(VFQs) [24, 77]. Instruments have long been the means of assessing the success or failure of rehabilitation programs (e.g., [10, 29, 88, 90]).

The rising use and interest in questionnaires has been driven by both need and, largely, by improvements in the methods of development and data analysis. The latter charge was lead in large part by Robert Massof. He applies techniques including Item Response Theory and Rasch analysis that have greatly increased the value and “interpretability” of the information gathered. Massof (2007) has quite clearly laid out the merits of and need for these techniques [68].

Visual function questionnaires contains activities to which difficulty ratings (related to vision) are assigned by study subjects/patients. There is an abundance of VFQs, including the NEI VFQ-25 [62], VAQ (visual activities questionnaire) [86], and Veterans Affairs questionnaires [89] for low vision (VA LV VFQ-48 and LV VFQ-20).

There are also many instruments addressing Activities of Daily Living (e.g., [46, 63]).

More recently, instruments assessing Health-Related Quality of Life (HR-QOL) or Quality of Life (QOL) have come into use. The content of HR-QOL questionnaires typically includes assessment of the ability to perform tasks of daily living, interactions with other people, emotional well-being and independence [33].

The broad range of instruments available, with varying content, and some developed before and some after the changes in design and scoring alluded to above, makes choosing the appropriate instrument tricky. The means to assess the quality of an instrument and to decide whether it is appropriate for use in a particular context as well as key issues for questionnaire development have recently been nicely laid out [77].

20.6  Summary

Assessing the efficacy of visual prostheses is a complex undertaking. There are many issues to consider in the assessment of visual prostheses. As the technologies continue to evolve, there will be a changing dynamic involving the steadily improving capabilities of the technology and the unique needs of the growing number of target populations. What is common in all circumstances is the need to assess visual function, visual performance, and self-perceived visual ability using tasks that are appropriate to the target population in terms of functional level and needs, with methodologies that meet generally adopted criteria scientific rigor, including adequate preand post-implant evaluation and appropriate control procedures.

Acknowledgments  The authors gratefully acknowledge the helpful discussions with and ­suggestions of Dr. Gunilla Haegerstrom-Portnoy, Dr. Lori Lott and Dr. John Brabyn. The authors also thank Prof. Michael Bach and Dr. Walter G. Wrobel for providing us with the BaLM test for examination and Prof. Ian Bailey for providing us with the Berkeley Rudimentary Vision Test.

Supported by The Smith-Kettlewell Eye Research Institute and NEI Grant EY09588 to John Brabyn.

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Chapter 21

Activities of Daily Living and Rehabilitation with Prosthetic Vision

Duane R. Geruschat and James Deremeik

Abstract  Now that technology has the capability to provide ultra-low vision to individuals who are functionally blind, there is a recognized need for vision rehabilitation to become part of the process of adaptation. This chapter will present concepts of rehabilitation as they relate to prosthetic vision, describe approaches to evaluation and instruction, address issues related to measuring outcomes, and offer thoughts on the future of rehabilitation for individuals with prosthetic vision.

The purpose of this chapter is to describe the challenges and opportunities of prosthetic vision in the context of using such vision for activities of daily living and to propose rehabilitation techniques that could assist patients as they adapt and integrate prosthetic vision into their lives. The chapter will be divided into four sections: Concepts of Functional Vision and Rehabilitation, Evaluation and Intervention with Prosthetic Vision, Measuring Functional Outcomes, and The Future.

Abbreviations

D.R. Geruschat (*)

Lions Vision Research & Rehabilitation Center, Wilmer Eye Institute, Johns Hopkins University School of Medicine, 550 N. Broadway, 6th Floor, Baltimore, MD 21205, USA e-mail: dgeruschat@jhmi.edu