Psychophysics of reading-II. Low vision

Gordon E. Legge, Gary S. Rubin, Denis G. Pelli, Mary M. Schleske

Research output: Contribution to journalArticlepeer-review

348 Scopus citations


Very little is known about the effects of visual impairment on reading. We used psychophysical methods to study reading by 16 low-vision observers. Reading rates were measured for text scanned across the face of a TV monitor while varying parameters that are likely to be important in low vision: angular character size, number of characters in the field, number of dots composing each character, contrast polarity (white-on-black vs black-on-white text), and character spacing. Despite diverse pathologies and degrees of vision loss in our sample, several major generalizations emerged. There is a wide variation in peak reading rates among low-vision observers, but 64% of the variance can be accounted for by two major distinctions: intact central fields vs central-field loss and cloudy vs clear ocular media. Peak reading rates for observers with central-field loss were very low (median 25 words/minute), while peak reading rates for observers with intact central fields were at least 90 words/minute (median 130 words/minute). Most low-vision readers require magnification to obtain characters of optimal size. Sloan M acuity was a better predictor of optimal character size than Snellen acuity, accounting for 72% of the variance. Low-vision reading is similar to normal reading in several respects. For example, both show the same dependence on the number of characters in the field. Our results provide estimates of the best reading performance to be expected from low-vision observers with characteristic forms of vision loss, and the stimulus parameters necessary for optimal performance. These results will be useful in the development of clinical tests of low vision, and in the design of low-vision reading aids.

Original languageEnglish (US)
Pages (from-to)253-265
Number of pages13
JournalVision Research
Issue number2
StatePublished - 1985

Bibliographical note

Funding Information:
Counselling and Information Office. Dr Roger Dreulcke. HandicappedR esourcesO ffices. Robert Hrrsman. O.D.. and Dr William Knobloch and 41s Sallv Coffinan. RS. from the University of hlinnesota Hospitals. W’c thank Wendy Willson Legge. Holli Rietmulder. and Maureen Karpan for their help. \lost of all. we thank our observers for their patience and care. This research was supported by Public Health SerLicr Grant EY0293-1 to GEL. DGP was supported by Grant EYOlJ32 during the writing of this paper.


  • Acuity
  • Contrast
  • Low vision
  • Psychophysics
  • Reading
  • Visual field


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