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R.L. McCally, R. Grebe, A. DeLaCruz, W.R. Green, D.E. Freund; Light Scattering Calculations From TEM of Healed Penetrating Corneal Wounds . Invest. Ophthalmol. Vis. Sci. 2005;46(13):2182.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Calculate the light scattering from structures depicted in TEM of aged (semi) transparent scars resulting from penetrating wounds in rabbit cornea and compare it with light scattering measurements made on the fresh tissue from which three scattering groups (moderate, intermediate and high) were identified. [McCally and Bonney–Ray, IOVS 43, E–abstract 1710 (2002)] Methods: 2 mm diameter penetrating wounds were made in the central cornea of rabbits in Dr. Charles Cintron’s laboratory and allowed to heal for periods of 3.5 to 4.5 years, at which time the rabbits were sacrificed and the corneas excised. Corneal transmissivity, T, was measured immediately and the tissue was prepared for TEM. TEM from corneas in the moderate and intermediate scattering groups having regions with an organized lamellar structure were analyzed to determine fibril positions and radii. Scattering was calculated using the direct summation of fields method. Results: Stromal lamellae in the moderate scattering group are mildly irregular at all depths. Calculations revealed high transparency (T>90% from 400 to 700 nm) and scattering characteristic of the short–ranged order in the fibril positions found in normal cornea – findings consistent with slit–lamp observations showing some highly transparent regions in these scars. Lamellar structure in the intermediate transparency group is highly irregular and is absent in some areas where fibrils often appear tangled. There are also many voids ("lakes"). Calculated transmissivity is lower (80%<T<93% from 400 to 700 nm) and scattering is characteristic of that expected from regions containing lakes – a finding consistent with the scattering measurements. Conclusions: Structural features in TEM are consistent with the scattering categories identified from scattering measurements. Not unexpectedly, transmissivity calculated from the regions having an organized lamellar structure is higher than that measured from the entire corneal depth, but is consistent with the scattering groups identified from measurements.
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