The SSY concept was initiated by Professor Anders Heijl in cooperation with Allergan. Its aim is to focus on the perimetric Rate of Progression (RoP), preservation of vision and vision-related quality of life, and the importance of lowering intraocular pressure (IOP) in patients with glaucoma. Allergan is working with this concept in the form of an educational program, which is now well established around the world.

Most perimeters (such as Humphrey and Octopus) can provide the current RoP by linear regression analysis of global visual field indices (Mean Deviation, Mean Defect, the Visual Field Index), if the minimum number of tests are available. As the disease process is linear in most cases, the trend line provides insight into the future visual function of each eye if treatment is unchanged and the IOP remains at the same level.

Until now, there has not been an easy way for physicians treating glaucoma to estimate the additional the levels at which the IOP needs to be lowered further in order to alter the situation and reduce the progression to acceptable levels. The aim of the SSY Engine is to help physicians estimate a tailored Target IOP by simulating a changed disease progression.