Modulation transfer function and optical quality after bilateral implantation of a +3.00 D versus a +4.00 D multifocal intraocular lens

Abstract

PURPOSE:To determine whether the improvement in intermediate vision after bilateral implantation of an aspheric multifocal intraocular lens (IOL) with a C3.00 diopter (D) addition (add) occurs at the expense of optical quality compared with the previous model with a C4.00 D add.SETTING: Department of Ophthalmology, University of São Paulo, São Paulo, Brazil. DESIGN:Prospective randomized double-masked comparative clinical trial. METHODS:One year after bilateral implantation of Acrysof Restor SN6AD1 C3.00 D IOLs or Acrysof Restor SN6AD3 C4.00 D IOLs, optical quality was evaluated by analyzing the in vivo modulation transfer function (MTF) and point-spread function (expressed as Strehl ratio). The Strehl ratio and MTF curve with a 4.0 pupil and a 6.0 mm pupil were measured by dynamic retinoscopy aberrometry. The uncorrected and corrected distance visual acuities at 4 m, uncorrected and distance-corrected near visual acuities at 40 cm, and uncorrected and distance-corrected intermediate visual acuities at 50 cm, 60 cm, and 70 cm were measured. RESULTS:Both IOL groups comprised 40 eyes of 20 patients. One year postoperatively, there were no statistically significant between-group differences in the MTF or Strehl ratio with either pupil size. There were no statistically significant between-group differences in distance or near visual acuity. Intermediate visual acuity was significantly better in the C3.00 D IOL group. CONCLUSION:Results indicate that the improvement in intermediate vision in eyes with the aspheric multifocal C 3.00 D add IOL occurred without decreasing optical quality over that with the previous version IOL with a C4.00 D add. The Acrysof Restor intraocular lens (IOL) (Alcon Laboratories, Inc.) was designed to achieve distance, intermediate, and near visual acuity without compromising visual performance.1 After the introduction of the 3-piece model (MA60D3), 2 the first 1-piece spherical version (SA60D3), 3 and the model with blue light-filtering chromophore (Acrysof Natural Restor SN60D3), 4 an aspheric design was incorporated into the optic of the IOL (model SN6AD3) [5][6][7][8] to provide better optical quality. The aspheric model has the same platform as the original spherical IOL; however, the symmetric biconvex design and an anterior aspheric optic were used with the aim of generating fewer higher-order aberrations (HOAs), and negative spherical aberration was incorporated to compensate for positive corneal spherical aberration. [5][6][7][8] In an attempt to meet patient needs for more functional intermediate vision, a new IOL model (Acrysof Restor SN6AD1) was developed. This multifocal IOL has the same symmetric biconvex design and anterior aspheric optic but a lower addition (add). Findings in previous studies [8][9][10][11][12][13][14][15] provide evidence that the C3.00 diopter (D) add version yields better intermediate vision and a more comfortable reading distance than the C4.00 D add version.The aim of this study was to determine in vivo whether the improvement in intermediate vision aft...

Multifocal and Accommodative Intraocular Lenses

“…Because of their double coaxial optics, multifocal IOLs provide lower optical quality as compar ed with monofocal IOLs [19]. Studies conduct ed with HartmannShack aberrometers demons trated complex pathways especially of spherical aberration that may be positive for smaller aper ture diameters, and negative for larger, reduc ing pointspread function [20].…”

Utility of the optical quality analysis system for decision-making in cataract surgery

“…It has been suggested that the MTF plots are associated with the subsystems that make up a complete electro-optical or photographic system [22]. The MTF is associated with tear film stability [23] or the type of intraocular lens [24]. The OSI is defined as the ratio between the integrated light intensity in the periphery and that around the central peak of the double-pass image [11].…”

“…The Strehl ratio expresses the ability of the eye to form a point image on the retina when a point object is seen [28]. It is related to wavefront errors [29], aging [17] and characteristics of the intraocular lens [24]. …”

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“…This lens provides better intermediate vision than the +4 model with no evident change in visual disturbances. The preferred reading distance for the +3 lens was near 40 cm, whereas with the +4 add the preferred reading distance was about 32 cm 3,4…”