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

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.

Blazed photon sieve for the correction of presbyopia

What we believe to be a new type of transparent photon sieve is presented with application for presbyopia correction. Inspired by blazed gratings, we propose to design an intracorneal implant with slanted holes. The slopes introduce a new degree of freedom, breaking the symmetry of energy distribution along the optical axis and allowing to balance the energy between near and far vision. This new implant design is presented together with the simulation, manufacturing and validation methods. The first experimental results obtained with an implant manufactured in a biocompatible material are presented confirming the potential of the approach.

Design of adjustable multifocal diffractive optical elements with an improved smooth phase profile by continuous variable curve with multi-subperiods method

Multifocal diffractive optical elements (MDOEs), which produce arbitrary light distribution, are widely used in lightweight and compact optical systems. MDOEs that are combined with multiple functions tend to have complex step structures, limiting their applications. We propose a facile method named continuous variable curve with multi-subperiods (CVCMS) to design adjustable multifocal single-layer diffractive optical elements. Through the analysis, the model achieved arbitrary diffraction efficiency distribution with an improved smooth continuous phase profile in each diffractive ring while retaining the periodicity. To display the high design freedom of the method, we utilized this method to design and discuss a broadband multifocal intraocular lens (MIOL) focused on the optimization of far focal point. Finally, the method was compared with other multifocal design methods. The results show that the CVCMS method achieved adjustable multifocal design with better performance and smoother profile than other MDOE design techniques. The proposed model can be applied to multifocal ophthalmic lens designs.

Clinical outcomes of a new four-haptic hydrophobic presbyopia-correcting intraocular lens

A new presbyopia-correcting intraocular lens (IOL) combining bifocal and extended-depth-of-focus profiles (Symbiose: Artis Symbiose Plus; Cristalens Industrie, Lannion, France) was introduced. We compared the output with that of a standard monofocal IOL (PL E: Artis PL E). The two four-haptic hydrophobic IOLs were made of the same material from the same company. Cataract patients bilaterally implanted with either PL E or Symbiose between November 2021 and August 2022 were reviewed. The principal measures of the postoperative results were uncorrected distance visual acuity (UDVA); corrected distance VA (CDVA); uncorrected intermediate VA; uncorrected near VA; objective optical quality; and distance-corrected defocus curves. This study included forty-eight patients (96 eyes), with 22 and 26 patients (44 and 52 eyes, respectively) being implanted with PL E and Symbiose, respectively. All patients received the same type of IOL implanted in both eyes. The average age of patients was 70.9 ± 7.1 and 60.0 ± 8.5 years in PL E and Symbiose groups, respectively, with significantly younger patients in Symbiose group (p < 0.001). Both IOLs displayed excellent UDVA and CDVA with no statistical difference (p = 0.081 (monocular UDVA), p = 0.599 (monocular CDVA), p = 0.204 (binocular UDVA), and p = 0.145 (binocular CDVA)). In comparison with PL E group, Symbiose group showed significantly superior postoperative intermediate and near VA (p < 0.001). PL E group showed significantly superior objective optical quality compared with Symbiose group (p < 0.001). Symbiose provides a continuous range of vision that ensures a seamless transition from far to near with no discontinuity. It also delivers a smooth defocus curve with a larger landing area than the PL E. But the objective optical quality was better in PL E.

Patient reported outcomes after implementation of an enhanced depth of focus intraocular lens with low postoperative myopia

Background

Enhanced depth-of- focus intraocular lenses (EDOF IOL) have filled the gap between monofocal and multifocal intraocular implants with optical qualities of monofocal lenses and usually minor dysphotopsias typical for multifocal lenses. The purpose of this study was to evaluate visual outcomes after bilateral implantation of a new EDOF IOL in patients with requirements for perfect near and intermediate vision.

Methods

The study included 15 patients (29 eyes as one was amblyopic) with bilateral implantation of LUXSMART EDOF IOL (Bausch & Lomb) with a targeted myopia (between -0.25 and -0.50D) in both eyes. Monocular corrected and uncorrected visual acuity for far, intermediate and near as well as refractive outcomes were evaluated at 1, 3, 6 and 12 months after the surgery. Additionally, binocular visual acuity, contrast sensitivity and defocus curve were measured at the final follow-up visit. At 12 months' visit patients completed a questionnaire evaluating patient satisfaction, spectacle independence and presence of dysphotopsias.

Results

Binocular uncorrected visual acuities at 12 month's visit were 0.13 ​± ​0.16, 0.06 ​± ​0.08, 0.07 ​± ​0.09 and 0.15 ​± ​0.09 logMAR for far distance, 80 ​cm, 66 ​cm and 40 ​cm respectively. Corrected binocular visual acuities at 12 months were 0.00 ​± ​0.00, 0.05 ​± ​0.07, 0.05 ​± ​0.06, 0.13 ​± ​0.16 respectively for distance, 80 ​cm, 66 ​cm and 40 ​cm. Automated refraction spherical equivalent at 12 months' visit stood at -0.70 ​± ​0.48D, which was 0.46D less than calculated biometric target, however spherical equivalent of subjective refraction at 12 months equaled -0.49 ​± ​0.46D, which was closer to preoperative biometric target. Defocus curve had gentle shape without peaks typical for monofocal IOLs. Binocular contrast sensitivity results were superior to average results for that age group and equaled 1.78 ​± ​0.16 logMAR without correction and 1.81 ​± ​0.13 logMAR with correction. Spectacle independence for near and intermediate distances was achieved in all patients and for far distance in 73.3% of patients. Burdensome dysphotopsias were not reported in any case.

Conclusions

EDOF IOLs targeted bilaterally at low myopia can provide excellent near and intermediate visual acuity and independence of any optical correction in majority of cases. This approach can be used in selected patients who are focused on stationary activities.

Theoretical model and optimization of diffractive optical elements with aspheric substrates in ophthalmology

Diffractive optical elements (DOEs), which can produce arbitrary light distribution, are widely applied in ophthalmic lens design with spheric substrates. However, diffraction substrates tend to be designed as aspheric surfaces to eliminate aberrations. In this case, the diffraction theory of plane substrates is no longer accurate, which affects the diffraction performance. Therefore, a diffraction theory of aspheric diffraction substrates is proposed in this paper. Using the range of common parameters for aspheric substrates in ophthalmology, the influence of the substrate diopter and the aspheric surface parameters on the period radius and phase delay is analyzed. Then, through a design example of a diffraction intraocular lens (IOL), an optimization equation is proposed and discussed. The results show that the diffraction theory of aspheric substrates and the optimization equation model can analyze and reduce the effect of aspheric diffraction substrates. This research can be used in DOE design with aspheric substrates in ophthalmology.