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Cited by 17Digital Holography and MicroscopyCorneal surgery and disordersAdaptive optics and wavefront sensing

Measuring the Refractive Index of Bovine Corneal Stromal Cells Using Quantitative Phase Imaging

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Gardner, Steven J., White, Nick, Albon, Julie, Knupp, Carlo, Kamma-Lorger, Christina S., Meek, Keith M.·2015·Biophysical Journal
DOI 10.1016/j.bpj.2015.08.046PMC PMC4624349
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Abstract

The cornea is the primary refractive lens in the eye and transmits >90% of incident visible light. It has been suggested that the development of postoperative corneal haze could be due to an increase in light scattering from activated corneal stromal cells. Quiescent keratocytes are thought to produce crystallins that match the refractive index of their cytoplasm to the surrounding extracellular material, reducing the amount of light scattering. To test this, we measured the refractive index (RI) of bovine corneal stromal cells, using quantitative phase imaging of live cells in vitro, together with confocal microscopy. The RI of quiescent keratocytes (RI = 1.381 ± 0.004) matched the surrounding matrix, thus supporting the hypothesis that keratocyte cytoplasm does not scatter light in the normal cornea. We also observed that the RI drops after keratocyte activation (RI = 1.365 ± 0.003), leading to a mismatch with the surrounding intercellular matrix. Theoretical scattering models showed that this mismatch would reduce light transmission in the cornea. We conclude that corneal transparency depends on the matching of refractive indices between quiescent keratocytes and the surrounding tissue, and that after surgery or wounding, the resulting RI mismatch between the activated cells and their surrounds significantly contributes to light scattering.

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  • Haze following laser refractive ablation results from the presence of fibroblasts in the ablated region.

    “Our cell refractive index measurements show that such haze (Fig. 3B) results from the presence of fibroblasts in the ablated region.”

    From Structural control of corneal transparency, refractive power and dynamics (2025) · cites this paper as [9]

    The Conclusions say that activation to fibroblasts increases scattering and that their proliferation during wound healing could explain haze after some refractive procedures. The Introduction also describes fibroblasts migrating to the wound site. The source presents fibroblasts as a likely contributor, not an established cause of haze specifically in a laser-ablated region. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

  • In modelled Mie scatter, increasing the proportion of keratocytes causes very little loss of transparency, whereas increasing the proportion of fibroblasts causes significant loss of transparency.

    “It can be seen that, as the proportion of keratocytes increases, there is very little loss of transparency, but the opposite is true for fibroblasts [9].”

    From Structural control of corneal transparency, refractive power and dynamics (2025) · cites this paper as [9]

  • Activated keratocytes (fibroblasts) have a lower refractive index than keratocytes.

    “When activated, however, they become fibroblasts that have a lower refractive index.”

    From Structural control of corneal transparency, refractive power and dynamics (2025) · cites this paper as [9]

  • The refractive index of keratocytes is 1.381 ± 0.004.

    “we used a technique called quantitative phase imaging to measure the refractive index of the keratocytes and showed that they have a refractive index of 1.381 ± 0.004 [9].”

    From Structural control of corneal transparency, refractive power and dynamics (2025) · cites this paper as [9]

  • Modelling shows that the change in refractive index when keratocytes become fibroblasts significantly increases light scatter.

    “Modelling shows that this change in refractive index significantly increases light scatter.”

    From Structural control of corneal transparency, refractive power and dynamics (2025) · cites this paper as [9]

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Authors
Gardner, S. J., White, N., Albon, J., Knupp, C., Kamma-Lorger, C. S., & Meek, K. M.
Affiliations
Cardiff University (GB)
Corresponding author
Meek, Keith M.
ORCID
Venue
Biophysical Journal
Publisher
Elsevier BV
Published
2015-10
Volume
109
Issue
8
Pages
1592-1599
ISSN
0006-3495 (ISSN-L)
DOI
10.1016/j.bpj.2015.08.046
PMC
PMC4624349
OpenAlex
W1796880010
Cited by
17
References
0
Citations by year
2026: 2 · 2025: 1 · 2024: 2 · 2022: 3 · 2020: 1 · 2019: 2 · 2018: 1 · 2017: 3 · 2016: 2
FWCI
0.96
Type
journal article
Language
en
Open access
Licence
Locations
  • Biophysical Journal (publishedVersion, cc-by)
  • Europe PMC (PubMed Central) (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • ORCA Online Research @Cardiff (Cardiff University) (acceptedVersion)
Funders
Medical Research Council (MR/K000837/1)
Topics
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Digital Holography and Microscopy
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Corneal surgery and disorders
  • Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Adaptive optics and wavefront sensing
Keywords
refractive index, corneal stromal cells, keratocytes, corneal haze, light scattering, corneal transparency, keratocyte activation, refractive index mismatch, quantitative phase imaging, bovine cornea, crystallins, corneal extracellular matrix
MeSH terms
Animals, Cattle, Cells, Cultured, Corneal Stroma, Cytoplasm, Models, Biological, Scattering, Radiation, Stromal Cells, Microscopy, Confocal, Cell Size, Corneal Keratocytes, Optical Imaging

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