Comparison of 25- and 27-gauge sutureless cannula-based intraocular lens scleral fixation visual acuity outcomes and complication rates

When an intraocular lens (IOL) cannot be safely placed “in the bag,” options for IOL placement include the anterior chamber, the ciliary sulcus, or fixation of the IOL to the iris or sclera.  When the iris and zonules are compromised, scleral fixation of an IOL may be the only viable option for a patient.  Scleral fixated IOLs (SFIOLs) can be classified as sutured or sutureless.  Sutured SFIOLs with Prolene are unfortunately prone to dislocation years after surgery as the Prolene suture degrades, though newer sutures such as Gore-Tex may offer enhanced durability. Sutureless techniques often rely upon the creation of scleral tunnels (either with a needle or a vitreoretinal cannula) though which the haptics of a 3-piece IOL are externalized and embedded. 

Kadakia and colleagues recently compared visual acuity outcomes and complication rates of 25 and 27 gauge sutureless cannula-based IOL scleral fixation.  They performed a retrospective study of sutureless intrascleral (SIS) IOL cases from a single surgeon between 2015 and 2020.  The study included 69 eyes, of which 27 underwent 25 gauge cannula fixation and 42 had 27 gauge fixation.  The authors found that visual recovery was faster in the 27 gauge fixation group.  For example, the mean postoperative month 1 Snellen equivalent visual acuity in the 25-gauge group was 20/270, whereas in the 27-gauge group it was 20/60. However, the main finding was that the 27-gauge group had a statistically significant reduction in IOL dislocation and need for repeat surgery compared to the 25-gauge group (5% vs 26%, respectively).

The generalizability of the study is limited by its retrospective nature and because one surgeon performed all of the cases.  However, this is the first study to demonstrate superiority (in terms of fewer postoperative IOL dislocations requiring a return to the operating room) using 27-gauge fixation cannulas compared to 25-gauge cannulas.  Visual recovery was faster in the 27-gauge group, which the authors postulate may be due in part to the reduction in postoperative complications (eg, vitreous hemorrhage, IOL dislocation, etc.) compared to the group in which 25-gauge fixation cannulas were used.  Additionally, more IOL exchanges (as opposed to secondary IOL placement or IOL repositioning) were performed in the 25-gauge group; removal of an existing IOL may have contributed to increased corneal edema postoperatively in the 25-gauge group, thus postponing the ultimate visual recovery.

In summary, the authors present an excellent retrospective, single surgeon comparative study of visual outcomes and complication rates following 25 vs 27 gauge SIS IOL surgery.  While previous studies have suggested that using 27 gauge fixation may result in a more stable IOL, this is the first study to demonstrate a clinically meaningful reduction in postoperative IOL complications when using 27-gauge fixation cannulas as opposed to 25-gauge fixation cannulas.