Objective Depth-of-Focus Estimation from Wavefront Measurements After Implantation of an Isofocal Intraocular Lens

To assess the objective depth-of-focus after implantation of isofocal intraocular lens (IOL) during cataract surgery based on VSOTF using ray tracing aberrometry.

In this prospective study, 40 eyes were implanted with the isofocal Isopure IOL (Beaver-Visitec International, Inc. [BVI], Waltham, USA). The patient assessments considered: refraction (sphere, cylinder and axis), uncorrected-distance visual acuity (UDVA), corrected-distance visual acuity (CDVA), uncorrected intermediate visual acuity (UIVA, at 60 and 80 cm), distance-corrected and uncorrected near visual acuity (DCNVA and UNVA), wavefront aberrations and objective depth-of-focus using ray-tracing optical technology from several percentages of degradation on the visual Strehl ratio based on the optical transfer function (VSOTF, 90%, 80% and 60%). Patients were assessed at 3 months post-surgery.

Eyes implanted with the isofocal IOL showed good outcomes in terms of refraction and visual acuity at the last follow-up visit. Specifically, half a dioptre was obtained for the spherical equivalent and about 20/20 for CDVA, about 20/25 for UIVA at 80 cm, about 20/30 for UIVA at 60 cm, and about 20/25 for DCNVA. In relation to the objective depth-of-focus computed from the wavefront analysis in our cohort, we obtained mean values of 2.12 D, 3.16 D and 4.94 D at 90%, 80% and 60% of degradation, respectively.

Our study shows that the isofocal IOL provides high values of objective depth-of-focus based on the VSOTF using ray tracing optical technology when implanted after cataract surgery.