Microfibril abnormalities of the lens capsule in patients with Marfan syndrome and ectopia lentis

To determine the distribution and structure of fibrillin microfibrils in the three fibrillin-rich lens capsule zones of subjects with the Marfan syndrome.

Capsules were dissected from nine lenses extracted intracapsularly from Marfan syndrome patients. The capsules were divided and mounted flat on gelatin-coated glass slides. ABC immunoperoxidase staining with monoclonal anti-fibrillin antibody was used to visualize and localize fibrillin in these specimens. The staining patterns and microscopic structure of microfibrils were compared to those of normal controls.

There were no bundles of fibrillin fibers in Zone I - a 0.75-mm wide peripheral ring of the anterior capsule that normally contains radial bunches of fibrillin fibers; instead, fine disorganized fibrillin-positive fragments were dispersed in this region. The size and shape of the fragments varied among patients. In contrast to normal lenses, there was only light staining for fibrillin in Zone II - a 1-mm wide meshwork of normally fibrillin-rich fibers that encircles the equator and serves as an insertion platform for most zonular fibers. The radial periodic bands of Zone III - a 0.1-mm wide ring on the most peripheral part of the normal posterior capsule - were identifiable in some samples, but stained only faintly for fibrillin.

Fibrillin microfibrils are disrupted and fragmented in the lens capsule of patients with the Marfan syndrome. The qualitative, quantitative, and structural abnormalities of fibrillin deposition in the lens capsule of these patients support a causal relationship to lens abnormalities in this disease.