How normal eyes perform in reading low-contrast texts.
OBJECTIVE
To assess the performance of normal eyes in reading low-contrast texts.


METHODS
We selected 14 subjects aged 20 to 31 years (mean, 23 +/- 3 years) with corrected visual acuity of 1.0 or better. The subjects were asked to read texts when the contrast between the characters and background was adjusted to 100%, 40%, 20%, and 10%. Using a computer-generated reading chart, reading acuity (RA), critical character size (CCS), and maximum reading speed (MRS) were assessed. The reading performance was compared at various contrast levels.


RESULTS
When the contrast between the characters and background was 100%, 40%, 20%, and 10%, the mean RA (logMAR) was -0.08 +/- 0.07, 0.03 +/- 0.09, 0.13 +/- 0.09, and 0.26 +/- 0.11, respectively; the mean CCS (logMAR) was respectively 0.10 +/- 0.09, 0.18 +/- 0.09, 0.29 +/- 0.14, and 0.41 +/- 0.10. The mean MRS (characters/min) was 379.2 +/- 41.9, 369.7 +/- 43.3, 369.2 +/- 60.2, and 343.7 +/- 67.0, respectively. In all subjects, a decrease in contrast was associated with an increase in RA and CCS, but the MRS was not affected.


CONCLUSIONS
In normal eyes, even when reading low-contrast texts, increasing the character size makes it possible to maintain the same MRS as when reading high-contrast texts.
Fujita
Kyoko
K
Department of Ophthalmology, Surugadai Nihon University Hospital, Tokyo, Japan. kfujita@med.nihon-u.ac.jp
Oda
Koichi
K
Watanabe
Junko
J
Yuzawa
Mitsuko
M
D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology*; D005260:Female; D006801:Humans; D009799:Ocular Physiological Phenomena; D011932:Reading; D014787:Vision Tests / Q000295:instrumentation; D014792:Visual Acuity / Q000502:physiology*