There appeared to be a qualitative change in the morphology of deposits found on outer segments at 12 months of age.

<p>The two panels show higher magnification scanning electron micrographs of debris on outer segments at 3 and 12 months. At the earlier stage the deposits are largely spherical with thin processes connecting them to the wall of the outer segment. At 12 months very different picture is present. Here the deposits appear as ruptured hemispheres that have partially collapsed leaving rough edges.