What are some alternatives?
When comparing Iris and Eyeleo, you can also consider the following products
Moka - Moka is a Gnome Shell theme that uses simple geometry & basic colouring.
Workrave - Workrave is a program that assists in the recovery and prevention of Repetitive Strain Injury (RSI).
Materia - Materia is a development environment to build advanced mobile and web applications.
stretchly - break time reminder app
adapta-gtk-theme - An adaptive Gtk+ theme based on Material Design Guidelines - adapta-project/adapta-gtk-theme
Eyes Relax - Eyes Relax is a little free utility that reminds you about rest-time and save your eyesight. Eyes, relax, freeware, download.