CHAPTER 3 Low Vision for O&M

What is Low Vision?  Definition has changed over the years  According to Foundation of Orientation and Mobility:  “…persons with usable visio that is not fully correctable by standard eyeglasses, who experience difficulty performing visual tasks for the purupose of mobility.”  They fall somewhere between fully sighted and total blindness

History of Low Vision  Legally Blind (20/200 or worse) until late 1960s  Dr. Natalie Barraga challenged the concept of “sight saving” 1964  First national low vision mobility conference 1971  First course in low vision was required by Western Michigan University’s professional prep program.  Within 10 years all universities followed suit  Increase in low vision research 1980s and early 1990s

Common Functional mobility problems for students with low vision  Lighting and glare  Adaptation, night lighting,  Changes in terrain and elevation  Unwanted contacts with obstacles  Head height and low-lying objects  Street crossings  Judging speed and distance, determining time to cross

Optical Devices for Mobility  Reverse telescopes and Fresnel prisms may assist students with severely restricted fields.  Driving with low vision is possible in many states. O&M teaches use of bioptics, NOT driving skills.  Electronic travel aids for low vision are still being developed. Head mounted displays are at the forefront of this technology.

Telescopes  2 types of Telescopes:  Galilean – plus lens and minus lens with space between Advantage: Large field of view Disadvantage: Only goes up to 3x  Keplerian – series of lenses with high amount of maginification Advantage – up to 10x Disadvantage – higher cost  Improve magnification while reducing visual field  Typically reduce light entering the eye (this can be good or bad!)  Most telescopes sold today have the ability to focus at close range  Advantages: small, lightweight and cosmetically appealling

Field Enhancement Devices  Reverse Telescopes (that peep-hole in your door!)  Handheld minus lens  Fresnel prisms  Series of prisms compressed into a transparent, thin, plastic membrane  Can be placed in lenses to see objects at approximately 80 degrees to the side

Addressing Low Vision  Evaluations on students with low vision must be done in a variety of settings during, different times of day, under different lighting conditions, etc.  Significant difference between reduced acuity and reduced fields.  Telescopes can assist students with orientation by improving distance visual acuity for spotting purposes.  Non-optical devices can help control illumination

Chapter 6 - Psychosocial Dimensions of O&M  Tuttle & Tuttle (2004) describe the 7 stages of adjustment to visual impairment:  Trauma  Shock & Denial  Mourning and Withdrawal  Succumbing and Depression  Reassessment and Reaffirmation  Coping and Mobilization  Self-Acceptance and Self-Esteem

 A student’s outcome expectations are likely to effect his/her motivation in O&M.  O&M’s need to be ready to help clients deal with uninformed attitudes of general public & families.