Abstract Details

Title A Visual World After Losing All Vision: The Preservation of Visual Imagery Following Complete Loss of Light Perception

Topic Aging, Dementia, and Behavioral Neurology

Presentation(s) P3 - Poster Session 3 (5:30 PM-6:30 PM)

Poster/Presentation
Number 9-020

Objective To determine whether long-term lack of visual input can result in loss of visual imagery, or “secondary aphantasia.”

Background “Aphantasia” refers to the loss or absence of visual imagery. This can occur with intact vision as a congenital disorder or an acquired form following a brain lesion. We asked whether visual imagery would also be impaired following longstanding bilateral blindness.

Design/Methods A battery of nine objective forced-choice visual imagery tests was developed with categories including object shape and size; colour lightness and hue; words and letters; and faces. A tenth questionnaire tested auditory imagery. These tests were validated in a pilot study with twenty sighted participants. Fifteen participants with no light perception were recruited from the Canadian National Institute for the Blind and local ocularist clinics. Four participants had lifelong severe visual impairment, while eleven had varying durations (range 1-36 years) of blindness after developing visual loss later in life (age at onset range 16 to 87 years). These participants were paired with fifteen age- and gender-matched sighted controls. We screened for pre-existing memory impairment using verbal components of the Wechsler Memory Scale.

Results

As expected, subjects with lifelong blindness, and thus no visual experience, showed severe difficulties. They did perform better than chance on questions about objects and colour, likely indicating some knowledge of the visual world derived form verbal semantic information. Subjects with later onset blindness performed similarly to controls except on imagery for famous faces, and better than the life-long blind on all categories. A multivariate analysis did not show a significant correlation of a global imagery score with age at onset or duration of blindness in this small sample.

Conclusions Most forms of visual imagery, with the exception of faces, persist after many years of blindness. This suggests that visual memories do not require ongoing visual input for their maintenance.

Authors/Disclosures
Connor Dietz, MD (The University of British Columbia) PRESENTER	Dr. Dietz has nothing to disclose.
	No disclosure on file
Jason Barton, MD, PhD, FRCPC (Beth Israel Deaconess Medical Center)	The institution of Dr. Barton has received research support from Canada research Chair. Dr. Barton has received publishing royalties from a publication relating to health care. Dr. Barton has received personal compensation in the range of $500-$4,999 for serving as a guideline for vision therapy in MTBI with ICBC.

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