The torque and tilt gamble

To analyze possible suture configurations at the haptics of posterior chamber intraocular lenses (IOLs) and estimate the resulting tilt.

King Khaled Eye Specialist Hospital, Riyadh, Kingdom of Saudi Arabia.

Using a plastic cylinder with two pairs of holes drilled on opposite sides and an IOL with eyelets in the haptics, we determined possible suture configurations and analyzed them for net torque on the IOL haptics that would result in tilting of the optic.

We identified 64 combinations of regular and countless combinations of irregular suture configurations. Among the 16 most likely combinations, only 4 were torque-free (or torque neutral), 2 caused maximum tilt, and 10 induced some tilting. Theoretically, torque could be eliminated by radial suture placement, but this is anatomically undesirable, and by positioning the eyelet perpendicular to the haptic, but this is technically difficult. Longer suture bites tended to lessen the torsion on the haptic but increased the risk of the suture looping around the free end of the haptic.

Surgeons using scleral fixation of a posterior chamber IOL should be aware of the possibility of inducing tilt and should aim for symmetrical suture configurations at the two haptics.