Presentation on theme: "F.Fazel MD The corneal specular microscope is a reflected- light microscope that projects light onto the cornea and images the light reflected from."— Presentation transcript:
The corneal specular microscope is a reflected- light microscope that projects light onto the cornea and images the light reflected from an optical interface of the corneal tissue, most typically the interface between the corneal endothelium and the aqueous humor. Although specular microscopes have been used primarily to evaluate the corneal endothelium, the corneal epithelium and stroma as well as the crystalline lens can also be visualized and evaluated.
The central endothelial cells of young people with normal eyes are hexagonal and approximately the same size; the distribution of cell area is approximately Normal (Gaussian). With age, the average cell area increases, the cellular pattern becomes distinctly pleomorphic, and the cell size distribution becomes skewed toward larger cell areas. In young people with normal eyes the cell side lengths are all roughly equal. In older individuals, the side lengths lose this regularity and one sees an increasing variation. As in the case with changes in endothelial cell size, alterations in shape have not been directly related to changes in the physiologic function of the affected cells.
cell size (cell area or cell density). polymegathism (variation of cell size such as coefficient of variation of mean cell area). pleomorphism (variation of cell shape such as percent of hexagonal cells or coefficient of variation of cell shape). Etc…
mean cell area. cell density or cell count. Cell area has been expressed in units of µm² per cell and cell density in units of cells per mm².
Mean cell size is150-350 micrm2 From birth to adolescence the cell density decreases rapidly. From age 20 through approximately age 50, endothelial cell density seems to be relatively stable. . After the age of 60, cell density decreases significantly in most people
350,000 cell / cornea at birth, 3000 - 4000 cell / mm 2 at middle age, 2500 cell / mm 2 at old age, 2000 cells / mm 2
In EDC between 300-700 cll per mm2 corneal edema ocures. Cell loss 0%-30% in anterior segmen surgery. At least EDC of 1000-1200 is needed for safe AC surgery. Polymorphism and polymegatism above 0.40 or hexagonal shape less than 50% is abnormal and risk.
Cornea guttate, characteristic for Fuch’s endothelial dystrophy, are focal accumulations of collagen on the posterior surface of Descemet's membrane that apparently are formed by stressed or abnormal endothelial cells; they appear as warts or excrescences of Descemet's membrane and can easily be seen with specular microscopy. Cornea guttate also occur as a result of aging and corneal inflammation.
★ Built in analysis software 1 Cell number 2 Cell Density （pcs/mm２） 3 Cell area （Average、maximum、minimum） 4 Standard deviation 5 Coefficient of variation 6 Histogram(Cell area and cell stroke count) 7 Percentage of hexagon cell 8 Topography map