Spatial compression produced by a stationary low-vision telescope.

Optom Vis Sci 2008 Jan;85(1):54-62

Illinois College of Optometry, Chicago, Illinois, USA.

Purpose: Geometrical analysis of the monocular information for visual space perception predicts that the magnification produced by a low-vision telescope will compress the depth dimension of space. To test this prediction we measured the compression in depth of perceived shape while looking through a stationary telescope. To control for the other aspects of telescopic viewing, apart from magnification, we also measured perception while looking through a plain tube having the same field of view.

Methods: A 2.75x Keplarian telescope was mounted 40 cm above a tabletop patterned with receding stripes. The 11.6 degrees field of view was centered on a series of rectangular stimulus cards lying flat on the table at a distance of 100 cm. Participants monocularly viewed each card through the telescope, or through a tube having the same field of view, and verbally judged the card's perceived length (in depth) relative to its width (in the frontal plane).

Results: Perceptual compression of shape was calculated by dividing the perceived proportion (length/width) by the actual proportion. The telescope and the tube both produced significant perceptual compression, but perception was significantly more compressed through the telescope (0.43) than through the tube (0.52).

Conclusions: The magnification produced by a stationary low-vision telescope can result in a compression of perceived depth. In addition, other aspects of telescopic viewing, such as monocular vision, restricted head movements, and a restricted field of view, can together contribute substantially to such compression. Further research is needed to assess the clinical implications of these results.

Download full-text PDF

Source
http://dx.doi.org/10.1097/OPX.0b013e31815ed727DOI Listing
January 2008

Publication Analysis

Top Keywords

low-vision telescope
12
field view
12
telescope tube
8
perceptual compression
8
aspects telescopic
8
telescope
8
magnification produced
8
telescopic viewing
8
stationary low-vision
8
tube field
8
produced stationary
8
compression
5
compression perceived
4
275x keplarian
4
series rectangular
4
perceived depth
4
keplarian telescope
4
rectangular stimulus
4
stimulus cards
4
052conclusions magnification
4

Similar Publications