The Smith-Kettlewell Technical File


The Smith-Kettlewell Technical File, edited by William Gerrey (WA6NPC), was a publication by and for blind and visually-impaired electronics professionals and enthusiasts. It was published by the Smith-Kettlewell Eye Research Institute from Fall 1980, through Spring 1998 and was at various times available in Braille, large print, audio cassette, and 5-1/4" floppy diskette.

Although The Smith-Kettlewell Technical File is no longer in active publication, we offer this online archive as a resource of both current and historical value.

While many of the articles about devices and techniques remain…

My Vision on Vision

These short chapters summarize insights that I have gained from more than four decades working in vision rehabilitation. They provide a broader perspective that may be missing in our daily routines, when focused on specific details. Vision involves much more than visual acuity alone. Vision serves our understanding of the environment and our ability to interact with it. To improve all aspects of that interaction is the mission of Vision Rehabilitation.

Parafoveal Crowding

Crowding increases with eccentricity, and is most readily observed in the periphery. During natural, active vision however, central vision plays an important role. Measures of critical distance to estimate crowding are difficult in central vision, as these distances are small. Any overlap of flankers with the target may create an overlay masking confound. The crowding factor method avoids this issue by simultaneously modulating target size and flanker distance and using a ratio to compare crowded to uncrowded conditions. This method was developed and applied in the periphery (Petrov &…

Fovea Use During Smooth Pursuit

There is continuing debate as to whether smooth pursuit relies on the foveation of a moving target, especially when the target is compact. Previous studies have shown that gaze is placed on the center-of-mass of a target during saccadic eye movements. This research aims to understand whether eye placement is similarly centered during smooth pursuit and whether foveation is necessary for pursuing a small stimulus.