Abstract
This study examined the differences in and origins of corneal mosaic patterns, which may be clinically observed as follows : (1) so-called anterior corneal mosaic induced by rubbing the cornea through the eyelids following instillation with fluorescein sodium ; (2) a pattern seen against a red reflex ; (3) a pattern during applanation tonometry ; and (4) a pattern in anterior crocodile shagreen and posterior crocodile shagreen.
Photographs revealed an accurate correspondence in the arrangement of the first three. Anterior corneal mosaic was observed in all normal cornea of over 500 Japanese people aged 3 to 90 and remained unchanged after one year.
Bovine cornea showed anterior corneal mosaic and a polygonal ridge pattern by fixation following massage of the cornea. Histological study revealed only a difference in stromal thickness under the ridge. The pattern of anterior crocodile shagreen was matched to the fluorescein pattern.
These observations suggest that the underlying basis of the anterior corneal mosaic is the particular arrangement of collagen lamellae in the anterior corneal stroma just basal to Bowman's membrane.
In posterior crocodile shagreen, slit-lamp examination showed oblique or V-shaped clear lines with apices pointing to Descement's membrane and rays directed toward the anterior third of the stroma. Even in normal eyes over the age of 50, such lines were observed in high incidence in the limbal area of the cornea.
Moreover, histological study of normal cornea revealed waving of collagen lamellae from the periphery to the center, which seems to correspond to the clear line.
It is suggested that the oblique waving line of collagen lamellae forms the posterior reticular structure in normal cornea.
