Abnormal scleral collagen in nanophthalmos. An ultrastructural study
D. H. Stewart 3rd, B. W. Streeten, R. J. Brockhurst, D. R. Anderson, T. Hirose and D. M. Gass
Department of Ophthalmology, State University of New York Health Science Center, Syracuse 13210.
Ten patients with bilateral nanophthalmos underwent sclerectomies for uveal
effusion. Ultrastructural examination of the sclera revealed abnormal
collagen in seven patients. Four showed dramatic fraying of the collagen
fibrils into fine filaments 2 to 3 nm in diameter. In three of these cases
and three other cases without fraying, there were foci of 10- to 35-nm
small collagen fibrils, some appearing to arise by splitting of otherwise
normal collagen fibrils. In areas of fraying, elastic fibers were absent.
All patients had a wider range of collagen diameters than did control
subjects. The youngest patient with fraying also had Hallermann-Streiff
syndrome. In three patients, no collagen abnormality was found. The
clinical feature correlating best with the presence of abnormal collagen
was an extremely small eye, since the three patients without collagen
abnormality had the largest eyes (range of anteroposterior diameters, 19.2
to 20.3 mm). Nanophthalmos appears to result from several distinct defects.
