In response to Matt Rontree-Carey’s article (“Coloured overlays: setting the tone”, 6 September), I am aware that the existence of visual stress is questioned, but I speak from personal experience when I say that coloured overlays and tinted lenses can make a significant difference.

Students may not be aware that other people do not see the disturbances on the page. Teachers should look for signs or ask students how words appear if they suspect visual stress. If an overlay is prescribed, observe the child. If they use the overlay consistently, it is making a difference and lenses might be a consideration. If they don’t use it, it hasn’t helped.

I agree that children’s vision should be checked but not all opticians are trained in the necessary tests; in some cases, an ophthalmologist may be more appropriate. But high-street opticians can often help parents to contact the appropriate professionals.

Jodie-Marie Toone, York.