Optics: eye examining – vision testing and correcting – Eye examining or testing instrument – Objective type
Reexamination Certificate
1999-12-17
2001-05-22
Manuel, George (Department: 3737)
Optics: eye examining, vision testing and correcting
Eye examining or testing instrument
Objective type
Reexamination Certificate
active
06234630
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a corneal endothelial cell measuring instrument for measuring cell density in a corneal endothelial cell image taken by using a specular microscope or the like.
2. Description of the Related Art
There are many kinds of methods of measuring the characteristics of corneal endothelial cells. A grid method is one of those known methods. As shown in FIGS.
4
(
a
) and
4
(
b
), in the grid method, a portion of a cell image is surrounded by a rectangle R of an optional size, then, the number N of cells included in the rectangle R are counted, and further, the number N of cells are divided by the area S of the rectangle R to determine a cell density CD. More specifically, when counting the number N of cells included in the rectangle R, the number of one cell entirely included in the rectangle R (i.e., nine cells P with a dot marked at their center in FIG.
4
(
b
)) is counted as 1.0 respectively, and the number of one cell partly included in the rectangle R is counted as 0.5 respectively, regardless of the size of the portion included in the rectangle R.
When counting the number of the cells according to the grid method, the operator must decide whether the cell is included entirely in the rectangle R or the cell is included partly in the rectangle R, which takes a long time for measurement.
It often occurs that cells having only a very small portion cut by the side of the rectangle R are mistaken for those entirely included in the rectangle R and cells having a very small portion included in the rectangle R are overlooked, which reduces the accuracy of measurement.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a corneal endothelial cell measuring instrument capable of reducing the necessity of operator's decision and operation to reduce time necessary for measurement and of achieving measurement in an improved measuring accuracy.
With the foregoing object in view, according to a first aspect of the present invention, a corneal endothelial cell measuring instrument comprises: a display means for displaying a corneal endothelial cell image picked up; a marking means for marking the centers of the respective cells in the corneal endothelial cell image displayed by the display means; a coordinate determining means for determining the coordinate value of the marked centers; a closed curve determining means for determining a closed curve formed by connecting the plurality of the marked centers; an area calculating means for calculating the area of a region enclosed by the closed curve by using output provided by the coordinate determining means; and a cell density calculating means for calculating cell density indicating the number of cells per unit area from the number of centers on the closed curve, the number of centers inside the closed curve and the area calculated by the area calculating means.
The necessity of operator's decision and operation is little, time necessary for measurement can be reduced and measuring accuracy can be improved.
According to a second aspect of the present invention, the closed curve determining means determines a maximum closed curve having a maximum area among closed curves which can be formed by connecting the marked centers.
Thus, measuring accuracy can further be improved.
According to a third aspect of the present invention, the corneal endothelial cell measuring instrument further comprises an informing means for informing that the continuation of the marking is necessary when the number of the marking cycles executed by the marking means is not greater than a predetermined number.
Thus, an accurate measurement can be prevented.
REFERENCES:
patent: 4340281 (1982-07-01), McIntyre
patent: 5436679 (1995-07-01), Ohtsuka et al.
Kabushiki Kaisha Topcon
Manuel George
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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