Effect of incision size and site on corneal endothelial changes in cataract surgery.

PURPOSE

To compare endothelial damage induced by different cataract incision sites and sizes using specular microscopy.

SETTING

Department of Ophthalmology, Hospital of San Donà di Piave, Venice, Italy.

METHODS

Eighty-one eyes having phacoemulsification were randomly assigned to 1 of 3 groups of 27 eyes each: 3.5 mm clear corneal incision (CCI) with silicone foldable intraocular lens (IOL) implantation; 5.5 mm sutured CCI with poly(methyl methacrylate) (PMMA) IOL implantation; 5.5 mm scleral tunnel with PMMA IOL implantation. All incisions were centered at the 120-degree semimeridian; that is, they were superotemporal in right eyes and superonasal in left eyes. Noncontact specular microscopy was performed in the center and at the 12 o'clock position preoperatively as well as 1 week and 1, 3, and 12 months postoperatively. The endothelial cell density, mean cell area, cell size variation coefficient, percentage of hexagonality, and corneal thickness were considered.

RESULTS

Progressive endothelial cell loss and an increase in mean cell area occurred in all groups during the follow-up. The cell loss percentages relative to the endothelial center appeared similar among the groups and slightly although not significantly lower in the scleral tunnel group. The scleral tunnel group had a statistically significant lower cell loss percentage at the 12 o'clock position than the 2 CCI groups at all follow-ups.

CONCLUSIONS

The scleral tunnel group had less postoperative endothelial damage than the 2 CCI groups, with a statistically significant difference at the 12 o'clock position. This is probably because the scleral tunnel incision is placed more posteriorly and therefore induces less direct and indirect endothelial trauma.