Purpose:
To evaluate two designs for hooks to enlarge small pupils and/or to support the anterior lens capsule during cataract surgery.
Methods:
Four human globes with clear corneas were reinflated to normal tension with saline. In each eye small incisions were created in four locations: clear cornea, just anterior to the conjunctival insertion, posterior to the conjunctival insertion, and through sclera just above the iris root. The anterior chamber (ACD) was deepened with viscoelastic. In two eyes the pupils were enlarged with standard straight hooks (Fig. 1), and in two eyes the pupils were dilated with angled hooks (Fig. 2). After capsulorhexis, the four hooks were inserted to hook the anterior capsule. The ACD was again deepened with viscoelastic.
Results:
When the hook is parallel or nearly parallel to the iris plane, the straight and angled hooks performed equally. As the "attack" angle of the hook increases, it is easier to grab both the iris and anterior capsule with the angled hook. As the attack angle increases, due to incision location or deepening of the ACD, the straight hook lifts the iris and capsule more than the angled hook.
Conclusions:
It is easier to grab both the border of the pupil and the edge of the capsulorhexis with angled hooks than straight hooks, and angled hooks lift these structures less than straight hooks. Angled hooks may facilitate surgery when the pupil is small or the iris is floppy, or when zonular support of the lens capsule is inadequate.
Keywords: cataract • small incision cataract surgery • iris