Estimating the focal distance for the use on adaptive eyeglasses

Abstract

Degradation of eyesight is a common issue in most humans. The lenses of the eye will begin to weaken due to defects or ageing, thereby impacting the clarity of vision. Prescription eyeglasses can treat and correct the vision in most cases with a static focal length. However, the lens fixed power is specific for individual cases. The aim of this thesis was to develop an appropriate approach for estimating the distance of the eye focal length by extracting information from the lateral movements of the eyes. We reviewed several approaches in an attempt to design adaptive glasses that use electrical components to measure the distance of an observed object and cause an appropriate change in the lens power. We also assessed other experiments that incorporated the direction of sight to implement an eye gazing direction into their designs. We analysed a neutral movement of the eye, the vergence movement, which cues distance estimation when the eye focuses on a specific object at a distance. The analysis of this movement provides a full understanding of how the eye performs when focusing on things. The methodology implemented in this thesis was to model the eye lateral movement by measuring the changes in the pupil position. We used a MATLAB program to perform mathematical simulations to measure the distance of the viewed object using the changes in the pupillary distance of the eyes. The results showed that this distance can be measured by tracking the pupil position. Additionally, with an additional estimation of the distance from the eyes, this method can be used as an automatically adjusting method for adjusting the lens power for electro-optical glasses to provide clearer vision for the wearer.