Dry eye Flashcards
tear film: SECRETARY SYSTEM is composed of
lipid phase- OUTER layer- stops evaporation, increases surface tension,lubricates the eyelid
meibomian glands
glands of zoll-eyelashes
glands of meiss- deficiency leads to blepharitis
aqueous phase- middle layer0 supplies o2- contains lysozymes- washes away debris- main lacrimal gland
glands of wolfing
glands of krause
mucus phase- conjuctival goblet cells
crypts of hence
superficial coneal epithelial cells
tear film: distributary system is composed of:
wiper effect towards punctae and drainage system
tear film- production- 1.2ul/min
vol- 7ul
turnover every 5min
eyelids- blinking distributes the tears
tear meniscus- along lower lid- reservoir
tear film- execratory system
drainage- tears move thorugh punctae to caniculai and then to lacrimal duct. lacrimal sac, pumping from lid action,
evaporation- 10% of aqueous evaporates
however lipid layer prevents evaporation
whats the point of a tear film:
optical properties- smooth optical surface for good va for nutrition to remove waste- mechanical for transparancy antibacterial- lysozyme lactoferin immunoglobulins allow cl to move- leave it be comfortable
what is dry eye
disorder of the tear film- due to tear deficiency or excessive evaporation- damage to ocular surface
discomfort, visual instability and tear film instability
also increased osmorality and inflammation
How does neural stimulation- lead to dry eye
a disruption in the neural stimulation-
tear secretion as a response to external stimuli- parasympathetic and sympathetic system
decreasing corneal sensitivity- diabetes, herpes zoster, long term cl, sjorgens also decreases tears
does dry eyes lead to inflammation
yes.
did u wish all this card said was yes.
sorry theres more to the answer hahaha
u can get
inflammatory cell infiltration
activation of ocular surface epithelium- increased expression of adhesion molecules and inflammatory cytokines also in test fluid
increased activity of matrix degrading enzymes
how would u do a tear film assessment
- H&S-age/gender, systemic conditions, atopy, med, environment, smoking. sx bilateral?
2.Secretion/ volume of tears- schemers strip, phenol read test, meniscus height, fl clearance
3.staining- rose bengal, florecine, lissamine green- NEW METHOD- Alcian blue- stains mucous and connective tissue
4.stability/ tear quality- TBUTwith fl, niTBUT, tearscope, meniscus shape
5.blink/ surface action
6.solute analysis
also do examination of lids and lashes- check for blepharitis/ mgd/ acne
does this px close lids fully
whats the lid wiper
lid ege-0.4-0.6mm- over ocular surface- 8000x
irritation and damage if tear film depleted
phenol red test
dry eye examination- string in lower conjuctival sac with ph indicator ph of tears changes string- 10 second quick test less reflex tearing
schirmers test
for dry eye reflex tearing strip of paper cheaper put in lower conjuctiva measured for 5 mins- av 30mm WHATMAN filter paper, WHATMAN you say WHATMAN, omg WHATMAN- better not forget this on the test
why would u look at tear meniscus
tear quality
dry eye assessment
maybe u just wanted to check out a tear meniscus
look at central height- should be 0.3 and regular
what can help with dry eye
In short: Artificial tears/ lubricating agents In long: Hydroxypropyl Methylcellulose (HPMC)
Carboxyl Methylcellulose (CMC)
Demulcent
Polyvinyl Alcohol (PVA)
Glycerine
oils/gels
ointments
clarymist
vitamin A
Fatty oils
omega 3
antiinflammatory
cortico- steroids
hormones
if due to Mgd/blepahritis- treat that?
if can’t blink properly- treat them
punctal plugs
refit cl- duh
Kerato-conjuctivitis sicca
exposure keratitis cause by dry eye kerato means cornea involved conjuctivitis sicca- no cornel involvement sterile punctate keratitis
whats the different TBUT
with fl- 15 seconds
a non invasive technique- like tearscope- more so 45 seconds
whats the thickness of a lipid layer
between 20-200 nm
reflections from anterior and posterior tear film- produce interference patterns- which change with the thickness
stuff about the tearscope
cold light source reflected image of tear film surface interference pattern NiTBUT tear meniscuc uses scattered light- thickness is implied- not actually measured but can look at tear thinning
how does a cl affect the tear film
-it splits the tear film
-reduced tbut
-soft cl reduces lipid layer
and RGP completely removes it- omg- RGPs are so mean- i feel u lipid layer x
these things could reduce cl wear- as get uncomfortable, reduce va, redness, unhappy px
whats Flourecine
ph indicator
as bowman’s layer is alkali- gets in here-green
tears are normally acidic- yellow
also fitting rgp
for soft cl- use fluroxen- high molecular weight- for HEMA- less fluorescence
BAD points- evil fl- susceptible to pseudomonas- resistant to many antibiotics- and usually used for corneal lesions-
also inhibits preservatives
pterygium can also be due to dry eye
no note- just learn that yeah babesss
corneal sensitivity
v sensitive
from periphery- and radiate centrally- inferior more than superior
affected by diurnal, age, iris, race, colour, pregnancy, menstruation
affected by cl use
- aesthesiometer- used to asses sensitivity
