss and moll glands
what is the function of the lipid layer
thicken, stabilize and decrease evaporation of the aqueous layer
what is the outermost layer of the tear film
lipid layer
in healthy eyes how thick should the lipid layer be
~0.10 um
t/f blinking releases the lipid layer
true
T/F forceful blinking releases more lipids
true
what is the middle layer of the tear film
aqueous layer
what produces the aqueous layer of the tear film
accessory exocrine glands of krause and wolfring
what is the function of the aqeuous layer of the tear film
provides oxygen to the cornea, cushions the globe from the eyelids and contains antimicrobial proteins
what are the antimicrobial proteins contained in the aqueous layer of the tear film
lactoferin and lysozymes
T/F Aqeuous layer tear film production rate decreases with age
True
What is the inner most layer of the tear film
Mucin layer
what procudes the mucin layer of the tear film
goblet cells and tarsal crypts of Henle
what is the function of the mucin layer of the tear film
lubrucate the lids and serves as the absorbing site for the aqueous layer, also performs waste management
What layer of the tear film lubcircates the lids and performs waste management
Mucin Layer
What will happen if the mucin layer of the tear film is disrupted or contaminated?
elicit tear break up
What layer has these?
Cholesteryl esters
cholesterol
triglyceride
phospholipids
Oily layer (0.1um)
What layer of the tear film has these
98-99% water
approx 1% inorganic salts
approx 0.2-0.6% proteins, globulins, and albumins
approx 0.02-0.06% lysozyme
rest: glucose, urea, neutral mucopolysaccharidse, and acidic mucopolysaccharides
Water Layer (8um)
What Layer of the tear film has these?
Conjunctival and goblet cells
Mucin Layer 0.8um
what percentage of tears pass through the nasolcarimal drainage system?
75%
What system is composed of the Puncta, canaliculi, lacrimal sac, nasolacrimal duct
nasolacrimal system
What can we use to evaluate the quality of the tear film?
Fluorescin staining, tear break up time, rose bengal/lissamine green
What can we use to evaluate the quantity of the tear film?
Schirmer test 1 and 2, red phenol thread
What ophthalmic dye penetrates areas of corneal epithelium and conjunctival epithelium where intracellular junctions are disrupted?
Fluroescein
What dye will be observed under direct diffuse cobalt blue at low mag
Fluroescein
T/F the wratten filter can be used with diffuse cobalt blue and fluorescein to observe the cornea
True
What dye is used to evaluate cornea and conjunctival epithelium disruptions
fluroescein
what dye is used in tear break up time
flourescein
What test quantifies the stability of the precorneal tear film
tear break up time
what test must be performed prior to anesthesia and tonometry
tear break up time
T/F TBUT must be performed before any other procedure that may mechanically or pharmacologically alter the ocular surface
True
These are the steps to what procedure?
1. apply fluroescein using a wet NaFl strip
2. under low mag w cobalt blue illumination scan the cornea. ask the patient to blink several times and stare ahead without blinking
3. count the seconds it takes for the first tear film breaks to appear
tear break up time
what is the name of this mechanism? who was it described by? in what year?
Holly and Lamps mechanism for tear film break up
Desribed by Holly in 1973
Values of less than 10s for TBUT
abnormal
Values of 5-9s for TBUT?
borderline dry eye
values of less than 5s for TBUT
indicates dry eye
T/F perfroming TBUT after installing anesthesia may provide false positives
true
What test is pictured?
TBUT w fluroscein dye
toposcope is used for
non invasive tear break up time
What dye is used in the picture?
Rose Bengal
what dye is used in dectection of keratoconjunctivitis sicca and early detection of ocular surface disease
rose bengal
T/F rose bengal is very painful and could be toxic
true
T/F lissamine green is an alternative for rose bengal
true
what dye is used in the picture
Lissamine green
Lissamine green has an affinity for staining what?
dead and degenerated cells
when evaluating with lissamine green, if illumination is too intense or bright what will happen to the contrast?
contrast will be diminished causing an underestimation of staining
what is the following picture used to grade
staining
What test measures primarily aqueous production due to the aqueous layer composing the largest part of the tear film and performed using Whatman no 41 filter paper?
Schimer Test I
what filter paper does the Schimer test I use?
Whatman no 41 filter paper
how much is the head of the whatman filter paper folded for the Schirmer test I?
5 mm
What test has the procedure below
- apply strip w folded end onto lower lid margin at lateral canthus after dryer the excess tears, ask patient to look nasal and insert temporal, instruct pt to keep eyes open and blink normally
Schimer test I
T/F in the Schimer test I you want to make sure the Whatman no 41 filter paper is touching the cornea at all times
FALSE
What test is depicted in the picture
Schirmer Test I
