Corneal structure and transparency

In the paper

“The corneal epithelium, on the other hand, is about 53 μm deep (Reinstein et al., 2008) and thus constitutes about 10% of the corneal thickness.”

What the sources say

• Supported

  The Discussion reports an average corneal-vertex epithelial thickness of 53.4 ± 4.6 μm in normal eyes, supporting the approximately 53 μm figure to which the citation is attached. The subsequent 10% statement is presented as the citing authors’ inference, not a separate finding attributed to this source. (LLM, conf=0.94)

  cites Reinstein et al., 2008 source

In the paper

“Over the last decade there has been an upsurge in the use of non-linear microscopy, in particular second harmonic generation imaging, to provide qualitative (Han et al., 2005, Morishige et al., 2006, Teng et al., 2006, Bueno et al., 2011) and quantitative (Mega et al., 2012, Tuer et al., 2012, Ghazaryan et al., 2013) information about the lamellar organisation within the cornea, a technique that,”

What the sources say

• Supported

  Han et al. is cited for qualitative information; the citing sentence assigns quantitative information to other papers. The Results and discussion section reports that SHG reveals the organisation of corneal collagen fibrils and describes its suitability for living-tissue studies and potential clinical use. The paper does not need to establish quantitative measurement to support the part attributed to it. (LLM, conf=0.88)

  cites Han et al., 2005 source
• Partly supported

  The paper’s Abstract describes a method for quantifying collagen-lamellar orientation in corneal SHG images, supporting the quantitative part for which Mega et al. is cited. The experiments used a bovine cornea placed on a microscope cover slip; our copy does not establish the claimed potential for in vivo use. In the printed sentence, the qualitative citations are to other papers. (LLM, conf=0.86)

  cites Mega et al., 2012 sourceExperimental — accuracy not yet measured
• Supported

  The Discussion (§5.1) reports that polarization-resolved SHG characterizes corneal lamellar-domain orientation and structure, including in vivo imaging of rat corneas. The Conclusion (§6) says the method provides quantitative structural information and could have future in vivo diagnostic applications. (LLM, conf=0.92)

  cites Latour et al., 2012 source

In the paper

“The posterior stroma can swell easily whereas the more interwoven anterior cannot (Müller et al., 2001).”

What the sources say

• Supported

  The Discussion describes swelling as decreasing from the posterior toward the anterior stroma and says the collagen lamellae become interwoven in the most anterior region (page not supplied). The Conclusions and Figure 2 caption report that this anterior region remains stable even under extreme swelling conditions, supporting the contrast in the citing sentence. (LLM, conf=0.92)

  cites Müller et al., 2001 source

In the paper

“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).”

What the sources say

• Partly supported

  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)

  cites Meek et al., 2003 sourceExperimental — accuracy not yet measured

In the paper

“The technique was recently used to show that mammalian corneas do not have an orthogonal arrangement of adjacent lamellae, whereas non-mammalian vertebrate corneas share a common orthogonal collagen structural organisation, which suggests that they have a divergent evolutionary background (Winkler et al., 2015).”

What the sources say

• Supported

  The Results state that nonmammalian vertebrate corneas have nearly orthogonal neighboring collagen layers, whereas mammalian corneas lack that pattern. The Conclusions explicitly describe a common nonmammalian organization and say the distinct mammalian structure suggests a divergent evolutionary background. (LLM, conf=0.95)

  cites Winkler et al., 2015 source

In the paper

“Across the anterior stroma, lamellae are highly interwoven (Radner et al., 1998) and randomly directed when observed en face (Abahussin et al., 2009).”

What the sources say

• ?Not checked — no full text of the sourcecites Radner et al., 1998 source
• Supported

  The discussion (p. 5161) reports an isotropic orientation of collagen fibrils in the anterior cornea, supporting the description of random directions when viewed en face. It notes that irregular orientation was most pronounced in the central 4 mm and that some lamellae farther out were orthogonally aligned. The interwoven description is attributed to Radner et al., not to this source. (LLM, conf=0.89)

  cites Abahussin et al., 2009 source

In the paper

“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”

What the sources say

• Partly supported

  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)

  cites Meek et al., 2003 sourceExperimental — accuracy not yet measured

In the paper

“This cross-linked rope-like structure with alternating twist at each hierarchical level conveys considerable strength to the narrow corneal fibrils, and is in contrast to the fibrils in the adjacent sclera, which are correspondingly wider and therefore have a more parallel arrangement of microfibrils within them (Yamamoto et al., 2000).”

What the sources say

• Partly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Yamamoto et al., 2000 sourceExperimental — accuracy not yet measured

In the paper

“From the reconstructions, it was evident that the collagen fibrils were not laying on a perfect hexagonal lattice, and also that there was nothing systematic in the geometry of the connections of adjacent or next nearest collagen fibrils.”

What the sources say

• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Lewis et al., 2010 source

In the paper

“fibromodulin plays a major role in development of the peripheral cornea but its presence in the normal cornea is uncertain (Chen et al., 2010).”

What the sources say

• Partly supported

  The Discussion supports an important role for fibromodulin in peripheral corneal development. But although the Results call its presence in mature corneal stroma controversial, the paper then reports barely detectable levels at P90 and concludes that fibromodulin is not a component of mature corneal stroma. It does not leave its presence in the adult cornea uncertain. (LLM, conf=0.88)

  cites Chen et al., 2010 sourceExperimental — accuracy not yet measured

In the paper

“Microfibrils have a right-handed twist within the fibrils (Orgel et al., 2006), and are stabilised by covalent intermolecular and intramolecular crosslinks (Yamauchi et al., 1996).”

What the sources say

• Supported

  The Results and Discussion describe a collagen microfibril as five staggered molecules with a right-handed supertwist, supporting the part of the sentence attributed to Orgel et al. The crosslink-stabilisation clause is cited to Yamauchi et al., not to this source. (LLM, conf=0.94)

  cites Orgel et al., 2006 source
• ?Not checked — no full text of the sourcecites Yamauchi et al., 1996 source

In the paper

“Doutch found that not only does its appearance closely resemble the collagen fibril organization seen in micrographs, but also that the wavelength dependence of the predicted transparency matches very closely the experimental one.”

What the sources say

• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Doutch (2009)

In the paper

“They are also a primary binding site for dermatan sulphate-containing proteoglycans (Scott and Haigh, 1988), which, as we will also see later, are necessary for preventing adjacent fibrils from fusing together (Chen and Birk, 2013).”

What the sources say

• Supported

  The Results identify chondroitin/dermatan sulphate-rich proteoglycan filaments in the collagen fibril gap zone at the d and e bands. The Discussion confirms that these bands are associated with chondroitin/dermatan sulphate proteoglycans. The separate claim about preventing fibril fusion is attributed to Chen and Birk (2013), not to Scott and Haigh. (LLM, conf=0.90)

  cites Scott and Haigh, 1988 source
• Partly supported

  The section “Instructive roles in collagen fibrillogenesis” (page unavailable) says that proteoglycan glycosaminoglycans extend into the space between fibrils and can influence their spacing and organization. It does not say that dermatan sulphate-containing proteoglycans are necessary to prevent adjacent fibrils from fusing. The surface-binding-site clause is cited to Scott and Haigh, not Chen and Birk, and is not judged here. (LLM, conf=0.84)

  cites Chen and Birk, 2013 sourceExperimental — accuracy not yet measured

In the paper

“The keratocytes are regarded as being quiescent but can be activated after injury generating myofibroblast precursors that can sometimes persist and cause corneal scarring due to their own opacity as well as their production of fibrotic tissue (Torreicelli and Wilson, 2014).”

What the sources say

• Supported

  Section 4, “Corneal opacity — development, persistence and regression” (page not provided), says keratocytes begin proliferating after injury and that this proliferation can generate myofibroblast precursors. It reports that after severe injury these cells may persist and contribute to stromal scarring through their own opacity and the disorganized extracellular matrix they produce. (LLM, conf=0.92)

  cites Torreicelli and Wilson, 2014 source

In the paper

“Corneal structural defects of this type are associated, for example, with genetic mutations involving proteoglycans (Chakravarti et al., 1998) which, ultimately, seem to have an effect on the repulsive forces between adjacent fibrils and allow them to fuse together.”

What the sources say

• Partly supported

  The Discussion reports corneal opacity in mice with a null mutation of the lumican gene, and its collagen-fibril section describes frequent lateral fusion of fibrils. The paper proposes that proteoglycan core proteins discourage lateral fusion, but it does not identify a change in repulsive forces between adjacent fibrils as the mechanism. (LLM, conf=0.85)

  cites Chakravarti et al., 1998 sourceExperimental — accuracy not yet measured

In the paper

“We found that UV transmission through the cornea decreases from the centre to the periphery, and attributed this to a combination of scattering and absorption (Doutch et al., 2012).”

What the sources say

• Supported

  The Abstract states that UV transmission decreases from the corneal center toward the periphery and attributes the decrease to scattering and absorbance. The Results and Discussion likewise describes reduced peripheral transmission across 310–400 nm and says the combined influence of scattering and absorption is likely. Page numbers are not provided in our copy. (LLM, conf=0.95)

  cites Doutch et al., 2012 source

In the paper

“Their mechanism, illustrated in Fig. 11, operates regardless of the direction of the perturbation and regardless of whether GAG chains are part of a duplex or are independent.”

What the sources say

• Supported

  Section 5.1 states that the restoring mechanism operates regardless of perturbation direction and whether GAG chains are duplexed or independent. The Discussion also says that all GAG chains can contribute to the local pressure perturbation in either form. (LLM, conf=0.95)

  cites Cheng and Pinsky (2013) source

In the paper

“On the other hand, the ions attracted by the unbalanced charge on the glycosaminoglycan chains of the interfibrillar PGs play a dominant role in keeping the fibrils on optimal lattice positions, by acting as restoring forces, and the authors showed that these, by themselves, can reproduce the image distribution of fibrils seen in the electron microscope.”

What the sources say

• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Cheng and Pinsky (2013) source

In the paper

“However, it was noticed that, in vitro, the fibrils formed by collagen I and collagen V are larger than those found in vivo. This indicates that there may be additional mechanisms such as microfibrillar coiling (Raspanti, 2010) or collagen-bound disaccharides (Harding et al., 1980) that regulate fibril diameter.”

What the sources say

• Supported

  The citation to Raspanti is attached to microfibrillar coiling, not to collagen-bound disaccharides. The Introduction describes helically wound microfibrils, and the Discussion says their helical substructure constrains fibril growth and produces uniform diameters. The paper therefore supports the proposed diameter-regulating mechanism. (LLM, conf=0.91)

  cites Raspanti, 2010 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Harding et al., 1980

In the paper

“Because both polyanionic charge per unit volume and tissue hydration are constant between species, regardless of the PG composition (Scott and Bosworth, 1990, Gyi, 1988), they proposed a model in which the fixed charges on GAGs are synthesised in proportion to the total fibrillar collagen (types I and V) (Meek and Leonard, 1993); the larger the collagen fibrils, the greater amount of fixed charge”

What the sources say

• Partly supported

  Split into 2 atoms — 0 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 1 unverifiable. Expand the claim to see per-atom verdicts.

  cites Scott and Bosworth, 1990 sourceExperimental — accuracy not yet measured
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Gyi, 1988
• Supported

  Split into 2 atoms — 2 confirmed, 0 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Meek and Leonard, 1993 source

In the paper

“A similar effect occurs in corneal oedema (bullous keratopathy, Fuch's dystrophy) but in this case there are local decreases in refractive index caused by pooling of fluid into so-called “lakes” (Casadessus et al., 2012) (Fig. 8). The influx of fluid into the stroma also leads to disruption of the fibril organisation and thus to the reduction in destructive interference of scattered light.”

What the sources say

• Partly supported

  Split into 2 atoms — 1 confirmed, 1 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites Casadessus et al., 2012 sourceExperimental — accuracy not yet measured

In the paper

“On the other hand, the opacity of corneal scars is a result of improper remodelling of the connective tissue matrix; collagen fibrils are wider than normal and poorly ordered in scar tissue (Boote et al., 2013).”

What the sources say

• Partly supported

  The Results (Collagen Spatial Organisation) report locally increased fibril diameter and reduced spatial order at the graft margins compared with unwounded corneas. The Discussion links these changes to incomplete remodelling and fibrotic scar tissue, but says they *could be a contributing factor* to visible opacity. The claim states a definite cause for corneal scars generally, beyond what the paper establishes for these graft margins. (LLM, conf=0.88)

  cites Boote et al., 2013 sourceExperimental — accuracy not yet measured

In the paper

“current work in our group has revealed that many fibres seem to originate in the limbus, forming sheets at the edge of the cornea which then split up and extend as microfibrils, possibly oxytalan or elaunin (Alexander and Garner, 1983), across the stroma (White et al., 2014).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites White et al., 2014

In the paper

“We have shown in the human cornea that these elastic fibres, though present throughout most of the stromal depth, are concentrated below the posterior-most keratocyte layer (unpublished results).”

In the paper

“Recent preliminary unpublished work by Knupp aimed at elucidating the role of keratocytes in corneal fibril deposition suggested that there may be another type of “attractive” force acting on the fibrils that would prevent them from drifting apart.”

In the paper

“What was evident, however, was that the distribution of distances between adjacent fibrils was narrow.”

In the paper

“Recent measurements from our group have shown that the refractive index of the keratocyte cytoplasm matches that of the stroma as a whole, whereas, upon activation, the refractive index falls.”

In the paper

“This simple case shows that, if the wavelength is smaller than the fibril separation as depicted, there can be directions in which secondary radiation cancels out completely and others where they reinforce so that the resulting secondary waves exist only along distinct directions which are related to the fibril separation.”

In the paper

“in a number of corneal pathologies, changes in one or more of the other layers can lead to increased light scattering and consequent loss of corneal transparency”

In the paper

“The lamellae have long been known to consist of narrow, parallel collagen fibrils embedded in a proteoglycan-rich hydrated matrix.”

In the paper

“This elastic system may have an important biomechanical role but it is unlikely to influence transparency in the centre of the normal cornea.”

In the paper

“when a so-called “big bubble” is induced, part of the posterior stroma often adheres to the Descemet's membrane, and that there is, therefore, a natural cleavage plane in the stroma about 10 μm above Descemet's membrane (Jafarinasab et al., 2010, McKee et al., 2011).”

What the sources say

• ?Not checked — no full text of the sourcecites Jafarinasab et al., 2010 source
• ?Not checked — no full text of the sourcecites McKee et al., 2011 source

In the paper

“in humans, Bowman's layer and Descemet's membrane, both collagenous tissues like the stroma, together contribute less than 4% to the total corneal thickness”

In the paper

“About 50 years ago the basic ultrastructure had been described (Jakus, 1962) and the principles behind corneal transparency finally elucidated (Maurice, 1957, Hart and Farrell, 1969, Benedek, 1971)”

What the sources say

• ?Not checked — no full text of the sourcecites Jakus, 1962
• ?Not checked — no full text of the sourcecites Maurice, 1957 source
• ?Not checked — no full text of the sourcecites Hart and Farrell, 1969 source

In the paper

“The X-ray technique does not allow direct imaging of the lamellar structures; the arrangement of lamellae has to be inferred from the diffraction patterns.”

In the paper

“In fact, collagen crimp, in combination with elastic fibres in the peripheral cornea, may explain why this region is more pliable and absorbs intraocular pressure fluctuations (Boyce et al., 2008), thus preventing deformation of the optically important central cornea.”

What the sources say

• ?Not checked — no full text of the sourcecites Boyce et al., 2008 source

In the paper

“Collagen fibrils within the cornea are narrower than in many other connective tissues and this is an important factor for transparency, which is a function of the diameter (Hart and Farrell, 1969).”

What the sources say

• ?Not checked — no full text of the sourcecites Hart and Farrell, 1969 source

In the paper

“There is a distribution of crimp angles, which can be altered under mechanical load.”

In the paper

“The basic principles of corneal structure and transparency have been known for some time, but in recent years X-ray scattering and other methods have revealed that the details of this structure are far more complex than previously thought”

In the paper

“For nearly a century it has been realised that these properties may derive from the arrangement of the constituents of the stroma (Eisler, 1930, Kolmer and Lauber, 1936).”

What the sources say

• ?Not checked — no full text of the sourcecites Eisler, 1930 source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Kolmer and Lauber, 1936

In the paper

“These structures are of variable thickness, in humans typically up to 0.2 mm broad and 2 μm thick (Polack, 1961, Komai and Ushiki, 1991).”

What the sources say

• ?Not checked — no full text of the sourcecites Polack, 1961 source
• ?Not checked — no full text of the sourcecites Komai and Ushiki, 1991

In the paper

“Furthermore, the X-ray data represent bulk averages throughout the tissue being sampled so, for instance, it is not possible to obtain information pertaining to adjacent lamellae using this approach.”

In the paper

“which are arranged axially with the typical 67 nm D-periodic stagger (Meek and Holmes, 1983) with gaps between the N- and C-termini of consecutive molecules (Fig. 2).”

What the sources say

• ?Not checked — no full text of the sourcecites Meek and Holmes, 1983 source

In the paper

“The lamella arrangement within the cornea helps to maintain the overall shape of the tissue and is also responsible for some optical properties such as corneal birefringence.”

In the paper

“In most mammals, the cornea is the only tissue requiring considerable tensile strength coupled with a perfectly defined shape and optical clarity.”

In the paper

“At the molecular level, modern technologies and theoretical modelling have started to explain exactly how the collagen fibrils are arranged within the stromal lamellae and how proteoglycans maintain this ultrastructure.”

In the paper

“The posterior lamellae in the central cornea are more hydrated and are believed to have less interlacing, lying on top of each other like the layers in plywood.”

In the paper

“The attractive forces are due to those proteoglycans that connect two or more fibrils. These proteoglycans would be subject to thermally driven conformational changes so that their glycosaminoglycan chains will experience a force that prevents them from assuming a fully extended conformation and which brings their terminal ends, and the collagen fibrils attached to them, closer together. These”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Feynman et al., 1963

In the paper

“As it turns out, the requirement of a perfect hexagonal lattice for the arrangement of the collagen fibrils is not a stringent one, in fact, to have a transparent cornea, it is sufficient for the distance between adjacent fibril to be constrained.”

In the paper

“Both collagen types, when purified, could assemble in vitro to form fibrils, but in this case type I collagen formed fibrils of varying diameters, while type V formed small fibrils.”

What the sources say

• ?Not checked — no full text of the sourcecites Birk et al., 1990 source

In the paper

“They postulated that stromal cells contain cytoplasmic molecules called corneal crystallins that act in much the same was as crystallins in the lens.”

What the sources say

• ?Not checked — no full text of the sourcecites Jester et al., 1999 source
• ?Not checked — no full text of the sourcecites Jester, 2008 source

In the paper

“This suggested that there may be another source of attractive forces between fibrils in the cornea which come from the pressure exerted by the adjacent lamellae. In this case, the fibrils at the interface between lamellae would be pushed inwards, creating a cascade effect that ultimately would hold all fibrils within any lamella close to each other.”

In the paper

“Corneal collagen fibrils, as the principal load-bearing constituents of the lamellae, have to resist the tensile forces due to the intraocular pressure and protect the inner ocular tissues from external trauma while at the same time remaining narrow to allow transparency of the tissue; these are competing requirements.”

In the paper

“The normal adult human stroma contains four small leucine-rich proteoglycans: decorin, lumican, keratocan and mimecan.”

In the paper

“This idea is in agreement with the model of Cheng and Pinsky (Fig. 11); if the collagen fibrils were larger in diameter and the interfibrillar space was constant, the repulsive forces generated by the GAGs and their associated ions would be increased, which would increase the swelling pressure and push the fibrils further apart in order to achieve equilibrium.”

In the paper

“The gel pressure that causes this swelling arises from net electrostatic charges within the stroma. Most of the electrostatic charge is contributed by the acidic groups of the glycosaminoglycans. The other contribution to net stromal charge arises from the temporary complexing of free chloride ions to ligands within the stroma (Hodson, 1997).”

What the sources say

• ?Not checked — no full text of the sourcecites Hodson, 1997 source

In the paper

“It was therefore proposed that the distances between adjacent collagen fibrils are a consequence of the balancing of two opposing forces acting on the fibrils brought about by the proteoglycans. In this model, both opposing forces depend on the separation between the fibrils, and the equilibrium distance between two fibrils is reached when the attractive forces between them cancel out the rep”

In the paper

“However, in real corneas, the incoming light is scattered by many more fibrils than those shown, so that the overall loss of intensity becomes significant and corneas with such structural defects exhibit impaired transparency.”

In the paper

“There are about 70 microfibrils within each fibril (Holmes and Kadler, 2005) which are tilted by about 15° to the fibril long axis (Holmes et al., 2001) and this reduces the usual 67 nm axial periodicity seen in tendon and sclera, to closer to 65 nm (Meek et al., 1981, Marchini et al., 1986, Yamamoto et al., 2000).”

What the sources say

• ?Not checked — no full text of the sourcecites Holmes and Kadler, 2005 source
• ?Not checked — no full text of the sourcecites Holmes et al., 2001 source
• ?Not checked — no full text of the sourcecites Meek et al., 1981 source

In the paper

“This mechanism would also be relevant to corneal development and to the establishment of the stromal matrix.”

In the paper

“This technique may be useful for comparative purposes as it is simple and quick, and we have used it ourselves (Mi et al., 2011). However, Maurice (2001) pointed out that this can be an extremely insensitive test”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Maurice, 2001

In the paper

“Many other microscopical techniques also reveal the presence of this microfibrillar substructure within corneal collagen fibrils (Meek, 2009).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Meek, 2009

In the paper

“The transparency of the corneal stroma has been studied since the nineteenth century and the general consensus was that the cornea needed to be optically homogenous to be transparent (Schweigger-Seidel, 1869, Von Fleischl, 1880, Ranvier, 1898).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Schweigger-Seidel, 1869
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Von Fleischl, 1880
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Ranvier, 1898

In the paper

“This would endow the whole cornea with a less rigid and more fluid overall structure which would make the cornea more resilient to deformations due to external stresses and would facilitate the transport of molecules and nutrients across the cornea.”

In the paper

“Opacities associated with corneal dystrophies (granular dystrophy, lattice dystrophy, macular dystrophy, Schnyder dystrophy) are caused mostly by different kinds of stromal deposits. Such deposits cause local changes in the refractive index of the stroma, and these refractive index discontinuities, if comparable with the wavelength of light, lead to increased light scatter.”

In the paper

“At the supra-molecular level, the initial building block is a 4–8 nm wide microfibril (Baldock et al., 2002) with a left-handed twist of the constituent molecules (Fig. 2).”

What the sources say

• ?Not checked — no full text of the sourcecites Baldock et al., 2002 source

In the paper

“Two other proteoglycans associated with the cornea are biglycan (containing dermatan sulphate) and fibromodulin (containing keratan sulphate).”

In the paper

“The models they proposed were based essentially on the collagen fibrils in the corneal stroma being connected to six adjacent fibrils by proteoglycans at regular axial intervals. The defined lengths of the proteoglycans would force the fibrils on a perfect hexagonal lattice, which would guarantee corneal transparency.”

What the sources say

• ?Not checked — no full text of the sourcecites Maurice in 1962 source
• ?Not checked — no full text of the sourcecites Hart and Farrell in 1969 source

In the paper

“The first contains dermatan sulphate and chondroitin sulphate, while the final three contain keratan sulphate GAGs.”

In the paper

“Boettner and Wolter (1962) found that the corneal transmittance rose rapidly from 300 nm, reaching 80% at 380 nm and more than 90% between 500 nm and 1300 nm.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Boettner and Wolter, 1962

In the paper

“It appears that fibrils have surface dips or grooves in the gap zone compared to the overlap zone, explained by the 4:5 ratio of molecular density in the two zones.”

In the paper

“The suggestion that collagen fibrils needed to have the same refractive index as their surroundings was stated specifically by Renault (1889).”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites Renault, 1889

In the paper

“Two of the most important structural factors for corneal transparency are the uniformity of the diameters of the collagen fibrils, and the restriction in the range of distances between adjacent collagen fibrils.”

In the paper

“Corneal opacity during corneal wound healing, or transitory haze following refractive surgery or corneal cross-linking, is caused by activated corneal keratocytes (Connon et al., 2003, Moller-Pedersen, 2004). Once activated, these cells have a lower refractive index than the surrounding connective tissue.”

What the sources say

• ?Not checked — no full text of the sourcecites Connon et al., 2003 source
• ?Not checked — no full text of the sourcecites Moller-Pedersen, 2004 source

In the paper

“Any change in cytoplasmic content when the keratocytes transform to myofibroblasts is likely to alter the refractive index, and this would then contribute to the increase in light scatter.”

In the paper

“It was found that corneal fibrils were a blend of type I and type V collagens, but unlike in other tissues, the collagen V to collagen I ratio was noticeably higher in corneal stroma (Birk et al., 1990).”

What the sources say

• ?Not checked — no full text of the sourcecites Birk et al., 1990 source

In the paper

“This type of fibrillar arrangement is said to possess short range order and this property is essential to corneal transparency.”

In the paper

“Biglycan occurs in the epithelium and in the stroma of some pathological corneas (Funderburgh et al., 1998)”

What the sources say

• ?Not checked — no full text of the sourcecites Funderburgh et al., 1998

In the paper

“The presence of similar oversized collagen fibrils, probably formed by fibril fusion (Fig. 7), is also a major cause of corneal light scatter seen in many of the mucopolysaccharidoses, though there is often accompanying deposition of stored proteoglycans with cells or within the matrix that also contributes.”

In the paper

“Thus haze or opacity within the cornea can have multiple causes, and it is often incorrect to attribute the light scattering to a single structural change that may be observed within the tissue.”