Changes in higher-order aberrations of intraocular lenses with intrascleral fixation

To determine the higher-order aberrations of intraocular lenses (IOLs) that are extended and fixed intrasclerally.

A computer-aided design system was used to calculate the length of an IOL when it was fixed to the sclera 2 mm posterior to the limbus in a Gullstrand eye model. An acrylic single-piece (SA60AT) or 2 three-piece IOLs (VA-60BBR; X-60) were fixed at lengths of 13, 14, 15 and 16 mm. A wavefront analyser was used to measure the higher-order aberrations within the central 3.0 and 5.2 mm optic diameters.

The length of the IOL with the intrascleral fixation was calculated to be 13.9-14.9 mm in the eye model. The astigmatic aberration of the three-piece VA-60BBR and X-60 IOLs increased significantly with an extension of the IOLs within the central 5.2 mm (both p<0.001) but not that of the single-piece SA60AT IOL. The coma aberration of the VA-60BBR IOL increased significantly within the central 5.2 mm with an increase in the extension (p=0.001) but not that of the SA60AT and X-60 IOLs. The astigmatic and coma aberrations were significantly greater within the central 5.2 mm than within the central 3.0 mm for all IOLs (p<0.05). The cylindrical power increased from 0.034 D to 0.082 D with extensions from 13 to 16 mm.

When three-piece IOLs are extended widely for intrascleral fixation, the astigmatic and coma aberrations increase but the degree of change should not alter the postoperative vision appreciably.