A histochemical and x-ray diffraction study of keratoconus epikeratoplasty. Report of two cases. 1996

Y Huang, and S J Tuft, and K M Meek
Open University, Oxford Research Unit, England.

Two epikeratoplasty lenticules (Epi-L) with keratoconus host corneas (Epi-H) were removed by penetrating keratoplasty because of poor visual acuity although they were clinically clear. Light microscopy showed that the keratocytes were underpopulated and unevenly distributed in Epi-L. Transmission electron microscopy showed that abnormal sized proteoglycans (PGs) were unevenly accumulated in the stromas of both Epi-L and Epi-H. The low-angle x-ray diffraction results from case 1 showed lower collagen interfibrillar spacings, compared with those from one keratoconus cornea, seven cryolenticules, and four normal human corneas. The fibril diameters and the collagen axial periodicity D were similar in all tissues. Allowing selected samples to swell, the interfibrillar spacing increased by 30.6-45.5% in Epi-H and by 29.8% in the keratoconus control. However, it increased by only 7.6-9.7% in Epi-L and by 11.4% in a cryolenticule. The uneven distribution of PGs and the lower interfibrillar spacings in the swollen lenticules suggest that there is an uneven distribution of water in different parts of the Epi-L and Epi-H stromas. This may lead to a variation of the refractive index or optical properties in the stroma and the deterioration of the visual image, which may explain the poor visual results.

UI MeSH Term Description Entries
D007211 Indoles Benzopyrroles with the nitrogen at the number one carbon adjacent to the benzyl portion, in contrast to ISOINDOLES which have the nitrogen away from the six-membered ring.
D007640 Keratoconus A noninflammatory, usually bilateral protrusion and thinning of the CORNEA, the apex being displaced downward and nasally. It occurs most commonly in females at about puberty. Two closely related noninflammatory corneal ectasias are pellucid marginal degeneration and keratoglobus. Keratoglobus,Pellucid Marginal Corneal Degeneration,Pellucid Marginal Degeneration,Degeneration, Pellucid Marginal,Marginal Degeneration, Pellucid,Pellucid Marginal Degenerations
D008297 Male Males
D008854 Microscopy, Electron Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen. Electron Microscopy
D008875 Middle Aged An adult aged 45 - 64 years. Middle Age
D009942 Organometallic Compounds A class of compounds of the type R-M, where a C atom is joined directly to any other element except H, C, N, O, F, Cl, Br, I, or At. (Grant & Hackh's Chemical Dictionary, 5th ed) Metallo-Organic Compound,Metallo-Organic Compounds,Metalloorganic Compound,Organometallic Compound,Metalloorganic Compounds,Compound, Metallo-Organic,Compound, Metalloorganic,Compound, Organometallic,Compounds, Metallo-Organic,Compounds, Metalloorganic,Compounds, Organometallic,Metallo Organic Compound,Metallo Organic Compounds
D003315 Cornea The transparent anterior portion of the fibrous coat of the eye consisting of five layers: stratified squamous CORNEAL EPITHELIUM; BOWMAN MEMBRANE; CORNEAL STROMA; DESCEMET MEMBRANE; and mesenchymal CORNEAL ENDOTHELIUM. It serves as the first refracting medium of the eye. It is structurally continuous with the SCLERA, avascular, receiving its nourishment by permeation through spaces between the lamellae, and is innervated by the ophthalmic division of the TRIGEMINAL NERVE via the ciliary nerves and those of the surrounding conjunctiva which together form plexuses. (Cline et al., Dictionary of Visual Science, 4th ed) Corneas
D004396 Coloring Agents Chemicals and substances that impart color including soluble dyes and insoluble pigments. They are used in INKS; PAINTS; and as INDICATORS AND REAGENTS. Coloring Agent,Dye,Dyes,Organic Pigment,Stain,Stains,Tissue Stain,Tissue Stains,Organic Pigments,Pigments, Inorganic,Agent, Coloring,Inorganic Pigments,Pigment, Organic,Pigments, Organic,Stain, Tissue,Stains, Tissue
D004577 Electron Probe Microanalysis Identification and measurement of ELEMENTS and their location based on the fact that X-RAYS emitted by an element excited by an electron beam have a wavelength characteristic of that element and an intensity related to its concentration. It is performed with an electron microscope fitted with an x-ray spectrometer, in scanning or transmission mode. Microscopy, Electron, X-Ray Microanalysis,Spectrometry, X-Ray Emission, Electron Microscopic,Spectrometry, X-Ray Emission, Electron Probe,X-Ray Emission Spectrometry, Electron Microscopic,X-Ray Emission Spectrometry, Electron Probe,X-Ray Microanalysis, Electron Microscopic,X-Ray Microanalysis, Electron Probe,Microanalysis, Electron Probe,Spectrometry, X Ray Emission, Electron Microscopic,Spectrometry, X Ray Emission, Electron Probe,X Ray Emission Spectrometry, Electron Microscopic,X Ray Emission Spectrometry, Electron Probe,X-Ray Microanalysis,Electron Probe Microanalyses,Microanalyses, Electron Probe,Microanalysis, X-Ray,Probe Microanalyses, Electron,Probe Microanalysis, Electron,X Ray Microanalysis,X Ray Microanalysis, Electron Microscopic,X Ray Microanalysis, Electron Probe
D006651 Histocytochemistry Study of intracellular distribution of chemicals, reaction sites, enzymes, etc., by means of staining reactions, radioactive isotope uptake, selective metal distribution in electron microscopy, or other methods. Cytochemistry

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