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Cited by 230Corneal surgery and disordersCorneal Surgery and TreatmentsOcular Surface and Contact Lens

Transparency, swelling and scarring in the corneal stroma

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Meek, K M, Leonard, D W, Connon, C J, Dennis, S, Khan, S·2003·Eye
DOI 10.1038/sj.eye.6700574
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Abstract

Purpose This paper briefly reviews current explanations for corneal transparency and uses a well-developed model to try to explain the increased light scattering either accompanying corneal swelling or following phototherapeutic keratectomy (PTK). Methods The direct summation of fields (DSF) method was used to compute light transmission as a function of wavelength. The method requires input of a number of structural parameters. Some of these were obtained from electron micrographs and others were calculated from X-ray diffraction data. Results By swelling sections of stroma cut from different depths in the tissue, we have shown that fluid entering the cornea causes more swelling in the posterior lamellae than in the anterior lamellae. Furthermore, posterior lamellae can reach a higher final hydration than anterior lamellae. Collagen-free regions ('lakes') exist in corneas swollen in vitro and in Fuch's dystrophy corneas, many of which may be caused by the death of cells. The DSF method shows that local fibril disordering, increased refractive index mismatch, and increased corneal thickness together can account for a 20% increase in light scattering in a Fuch's dystrophy cornea at H=5.8 compared to the normal cornea. Additional scattering is probably caused by 'lakes'. The DSF method applied to PTK rabbit stroma with high levels of haze suggests that the newly deposited collagen is not the cause of the increased light scattering. Conclusions Fluid is not uniformly distributed within the corneal stroma when the cornea swells. Increased hydration of posterior lamellae may be because of known differences in the glycosaminoglycans between the anterior and posterior stroma. Lamellar interweave in the anterior stroma probably limits the extent to which the constituent lamellae can swell. The DSF method can be used to account for increased light scattering in oedematous corneas but cannot account for haze following PTK.

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  • The lamella arrangement plays no significant role in corneal transparency.

    “However, it plays no significant role in corneal transparency”

    From Corneal structure and transparency (2015) · cites this paper as Meek et al., 2003

    The Phototherapeutic keratectomy section (p. 9) predicts only a very small loss of light transmission despite poorly organised collagen in a thin layer newly deposited after PTK. That limited finding does not establish that lamellar arrangement plays no significant role in corneal transparency generally; the Direct summation of fields method section (p. 5) says that destroying fibril order increases scattering. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • Corneal transparency is defined at the microscopic level by the absence of scatter by corneal cells or by other structures that could cause local changes to the refractive index.

    “this property is defined at the microscopic level by the absence of scatter by corneal cells or by other structures that could cause local changes to the refractive index”

    From Corneal structure and transparency (2015) · cites this paper as Meek et al., 2003

    The Direct summation of fields method section (p. 5) links low scattering by corneal cells to their refractive indices, but calls the cells weak scatterers—not non-scatterers—and notes that their nuclei scatter. The discussion on p. 3 also says collagen fibrils scatter light because their refractive index differs from the surrounding material; transparency involves interference of that scattered light. Thus the paper supports the importance of limiting scatter, but not the claimed microscopic absence of it. (LLM, conf=0.84)

    Experimental — accuracy not yet measured

  • At the nanoscopic level, corneal transparency is defined by the absence of pigments or blood vessels (in most species), and by the structure and organisation of the collagen fibrils within the lamellae.

    “and at the nanoscopic level, by the absence of pigments or blood vessels (in most species), and by the structure and organisation of the collagen fibrils within the lamellae (Meek et al., 2003).”

    From Corneal structure and transparency (2015) · cites this paper as Meek et al., 2003

    The discussion of corneal transparency (pp. 2–3) links light transmission to the structure and arrangement of collagen fibrils within lamellae. Our copy does not state that transparency depends on the absence of pigments or blood vessels, including the qualification about most species. (LLM, conf=0.88)

    Experimental — accuracy not yet measured

  • If the endothelial pumping mechanism fails and the cornea swells, regions devoid of collagen fibrils (lakes) impair corneal transparency.

    “If this mechanism fails and the cornea swells, regions devoid of collagen fibrils (termed lakes) impair corneal transparency (Clark, 2004, Meek et al., 2003).”

    From Corneal structure and transparency (2015) · cites this paper as Meek et al., 2003

    The Abstract (p. 2) reports collagen-free ‘lakes’ in swollen corneas and says they probably cause additional light scattering; Cornea oedema (p. 6) likewise says lakes could increase scattering. The claim states their effect categorically, and the passages do not establish that failure of the endothelial pumping mechanism causes the swelling. (LLM, conf=0.85)

    Experimental — accuracy not yet measured

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Research works printed but not linked: 53

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Authors
Meek, K. M., Leonard, D. W., Connon, C. J., Dennis, S., & Khan, S.
Affiliations
  • Cardiff University (GB)
  • The Open University (GB)
Corresponding author
Meek, K M
ORCID
Venue
Eye
Publisher
Springer Science and Business Media LLC
Published
2003-11
Volume
17
Issue
8
Pages
927-936
ISSN
  • 0078-5334 (ISSN-L)
  • 0950-222X
  • 1476-5454
DOI
10.1038/sj.eye.6700574
OpenAlex
W2040427221
Cited by
230
References
0
Citations by year
2026: 3 · 2025: 6 · 2024: 11 · 2023: 9 · 2022: 9 · 2021: 15 · 2020: 9 · 2019: 16 · 2018: 5 · 2017: 19 · 2016: 13 · 2015: 18 · 2014: 13 · 2013: 11 · 2012: 12
FWCI
0.72
Type
journal article
Language
en
Open access
Licence
www.springer.com/tdm (tdm)
Locations
  • Eye (publishedVersion)
  • PubMed (publishedVersion)
  • ORCA Online Research @Cardiff (Cardiff University) (submittedVersion)
Funders
  • Wellcome Trust
  • Medical Research Council
Topics
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Corneal surgery and disorders
  • Health Sciences › Medicine › Radiology, Nuclear Medicine and Imaging › Corneal Surgery and Treatments
  • Health Sciences › Medicine › Public Health, Environmental and Occupational Health › Ocular Surface and Contact Lens
Keywords
corneal transparency, corneal stroma, corneal edema, light scattering, phototherapeutic keratectomy, corneal haze, corneal hydration, refractive index mismatch, glycosaminoglycans, corneal thickness
MeSH terms
Corneal Opacity, Corneal Stroma, Humans, Models, Biological, Scattering, Radiation, Corneal Edema, Photorefractive Keratectomy, Lasers, Excimer

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