CSIR student researcher, Natasha Botha, uses modelling as a tool to investigate ways to accurately measure intra-ocular pressure (IOP). An elevated IOP indicates the development of glaucoma, a disease that damages the optic nerve and leads to gradual loss of vision. This project, still in its early stages, aims to understand the measurements made by existing devices leading to more accurate methods to determine IOP.
Botha says that glaucoma is the leading cause of irreversible blindness in South Africa as one in 20 people suffers from chronic glaucoma. However, one of the primary challenges in treating glaucoma is early diagnosis. The treatment of chronic glaucoma is effective if the patient is diagnosed early enough. Early diagnosis is vital since glaucoma is a painless condition, with the consequence that sufferers typically only realise that something is wrong once there has been significant loss of vision. The major risk factor that indicates the development of glaucoma is elevated IOP, the pressure of the fluid in the eye. As an elevated IOP is indicative of glaucoma, it would be ideal to detect the rise in IOP before glaucoma develops.
“Based on this project, we want to develop an accurate and affordable device that can be rolled out at clinics and in rural areas, as the current glaucoma screening tests are only available at specialists,” explains Botha.
The current method used to screen for elevated IOP is to estimate IOP by indenting the cornea and measuring the force required for indenting. This method is known as Goldmann Applanation Tonometry. However, the existing methods ignore patient-specific cornea properties such as the thickness and stiffness of the cornea. The estimation of IOP-based on cornea indentation measurements can be improved by using modelling techniques. CSIR researchers are using computational mechanics techniques to both improve the current screening methods and the estimation of IOP. “I am currently using computational modelling to simulate Goldmann Applanation Tonometry – a standard used to calibrate other diagnotic techniques,” explains Botha. Botha will use the results from the computational model to develop a method that accurately estimates the intra-ocular pressure independent of the cornea properties.
Ideally, glaucoma-screening testing could become as routine as measuring blood pressure. CSIR researchers are working on an affordable technology or device that would be accessible to all South Africans.
This research is part of Botha’s Master’s degree at the University of Pretoria.