Studies on the development of extra-endothelial and intra-endothelial pigment deposits by means of direct and indirect contact specular microscopy of the cornea.

Retro-corneal pigmentation as a result of primary (degenerative) or secondary (inflammatory, traumatic) pigment dispersion represents one of the most frequent findings in specular microscopy. The analysis of the pigment distribution patterns of dense deposits like those in Krukenberg spindle (KS) permits the postulation of a hypothesis concerning the development of such typical corneal pigmentations and the pigmentation of the posterior surface of the cornea in general, such as diffuse pigment dispersion (Vogt 1930), which is seen frequently. In a particular case of double KS with extreme myopia and cataract, endothelial morphological findings were documented over a period of 1 year, both before and after cataract extraction. This was done by means of contact and non-contact specular microscopy in various spindle areas. The morpho-metric studies (cell density/mm2; cell perimeter; largest smallest and average cell diameter; specific surface; horizontal and vertical cell orientation) were carried out automatically using a computerised video image analyser. The changes in the area of densest pigmentation in the KS centre confirm the histologically proven capacity of pigment phagocytosis by human corneal endothelium. These findings indicate that in specular microscopy, both endothelial cellular surface modifications and intra-cellular changes are documentable. The extracellular pigment deposits can also be shown by means of 'indirect' specular microscopy, the optical principle of which is described.