- History - Visual Acuity - Pupil Reflexes - Intraocular Pressure - Anterior Chamber Angle

Dilation Protocol Flashcards by Maivys Hernandez

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

How well did you know this?

Not at all

Perfectly

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.

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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)

How well did you know this?

Not at all

Perfectly

Pre-Dilation Work-Up

History
Visual Acuity
Pupil Reflexes
Intraocular Pressure
Anterior Chamber Angle

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

IOP Measurement

Digital Palpation
Non Contact Tonometry
Goldman Applanation Tonometry
The Gold Standard for IOP measurement

How well did you know this?

Not at all

Perfectly

IOP Measurement
Digital Palpation (KEY)

Simplest and least expensive technique for approximate Intraocular (IOP) assessment
• Used for conditions where tonometry
is not possible

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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

How well did you know this?

Not at all

Perfectly

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.