An important indicator of the biomechanical properties of thecornea is co meal hysteretic. It is an indicator of viscous damping in thecome an during inward and outward application pressure event.Abnormalities in corneal hysteretic have been detected in a varietyof corneal disease including glaucoma suspects normal tension glaucoma,post-LASIK patients, keratinous and other corneal pathological cornmealhysterias can been measured using ocular response analyzer and dynamicco meal imaging .