Innovating an anti-tilt human eye topographer

Description

The project aims to design a human eye topographer that able to scan the eye topography without tilting.

As the visual acuity is tested by Snellen chart at a six-meter distance to simulate the focus on distant objects at infinity while keeping the fellow eyes parallel, this is not the case when scanning corneal topography. When the surface of the eye is being reconstructed by a topographer, the fixation target is positioned within the device’s head close to the eye, which stimulate accommodation and convergence.

Therefore, fixation on an object, at a short distance requires a response from the ocular system to achieve a clear focused vision. The eye has to rotate to a tilted position in relation to the optical axis to allow the refracted light rays to fall on the fovea (the sensitive part of the retina). Consequently, the eye becomes oriented in such a way that its visual axis aligns with the topographer’s axis, resulting in tilted topography maps in relation to cornea’s geometrical centre.

In this project, the candidate will design a prototype of a new generation of eye topographers that not require the subject to focus on a close target. By doing that, the new topographer will be able to scan the eye surface in its natural position for the first time and provide a levelled eye topography.

The findings of the project can be used to improve the quality of applications that rely on the use of corneal topography data, such as contact lenses fitting, corneal implant design and refractive surgery planning. Obtaining the un-tilted eye topography can further improve accuracy in locating the keratoconus cone or orientating the astigmatism axis for individual patients.