Effect of Decentration on the Optical Quality of Two Intraocular Lenses

Biometric factors associated with the postoperative visual performance of a multifocal intraocular lens

Purpose

To identify the biometric factors associated with postoperative visual performance after uneventful phacoemulsification with multifocal intraocular lens (MIOL) implantation.

Methods

In this retrospective cohort study, 72 eyes of 72 patients implanted with the HumanOptics Diff-aAY MIOL were included. Preoperative examination data including the white-to-white distance (WTW), anterior chamber depth (ACD), axial length and corneal astigmatism were gathered through the electronic medical records. One month postoperatively, the pupil parameters, corneal aberrations, corneal astigmatism, IOL tilts and IOL decentrations were measured using an OPD-Scan III aberrometer. Postoperative visual performance parameters were recorded as the visual acuity, depth of focus, modulation transfer function (MTF) and point spread function (PSF) values, area under log contrast sensitivity function (AULCSF), retinal straylight and visual function questionnaire scores. Univariate and multivariate linear regression analyses were then performed to evaluate the associations between the potential biometric factors and postoperative visual outcomes.

Results

Younger age predicted greater MTF and PSF values, better AULCSF and better retinal straylight (P < 0.05). A lower corneal trefoil predicted better MTF and PSF values (P < 0.05). Smaller IOL decentration predicted better distance-corrected near visual acuity, greater AULCSF and better retinal straylight (P < 0.05). A less negative spherical equivalent (SE) predicted better MTF values (P = 0.017), while a more negative SE predicted better Visual Function Index-14 (VF-14) questionnaire scores and satisfaction scores (P < 0.05). A higher IOL power predicted better best corrected distance visual acuity (P = 0.005). Lower preoperative corneal astigmatism predicted greater MTF values (P = 0.020). Lower postoperative corneal astigmatism, smaller corneal high-order aberrations (HOAs), smaller photopic pupil size, larger WTW and deeper ACD predicted a better AULCSF (P < 0.05).

Conclusions

IOL decentration, IOL power, age, preoperative and postoperative corneal astigmatism, SE, photopic pupil size, corneal trefoil, WTW, ACD and corneal HOAs were significantly associated with postoperative visual performance. These findings might aid in patient selection prior to MIOL implantation.

Effect of decentration and tilt on the in vitro optical quality of monofocal and trifocal intraocular lenses

PURPOSE

To evaluate and compare the effect of decentration and tilt on the optical quality of monofocal and trifocal intraocular lenses (IOL).

METHODS

Optical quality of a monofocal IOL (AcrySof IQ SN60WF; Alcon Laboratories, Inc., USA) and a trifocal IOL (AcrySof IQ PanOptix; Alcon Laboratories, Inc., USA) was assessed using an in vitro optical bench (OptiSpheric IOL R&D; Trioptics GmbH, Germany). At apertures of 3.0 mm and 4.5 mm, modulation transfer function (MTF) at spatial frequency of 50 lp/mm, MTF curve and the United States Air Force (USAF) resolution test chart of the two IOLs were measured and compared at their focus with different degrees of decentration and tilt. Optical quality at infinity, 60 cm and 40 cm and the through-focus MTF curves were compared when the two IOLs were centered at apertures of 3.0 mm and 4.5 mm. Spectral transmittance of the two IOLs was measured by the UV-visible spectrophotometer (UV 3300 PC; MAPADA, China).

RESULTS

The SN60WF and the PanOptix filtered blue light from 400 to 500 nm. Both IOLs at the far focus and the PanOptix at the intermediate focus showed a decrease in optical quality with increasing decentration and tilt. The PanOptix demonstrated enhanced optical quality compared to the previous gradient at the near focus at a decentration range of 0.3-0.7 mm with a 3.0 mm aperture, and 0.5 mm with a 4.5 mm aperture, whereas other conditions exhibited diminished optical quality with increasing decentration and tilt at the focus of both IOLs. When the two IOLs were centered, the SN60WF had better optical quality at infinity, while the PanOptix had better optical quality at 60 cm and 40 cm defocus. The optical quality of the SN60WF exceeded that of the PanOptix at far focus, with a 3 mm aperture decentration up to 0.7 mm and a 4.5 mm aperture decentration up to 0.3 mm; this observation held true for all tilts, irrespective of aperture size. As both decentration and tilt increased, the optical quality of the SN60WF deteriorated more rapidly than that of the PanOptix at the far focal point.

CONCLUSIONS

The SN60WF showed a decrease in optical quality with increasing decentration and tilt. Optical quality of the PanOptix at the near focus increased in some decentration conditions and decreased in some conditions, while it showed a decrease at the other focuses with increasing decentration. While tilt only had a negative effect on optical quality. When both IOLs were centered, the PanOptix provided a wider range of vision, while the SN60WF provided better far distance vision. At the far focus, the SN60WF has better resistance to tilt than the PanOptix, but the optical quality degrades more quickly when decentered and tilted.

Tolerance to decentration of biaspheric intraocular lenses with refractive phase-ring extended depth of focus and diffractive trifocal designs

PURPOSE

This study aimed to investigate the in vitro tolerance to decentration of biaspheric intraocular lens (IOLs) with refractive phase-ring extended depth-of-focus (EDOF) and diffractive trifocal designs.

METHODS

This experimental study was carried out at the Department of Optics and Optometry and Vision Science, University of Valencia, Spain. The modulation transfer function (MTF) of the ETLIO130C EDOF and the TFLIO130C trifocal IOLs (AST Products Inc., Billerica, MA, USA) were determined at different levels of decentration for a given wavelength and pupil diameter using the PMTF optical bench (Lambda-X Ophthalmics, Nivelles, Belgium). The modulation transfer function (MTF) curves, the through-focus MTF curves, and the Strehl ratios were measured at 3-mm pupil aperture for 0.25-, 0.50- and 0.75-mm decentration.

RESULTS

The optical design of the trifocal TFLIO130C IOL is robust to small decentrations, with virtually no change in MTF response for 0.25 mm decentration. For greater decentration levels, the MTF response is slightly reduced with increasing decentration. The ETLIO130C EDOF design is robust to decentration, as the MTF response is only minimally affected when increasing the decentration up to 0.75 mm.

CONCLUSIONS

MTF responses are slightly reduced with greater levels of decentration, but the range of focus provided by both trifocal and EDOF designs are preserved. The effects for average levels of decentration reported in the literature are minimum for both IOL designs.

Clinical prospective intra-individual comparison after mix-and-match implantation of a monofocal EDOF and a diffractive trifocal IOL

OBJECTIVES

To assess intra-individually visual acuity (VA) and subjective outcome after mix-and-match implantation of a monofocal EDOF IOL and a diffractive trifocal IOL.

METHODS

The monofocal EDOF Isopure IOL was implanted in the dominant eye and the trifocal FineVision HP IOL in the non-dominant eye. Postoperative evaluation included VA at various distances, contrast acuity, monocular defocus curves, decentration and tilt, wavefront aberrometry, VF-7 questionnaire and a halo and glare simulator.

RESULTS

50 eyes of 25 subjects were enroled. The trifocal IOL performed better at monocular DCNVA (p < 0.01) and at defocus levels of -1.5D to -4.0D (p < 0.01), the monofocal EDOF IOL was better at -0.5D (p = 0.013). No differences in monocular BCDVA, DCIVA, contrast acuity, decentration or tilt were observed (p > 0.05). Wavefront analysis revealed lower HOAs in the trifocal group at 5 mm (p < 0.01) and no difference (p = 0.107) at 3 mm pupil aperture. The monofocal EDOF IOL displayed increased negative SA at 5 mm (p < 0.01) and 3 mm (p < 0.01) pupil diameter. Low values of optical phenomena and satisfying results of the VF-7 questionnaire were obtained.

CONCLUSION

Excellent visual performance and low rates of optical phenomena were achieved after mix-and-match implantation of the monofocal EDOF Isopure IOL and the trifocal FineVision HP IOL. Trifocal IOL implantation in the non-dominant eye may decrease optical disturbing phenomena. Similar results were observed for monocular distance, intermediate and contrast VA. The trifocal IOL provided better monocular near VA. Decentration and tilt and HOAs were low.

Comparison of the optical behaviour of five different multifocal diffractive intraocular lenses in a model eye

The purpose of this study was to investigate and compare the optical performance of five trifocal intraocular lenses (IOLs) following the ISO 11979-2 standards, analysing the impact of tilt and decentration. Five different diffractive trifocal IOLs were evaluated in this experimental study: Acriva Trinova (VSY-Biotechnology) (AT), FineVision HP (PhysIOL) (FVHP), AT LISA tri 839 MP (Zeiss) (ATLT), PanOptix TFNT00 IOL (Alcon) (PO), and Tecnis Synergy (J&J Vision) (TS). In-vitro optical quality analysis of them was performed with the Lambda PMTF system that has an aberration neutral cornea model (Lambda-X Ophthalmics). Measurements were performed on-axis, with 5º of IOL tilt and with 0.5 mm of IOL decentration using 543-nm monochromatic light. Finally, IOL dimensions and diffractive disk profile inspection was performed using the VisIOLA system (Rotlex). On-axis measurements showed a far through-focus MTF > 0.3 at 3 mm aperture, except for TS. FVHP and PO showed better far MTFs for larger apertures (3.75 mm and 4.5 mm) while AT showed good intermediate and near vision for such apertures. With 5º of IOL tilt, the better optical performance at all distances was found with AT for medium-sized pupils (3 mm) and an important reduction of MTF was found for ATLT and PO, especially in the intermediate focus. The induction of 0.5 mm of IOL decentration especially affected the intermediate focus of ATLT and TS and the far focus of FVHP and PO. IOL dimensions and diffractive profile were consistent with those described by the manufacturer. In conclusion, there are differences in the optical performance according to the pupil aperture of the five trifocal IOLs evaluated and this should be considered in clinical practice when selecting the most appropriate implant in each specific case. IOL tilt and decentration can affect significantly in most of the designs evaluated the performance of the IOL at intermediate vision range. It should be noted that measurements were made with an aberration-free cornea, being necessary future studies analysing the impact of different levels of corneal aberrations.

Laboratory Evaluation of Optical Performance of Aspheric Monofocal Intraocular Lenses With Various Anti-misalignment Designs Under the Influence of Decentration and Tilt

PURPOSE

To assess the effectiveness and characteristics of aspheric monofocal intraocular lenses (IOLs) with different anti-misalignment designs.

METHODS

Three types of anti-misalignment IOLs (with aspheric balance curve design, ZO optic design, and high-order optical aspheric surface design) and no anti-misalignment IOLs were involved. From each type of these IOLs, +8.00, +17.00, and +26.00 diopter (D) lenses were used for detection at the 3- and 4.5-mm apertures. The modulation transfer function (MTF) and 50% of the maximum value of the MTF (MTF50) were measured while IOLs were centered, decentered by 0.3, 0.5, and 0.7 mm, and tilted by 3, 5, and 7 degrees.

RESULTS

Within the average clinical range of IOL malpositions (0.3-mm decentration or 3.00-D tilt), the anti-misalignment design slightly reduced the negative effect of decentration and tilt (P = .1845 and .6495, t test) on the optical performance of IOLs. Beyond the average range, the anti-misalignment design narrowed the reductions of MTF50 from 23.18% to 8.60% for decentration and from 40.31% to 27.96% for tilt (P = .0010, two-factor analysis of variance). The optical performance varied in anti-misalignment IOLs with different diopters, types, and degrees of malpositions at different aperture sizes. In both photopic and mesopic conditions and all probable misalignments, from the perspective of MTF50, better sharpness generally may be achieved with the 8.00-D ZO optic designed lens and 17.00-D high-order optical aspheric surface designed lens. For 26.00-D IOLs with different misalignments, the ABC design was more resistant to decentrations, whereas the high-order optical aspheric surface design was more resistant to tilts.

CONCLUSIONS

Aspheric monofocal IOLs with an anti-misalignment design can effectively resist decentration and tilt. Anti-misalignment IOLs for complicated cataract could be selected according to diopter of IOL and types and degrees of probable IOL malpositions. [J Refract Surg. 2023;39(7):446-455.].

Latest Development in Extended Depth-of-Focus Intraocular Lenses: An Update

In recent years, there has been an overwhelming influx of different types of intraocular lenses (IOLs) as treatment for presbyopia. The extended depth-of-focus (EDOF) technology creates a single elongated focal point to enhance depth of focus, in contrast to the multiple foci of multifocal (MF) lenses. In this way, the EDOF lenses aim to reduce photic phenomena, glare, and halos, which have been reported in MF IOLs. A potential disadvantage of this is a blur due to decreased retinal image quality when the amount of the aberrations is increased excessively. Multifocality and EDOF characteristics are not exclusive of each other. Frequently, EDOF IOLs are combined with MF optical designs, a bifocal IOL may exhibit EDOF characteristics, likewise an aspheric monofocal IOL or a diffractive or refractive trifocal IOL. Thus, EDOF lenses are commonly subjected to confusion. A wide range of different types of EDOF lenses are available on the market to surgeons. In this practical update, we aim to clarify what is a true EDOF lens, classify the different types of the EDOF lenses based on their optical principle and review their recently reported outcomes. Comprehensive patient examination and selection, combined with knowledge of the most updated options and adequate patient counseling, can avoid dissatisfaction and yield the desired outcomes.

Influence of anterior capsulorhexis shape, centration, size, and location on intraocular lens position: finite element model

PURPOSE

To evaluate the influence of anterior capsulorhexis shape, dimension, and eccentricity on intraocular lens (IOL) position.

SETTING

Laboratory investigation.

DESIGN

Computational model.

METHODS

A finite element model of the human crystalline lens capsule and zonule was created and the anterior capsule opened to simulate centered and decentered circular and elliptic rhexis. The model calculated capsular bag stress, IOL rotation, tilt, decentration, and vaulting, related to both capsular landmarks (absolute) and a reference IOL position defined as that obtained with a 5.0 mm circular and centered rhexis.

RESULTS

Mean von Mises stress along the IOL major z-axis was significantly higher than that along the perpendicular x-axis in all cases (P < .001), both at the equator and at the rhexis edge. Stress at the equator was always greater than that at the rhexis edge (P < .001) regardless of the rhexis shape and position. As rhexis eccentricity increased, the stress difference between the z- and x-axes increased. Absolute IOL tilt (range 10-1 to 10-7 degrees), decentration (10-3 to 10-7 mm), rotation (10-2 to 10-3 degrees), and vaulting (10-1 mm) were negligible from an optical standpoint, but all of them were significantly greater for decentered rhexis (both round and elliptic) compared with centered (P < .05).

CONCLUSIONS

Anterior capsulorhexis irregularity and/or eccentricity increase IOL tilt, decentration, rotation, and vaulting in a numerically significant but optically negligible way. Von Mises stress is much greater at the capsular bag equator compared with the rhexis edge and highly asymmetrically distributed in all cases. Stress asymmetry may influence postoperative biologic processes of capsular bag shrinking and further IOL tilting or decentration.

Optical Bench Analysis of 2 Depth of Focus Intraocular Lenses

Background

The aim of the study was to analyze the objective optical properties of 2 enhanced depth of focus (EDoF) intraocular lenses (IOLs) using optical bench analysis.

Methods

This experimental study investigates 2 new EDoF IOLs, the Alcon AcrySof IQ Vivity and the Bausch & Lomb LuxSmart Crystal, on the optical bench, using OptiSpheric IOL PRO2 (Trioptics, Germany) in order to assess the optical quality according to ISO 11979 with ISO-2 Cornea. IOLs (power 22.0 D) were evaluated regarding modulation transfer function (MTF) at 50 lp/mm and Strehl ratio (SR) using a 3.0-mm and a 4.5-mm aperture. In addition, wavefront measurements were obtained using WaveMaster® IOL 2 device (Trioptics, Germany), and USAF targets were analyzed.

Results

Centered: the MTF (mean) at 50 lp/mm (AcrySof IQ Vivity/LuxSmart Crystal) with 3.0 mm aperture was 0.250/0.257 and with 4.5 mm aperture 0.202/0.243. The SR (mean) with 3.0 mm aperture was 0.261/0.355 and with 4.5 mm aperture 0.176/0.206. Decentered by 1 mm: the MTF (mean) at 50 lp/mm (AcrySof IQ Vivity/LuxSmart Crystal) with 3.0 mm aperture was 0.266/0.247 and with 4.5 mm aperture 0.126/0.215. The SR (mean) with 3.0 mm aperture was 0.272/0.234 and with 4.5 mm aperture 0.133/0.183. Tilted by 5 degree: the MTF (mean) at 50 lp/mm (AcrySof IQ Vivity/LuxSmart Crystal) with 3.0 mm aperture was 0.221/0.360 and with 4.5 mm aperture 0.214/0.229. The SR (mean) with 3.0 mm aperture was 0.232/0.428 and with 4.5 mm aperture 0.225/0.229. The simulated visual function using USAF test targets showed corresponding qualitative results. Wavefront measurements proved a complex optical design. Higher order aberrations in the central part of the optics were modulated up to the 10th order to enhance the range of functional vision to near distance, leaving the peripheral parts of the optics aberration free or as aberration correcting.

Conclusion

The diversity of EDOF IOLs, their optics, and their respective impact on the vision quality must be understood in order to select the appropriate IOL in each individual case. This analysis of new, innovative IOL optics based on increased negative spherical aberration may help the ophthalmic surgeon to select the IOL which meets the individual requirements of the patient for best postoperative outcomes. It seems that there is no perfect IOL that is equally suitable for all patients, but the right choice is an individual, customized approach dealing with patients' expectations.

Scleral fixation of subluxated or dislocated multifocal and multifocal toric intraocular lenses

PURPOSE

To evaluate the feasibility of scleral fixation of subluxated or dislocated multifocal/multifocal toric intraocular lenses (IOLs) to rescue the IOL and restore both near and far vision.

METHOD

A total of 18 eyes of 17 patients who underwent transscleral or intrascleral fixation of subluxated or dislocated multifocal or multifocal toric IOLs at 2.5 mm posterior to the limbus were enrolled. Preoperative uncorrected distance visual acuity (UDVA) and postoperative UDVA values were compared in this retrospective cross-sectional study. The postoperative corrected distance visual acuity (CDVA), uncorrected near visual acuity (UNVA) at 40 cm, residual sphere, cylinder, spherical equivalent, and IOL centration were evaluated.

RESULTS

The mean follow-up period was 4.0 ± 5.0 months. The mean preoperative UDVA was 0.73 ± 0.71 logMAR and the postoperative UDVA was 0.05 ± 0.10 logMAR, which was significantly improved relative to the preoperative UDVA. The mean postoperative CDVA was 0.00 ± 0.00 logMAR and the mean postoperative UNVA at 40 cm was 0.05 ± 0.07 logMAR. The mean postoperative residual sphere, cylinder, and spherical equivalent values were - 0.21 ± 0.41 D, - 0.29 ± 0.26 CD, and - 0.33 ± 0.39 D, respectively. Postoperative anterior segment photographs showed good centration of optics in all cases of single-piece foldable multifocal IOLs but a slight inferior decentration in one case of a three-piece multifocal IOL.

CONCLUSION

Scleral fixation of subluxated or dislocated multifocal and multifocal toric IOLs could be one of the treatment options to rescue subluxated or dislocated multifocal IOLs and restore both near and far vision.

Changes in Optical Quality Induced by Tilt and Decentration of a Trifocal IOL and a Novel Extended Depth of Focus IOL in Eyes With Corneal Myopic Ablations

PURPOSE

To assess the effect of decentration and tilt combined with prior myopic ablations on the optical performance of a trifocal intraocular lens (IOL) and a novel IOL with an extended depth of focus (EDOF) design.

METHODS

The XACT Mono-EDOF ME4 (Santen Pharmaceutical Co Ltd) and the trifocal FineVision (PhysIOL) IOLs were analyzed with and without simulated previous myopic ablations. The optical quality of the IOLs was evaluated with the PMTF optical bench (LAMBDA-X). The through-focus modulation transfer function (MTF) curves were recorded. Measurements were done for three situations: centered, 0.4 mm decentered, and 4 degrees tilted.

RESULTS

The trifocal IOL showed three peaks of vision and the EDOF IOL showed a far distance peak with intermediate addition. When decentration or tilt were induced, the trifocal IOL showed negligible changes but the EDOF IOL showed a -0.50 diopters (D) shift of the overall curve. With simulated myopic ablation, the trifocal IOL showed a -0.50 D shift of the curve. When tilt or decentration were also induced, the better optical results were found at -1.00 D. With myopic ablations, the EDOF IOL showed a -0.50 D shift of the optical quality and when decentration or tilt were then induced, negative shifts over -1.00 D were found.

CONCLUSIONS

The trifocal IOL was less affected by mis-alignments. When myopic ablations were induced, both lenses decreased their optical quality and the effects of misalignments were higher. In patients who have undergone corneal myopic ablation procedures, proper alignment of the implanted IOL and obtaining effective emmetropia becomes even more critical. [J Refract Surg. 2021;37(8):532-537.].

Effect of defocus combined with rotation on the optical performance of trifocal toric IOLs

PURPOSE

To objectively analyze the optical quality of the FineVision Toric intraocular lens (IOL) with two cylinder powers when different combinations of rotations and residual refractive errors are induced.

METHODS

This study assessed the FineVision Toric IOL with two different cylinder powers: 1.5 and 3.0 diopters (D). Three different rotation positions were considered: centered, 5° and 10° rotated. An optical bench (PMTF) was used for optical analysis. The optical quality of the IOLs was calculated by the modulation transfer function (MTF) at five different focal points (0.0, 0.25, 0.50, 0.75, and 1.00 D).

RESULTS

The MTF averaged value of the reference situation was 38.58 and 37.74 for 1.5 and 3.0 D of cylinder, respectively. For the 1.5 D cylinder, the combination of 5° of rotation with a defocus of 0.25, 0.50, 0.75, and 1.0 D induced a decrease on the MTF of 12.39, 19.94, 23.43, 24.23 units, respectively. When induced rotation was 10°, the MTF decrease was 17.26, 23.40, 24.33, 24.48 units, respectively. For the 3.0 D cylinder, the combination of 5° with 0.25, 0.50, 0.75, and 1.0 D of defocus, induced a decrease on the MTF of 12.51, 18.97, 22.36, 22.48 units, respectively. When induced rotation was 10°, the MTF decrease was: 18.42, 21.57, 23.08, and 23.61 units, respectively.

CONCLUSION

For both FineVision Toric IOLs there is a certain optical tolerance to rotations up to 5° or residual refractive errors up to 0.25 D. Situations over these limits and their combination would affect the visual quality of patients implanted with these trifocal toric IOLs.

The impact of visual axis position on the optical quality after implantation of multifocal intraocular lenses with different asphericity values

PURPOSE

To evaluate the effect of visual axis positioning on the optical performance of the Tecnis MIOL and the Diff-aA MIOL.

METHODS

In this prospective, randomized comparative study, 70 eyes of 35 subjects with senile cataract were implanted with the spherical aberration-correcting diffractive, bifocal Tecnis ZLB00 IOL and 60 eyes of 30 age-matched subjects with the spherical aberration neutral, diffractive, bifocal Diffractiva IOL. Observation procedure was performed 1, 3, and 6 months postoperatively. Main outcome measures included uncorrected and corrected distance and near visual acuity, manifest refraction, ocular aberrations, and visual quality metrics with 2 mm and 4 mm pupil and the position of visual axis.

RESULTS

At the 6-month visit, no significant difference was found in monocular and binocular uncorrected (UDVA) and corrected (CDVA) distance and near (UNVA, CNVA) visual acuity between the groups. Spherical and coma-like aberrations were similar measured with a 2-mm pupil, but with a 4-mm pupil, the SA was significantly larger (in negative direction) in the Diffractiva group. The higher-order Strehl ratio and MTF was significantly larger in the Diffractiva group measured at 2 mm entrance pupil; however, this difference disappeared by the 4-mm pupil measurements. Postoperative angle alpha distance had a significant influence on HO Strehl value.

CONCLUSIONS

The size of angle alpha is a predictive factor of image quality by multifocal IOL patients.

TRIAL REGISTRATION

Trial registration number and date of registration: NCT04274088, 14.02.2020.

Optical tolerance to rotation of trifocal toric intraocular lenses as a function of the cylinder power

BACKGROUND

The aim was to assess the impact of 5- and 10-degree rotations in the optical quality of a trifocal toric intraocular lens with different amounts of cylinder.

METHODS

Two Physiol Toric intraocular lenses with 1.5 and 3.0 D of cylinder were analysed in three different positions: centred, 5 and 10 degrees rotated. The optical quality of the intraocular lenses was evaluated with the PMTF optical bench through specific perpendicular targets. The analysis was performed by the through-focus modulation transfer function curves and the modulation transfer function corresponding to distance vision (0 D of vergence).

RESULTS

For a centred situation, the through-focus modulation transfer function curves of both intraocular lenses showed the classical three peaks corresponding to the powers of the two principal meridians of the intraocular lenses. When 5 and 10 degrees of rotation were induced, the three peaks were attenuated in both cases. The case with the intraocular lens with 3.0 D of cylinder and 10 degrees of rotation showed the worst optical quality and a significant loss of trifocality. The modulation transfer function values obtained for distance vision also showed the worst optical quality for the intraocular lens with 3.0 D of cylinder and 10 degrees of rotation.

CONCLUSION

Rotations over 5 degrees decreased the optical quality of trifocal toric intraocular lenses, being this reduction moderate from 5 to 10 degrees for low levels of cylinder (≤1.5 D). For mid-high levels of cylinder (≥3.0 D), rotations over 5 degrees cause a significant loss of optical quality at all object distances.

Automated refraction after trifocal and trifocal toric intraocular lens implantation

BACKGROUND

To analyze the correlation between automated refraction and manifest refraction after implantation of a trifocal intraocular lens or its toric version.

METHODS

This cross-sectional study involved 105 eyes of 105 patients. Subjects were divided in two groups: 62 with trifocal (AcrySof PanOptix) and 43 with trifocal toric (AcrySof PanOptix Toric) intraocular lenses. Automated refraction was employed as starting point for obtaining the manifest refraction. Automated refraction and manifest refraction measurements were analyzed and compared using the vector analysis 3 months after the surgery.

RESULTS

In both groups, the higher differences between automated refraction and manifest refraction measurements were found for the cylinder and the spherical equivalent (M). Cylinder values for PanOptix were: -0.60 ± 0.36 D with automated refraction and -0.17 ± 38 D with manifest refraction (p < 0.001); for PanOptix Toric, the values were: -0.49 ± 0.31 D with automated refraction and -0.05 ± 0.21 D with manifest refraction (p < 0.001). M values for PanOptix were: -0.23 ± 0.31 D with automated refraction and -0.03 ± 0.16 D with manifest refraction (p < 0.001); for PanOptix Toric, the values were: -0.13 ± 0.40 D with automated refraction and 0.01 ± 0.12 D with manifest refraction (p < 0.001). For the PanOptix group, intraclass correlation coefficients were: 0.51 (sphere), 0.64 (cylinder), 0.42 (M), 0.62 (J0), and 0.37 (J45). For the PanOptix Toric group, the intraclass correlation coefficients were: 0.39 (sphere), 0.61 (cylinder), 0.39 (M), 0.53 (J0), and 0.09 (J45).

CONCLUSION

The results of this study suggest that patients implanted with the trifocal and the trifocal toric intraocular lens under study showed similar automated refraction results between them, with a slight trend to more negative amounts of cylinder and M. Nevertheless, clinicians should carefully confirm all parameters of the refraction with manifest refraction.

Patient selection to optimize near vision performance with a low-addition trifocal lens

PURPOSE

To assess the impact of ocular biometric variables on the visual performance achieved with a low addition trifocal intraocular lens (MIOL).

METHODS

Retrospective observational study including 34 eyes. Preoperative measured variables included mean corneal power (Km), corneal regular astigmatism (RA), anterior chamber depth (ACD), axial length (AXL), total irregular astigmatism (IA), spherical aberration (SA) and distance from pupil center to vertex normal (µ). Same variables were retrieved from the three month visit follow-up in addition to the actual lens position (ALP), the calculated effective addition (EA), the IOL centration from vertex normal (d), and the visual acuity defocus curve. The area under the defocus curve was computed along the total curve (TAUC) and ranges for far (FAUC), intermediate (IAUC) and near vision (NAUC). The sample was split in two groups of 17 eyes with TAUCs above and below the mean, and the differences among groups for different ocular parameters were assessed.

RESULTS

The group of eyes above TAUC of 2.03 logMAR*m-1 showed significantly lower Km and greater AXL and SA. Km was negatively correlated with TAUC and NAUC. NAUC was negatively correlated with IA and positively with d. A multiple lineal regression model including Km, d, and IA predicted NAUC (r-square = 34%). No significant differences between IA and SA were found between preoperative and postoperative values but µ significantly decreased after surgery.

CONCLUSIONS

The mean corneal power, irregular astigmatism, and centration from vertex normal should be considered for optimizing the near visual performance with this MIOL.

Optical evaluation of new-design multifocal IOLs with extended depth of focus

In this study, we investigate in vitro the optical performance of new-design extended depth of focus (EDOF) complementary intraocular lenses (IOLs) (ACTIVE, Cristalens Industrie, France), compared with traditional bifocal ones. Evaluation of their optical quality was achieved by measuring the point spread function at multiple distances (through focus) using an optical bench. In addition, the modulation transfer function through focus was calculated, correlating our results with actual visual outcomes. Our results may suggest that these new EDOF IOLs, when implanted together, could possibly better control multifocality, offering an increased DOF at all distances.

Biometric Factors Associated with the Visual Performance of a High Addition Multifocal Intraocular Lens

Purpose/Aim: To evaluate the impact of ocular parameters on the visual performance achieved with the multifocal intraocular lens (IOL) Bi-Flex M 677MY.

MATERIALS AND METHODS

About 26 subjects were included in the current study. Several physiological variables were retrieved from the 3-month follow-up visit, including pupil diameter and distance from pupil center to the vertex normal of the anterior cornea (µ). These variables were also obtained in the preoperative visit. Binocular and monocular visual acuity defocus curves were measured at 1 and 3 months after surgery, respectively. The monocular Area Under the Curve (AUC) was computed along the total range (Total Area Under the Curve (TAUC), +1.00 to -4.00 D) and for the ranges of Far (Far Area Under the Curve (FAUC), +0.50 to -0.50 D), (Intermediate Area Under the Curve (IAUC), -1.00 to -1.50 D) and Near vision (Near Area Under the Curve (NAUC), -2.00 to -4.00 D). Correlations between these areas and the postoperative physiological variables were assessed.

RESULTS

The mean µ was reduced from 0.21 to 0.10 mm after surgery, as well as pupil diameters, either photopic (-7.4%) or mesopic (-8.1%) (p < 0.05). The mean AUCs were 2.08 ± 0.74 for TAUC, 0.57 ± 0.17 for FAUC, 0.16 ± 0.09 for IAUC, and 0.81 ± 0.29 for NAUC. Significant correlations were found between NAUC and corneal power  (r = -0.39, p = 0.05) as well as between IAUC and temporal decentration of the lens from vertex normal (ρ = -0.41, p = 0.04).

CONCLUSIONS

The visual performance at near distance with the IOL evaluated improved in eyes with less corneal power. On the other hand, a slight temporal IOL decentration from vertex normal also improved intermediate visual acuity. The binocular defocus curve was similar to other trifocal IOLs.