Reading and Myopia: Contrast Polarity Matters

Area of Science:

• Ophthalmology
• Neuroscience
• Human Physiology

Background:

• Myopia, or nearsightedness, is increasing globally and linked to education.
• The exact visual stimuli that promote eye growth in children are unknown.
• Animal studies suggest distinct retinal pathways (ON and OFF) differentially affect eye growth.

Purpose of the Study:

• To investigate the impact of text color and background on retinal pathway stimulation.
• To explore the relationship between visual stimuli, choroidal thickness, and myopia development in humans.

Main Methods:

• Developed software to quantify ON and OFF visual stimulus strengths in real-time.
• Measured changes in choroidal thickness using optical coherence tomography (OCT) in young adults.
• Compared visual environments: black text on white vs. white text on black.

Main Results:

• Natural environments showed balanced ON and OFF pathway stimulation.
• Black text on white significantly overstimulated OFF pathways.
• White text on black significantly overstimulated ON pathways.
• Reading black text on white thinned the choroid by 16µm/hour.
• Reading white text on black thickened the choroid by 10µm/hour.

Conclusions:

• Conventional reading (black on white) may promote myopia development by thinning the choroid.
• Reading white text on black may inhibit myopia by thickening the choroid.
• Visual display settings could be a strategy for myopia prevention.