Focus Reader: A Major Upgrade
The recent introduction of Pretext a text manipulation library prompted me to explore how it can be used in Focus Reader to improve readability and accessibility in long form content on the web. Focus Reader is an open source Chrome extension I've been working on, it's live on the Chrome Web Store here and the code is available on GitHub
What was added
Pretext allows to find the exact height of a line of text, and lightweight manipulation of text in the page, I've been using it to introduce extra letter spacing which is a research-backed method to improve readability for people with dyslexia and bionic reading which is less research-validated but which I find enjoyable. Additionally I added precise height settings, improved scrolling and settings.
Learn more
Read my previous blog post to learn more about Focus Reader here
Collaborate
Have ideas for improvement or found a bug? Open an issue on the GitHub repository or submit a pull request. All contributions welcome! This is very much WIP.
Research references
- Extra-large letter spacing improves reading in dyslexia — PNAS (2012) — the study behind the letter spacing feature; extra spacing reduces crowding and substantially improved reading in dyslexic children.
- Inter-letter spacing, inter-word spacing, and font with dyslexia-friendly features — PMC — broader research on typography interventions for dyslexia.
- No, Bionic Reading does not work — Acta Psychologica (2024) — peer-reviewed study finding no significant speed benefit for general readers.
- Guiding the Gaze: How Bionic Reading Influences Eye Movements — PMC — Utrecht University EEG study suggesting possible benefits for ADHD readers.
- Usability of Bionic Reading on Different Mediums: Eye-Tracking Study (2025) — no benefit for print, but strong anecdotal self-reporting from the ADHD community.
- chenglou/pretext on GitHub — the text measurement library powering the precision features.