July 2019
Volume 60, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2019
Corneal topography by specular reflection: a low-cost null-screen dynamic method
Author Affiliations & Notes
  • Martin Isaias Rodriguez Rodriguez
    School of Physics, , University College Dublin, Dublin, Ireland., Dublin, Dublin, Ireland
  • Alessandra Marie Carmichael Martins
    School of Physics, , University College Dublin, Dublin, Ireland., Dublin, Dublin, Ireland
  • Brian Vohnsen
    School of Physics, , University College Dublin, Dublin, Ireland., Dublin, Dublin, Ireland
  • Footnotes
    Commercial Relationships   Martin Rodriguez Rodriguez, None; Alessandra Marie Carmichael Martins, None; Brian Vohnsen, None
  • Footnotes
    Support  Scolarship from Consejo Nacional de Ciencia y Tecnología (CONACyT), Mexico
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 2130. doi:
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    • Get Citation

      Martin Isaias Rodriguez Rodriguez, Alessandra Marie Carmichael Martins, Brian Vohnsen; Corneal topography by specular reflection: a low-cost null-screen dynamic method. Invest. Ophthalmol. Vis. Sci. 2019;60(9):2130.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The anterior corneal surface provides about 80% of the total dioptric power of the human eye. The aim of this study is to validate a rapidly reconfigurable null-test dynamic screen using a Hartmann pattern on an LCD screen. The image of reflected light from a spherical reference sphere is used to test the capability of the corneal surface characterization method.

Methods : A numeric integration method is used to derive the shape of the reflective surface using a reflective spherical reference surface as a corneal simulator. Reconstruction using the trapezoid rule offers an easy solution but is limited by truncation errors [Rodriguez-Rodriguez, et al, Appl. Opt. 2015]. In turn, the use of LCD displays with dynamic point shifting allows minimization of the reconstruction error. Thus, an array of LCDs is used for real-eye evaluations. Measurements are performed on 5 healthy subjects’ eyes.

Results : The reflection of the adaptable Hartmann pattern provided data that allowed accurate reconstruction of the surface profile of the reference sphere. Tuning of the Hartmann pattern on the LCD screen until the reflected grid image was entirely uniform allowed the error to be reduced to less than 1% for the reference sphere with dense sampling. In the human eye, the reconstruction was more position sensitive and rapid capture was required.

Conclusions : The quantification of the corneal surface is of great importance in clinical and research applications of relevance for refractive corrections and the diagnosis and monitoring of corneal ectasias and keratoconus. A rapidly reconfigurable and low-cost system with reconfigurable parameters as demonstrated here may suffice for corneal reconstruction.

This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.

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