A new device for pupillary dilatation in vitreous surgery.

A completely new surgical technique to obtain pupillary dilatation is presented. It permits achievement of a mydriasis sufficient to observe the vitreous cavity in both phakic and aphakic eyes during vitreous surgery. Miotic immobile pupils not dilatable pharmacologically are enlarged by means of a silastic ring with a C-shaped groove on its outer part. This is introduced into the eye through a limbic opening. When in place, the external sulcus of the ring hosts the pupillary rim. Twelve patients (three phakic and nine aphakic) were treated. In two patients operated upon previously with silicone oil tamponade, some difficulties were encountered during the insertion of the device owing to the lubricating effect of the oil. After the removal of the ring, all the pupils returned to a round shape, with no apparent damage to the iris structure.