A method of calibration and reconstruction for corneal topographer

Corneal topography is used in contact lens fitting and ocular disease management. Placido cone-based corneal topographers allow measurements over a large corneal area, but often required an additional distance sensor for the accurate reconstruction of corneal topographic maps. The distance sensor increases the cost and the weight, and therefore, hinders the development of a handheld corneal topographer.

• We proposed a 3D nonlinear calibration model, and the specific method of calibration, for the reconstruction of corneal topography from raw images.
• We proposed the hardware requirements to support the aforementioned calibration algorithm, maximizing the measurement accuracy by using a focusing lens with a narrow depth of focus.

• Cheaper and easier to manufacture corneal topographers without the need of a distance sensor
• Our 3D nonlinear model minimized the spherical bias in the traditional 2D linear modeling
• Corneal topographers can be made with less parts and lighter weight, so handheld versions can be made

• Our method can be applied in any Placido-based corneal topographic systems to lower the manufacturing complexity and costs.
• Our method can be used in portable topographers that are capable to obtain measurements in uncooperative infants and kids, or patients with physical disabilities.

• Prof. KEE​ Chea-su
• Mr. CHAN Kin Ho​
• Ms. LIN Jiachun​

• Filed HK standard patent 22022052772.9
• Filed CN patent 202210464208.3