Abstract
Purpose: :
Reading posture can affect the pleasure and effectiveness of reading as well as such factors as retinal image quality, convergence and accommodation demands, and binocular comfort during reading. Yet, people appear to adopt many different strategies for reading posture and these strategies vary with different reading tasks. In this study, we use a new technology to examine how people read when confronted with different reading challenges.
Methods: :
Twenty optometry students read "Harry Potter and the Sorcerer’s Stone" while sitting in an armchair and "Adler’s Physiology of the Eye" while reading at a desk. Selections were presented in three font sizes (9, 10, and 12 point font). Subjects read 3 to 4 pages of each text for 3 minutes. Electromagnetic sensors (Polhemus Patriot system) were attached to the subject’s forehead and the spine of the book. The positions of each were measured 60 times per second in 3 positional and 3 rotational dimensions. Distance and angle from eyes to book, head tilt angle, and vertical gaze angle were determined.
Results: :
The most consistent result was that readers maintained a vertical angle of eye gaze (eye position within the head) that was very similar for all subjects, for the two reading environments, and for the different font sizes (almost always between 20° and 30°). Yet, the position of the text versus the head varied greatly. The text was held about 45° below the eyes when reading in the armchair and significantly lower (about 63°) when reading at the desk. This means that heads were tilted forward much more when reading at the desk than in the armchair. Head tilts but not the eye gaze positions varied significantly with font size and between subjects. Reading distance was significantly closer when reading at a desk than in an armchair. Most subjects adjusted viewing distance to partially compensate for font size with reading distance increasing for larger fonts. In the armchair, subjects moved larger font size text lower when they moved it away; at the desk, they pushed it back on the desk thereby raising the angle of regard.
Conclusions: :
All readers maintained a similar steady downward eye gaze position despite variations in reading environment and text that caused them to make numerous other adjustments in their reading posture. Most subjects reported greater comfort when reading larger text with just a small head tilt. Reading at a greater viewing distance also leads to clearer retinal images of the text as shown in Thorn et al (ARVO, 2006).
Keywords: reading • myopia