Altering chromatic aberration: how this latest trend in intraocular-lens design affects visual quality in pseudophakic patients.

BACKGROUND: Chromatic aberration of the eye results from the dispersion of polychromatic light at the interfaces of ocular media. An intraocular lens (IOL) based approach utilizing the diffractive-multifocal principle has been proposed for its correction, but the clinical evidence on the impact of reducing or increasing chromatic aberration on the visual quality of pseudophakic patients remains scarce. METHODS: In this cross-sectional study, longitudinal chromatic aberration (LCA) effects were studied monocularly in 37 patients implanted with a monofocal lens. LogMAR corrected distance visual acuity (VA) and defocus curve at the + 1.0 D to - 2.0 D range were assessed. Contrast sensitivity (CS) was evaluated at far and at four spatial frequencies. Measurements were performed with the eye's natural conditions, as well as with increased and corrected (by the same amount) LCA, which was altered by introducing zero-power trial triplets. RESULTS: The mean (± standard deviation) logMAR VA was - 0.11 ± 0.07 for the natural condition, - 0.13 ± 0.07 for the LCA-corrected eye, and - 0.06 ± 0.08 for the eye with increased LCA. A sharp decline of the defocus tolerance was found after the LCA correction with the VA value of 0.38 ± 0.15 logMAR at - 1.5 D. However, for the natural and increased LCA, it was 0.32 ± 0.16 logMAR and 0.25 ± 0.13 logMAR, respectively. CS was improved at all spatial frequencies after the LCA correction, which was closely followed by the natural-eye performance. Increased LCA resulted in reduced CS, mainly at higher spatial frequencies. CONCLUSIONS: We demonstrated that elevating chromatic aberration above the natural level of monofocal patients extends their depth of focus while causing a measurable albeit minimal reduction in visual function. Still, the observed changes indicate that neither correction nor increase of LCA yields a substantial clinical effect on distance VA and CS in monofocal pseudophakia.

[Fixation of an intraocular lens using reverse optic capture with haptic tuck for intraoperative posterior capsule rupture]. / Fixation einer Intraokularlinse bei intraoperativem Hinterkapseldefekt durch Einklemmen der Linsenoptik in der vorderen Kapsulorhexis.

Exact positioning and optimal axial alignment are mandatory to achieve satisfactory postoperative refractive results after implantation of a toric or presbyopia correcting intraocular lens (IOL). Posterior capsule rupture can preclude stable capsular fixation. In such cases, reverse optic capture with haptic tuck results in stable fixation of the lens with respect to centering, rotation and axial position. Only the haptics are positioned in the capsule, behind the anterior capsulorrhexis. The optic remains in the sulcus; thus, the lens is fixed in the rhexis, providing long-term stability despite the presence of posterior capsule rupture.