Low contrast modes that rely on colour are not a boon, despite the design trends. Complementary colour contrasts may be perceived as strenuous but overall eye fatigue is reduced and readability improved if the contrast is high!
Themes like "solarized" are quite terrible in most situations.
It was believed that because screen reflections are imaged behind the computer monitor, potentially conflicting cues could be created to initiate inappropriate accommodation responses and possibly affect blink rates. Collins et al, however, found little evidence that reflections influence the accuracy of a user’s accommodation response under binocular viewing conditions. They did, however, detect errors to a small degree ( 0.25 D) under some monocular viewing conditions.
In cases where it is not practical to reduce surrounding light, reduction of reflections and increase of contrast may be obtained from anti-glare filters. Whereas ambient light from the room passes through the glare filter twice (once on the way in and once on reflection), direct light emitted from the VDT passes through the filter only once. This increases the overall contrast of the picture as the background is attenuated more than the characters.
As previously discussed, anti-glare filters may not reduce symptoms of asthenopia, but have been shown to reduce glare and improve contrast from the screen. This provides an effective means to eliminate reflections and therefore improve visual comfort.
Color-contrast optic filters are known to improve the color discriminating capacity when exposed to video display terminals. Feigin et al revealed that 20 of 23 subjects reported an improvement of visual fatigue after 4 weeks of using the eyeglasses with spectral filters.
Clayton Blehm et al.: "Computer Vision Syndrome: A Review", Survey of Ophthalmology, Volume 50 • Number 3 • May–June 2005. (DOI)
This should be evident to anyone trying to use those terrible websites or apps or even operating systems that use light grey on dark grey for text. It's designed to be unergonomic.
Prolonged VDU work leads to a reduction in visual contrast sensitivity over a broad range of spatial frequencies, and a corresponding impairment of visual acuity. The results are consistent with previous findings, revealing two factors in contrast sensitivity impairments after VDU work: an overall impairment probably due to transient myopia (Jaschinski-Kruza 1984) affecting high spatial frequencies and the acuity determination, and an effect of spatial adaptation affecting contrast sensitivity selecting the low-to-medium and high spatial frequencies (Lunn and Banks 1986, Magnussen et al. [992).
REIDULF G. WATTEN , IVAR LIE & SVEIN MAGNUSSEN: "VDU work, contrast adaptation, and visual fatigue, Pages 262-267 | Published online: 27 Apr 2007. (DOI)
And contrast is the primary determinant of readability. In a study comparing light on dark vs dark on light:
Letter identification responses times showed polarity effects at all contrasts and display resolution levels. Observers were also more accurate with higher contrasts and more pixels per degree.
Lauren V. Scharff & Albert J. Ahumada: "Why is light text harder to read than dark text?", Journal of Vision September 2005, Vol.5, 812. doi:10.1167/5.8.812.
Also by Sharff, sort of:
Color Test Results
This points to a fundamental misconception those 'designers' have, including the one who made "solarized":
On a sunny summer day I love to read a book outside. Not right in the sun; that’s too bright. I’ll hunt for a shady spot under a tree. The shaded paper contrasts with the crisp text nicely. If you were to actually measure the contrast between the two, you’d find it is much lower than black text on a white background (or white on black) on your display device of choice. Black text on white from a computer display is akin to reading a book in direct sunlight and tires the eye.
Solarized reduces brightness contrast but, unlike many low contrast colorschemes, retains contrasting hues (based on colorwheel relations) for syntax highlighting readability.
The paper analogy is much less about brightness contrast, but glare from the often overwhite paper compared to the different background and surroundings off the pages.
And going for eye or vision fatigue, the listed causes and remedies are
WebMD: Use a glare filter for your screen. Change lighting to get rid of glare and harsh reflections.
Statewide Vision Ressource Center: lighting and glare; if glare is a problem, allow student to move to a darker area in the room or lower the blinds –– mask out some of the print on the page or computer screen to reduce visual clutter ––
change the lighting conditions eg use a near soft light, move closer to the natural light of the windows, or create more shade on the page –– avoid glare
Mayo-Clinic: Computer use strains eyes more than reading print material because people tend to: Use devices that have glare or reflection; Use devices with poor contrast between the text and the background
Nothing has changed in the science since
Andrew Dillon: "Reading from paper versus reading from screens", The Computer Journal, 31(5), 457-464, (1988).
Only the marketing and design trends had people made believe the contrary in some areas.
That is the most important aspect: glare and other lighting conditions is the bad guy, and prolonged time staring at displays. So glare displays are unergonomic from the start. Even when using a high-pixels count and otherwise high contrast technology, like Apple's so-called Retina:
Dong Ju Kim: "Visual Fatigue Induced by Viewing a Tablet Computer with a High-resolution Display", Korean J Ophthalmol. 2017 Oct; 31(5): 388–393 (DOI):
Visual fatigue and discomfort were significantly induced by viewing smart mobile devices, even though the devices were equipped with state-of-the-art display technology.
So these themes look cool, work in a few circumstances, but don't work in most circumstances and are based on a faulty reasoning to begin with.
The problem is that display manufacturers managed to bring about the seemingly popping contrast and blacks, that result from omitting anti-glare measurements and reduce cost, as equivalent in effect for good vision.
But the order of badness is glare first, contrast next, colour last. Not in the least as not all people have the same colour vision ability and colour also increases visual clutter, another reason for eye fatigue as listed above.
R. John Brockmann: "The Unbearable Distraction of Color", IEEE Transactions on Professional Communication, Vol. 34, No. 3, September 1991. (PDF):