Finite Element Modeling of an Elderly Person’s Cornea and Rigid Gas Permeable Contact Lenses for Presbyopic Patients

Rigid gas permeable (RGP) contact lenses are a common presbyopic correction tool. However, many patients clinically need a long period of adaptation after wearing. This study adopted finite element modeling to analyze the contact stress between RGP contact lens and an elderly person's cornea. The RGP-lens-produced stress concentration at the corneal edge and maximum pressure on the cornea of elderly subjects aged >64 years was 104.140 kPa, but only 86.889 kPa for the 15-64 group. Therefore, how to decrease the stress concentration on the cornea is important to increasing elderly user comfort while wearing lenses. This study found that when the contact angle is designed on the basis of patient's actual radian of corneal edge, the contact stress dropped sharply to 60.966 kPa, thus increasing user's wearing comfort.