June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Detecting deformation asymmetries on multiple meridians in an ex vivo keratoconic eye model
Author Affiliations & Notes
  • Andrea Curatolo
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Judith Sophie Birkenfeld
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Eduardo Martinez-Enriquez
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • James Germann
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Jesus Palaci
    2EyesVision SL, Madrid, Spain
  • Daniel Pascual
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Geethika Muralidharan
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Ashkan Eliasy
    University of Liverpool, United Kingdom
  • Ahmed Abass
    University of Liverpool, United Kingdom
  • Jedrzej Solarski
    Institute of Physical Chemistry, Poland
  • Karol Karnowski
    Institute of Physical Chemistry, Poland
  • Maciej Wojtkowski
    Institute of Physical Chemistry, Poland
  • Ahmed Elsheikh
    University of Liverpool, United Kingdom
  • Susana Marcos
    Instituto de Óptica "Daza de Valdés", Consejo Superior de Investigaciones Científicas (IO, CSIC), Madrid, Spain
  • Footnotes
    Commercial Relationships   Andrea Curatolo, None; Judith Birkenfeld, None; Eduardo Martinez-Enriquez, None; James Germann, None; Jesus Palaci, None; Daniel Pascual, None; Geethika Muralidharan, None; Ashkan Eliasy, None; Ahmed Abass, None; Jedrzej Solarski, None; Karol Karnowski, None; Maciej Wojtkowski, None; Ahmed Elsheikh, None; Susana Marcos, Consejo Superior de Investigaciones Científicas (IO, CSIC) (P)
  • Footnotes
    Support  European Project COFUND Multiply H-2020-MSCA-COFUND-2015 Ref. 713694; European Project IMCUSTOMEYE H2020-ICT-2017 Ref. 779960; European Project MyFUN H2020-MSCA-ITN-2015 Ref. 675137; Spanish government grant FIS2017-84753-R
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 4723. doi:
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      Andrea Curatolo, Judith Sophie Birkenfeld, Eduardo Martinez-Enriquez, James Germann, Jesus Palaci, Daniel Pascual, Geethika Muralidharan, Ashkan Eliasy, Ahmed Abass, Jedrzej Solarski, Karol Karnowski, Maciej Wojtkowski, Ahmed Elsheikh, Susana Marcos; Detecting deformation asymmetries on multiple meridians in an ex vivo keratoconic eye model. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4723.

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

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Abstract

Purpose : Ocular biomechanical simulations show that air-puff induced corneal deformation imaging (APCDI) can reveal pathological asymmetric responses, as in eccentric keratoconus. Such asymmetries often go undetected when monitoring deformation on only one meridian (Birkenfeld et al., IOVS, 2019), as is the case with commercial instruments. We present a novel custom optical coherence tomography (OCT) system coupled with an air-puff module capable of detecting deformation asymmetries on multiple meridians in a keratoconic-mimicking ex vivo porcine eye model.

Methods : Corneal deformation was induced by a piston-based air-puff module colinearly coupled to a custom OCT system. The puff module provided an air-puff FWHM duration of ~11 ms, reaching a maximum pressure on the corneal apex of ~13 kPa. Our OCT system used a 200 kHz 1300 nm VCSEL swept source, with an axial range of 26 mm.
A freshly enucleated porcine eye globe was treated with a cross-linking (CXL) protocol with Rose Bengal (RB) photosensitizer and Green light irradiation (0.25 W/cm2, 2x200 s) of only the lower half of the cornea. We performed OCT APCDI measurements under controlled intraocular pressure (IOP, 15-30 mmHg) after application of RB (=baseline, BSL) and after partial CXL.
We quantified the displaced area (DA) between the undeformed and deformed anterior cornea positions and asymmetry in displaced area (ADA), i.e. the difference between the nasal/temporal (or superior/inferior) DA referenced to the undeformed corneal apex.

Results : We implemented a cross-meridian scan pattern over a lateral range of 15 mm sampled with 64 points at a repetition frequency of 1 kHz.
For the BSL case, we validated the system by verifying the reduction of DA, from a maximum of ~4.3 to 1.8 mm2, with increasing IOP, from 15 to 30 mmHg. ADA was limited to below 0.2 mm2 in all cases for both meridians.
For the partial CXL case and an IOP of 15 mm Hg, the ADA peaked at 0.5 mm2 for the vertical meridian, while it was below 0.2 mm2 at all times for the horizontal meridian.

Conclusions : We acquired corneal deformation images with a cross-meridian scan pattern over a field of view of 15 mm at unprecedented scan rates. In keratoconus-mimicking cases, we detected deformation asymmetries up to 0.5 mm2, otherwise missed on a single meridian, that will substantially aid in corneal biomechanics diagnostics and pathology screening.

This is a 2020 ARVO Annual Meeting abstract.

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