Straßer Lab

Applied Vision Research

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Visual Acuity At different levels of Contrast and Ambient Luminance (VA-CAL)

Clinical visual acuity assessment is performed with maximum optotype contrast within a very narrow luminance range (80-320 cd/m²), barely reflecting patients’ visual capabilities in daily life. However, visual acuity alone does not adequately assess the visual performance in retinal disorders, especially in those causing an increased glare-sensitivity like achromatopsia.

For a more realistic assessment of patients’ visual performance under everyday life conditions with different contrast levels (C) and ambient luminance (AL), we develop a novel visual acuity score, called VA-CAL in cooperation with the Zrenner Lab.

The project is supported by


  1. Hilmers J, Straßer T, Bach M, Stingl K, Zrenner E. Quantification of the Dynamic Visual Acuity Space at Real-World Luminances and Contrasts: The VA-CAL Test. Transl Vis Sci Technol. 2022;11: 12. doi:10.1167/tvst.11.4.12