Optometry & Vision Science:
Levi, Dennis M.
Fixing My Gaze: A Scientist’s Journey into Seeing in Three Dimensions
Susan R. Barry. New York: Basic Books; 2009. $26.00.
Susan Barry, a Professor of Neurobiology had infantile strabismus and had been stereoblind essentially all her life. Fixing My Gaze provides a fascinating, informative, and beautifully written account of her acquisition of stereopsis after vision therapy at the age of 48 years. There is a long history of introspection informing vision science, dating back to Helmholtz, and Barry’s insights about her own vision provide wonderful insights into what it means to not have stereopsis, and the profound, life-changing effect of acquiring it.
One major contribution of the book is to call into question the notion that amblyopia and strabismus can only be treated during a “critical period” of development when the visual system is still plastic. This idea, dating back to Worth,1 led a number of practitioners to tell Susan and her mother that “nothing can be done” about her vision (and one to suggest that she might need a psychiatrist). Because binocular neurons are present in the visual cortex of primates within the first week of life,2 Barry surmises that some of the innate wiring of her binocular connections remained intact, and that vision therapy taught her to move her eyes into position for stereovision, “finally giving these neurons the information they were wired to receive.” Recent studies of perceptual learning in adults with amblyopia,3 give strong credence to the notion that amblyopic vision can improve long after the “critical period.”
Barry’s book will be of interest to practitioners, scientists, and patients afflicted with strabismus and/or amblyopia. It is scholarly, with many footnotes and references, and Barry is able to explain the science in simple, clear terms. The book provides a strong testament to the potential of vision therapy. It also raises many interesting questions. For example, did she regain function that was present earlier, by unmasking neural connections? Was her early surgery important in allowing her to retain some stereopsis? We know that Sue’s stereopsis is still not normal, and one wonders whether she has reached her limit or whether her stereoacuity will continue to improve. Finally, we do not know what proportion of patients will respond to this type of treatment, or which specific techniques are key to success. Hopefully that this book will inspire clinicians to undertake randomized clinical trials to answer the many important questions raised by this book.
Dennis M. Levi
1. Worth CA. Squint: Its Causes, Pathology and Treatment. Philadelphia: Blakiston; 1903.
2. Chino YM, Smith EL III, Hatta S, Cheng H. Postnatal development of binocular disparity sensitivity in neurons of the primate visual cortex. J Neurosci 1997;17:296–307.
3. Levi DM, Li RW. Perceptual learning as a potential treatment for amblyopia: a mini-review. Vision Res. February 27, 2009. [Epub ahead of print].