Eccentric viewing - AndreasHead

PENNSYLVANIA COLLEGE OF OPTOMETRY 816: LOW VISION TECHNOLOGY AND PRACTICE
TABLE OF CONTENT
PAGE I. INTRODUCTION 3 II. LIGHTING/ILLUMINATION 4 III. READING STANDS 14 IV. ACETATE FILTERS 19 V. ECCENTRIC VIEWING TECHNIQUES 25 VI. NEAR TRAINING DEVICES 29
(Microscopes, Telemicroscopes and Magnifiers, Hand-held and Stand) VII. CLOSED CIRCUIT TELEVISION (CCTV) 39 VIII. TRAINING PROCEDURES FOR DISTANCE 52 IX. DISTANCE TRAINING DEVICES 60
(Monocular Telescope or Spectacle Mounted Binoculars) X. FIELD EXPANDERS 65
A. Fresnel Prisms
B. Reverse Telescopes XI. ABSORPTIVE/SUN LENSES 89 XII. ABSORPTIVE LENSES EVALUATION 101 XIII. FORMAT FOR PLANNING 103
LOW VISION INSTRUCTION XIV. ASSISTIVE DEVICES 111 XV. SUMMARY 122 I. INTRODUCTION
[pic] Planning for Low Vision Instruction
In the following sections of this document, you will find instructional
plans for teaching children and adults how to effectively use near and
distance devices, closed circuit television, field expanders, and eccentric
viewing, The instructional resources represent a complete set of
instructional plans for current and future use. The plans were developed
collectively and individually by the participants in the Low Vision
Technology and Practice Course in spring, 2004 for current and future
learning and development, in addition to the course requirement. The set
of instructional resource plans include the following: 1. Instruction in use of near devices-microscopes, magnifiers (hand held
and stand), stereomicroscopes
2. Instruction in use of distance devices (hand held telescopes and
spectacle mounted)
3. Instruction in eccentric viewing
4. Instruction in use of electronic devices such as closed circuit
televisions (reading and writing)
5. Instruction in use of field expanders (e.g. Fresno prisms, reverse
telescopes, spectacle mounted mirrors for field losses)
6. Lighting and reading stands
7. Sun lenses (how to evaluate and instruct individuals in use)
8. Related resources, websites and manufacturers
Obtained from course syllabus and documents prepared by
instructors, Dr. Janice Smith and Dr. Laura Edwards II. LIGHTING/ILLUMINATION [pic] INSTRUCTIONAL RESOURCE PLAN FOR
LIGHTING/ILLUMINATION
By
Riki Nitz
Learning Objectives
[pic] The individual will make an informed and preferred choice
regarding lighting options to maximize their vision and increase
reading and writing efficiency.
[pic] The individual will know and be able to maintain appropriate
positioning and wattage for his/her preferred lighting choice.
Materials
[pic] Variety of Reading/Writing Materials, based on the goal/s of the
individual
[pic] Clipboard or Reading Stand
[pic] Variety of Lighting Sources
. Natural/Fluorescent/Incandescent/Combination
. Table/Desk/Floor
[pic] Variety of Light Bulbs with Different Wattages
[pic] Light Meter
Teaching Sequence
[pic] Introduction and informal conversation to establish a
level of comfort, rapport, and understanding
. Discussion of the eye condition of the individual and related
lighting issues and concerns
. Prefer bright or dim light?
. Under what circumstances?
. Bothered by glare? Where? When?
. Fluctuations in vision?
. Explanation of a lighting evaluation and resulting optimal
lighting recommendations specifically determined for the
individual
. Discussion of the importance of proper lighting for reading and
writing and how good lighting may help the individual achieve
his/her goals
. Determination of the near vision goals of the individual -
specific tasks to be performed and the priority of tasks
[pic] Select material for the individual to read/write during the
lighting evaluation, preferably using his/her own materials from home if
available.
[pic] Introduce a lighting source, orienting the individual to the
features and functions of the source and explaining the advantages of
using an appropriate lighting source for reading and writing.
. Increases speed and efficiency of reading
. Encourages correct posture
[pic] Seat the individual at a table/desk with selected
reading/writing material. Be sure the desk/table is an appropriate
height for the individual and allows for proper and comfortable posture.
[pic] Position lighting according to the individual's visual needs and
explain the reason for the specific positioning and placement of the
light.
. As close to the task/materials as possible or is comfortable.
The greater the distance from the light source to the
task/materials, the less the effect of the lighting.
. Reading - directly over the task/materials on the same side as
the individual's better eye
. Writing - in front on the opposite side of the individual's
working hand
[pic] Have the individual view the reading/writing material and
introduce light #1. Turn light off.
[pic] Introduce light #2. Turn light off.
[pic] Instruct the individual to compare lights #1 and #2 as you turn
them on and off again.
[pic] Document the individual's preference.
[pic] Introduce light #3.
[pic] Instruct the individual to compare the chosen light between #1
and #2 to light #3 as you turn them on and off again.
[pic] Document the individual's preference.
[pic] Repeat comparison procedure using a variety of fluorescent and
incandescent options and bulb wattages until a preferred choice is
determined.
[pic] If glare or too much light is problematic, change wattage of
bulb and repeat procedure.
[pic] Demonstrate different wattages of bulbs and proper installation
and maintenance.
[pic] If other problems arise, consider additional environmental
modifications for illumination control:
. Redirect lighting
. Adjust the angle at which the material is presented/viewed
. Reduce bulb-to-task distance
. Try a supplemental light source - portable lamps or illuminated
optical aids
. Try gooseneck or flex-arm lamps
. Use dimmers/rheostats
. Change background to control contrast and level of illumination
. Try colored filters
. Position self away from windows
. Check/close drapes or shades on windows
[pic] Document the individual's comments and reactions regarding the
various lighting options presented.
. Which is better?
. Which causes glare?
. Which has too much heat?
[pic] Measure the individual's lighting preference with a light meter
for reference at later training sessions.
[pic] Document the final results of the lighting evaluation - the
individual's lighting preference. General Tips
[pic] Have the individual wear his/her prescription/reading glasses
and use prescribed near vision devices (if appropriate) during the
lighting evaluation.
[pic] Lighting needs generally increase with age.
[pic] Adequate room lighting is important. Avoid using a bright lamp
in a dark room.
[pic] Factors Affecting Lighting Requirements:
. Extent and location of visual impairment
. Type of task
. Size of material
. Quality of material (shiny/glossy or dull/matte)
. Viewing distance
. Contrast of materials to background
. Light adaptation ability
. Time of day
. Changes in weather (sunny or cloudy)
. Fatigue
. Age
. Personal preference
[pic] Lamps
. Should be shaded to protect the individual from heat and to
eliminate glare
. Should be flexible - gooseneck or flex-arm
. Should provide a range of illumination - dimmers/rheostats
[pic] Fluorescent Lighting
. "Cool" light source providing high levels of illumination
. May produce visual fatigue, glare, and/or discomfort,
particularly from its strobe like properties
[pic] Incandescent Lighting
. "Warm" light source, but produces more heat and may not provide
high enough levels of illumination
. Produces a more comfortable lighting environment and more
contrast
[pic] Position and placement of the light source is more important
than the wattage of the bulb.
[pic] Be aware of the washout effect from over lighting a task.
[pic] Replace and clean bulbs frequently. Home Practice [pic] Give reading/writing task assignments to be completed with the
preferred lighting.
[pic] In