Dilation Flashcards
purpose of dilation
- improve visualization of the fundus
- improve visualization increases detection rate of abnormalities
Is dilation required for a thorough evaluation of ocular structures?
-according to the AOA it is
who should be dilated?
ALL patients
How often should you get a comprehensive eye exam?
18-39 should be at least every 2 years
65 and older, every year IN THE ABSENCE OF OCULAR CONDITION
when else should you dilate?
- patients with previous ocular pathology
- patients with high risk of intraocular disease
- patients that come in with certain chief complaints
if people are sensitive to dilation drops, what are they sensitive to?
-the preservative
when you see someone with_______, you should not dilate
- narrow anterior chamber angle
- iris-fixed intraocular lens
why is history important before dilation?
- guides the DFE
- aids in what you are looking for during ophthalmoscopy
Why should you do VA?
- before any procedure for legal reasons
- detect refractive error, problems with retina, optic nerve, etc
Do all disorders affect VA?
-nope
pupil reflexes
- screen for abnormalities prior to dilation
- determine if vision loss is macular or optic nerve related
- VERY important when people have APD and decreased acuity in one eye
normal range of IOP
8-23 mmHg
average: 15.5
when is a difference in pressure between two eyes considered significant?
-difference more than 2 mm Hg
what time of day are pressures higher?
-morning
Diurnal variations of what are considered normal?
3-4 mm Hg
What patients will see a elevation of IOP after dilation?
-open angle glaucoma
how do pressures change in age?
-increase
What are the three ways you check IOP?
- digital palpation
- non contact tonometry
- goldman
advantages of digital palpation
- simple
- inexpensive
- no instrument
- good when external tonometrty is not possible
- when patients are unable to do other methods
Disadvantages of digital palpation
- least accurate
- you should avoid in eyes with trauma or in post op conditions
what fingers do you use for digital palpation?
-two pointer finers
soft IOP
less than 6-8
Hard IOP
greater than 30
using other body parts, what does the eye feel like?
- nose is normal
- chin is hard
- cheek is soft
should you record time for digital palpation?
-hell yea
NCT
- cornea is applanated by air pulse
- IOP mesured without direct contact between eye and instrument
- useful when there are infections
advantages of NCT
- quick
- no anesthetic
- can be delegated to tech
- no epithelial damage
- measure through contact lenses
disadvantagegs of NCT
- cost
- large instrument
- less portable
- must be factory callibrated
- multiple readings necessary
- most patients hate it
applanated
-force it takes to flatten the cornea
a narrow anterior chamber angle increases risk of?
angle closure glaucoma
shadow test book definition
-anterior chamber depth estimated with oblique penlight illumination across the surface of the iris
three ways to evaluate anterior cahmber depth
- shadow test
- slit lamp
- gonioscopy
shadow testttttt
- GROSS ESTIMATION
- used only when slit lamp is not available
- light is presented from temporal side
what level of brightness should you do shadow test?
FULL ILLUMINATION
grade 1
-less than 1/3 iris is illuminated
grade 2
-1/3-2/3 illuminated
grade 3
2/3 illuminated
grade 4
fully illuminated
what should you warn patients with narrow anterior chamber angles about?
- signs and symptoms of angle-closure glaucoma
- could have increases of IOP after dilation
who is more at risk of narrow angle glaucoma?
- older patients
- asians
- women
hyperopia
-more likely to have shallow anterior chambers and narrow angles
signs of angle closure glaucoma
- severe pain
- blurred vision/halos
- headache
- nausea
- red eye
- dilated pupils
is angle closure glaucoma an ocular emergency?
YES
go look at summary
do it
what is the purpose for dilation?
- improve visualization of the fundus
- improved visualization means more detection of disease!
mydriasis
dilation
mydriatics
agent that induces dilation of the pupil
why use an anesthetic before instillation of mydriatic?
- decreases blinking and tearing
- reduces burning or stinging
why do light eyes dilate faster?
-less pigment in the iris to sequester the drug
what does uncontrolled diabetes have to do with dilation?
-uncontrolled diabetics will have smaller pupils and are slower to dilate
increase in age does what?
smaller pupils
-increase in latency time to dilate
miotic
-small pupil
side effects of dilation
- blurred vision for near tasks
- photophobia
- decreased ability to recognize low-contrast
- glare sensitivity
- can contribute to angle-closure
can you drive with dilation?
yea
what is under the sympathetic pathway?
dilator
what is under the parasympathetic pathway?
sphincter
in general, dilation has what kind of innvervation?
autonomic
cholinergic drugs-agonist
- parasympathomimetics
- cause iris sphincter contraction (miosis)
- causes ciliary body contraction(accommodation)
what color cap do agonists have
green
example of agonist cholinergic drug
pilocarpine
cholinergic drugs-antagonist
- anticholinergics
- bind to and inhibit cholinergic receptors
- pupil sphincter inhibition-mydriasis
- ciliary body inhibition- cycloplegia
cycloplegia
-inability to accommodate
what color cap do antagonists have?
red
examples of antagonists
-tropicamide, cyclo, atropine
tropicamide
-fastest onset and shortest duration of mydriatic effects
what is the drug of choice for routine mydriasis?
tropicamide
does the concentration of tropicamide change the effects?
-mydriasis is the same, but cycloplegia is worse in 1%
what is the most potent mydiatic/cyclo drug?
-atropine
when do you use atropine?
- when you need complete cyclo
- can last up to 7 days
what is the drug of choice for routine cycloplegic refraction?
cyclopentolate
cyclopentolate
-faster cycloplegia with less residual accommodation
adrenergic drugs-direct
- stimulation of dilator to cause mydriasis
- no cycloplegia effect!
what is an example of adrenergic-direct drugs?
phenylephrine
what color cap do adrenergic drugs have?
red
indirect alpha adrenergic drugs
-release stored norepi of inhibit reuptake of norepi
example of adrenergic-indirect drug
hydroxyamphetamie
phenylephrine
- dilation without cycloplegia
- combined with anticholinergics
what is routinely used for maximum dilation?
2.5% phenylehrine with tropicamide
side effects of phenylephrine
STINGING
what is the preferred method for drop instillation?
inferior fornix delivery
why use inferior fornix delivery?
- max ocular contact time of drug
- minimize drug loss
- increase ocular absorption
- decrease systemic absorption
what should you do after you have properly instilled the drop?
-punctal occlusion
what should you include in the recording of drops?
- name of the drug
- its concentration
- how many drops for each eye
- time
what are alternate methods of drop instillation?
- medial canthus delivery
- spray bottle
- pledgets
what does pregnancy group C mean?
-tests have been done on animals and have seen bad results, but not done on prego humans
should you just out like a million drops in all at once?
- nah
- no anesthetic first, wait 2-5 min, then do dilation
- sit in dark room
