INSTRUCTIONAL RESOURCE PLAN

FOR FRESNEL PRISMS

Learning Objectives: Student will be able:

1.  To move eyes smoothly in and out of prism area.

2.  To identify the amount of displacement that is created when viewing through the prisms.

3.  To accurately reach and retrieve stationary objects when looking through prism.

4.  To accurately reach and retrieve moving objects when looking through prism

5.  To move through an indoor environment and accurately identify obstacles when looking through prism

6.  To stand stationary in an outdoor environment and identify stationary object while looking through prism

7.  To stand stationary in an outdoor environment and identify moving object while looking through the prism

8.  To move through a non congested outdoors environment and identify stationary object and places of business when looking through the prisms

TEACHING SEQUENCE

The nature of the prism and its function will be explain again to make sure that student has a clear understanding of the purpose of this aid. Once this has been accomplished the skill areas will be taught in the following order:

1.  movement of eyes in and out of prism area

2.  identify amount of displacement of object

3.  indoor seated reach for stationary object

4.  indoor seated reach for moving object

5.  indoor walking identify stationary objects

6.  indoor standing identify moving object or person

7.  outdoor standing identify stationary objects

8.  outdoor standing identify moving objects

9.  outdoor walking identify local store

10.  outdoor walking identify moving objects or people

GENERAL TIPS

1.  Never remove prism from glasses

2.  Clean spectacles and prisms under warm water, mild soap and toothbrush to clean groves

3.  Color will fade over time

4.  Can cause decrease in visual acuity

5.  Can cause a decrease in contrast sensitivity

6.  may fall off over time

MATERIALS USED

1. Brilliant, Richard L.: Essentials of Low Vision Practice:

pages 256-258; Appendix A and B pgs 2660267

2. Ferraro, John, M.A.; Jose, Randall T.; Understanding Low vision; Training Programs for Individuals with Restricted Fields pages 367-373

3. Smith, Audrey J. Ph.D and Geruschat, Duane R. Ph.D:

Functional Evaluation and Training Techniques in the use of Fresnel Prisms for Individuals with restricted Visual Fields

HOME PRACTICE

1.  While indoors and seated the student can practice reaching for an object or hold the object in one hand and point to it with the other hand: pencils, toys, books, plastic cups then look through the conventional lens to note the amount of displacement. This activity can be performed for 10 to 15 minutes daily.

SPECIAL PROBLEMS

1A. Prism Blur can be reduced by:

*removing and cleaning the prism to eliminate dirt and air bubbles;

*slightly changing the position of the prism on the spectacles lens

*slightly tinting spectacles lens

*incorporating the use of sun filters

1B Confusion can be minimized by:

*more training necessary in a structured setting

1C Double Vision can be eliminated by:

*more instruction in hand-eye feedback to the amount of displacement

(Ferraro, John M.A. and Jose, Randall T.: Understanding Low vision;: Training Program For Individuals with Restricted Fields; pages 363-373)