Uveal melanoma is one of the few forms of cancer treated before a pathologist can examine tissue to assess the risk of metastasis by assigning a histological grade. Study of the microcirculation architecture in these tumours was initially aimed at evaluating the prognostic significance of microcirculatory patterns in tissue sections of eyes removed for choroidal or ciliary body melanoma and also to determine if these patterns could be imaged by ultrasonographic or angiographic techniques.

Patterns formed by the microcirculation architecture in uveal melanomas were found to be strongly associated with death from metastatic melanoma by our research group1 2-7 and by others.8 9 Ophthalmic pathologists have shown interest in using a simple histological technique developed in our laboratory to detect these microcirculatory patterns and compare features of prognostic significance in uveal melanomas.10 By using a periodic acid Schiff (PAS) stain without haematoxylin counterstaining for nuclei, the amount of visual ‘noise’ is reduced, improving the sensitivity of detecting small microvessels. After a green filter is placed into the light path of the microscope, visualisation of the microcirculation is enhanced. The PAS stain resists bleaching …