Ocular Decompression Rest Calculator
Personalised formula: 2 minutes of rest per hour of screen exposure.
4 fatigue levels: Low, Moderate, High and Critical with adapted recommendations.
20-20-20 rule: break intervals calculated from your actual hours of use.
Timeline: visualisation of your ideal day with work and rest blocks.
# Digital Eye Strain: The Hidden Cost of Screen Work
More than 60% of digital workers experience symptoms of digital eye strain daily: irritated eyes, blurred vision, frontal headaches, or a feeling of ocular heaviness. This syndrome, clinically known as Computer Vision Syndrome (CVS), is the direct consequence of subjecting the visual system to sustained close-focus effort without the rest that ocular physiology demands.# The 20-20-20 Rule: Scientific Basis and Practical Application
The 20-20-20 rule was popularised by Dr Jeff Anshel as a mnemonic method for implementing visual breaks. Every 20 minutes of screen work, look at an object 20 feet (≈6 metres) away for 20 seconds. This interval is sufficient for the ciliary muscle to reach its state of complete relaxation, equivalent to infinite vision.| Screen hours | Risk level | Common symptoms | Recommended rest |
|---|---|---|---|
| 0-2 h | Low | Virtually none | 4 min/day |
| 2-4 h | Low-Moderate | Occasional mild dryness | 6-8 min/day |
| 4-8 h | Moderate | Dryness, headache, afternoon blur | 10-16 min/day |
| 8-12 h | High | Marked fatigue, transient double vision | 18-24 min/day |
| >12 h | Critical | Persistent symptoms, risk of pathology | >24 min/day |
Blinking: The Forgotten Variable
Under normal conditions we blink 17 times per minute, distributing the tear film over the cornea. In front of a screen that rate drops to 7 times per minute — a 59% reduction. The result is accelerated tear evaporation, dryness and increased irritation. Blinking consciously every few minutes is as important as visual breaks.# Blue Light: Effects on the Visual System and Sleep
LED screens emit in the 380–500 nm range (high-energy blue light). This spectrum has two documented effects: it stimulates the retinal ganglion cells that regulate circadian rhythm, suppressing nocturnal melatonin secretion; and it generates oxidative stress in the retinal pigment epithelium with chronic and cumulative exposure.# Visual Ergonomics: Posture and Working Distance
Working distance is not an arbitrary figure: at 60 cm the ciliary muscle works at 50% of its maximum accommodation capacity; at 90 cm the effort falls to near zero. For intensive users (>8h), increasing working distance and using a larger font size significantly reduces cumulative daily ciliary load.# When to See an Ophthalmologist
- Blurred vision persisting more than 30 minutes after leaving the screen.
- Frequent frontal or occipital headaches associated with digital work.
- Transient double vision or difficulty shifting focus between distances.
- Persistent foreign-body sensation, itching or stinging.
- Sudden changes in visual acuity unrelated to fatigue.
- Symptoms that do not improve with standard preventive measures.