Dilation Protocol Flashcards
Dilation Protocol Learning Objectives (KEY)
Understand the purpose and indication for a
dilated fundus exam
Understand contraindications and precautions with
dilation
Important components of pre-dilation work-up
Intraocular pressure measurement; advantages
and disadvantages of techniques presented
Anterior chamber angle evaluation, advantages
and disadvantages of technique presented
The Dilated Fundus Exam
PURPOSE (KEY)
Improve visualization of the fundus (BACK OF THE EYE)
Improve visualization increases detection rate of abnormalities
The American Optometric Association’s 2015 evidence-based clinical practice guideline states that pharmacological dilation is generally required for the thorough evaluation of ocular structures.
The Dilated Fundus Exam
INDICATIONS (KEY)
Routine examination on ALL patients
For patients between the ages of 18 and 39, a comprehensive eye examination including ocular health evaluation is recommended at least every
two years
For patients age 65 and older, comprehensive eye examinations are recommended annually in the absence of a diagnosed ocular condition
More frequent monitoring with dilation is
indicated in a patient with a previous diagnosis of ocular pathology
Patients at higher risk of intraocular disease
• Diabetic, high myopia
Patients with symptoms or signs indicative of intraocular disease
• Flashing lights (photopsia), floaters, and
reduced visual acuity
The Dilated Fundus Exam
CONTRAINDICATIONS AND PRECAUTIONS (KEY)
In this part just know that people are sensible to medications. That’s it!
Also:
Narrow anterior chamber angle
• Consider prophylactic peripheral laser
iridotomy prior to DFE if angle appears
susceptible to closure on gonioscopy
Presence of iris-fixed intraocular lens
• Risk of IOL dislocation with pupil dilation
Documentation/Preservation of pupil status
• Pupil status may serve as an important vital sign
in patients with intracranial disease (coma
evaluation)
• Dilate with care in patients with recent history of
head trauma
• Unilateral pharmacologic mydriasis may
masquerade as a sign of intracranial disease
(Hutchinson’s pupil)
Pre-Dilation Work-Up
- History
- Visual Acuity
- Pupil Reflexes
- Intraocular Pressure
- Anterior Chamber Angle
Pre-Dilation Work-Up VISUAL ACIUTY (KEY)
Always be performed prior to any other procedure for medico-legal reasons Helps detect problems associated with: • Refractive error, optical media, the retina, optic nerve, and the visual pathways, however there are serious disorders that do not affect visual acuity Review lecture on visual acuity
If the pt cant see the Snellen Chart big E what are the other techniques we use
Counting Fingers, Hand Motion, Light projection, Light perception
VA
Recording in patient chart
Example Visual Acuities: VAsc: OD 20/100⁻, 20/25 @ 40cm OS 20/100⁺, 20/25⁺ @ 40cm VAcc: OD 20/15⁻, 20/15 @ 40cm OS 20/15⁻, 20/15 @ 40cm
Pre-Dilation Work-Up
Pupil Reflexes (KEY)
NOTE: DILATED EYES DO NOT REACT TO LIGHT AND DO NOT CONSTRICT
Screen for abnormalities prior to dilation Especially important to search for an afferent pupillary defect in patients with decreased acuity in one eye
Intraocular Pressure
(IOP) KEY
NOTE: (EYE PRESSURE IS HIGHER IN THE MORNING!)
Serves as a baseline against which post-dilation IOP can be compared
Normal range is considered to be 8 to 23 mm Hg
The average intraocular pressure is 15.5 mm Hg
A difference in pressure readings of more than 2 mm between the two eyes is considered significant (THIS IS NORMAL BIGGER THAT THAT IS SIGNIFICANT)
Diurnal (MEANS DAILY) variations of 3 to 4 mm Hg are considered normal
Patients with open-angle glaucoma will
often experience a mild transient elevation
of IOP following dilation with an anticholinergic agent
IOP Measurement
Digital Palpation
Non Contact Tonometry
Goldman Applanation Tonometry
The Gold Standard for IOP measurement
IOP Measurement Digital Palpation (KEY)
Simplest and least expensive technique for approximate Intraocular (IOP) assessment
• Used for conditions where tonometry
is not possible
Digital Palpation
ADVANTAGES
Simplest, least expensive
Instrumentation not required
Useful when external tonometry is not possible, for example, after penetrating keratoplasty or corneal scarring
Palpation may be the only feasible technique in patients who are unwilling or unable to undergo other methods of IOP measurement
Digital Palpation
DISADVANTAGES (KEY)
Least accurate method of IOP measurement (MOST IMPORTANT) Palpation is best avoided in eyes with significant trauma or in certain postoperative conditions
Digital Palpation
Technique
Make sure hands are clean
Say to patient:
“I’m going to check the pressure in your eyes,” then
follow with appropriate patient directions.
Ask patient to close their eyes
Feel eyeballs with fingertips through
closed lids
• Video demonstration:
https://www.youtube.com/watch?v=9fz7GXwgw3I
Digital Palpation
IOP Measurement
Determine if eye feels
• Soft (IOP <6 – 8)
•Hard (IOP > 30)
•Or somewhere in between
Digital Palpation
Recording in patient chart
IOP OD, OS • Low to palpation • Normal to palpation • High to palpation Plus time!
Digital Palpation
Recording in patient chart EXAMPLE
IOP
OD, OS Normal to palpation @ 1:00 pm
Non Contact Tonometry
NCT
The cornea is applanated (THE AMOUNT OF FORCE THAT IT TAKES TO FLTTED THE CORNEA) by an air pulse, and IOP is measured without direct contact
between the eye and the instrument
Particularly useful when contact techniques
are contraindicated, as in the case of a red eye of infectious origin
NCT
Advantages
Quick No anesthetic required Can be delegated No epilthelial damage Measure thru contact lenses
NCT
Disadvantages
Cost Large instrument Less portable Must be factory calibrated Multiple readings necessary (ocular pulse) Most patients are apprehensive
NCT
Technique
Say to patient
“I’m going to check the pressure in your eyes. Please keep both
eyes open and look at the light, you will feel a light puff of air.”
Set-up
• Turn instrument on
• Disinfect forehead and chin rest
• Adjust table and chin rest to align the patient’s outer canthus with the notch on the upright support of the headrest
NCT
Recording in patient chart
o Example
IOP
NCT@ 10:30 am
• OD 15mmHg
• OS 15mmHg
Pre-Dilation Work-Up
Anterior Chamber Angle Assessment (KEY)
(KEY) A narrow anterior chamber angle increases the risk of angle closure glaucoma
Anterior Chamber Angle
Evaluation
Shadow Test (FOCUS ON THIS ONE)
Anterior chamber depth can be estimated with oblique penlight illumination across the surface of the iris
Slit Lamp Evaluation (MOST USED)
Van Herick technique of peripheral anterior chamber depth estimation
Gonioscopy
The Gold Standard for anterior chamber angle evaluation
Shadow Test (KEY)
Gross estimation method Used only when slit lamp is not available Light is presented from the temporal side Shadow provides a rough estimate of chamber depth
Shadow Test
Technique
Instruct patient to look straight ahead Light is presented from the temporal side Shadow provides a rough estimate of chamber depth
Shadow Test (KEY)
Useful for basic screening where availability of more sophisticated equipment may be limited Video demonstration: https://www.youtube.com/watch?v=81jEkGmQ4 so
Shadow Test
Say to patient
“I’m going to take a quick measurement using this light,” then follow with appropriate patient directions. Recording in patient chart o Example Anterior Chamber Angle estimation OD: Grade 4 OS: Grade 3
Anterior Chamber Angle Evaluation (KEY)
Patients with narrow anterior chamber angles may
develop acute angle-closure glaucoma following pupil dilation, with a rapid and severe elevation of IOP
Post-dilation IOP check recommended in persons with narrow angles
(KEY) Warn about the signs and symptoms of angle-closure glaucoma and instruct patient to contact you if the symptoms occur
Document warning and instructions gave to patients
Angle-closure Glaucoma
Risk Factors for Narrow-Angle Glaucoma
Age
As we grow older, the lens inside our eyes gets larger, increasing the risk for pupil block. Also, the anterior chamber tends to become increasingly shallow, and the drainage angle may narrow as we age
Race
Asians, as well as Inuits and other northern indigenous people, who have anatomically narrower anterior chamber angles than
whites, have a higher incidence of angle-closure glaucoma
Sex
3x more frequently in women than in men
Among African-Americans, men and women appear to be affected equally
Narrow-Angle Glaucoma Causes of Narrow-Angle Glaucoma Hyperopia (NOTE: EXPLANATION HERE IS JUST FOR THIS THE REST WILL BE DISCUSS IN THE FUTURE) Pupillary Block* Iris Plateau* Tumors and other causes*
People who are farsighted are more likely to have eyes with shallow anterior chambers and narrow angles, increasing their risk for angle-closure glaucoma from pupil dilation or aging changes in the eye
Angle-closure Glaucoma
Signs and symptoms of include:
Severe eye pain
Blurred vision and/or seeing halos around lights
Headache
Nausea and vomiting
Profuse tearing
Red Eye
Dilated pupils
(KEY) Ocular Emergency!
• If not reduced within hours, may cause permanent vision loss
• If experience any symptoms, need to contact eye care
provider ASAP or go to a hospital emergency room
Summary
Dilation is a key component of an annual comprehensive exam, but may is also indicated more often in certain cases.
A complete history is key to determining indications, contraindications, and precautions when dilating.
Important components of pre-dilation work-up include history, VAs, Pupils, IOP, and anterior camber evaluation.
There are several techniques to measure IOP, and advantages and disadvantages with each.
Pre-dilation IOP and anterior chamber angle evaluation are important, particularly in cases where patients are at risk for
angle closure glaucoma. It is important to make sure the patient is aware of the signs and symptoms.
