A method of calibration and reconstruction for corneal topographer


Our aim is to develop a novel method for the calibration of corneal topographer. Our method allows an accurate reconstruction of corneal without an additional distance sensor, which favors the development of low-cost, handheld corneal topographers.

  • A method of calibration and reconstruction for corneal topographer 0
  • A method of calibration and reconstruction for corneal topographer 1
  • A method of calibration and reconstruction for corneal topographer 2
Commercialisation opportunities
Potential licensing to ophthalmic device manufacturers for the production of corneal topographers, which could be sold to hospitals, clinics, and research institutes.
Problem addressed

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.
Key impact
  • 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.

Project Members

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


  • Filed HK standard patent 22022052772.9
  • Filed CN patent 202210464208.3

The Centre for Eye and Vision Research (CEVR)  is a research collaboration between The Hong Kong Polytechnic University and the University of Waterloo in Canada under the InnoHK initiative of the HKSAR Government. It is located at the Hong Kong Science Park, Shatin, Hong Kong. It is the first global hub performing ground-breaking research in five key areas Myopia and Eye Growth, Ocular Drug Discovery and Delivery, Vision Enhancement, Tear Film and Ocular Surface, and Advanced Optometric Technology. The mission of CEVR is to generate technologies to prevent vision loss in the aging population and preserve healthy vision.