June 2020
Volume 61, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2020
Influence of intraocular pressure on corneal OCT speckle distribution. An animal ex-vivo study
Author Affiliations & Notes
  • Marcela Niemczyk
    Wroclaw University of Science and Technology, Wroclaw, Poland
  • Malgorzata Anna Kostyszak
    Wroclaw University of Science and Technology, Wroclaw, Poland
  • Monika Ewa Danielewska
    Wroclaw University of Science and Technology, Wroclaw, Poland
  • D. Robert Iskander
    Wroclaw University of Science and Technology, Wroclaw, Poland
  • Footnotes
    Commercial Relationships   Marcela Niemczyk, None; Malgorzata Kostyszak, None; Monika Danielewska, None; D. Robert Iskander, None
  • Footnotes
    Support  Polish National Agency for Academic Exchange under the International Academic Partnerships Programme PPI/APM/2019/1/00085
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 4712. doi:
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      Marcela Niemczyk, Malgorzata Anna Kostyszak, Monika Ewa Danielewska, D. Robert Iskander; Influence of intraocular pressure on corneal OCT speckle distribution. An animal ex-vivo study. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4712.

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

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Abstract

Purpose : The distribution of the Optical Coherence Tomography (OCT) speckle of cornea is thought to be associated with its microstructure. It is hypothesized that there is an influence of intraocular pressure (IOP) on this distribution. Our purpose was to evaluate this relationship in a controlled environment of an ex-vivo study.

Methods : 14 porcine eyes acquired from a local abattoir were measured with spectral-domain OCT (SOCT Copernicus REVO) within the maximum of 8 hours post mortem. A custom-made system was used with a computer-controlled syringe pump that allows delivering a stable set level of IOP to the anterior chamber. The range of IOP was from 10 to 40 mmHg with steps of 5 mmHg. Three horizontal and three vertical OCT B-scans of the central cornea (5 mm) were acquired at each IOP level. Raw data was used for subsequent calculations. The intensity of pixels in OCT scans was assumed to be Gamma distributed. Spatial distribution maps of Gamma parameters (scale parameter aG, shape parameter vG), corresponding to the central stroma, were computed from OCT scans of size 592 x 1529 pixels using 41 x 41 pixel scanning window. Then, a region of interest (ROI) was selected from the maps and values of the shape and scale parameter were averaged from ROI. The nonparametric Wilcoxon sign-rank test was used to evaluate changes in the averaged values of Gamma distribution parameters with IOP.

Results : Corneal OCT speckle distribution responds to changes in IOP. Statistically significant differences were observed between values of aG parameter at different IOP levels, particularly in the lower range of IOP values from 10 to 20 mmHg (see figure, bottom panel). Such relationship was less evident for the shape parameter vG.

Conclusions : The study proves that variation in IOP results in changes in corneal OCT speckle statistics. Hence, evaluation of OCT speckle may allow characterizing corneal microstructure and its dependence on IOP.

This is a 2020 ARVO Annual Meeting abstract.

 

Top panel: example of an OCT scan of porcine eye (central 5 mm), middle panel: spatial distribution map of the aG parameter with selected ROI (light blue outline), bottom panel: boxplots of group aG statistics from ROIs for different IOP levels together with the results of the Wilcoxon sign-rank test (p-values).

Top panel: example of an OCT scan of porcine eye (central 5 mm), middle panel: spatial distribution map of the aG parameter with selected ROI (light blue outline), bottom panel: boxplots of group aG statistics from ROIs for different IOP levels together with the results of the Wilcoxon sign-rank test (p-values).

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