—If existing methods of measuring tumor dimensions were satisfactory, Dr O'Rourke's equation for the volume of a sphere segment would give a better approximation for volume of most ocular melanomas than formulas for the other solids he mentions.Linear tumor dimensions are not, however, easy to measure accurately. Standard histologic sectioning of a melanoma-bearing eye in the pathology laboratory places the geometric center of the tumor in the axis of pupil and optic nerves, several millimeters from the cut surface of the formalin-fixed eye. In the gross specimen, therefore, the basal diameters are usually measured by transillumination prior to sectioning, whereas height is estimated with calipers approximating the point of maximal tumor elevation, several millimeters from the cut edge of sclera. In addition to recording these measurements, we now photograph the specimen with a right-angle millimeter scale devised and constructed by our chief laboratory technician, Mr Manuel Solis
Nicholson DH. The Mathematics of Melanoma Volume-Reply. Arch Ophthalmol. 1986;104(7):974–975. doi:10.1001/archopht.1986.01050190031018
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