Advancing functional vision assessment for modern, screen-based practice
NevadaCloud is proud to introduce a revised and clinically optimized Greyscale Contrast Test for eye care practitioners, now included in the latest release of EyeVaultEHR. This update represents a thoughtful re-engineering of the traditional greyscale contrast concept—modernized for digital clinical environments, aligned with ETDRS and Borish principles, and designed to deliver greater reproducibility, consistency, and clinical relevance on screens.
Why revise the greyscale test?
Traditional high-contrast visual acuity charts remain essential—but they do not fully reflect how patients experience vision in the real world. Many patients report symptoms such as poor vision in low contrast environments, difficulties at dusk or night, visual discomfort on screens, or “blur” despite good Snellen acuity.
Greyscale and low-contrast tests were originally introduced to help uncover these functional visual limitations, often before standard acuity changes become apparent. However, many historic implementations were designed for print, not screens, and were vulnerable to optotype bias or inconsistent contrast steps.
Modelled on established work — optimized for screens
The revised test is modelled on the original greyscale contrast work by Sherik, respecting its clinical intent and foundational principles. However, rather than forcing print-era mathematics onto modern hardware, the test has been systematically redesigned for screen-based use, acknowledging the realities of 8-bit RGB display pipelines and gamma-encoded luminance behavior.
The result is a screen-native greyscale test that behaves consistently, ensuring that all patients tested on the same screen are assessed under the same rigorous rule set.
Clinically balanced by design
To improve accuracy and reduce measurement noise, the revised test incorporates multiple layers of standardization:
- Optotype construction: True Sloan letters (not fonts) with 5×5 wide construction and ETDRS-compliant spacing.
- Letter difficulty control: Balanced using Borish clinical refraction difficulty ratings to ensure row and column difficulty is equalized.
- Reliable Contrast Steps: Uses fixed RGB contrast offsets (S6 → S1) that remain stable on real-world screens, preserving relative changes in contrast.
Integrated into EyeVaultEHR
The revised Greyscale Contrast Test is fully integrated into EyeVaultEHR, allowing clinicians to identify early or subtle visual performance issues and document findings consistently within the patient record. Because the test is screen-optimized, it supports longitudinal comparison within a practice - something many legacy charts struggle to achieve.
For clinicians who want technical details
NevadaCloud recognizes that many optometrists want to understand exactly how a test is constructed. A detailed technical specification document is available, covering optotype construction, RGB implementation, and letter difficulty balancing.
👉 Download the Submission Manuscript
A practical step forward in functional vision testing
This revision is not about reinventing contrast testing - it’s about making it work properly in modern practice. By combining established clinical principles with honest, screen-aware engineering, NevadaCloud has delivered a test that is more reproducible, more interpretable, and more clinically useful in day-to-day optometric care.
