July 2019
Volume 60, Issue 9
Free
ARVO Annual Meeting Abstract  |   July 2019
Comparative analysis of Pellucid marginal degeneration and Keratoconus corneas show divergence in molecular expression and tissue structure.
Author Affiliations & Notes
  • Pooja Khamar
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Arkasubhra Ghosh
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Swaminathan Sethu
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Abhijit Sinha Roy
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Nimisha R Kumar
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Rohit S
    Narayana Netralaya Foundation, Ahmedabad, Gujarat, BIHAR, India
  • Footnotes
    Commercial Relationships   Pooja Khamar, None; Arkasubhra Ghosh, None; Swaminathan Sethu, None; Abhijit Sinha Roy, None; Nimisha Kumar, None; Rohit S, None
  • Footnotes
    Support  NONE
Investigative Ophthalmology & Visual Science July 2019, Vol.60, 5113. doi:
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      Pooja Khamar, Arkasubhra Ghosh, Swaminathan Sethu, Abhijit Sinha Roy, Nimisha R Kumar, Rohit S; Comparative analysis of Pellucid marginal degeneration and Keratoconus corneas show divergence in molecular expression and tissue structure.. Invest. Ophthalmol. Vis. Sci. 2019;60(9):5113.

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

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Abstract

Purpose : Keratoconus (KC) and Pellucid marginal degeneration (PMD) are both ectatic corneal diseases characterized by classic topographical features leading to loss of visual acuity. However, it is unclear if the two disorders are simply different manifestations of the same underlying molecular and structural pathology. Thus, we investigated the structural, biomechanical and molecular profiles of PMD and KC.

Methods : 12 healthy controls undergoing PRK (n=24 eyes), 32 KC subjects (n=64 eyes) undergoing CXL or T-PRK with CXL and 13 PMD patients (n=26 eyes) undergoing CXL or Corneal transplant were included in the study with prior ethics committee approval and written, informed consent of the study subjects. Tear samples (using schirmer’s strip) were collected from all subjects and corneal epithelium was collected only from those undergoing corrective surgery. Each subject underwent by corneal topography imaging (Pentacam), air-puff applanation (CorvisST), in vivo confocal microscopy (IVCM), tear cytokine by multiplex ELISA and tissue gene expression analysis (QPCR).

Results : a significant amount of hyper-reflective fibrotic tissue on IVCM analysis in the ectatic inferior stroma of PMD subjects but not in KC or controls at the same depth. Corneal epithelial and stromal samples revealed significantly higher Lysyl Oxidase and collagen expression levels in PMD compared to KC. CorvisST data showed PMD corneas to have significantly higher biomechanical strength than KC. Tear levels of ECM remodeling enzymes (MMP9 and MMP2), as well as inflammatory cytokines (TNF, IL-8, IL-17, IFN, etc) were higher in both PMD and KC compared to control (p<0.05) but not among themselves. However, the cytokine IL-12 was significantly lower in PMD compared to KC. In addition, we found perforins and granzymes to be significantly higher in PMD compared to KC and controls.

Conclusions : Higher corneal tissue structural gene expression levels in PMD supports its greater biomechanical strength when compared to KC. While classic inflammatory and proteolytic markers are similarly raised between both conditions, the distinct expression of cytolytic factors in PMD is a unique characteristic. The data indicate that KC and PMD are likely distinct conditions with unique molecular and structural features which should be taken into account for treatment planning.

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

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