The notches of these sample COMS plaques are all less than 4 mm wide. The ring shaped pattern of the seeds near the lip prevents adjacent seeds from straddling the disc and conforming to tumors that grow over and/or wrap around the disc.
In the three larger diameter plaques, only 1 seed lies close to, and is oriented tangentially to the disc. In the two smaller plaques, none of the seeds come close to the disc.
The orientation of the seeds with respect to the notch is inconsistent in this sampling. It is subject to variation depending upon where the notch is cut into the silicone carrier.
If the width of the notch is narrower than 5 mm, the notch will be a tight fit to the nerve. It will be more difficult to seat the posterior edge of the plaque near the disc and the sheath surrounding the optic nerve will be compressed by the notch.
Plaque Simulator detects and warns of notch-sheath collisions. Collision regions are illustrated with a red tint in the retina diagram.