Regular breaks are required to rest the eyes and break from continuously using a single focus to avoid eyestrain and fatigue. Struggling with uncorrected vision will make eyestrain and eye fatigue worse and diminish performance.
There is no evidence that Display Screen Equipment (DSE) work causes any permanent damage to eyes. However, long spells of DSE work can lead to tired eyes, discomfort, temporary short-sightedness and headaches. DSE work is visually demanding, so it can make you aware of eyesight problems not noticed before (including changes in eyesight that happen with age)