PERFORMING RELIABLE VISUAL FIELDS

NOA Fall Conference Presented by Jill Luebbert, CPOT, ABOC

What are “Visual Fields”

 A test?

 A view of the plains of Nebraska?

 “the area or extent of physical space visible to the eye in a given position

How much can we see?

 Monocular visual fields usually measure  60 degrees superior  75 degrees inferior  105 degrees temporal  60 degrees nasal

Making a map

a.k.a.

Performing Visual Fields

Meridians and Quadrants

 Horizontal meridian  Vertical meridian  Quadrants  Circles of eccentricity

Two methods of presenting Visual Fields

 Kinetic  Static

Kinetic

 Target in motion moved from non-seeing to seeing

Static

 Stationary target  Threshold or suprathreshold

Terminology

 What are they talking about?

Terms used



Perimetry

 Visual field testing with eye located at the center of a curved instrument 

Campimetry

 Visual field testing eye located a specified distance from a flat surface 

Scotoma

 Vision entirely absent   

Blind Spot (natural)

 Approximately 15 degrees temporal to fixation (Optic Nerve)

Isopter

  Boundary mapped for a particular stimulus size and intensity Iso = equal opter = sight

Decibel



Relative unit, 1/10 log unit



Threshold

 Every test point is evaluated by bracketing or staircase method 

Suprathreshold

 Target value assumed to be above threshold value for all points 

False negative

 Patient does not respond when a maximally bring stimulus is present at a point previously found to be normal 

False positive

 Patient responds when no stimulus was present



Grayscale

 To be used for patient education – Represents tested points, which have been assigned value 

Mean Deviation

 Difference in decibels between “normal” and patient’s hill of vision 

Pattern Standard Deviation

 The measurement of the degree which the shape of patient’s measured “hill” of vision departs from normal 

Short Term Fluctuation

 A measurement of the degree of variation of threshold during the test

Types of Visual Fields

 Confrontation  Harrington Flocks (Burton) Screener  Tangent Screen

Arc Perimeter

Amsler Grid

Frequency Doubling Technology  FDT

Goldmann introduced in 1945

Auto Perimeters

 Humphrey  (Carl Zeiss Meditec)  Octopus (Haag-Steit)

What is the “hill of vision”?

Why do we perform Visual Fields?

 To monitor area of vision utilized  Monitor diseases  Glaucoma  Macular Degeneration  Stroke

The technician’s responsibility

 To be comfortable and knowledgeable with the instrument used  To perform accurate and reliable visual fields  To perform repeatable visual fields  To accurately gather diagnostic data  To keep the patient as comfortable and relaxed as possible  This is not a speed test

Setting up and Preparing

 Data entry can be completed before the patient sits down  Choose the correct test  Set variables

Setting up

 Choose the pre-determined test  Variables  Color  Fluctuation  Blind Spot Size  Test Speed

Setting Up

 Enter Patient Information  Spell the name same format every time  All caps or upper and lower case  Last name first or first name fist  Middle initial with period or without period  Date of Birth  Vision Acuities  Lens Used  Pupil Size

Preparing the patient

 Introduce yourself  Acknowledge them by their name  Comfortable atmosphere  Explanation of what to expect  What to see or not to see  How long to expect  Breaks??

Ready to start

 Clean the instrument  New chin cover sheet  Give them the controller  Occlude non-testing eye

Positioning

 Make this as comfortable as possible  Adjust the instrument height  Adjust the chin rest height  Chin and forehead firmly in place  Keep teeth clenched together  Adjust lens holder  Not too close or too far away

Ready???

 Verify the patient is in position  Give them a short test run first  All OK??

 Ready  Set  Start

Now what?

 MONITOR  DO NOT LEAVE THE PATIENT  Monitor fixation  Monitor attentiveness  Is the patient staying securely to forehead rest and in chin rest

Remember

 Restart if necessary  It is important to achieve reliable results  Is the patient staying attentive  Take breaks as you judge necessary  This is not a race

Finished

 Are you performing the same test on the other eye?

 Take a short break between  Let the patient stretch their fingers, neck  Occlude next eye  Give the patient the control  Any questions???

 Position

Keep a watchful eye

 Monitor  Fixation  Patient attentiveness

Testing Complete

 Save results  Return instrument control  Return testing lens  Return occluder  Print or send results to correct station  Note any observations  patient restless, etc  Escort patient to next station

“How did I do?”

 Do not share results  Let the patient know they provided lots of data for the doctor to review  The doctor will visit with them regarding the results

Congratulations on performing



Thorough



Accurate



Repeatable



Visual Fields

Enjoy Nebraska Optometric Conference Experience Jill J Luebbert, CPOT, ABOC [email protected]

www.jjlconsulting.com

Luebbert Consulting & Training