Understanding Color Uniformity and Dark Mode for Low Vision Accessibility

Color uniformity plays a crucial role in creating accessible digital experiences, particularly for users with low vision impairments. While accessibility guidelines like WCAG provide essential frameworks for ensuring inclusivity, they don’t always address every barrier users face. One such challenge is the impact of dark mode and inconsistent color themes on people with low vision.

Erich Manser's Perspective on Color Uniformity

Erich Manser, a user with low vision, shared his experience with interfaces that lack color uniformity:

"I am someone with low vision who relies on magnification and inverted colors in order to see what's on my screen. The appearance of light text on a dark background is softer and less glaring for me and enhances my ability to perceive what's there and view it without pain or discomfort. Recently, however, I've noticed more interfaces that combine both light and dark themes in a single user experience, giving a split-like dark appearance almost like the traditional Chinese Yin Yang symbol. From my perspective as a user, this is problematic because it automatically means there is some portion of the page or app that I will be unable to view comfortably. Yet there is nothing in current WCAG guidelines to require color uniformity across a user interface."

This example highlights how inconsistent color themes—like mixing light and dark modes within a single interface—can create barriers that are not addressed by existing guidelines.

Why Color Uniformity Matters

1. What Is Color Uniformity?

Color uniformity refers to the consistent use of colors and themes across a user interface. For example, in dark mode, the interface should predominantly use dark backgrounds with light text, without abruptly transitioning to lighter sections that disrupt the visual flow.

2. Challenges for Low Vision Users

For people with low vision, abrupt changes between light and dark sections can:

• Cause glare or visual discomfort.
• Make portions of the interface difficult or impossible to read.
• Disrupt navigation and overall usability.

3. Dark Mode: A Double-Edged Sword

Dark mode can significantly benefit users who experience discomfort with bright screens. It reduces glare, eye strain, and light sensitivity. However, as Stephanie Walter discusses in her article “Dark Mode Accessibility Myth Debunked”, dark mode isn’t inherently accessible. It needs to be thoughtfully implemented to ensure it works for everyone.

Considerations for dark mode:

• Contrast Ratios: WCAG requires a contrast ratio of at least 4.5:1 for text against its background, which applies to dark mode as well.
• Color Combinations: Ensure colors in dark mode are not overly saturated or neon, as they can be harsh on the eyes.
• Consistency: Avoid mixing light and dark themes within the same interface, as this creates accessibility barriers.

How to Achieve Color Uniformity

1. Choose a Primary Theme: Decide whether your interface will primarily use light mode or dark mode. Allow users to select their preference.
2. Ensure Consistent Application: If the user selects dark mode, apply it across all elements of the interface, avoiding sections that revert to light mode.
3. Test for Low Vision Usability: Use tools like magnifiers and screen inversion to evaluate your interface from the perspective of someone with low vision.
4. Provide Options: Include toggles for light mode, dark mode, and high-contrast modes to give users control over their experience.
5. Test Across Devices: Ensure the implementation of themes remains consistent across different screen sizes and devices.

Balancing Light Mode and Dark Mode Preferences

While dark mode is a popular choice for reducing eye strain, some users with low vision or specific conditions may prefer light mode. This is why offering both options is critical. Additionally, interfaces should be designed to ensure that:

• Users can easily toggle between modes.
• Modes retain uniformity in text, backgrounds, and other UI elements.
• Accessibility remains a priority regardless of the selected mode.

Moving Beyond WCAG

As Erich Manser pointed out, not all accessibility barriers are addressed by WCAG. It’s up to designers and developers to anticipate user needs and go beyond the guidelines. Color uniformity is one such area where thoughtful design can make a significant impact.