Visual, clinical and quality of life outcomes of a new multifocal IOL with optimized diffractive grating: a non-randomized clinical trial

Abstract

Background

Multifocal intraocular lenses (IOLs) are designed to reduce dependence on spectacles by providing multiple focal points. However, they are associated with photic phenomena such as halos and glare, and may reduce contrast sensitivity. The BIOS Trifocal is a single-piece acrylic diffractive IOL with a closed-loop haptic design, optimized for centration and stability. It features an aspheric, aberration-neutral surface and a precisely engineered diffraction grating for effective energy distribution across multiple distances. This study aims to evaluate the visual, clinical, and quality of life outcomes of the BIOS Trifocal IOL for treatment of cataract and presbyopia.

Methods

Participants who met the inclusion criteria underwent implantation of the BIOS Trifocal IOL and were assessed at 30 and 90 days post-surgery. The evaluations included measurements of patient-reported outcomes using the NEI-VFQ 25 at postoperative day 30 and uncorrected and corrected distance visual acuity and defocus curves at postoperative day 90. Additionally, intraoperative and postoperative complications were documented. Visual acuity assessments were performed under photopic conditions, with a range of defocus from + 1.5 D to -3.0 D.

Results

Significant improvements were observed in uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and near visual acuity (UNVA) at both 30 and 90 days post-surgery (p < 0.001). The defocus curve demonstrated functional vision from + 1.5 D to -3.0 D, supporting the lens’s efficacy for near, intermediate, and far distances. Quality of life, as assessed by the NEI-VFQ 25, showed marked improvement across all domains (p < 0.05), with no significant complications directly attributable to the IOL.

Conclusions

The BIOS Trifocal IOL presented satisfactory effectivity in the treatment of cataract and presbyopia, providing functional vision across near, intermediate and far distances and maintaining good patient satisfaction.

Trial Registration

This trial was registered at the ReBEC (Registro Brasileiro de Ensaios Clínicos – Brazilian Registry of Clinical Trials)database under the registration code RBR-772s6y at April 6th, 2020.

Introduction

Cataract is a frequent phenomenon most often associated with aging, where lens fibers become disorganized and opaque, reducing visual quality and acuity. Even though it is a curable disease, it is still one of the leading causes of blindness across the world [1]. Cataract treatment is surgical, consisting of the extraction of the opaque lens and replacement by a transparent intraocular lens (IOL). The first IOLs were developed to correct distance vision [2], focusing light in a single spot in the fovea, calculated by specific biometric formulae, and therefore have been labeled monofocal [3]. Considering that the removal of the natural lens severely hampers the accommodation process, which is also affected by age, most patients who receive monofocal IOL implants need spectacle assistance for near and intermediate distance vision.

Multifocal IOLs have been designed to reduce or eliminate spectacle dependence across multiple distances without the constraints of monovision strategies, dividing light to provide more than one focus [4–7]. Multiple design strategies have been proposed, such as diffractive lenses, different refraction areas, spherical aberration, apodization, pseudoaccommodation, and stenopeic principles [4, 7, 8].

However, multifocal and EDoF IOLs have been associated with an increased occurrence of photic phenomena [7, 8], such as halos and glare. A study by Böhm et al. [9] evaluated self reported quality of vision and photic phenomena in patients with a trifocal, a panfocal and an EDoF IOL. While present in all multifocal IOL models, these photic phenomena seem to be less intense in EDoF users. In comparison, spectacle independence was significantly more common in multifocal and panfocal IOL users. It has also been shown that presbyopia-correcting IOLs might reduce contrast sensitivity [4, 7, 8]. New IOL designs aim to enhance spectacle independence without generating visual effects, such as photic phenomena and loss of contrast sensitivity, which might generate significant dissatisfaction in a patient.

The BIOS Trifocal (Mediphacos Indústrias Médicas SA, Belo Horizonte/MG, Brazil), is a single-piece acrylic diffractive intraocular lens designed for implantation in the capsular bag. The BIOS IOL’s patented mechanical platform has a closed-loop haptic design with 6 mm optical zone and 11 mm of overall diameter. According to the manufacturer, the proprietary IOL platform was developed to provide adequate implant centration, axial and positional stability in a wide range of capsular bag diameters and capsular contraction scenarios. The optic has a 6 mm biconvex design with an aspheric, spherical aberration-neutral anterior surface. The posterior optical surface has a diffraction grating consisting of 16 diffractive steps for asymmetric energy distribution into far, intermediate and near distances. The diffraction grating is optimized for each IOL power using a patented algorithm to maximize optical efficiency and compensate for the variations in optic thickness across the diopter range. The inner and outer diffractive steps have 1.21 mm and 4.83 mm in diameter, respectively (Fig. 1).

Fig. 1.

BIOS Trifocal IOL Design Image depicting the anterior (left) and posterior (right) designs of the BIOS Trifocal IOL, with an optimized diffractive grating for each diopter step available

This study aims to evaluate the visual, clinical and quality of life outcomes of the BIOS Trifocal IOL for treatment of cataract and presbyopia, translated as visual acuity in different distances, defocus curves, quality of life questionnaire results, and frequency of complications.

Materials and methods

Study Design

This was a prospective, non-randomized clinical trial where a BIOS Trifocal IOL was implanted in participants meeting inclusion criteria with an emmetropic target in both eyes. This clinical study was performed at Fundação João Carlos Lyra in Maceió, Brazil, and registered at the ReBEC clinical trial database under the registration code RBR-772s6y.

Inclusion and exclusion criteria

Inclusion criteria included participants of 21 years of age or more, who had a diagnosis of senile cataract with a visual potential of 0.30 logMAR or better in the operative eye and considered to be eligible for phacoemulsification. Exclusion criteria included patients with best corrected visual acuity less than or equal to 1.0 logMAR in the contralateral eye, participants with any active ocular pathology in which phacoemulsification procedure with primary IOL implantation was contraindicated, and other ocular or systemic health issues that could interfere with surgical results, such as significant retinal or corneal pathologies, advanced glaucoma, active ocular infection or inflammation, systemic diseases with active ocular manifestations, and recent intraocular procedures.

Sample size calculation

The endpoint used for the sample size calculation was the improvement in visual acuity across repeated measurements at three time points: preoperative, 30th postoperative day, and 90th postoperative day. Sample size was calculated to attain a significance level of 0.05, an effect size of approximately 0.25, and a power of the test to be reached at 0.95. The G*Power 3.1.9.6 software for macOS was used for calculation, with the following parameters: target effect size of 0.25, significance level of 0.05, power of 0.95, one group, the number of measurements equal to three (preoperative and 30th and 90th postoperative days), the minimum estimated correlation between repeated measurements of 0.50, and a biased estimate of sphericity of 0.60. The software yielded a minimum of 105 eyes to obtain the required statistical specifications.

Surgical technique

All surgical procedures were performed by an experienced surgeon (J.M.A.G.L.), under topical anesthesia or, when necessary, peribulbar anesthesia. Initially, 2 self-sealing clear cornea incisions were performed on nasal and superior temporal regions, followed by injection of 2% Hydroxypropyl Methyl Cellulose (HPMC) in the anterior chamber. Manual continuous curvilinear capsulorhexis was performed, followed by lens phacoemulsification and cortical aspiration. The BIOS Trifocal IOL was introduced through a 1.8 mm injector, filled with 2% HPMC, and positioned in the capsular bag. HPMC was fully aspirated, and no sutures were placed. Upon discharge, patients were prescribed moxifloxacin 5 mg/ml and dexamethasone 1 mg/ml eye drops 6 times a day for 7 days, followed by a tapered dosing scheme of dexamethasone 1 mg/ml.

Clinical evaluation protocol

Participants underwent clinical evaluation and complementary exams preoperatively and on days 30 and 90 after surgery. The primary endpoint for this study was the improvement in visual acuity across repeated measurements at these time points. Manifest refraction at 3 m and evaluation of uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA) at 3 m using Snellen charts projected by a calibrated and adjusted ACP-8 Auto Chart Projector (Topcon Corporation, Japan) was performed preoperatively and at 30 and 90 days after surgery, in photopic conditions. Corrected near visual acuity (CNVA) was measured at 44 cm preoperatively using a Jaeger chart. Distance-corrected intermediate visual acuity (DCIVA) was measured at 71 cm and distance-corrected near visual acuity (DCNVA) was measured at 44 cm using Jaeger charts, under photopic conditions, at 30 and 90 days after surgery. The monocular and binocular defocus curves were performed on participants who received a binocular implant, ranging from + 1.5 to −3.0 D in 0.5 D intervals, using a projected Snellen chart at a distance of 3 m, at day 90 after the second eye surgery. Slit lamp biomicroscopy, Goldmann applanation tonometry and keratometry were performed preoperatively and at days 30 and 90 postoperative evaluations. Optical Biometry using an IOL Master 500 biometer (Carl Zeiss Meditec, Germany) was performed preoperatively, and the Barrett Universal II formula was used to determine adequate IOL power. In addition, a validated Portuguese translated Quality of Life Questionnaire (NEI-VFQ 25) [10] was applied preoperatively and at day 30 after surgery.

Statistical analysis

Statistical analysis was performed using Jamovi (version 2.3, Computer Software) for macOS and data visualization using Datawrapper (https://www.datawrapper.de). All visual acuity measurements were converted to logMAR, and a reference table^A for near and intermediate Jaeger-to-logMAR conversions was used. Both the defocus curves and refraction measures were adjusted to the infinity with the addition of −0.33 D [11, 12]. The repeated measures analysis of variance, the post hoc Bonferroni test, and the partial eta-squared effect size were used to figure out how different the visual acuities and refraction were before and after surgery (0.01 is a small effect, 0.06 is a medium effect, and 0.14 is a large effect). Normality was evaluated with Kolmogorov-Smirnov’s test. The assumption of sphericity was evaluated with Mauchly’s test and used for the Greenhouse-Geiser sphericity correction. The paired sample t-test was used to compare preoperative and postoperative mean scores for the overall score and subdimensions of the NEI-VFQ 25 questionnaire. Continuous variables are reported as mean ± standard deviation, and categorical variables as frequency and percentage. The significance level adopted for the tests was 0.05.

Results

Demographic description

A total of 105 eyes of 61 consecutive participants who met the inclusion criteria were recruited and examined between September 4th, 2020 and October 27th, 2022. The mean age of this group was 65.00 ± 6.68 years, ranging from 41 to 79 years old. Of the 61 patients, 38 (62.3%) were female and 23 (37.7%) were male. Fifty-three implants were made in the right eye, and fifty-two in the left eye. Sixty-six patients were originally recruited. However, one patient died due to unrelated causes during the execution of this study, and 4 patients who had been initially recruited retracted consent to participate in this study before implantation of the first IOL. The trial was concluded when the final postoperative evaluation of all recruited participants was executed.

Visual acuity and defocus curve

Mean UDVA was 0.64 ± 0.32 preoperatively, 0.14 ± 0.15 at day 30 and 0.12 ± 0.12 at day 90 after surgery. Mean CDVA was 0.30 ± 0.21 preoperatively, 0.10 ± 0.13 at day 30 and 0.06 ± 0.10 at day 90 after surgery. Mean UNVA was 0.25 ± 0.16 preoperatively, 0.12 ± 0.11 at day 30 and 0.11 ± 0.10 at day 90 after surgery. Improvements in monocular UDVA, UNVA and CDVA were significant (p < 0.01) at days 30 and 90 after surgery. CNVA was 0.11 ± 0.14 preoperatively. DCNVA was 0.10 ± 0.11 at day 30 and 0.07 ± 0.10 at day 90 after surgery. UIVA was 0.19 ± 0.09 at day 30 and 0.17 ± 0.10 at day 90 after surgery. DCIVA was 0.16 ± 0.10 at day 30 and 0.14 ± 0.10 at day 90 after surgery. Standard refractive outcome in IOL-related procedures reporting graphs [10] were presented in Figures 2, 3, and 4.

Fig. 2.

Cumulative Frequencies of Uncorrected and Corrected Distance Visual Acuity Cumulative percentages of individuals achieving each level of uncorrected (red) or corrected (blue) distance visual acuity. More than 80% of participants reached a visual acuity of at least 0.1 LogMAR (20/25 Snellen) with distance correction

Fig. 3.

Cumulative Frequencies of Uncorrected and Distance Corrected Intermediate Visual Acuity Cumulative percentages of individuals achieving each level of uncorrected (red) or distance-corrected (blue) intermediate visual acuity (71 cm). More than 85% of eyes achieved a visual acuity of at least 0.1 LogMAR (20/25 Snellen) with correction, and 95.5% achieved at least 0.2 LogMAR (20/32 Snellen)

Fig. 4.

Cumulative Frequencies of Uncorrected and Distance Corrected Near Visual Acuity Cumulative percentages of individuals achieving each level of uncorrected (red) or distance-corrected (blue) near visual acuity (44 cm). More than 90% of participants attained a visual acuity of at least 0.2 LogMAR (20/32 Snellen) with distance correction

Only 2 eyes achieved monocular CDVA worse than 0.3 LogMAR at 3 m at day 90 after surgery. One of the cases of persistent low corrected visual acuity was caused by macular edema, and the other by a recently formed epiretinal membrane. No patient had a DCVA worse than 0.3 LogMAR at 3 m at 90 days after surgery. Binocular and monocular defocus curves and their expected adjusted curves for infinity (represented as continuous and dotted lines, respectively) at 90 days after surgery have been presented in Fig. 4. A functional binocular visual acuity, better than 0.1 LogMAR (or 20/25 acuity), was achieved from + 1.5 D to −2.00 D, and better than 0.2 (20/32) from − 2.00 to −2.50D (Fig. 5).

Fig. 5 .

Defocus Curves. Defocus curves illustrating visual acuity (LogMAR) for each addition step of the curve. The dashed lines represent a fixed correction of 0.33 D for infinity. Useful binocular vision was achieved from +1.5 D to -2.0 D.

A constant optimization and refractive results

Preoperative mean spherical error was − 0.09 ± 2.48 D and mean cylinder was − 0.85 ± 0.54 D. Postoperative measures at day 90 after surgery were 0.12 ± 0.59 D of mean spherical error and − 0.73 ± 0.50 D of mean cylinder, using a theoretical A Constant of 118.4. Overall, the mean refractive error was 0.504 D, mean absolute error was 0.604 ± 0.454 D, and median absolute error was 0.468 D, resulting in 52.94% of eyes within 0.5 D of error and 83.82% within 1.0 D.

These refractive results may be due to an unoptimized A Constant. When recalculating IOL Power with an A Constant of 118.0, a mean refractive error of 0.002 D, a mean absolute error of 0.441 ± 0.326 D, a median absolute error of 0.383 D were obtained. Using this constant, 69.12% of patients would have achieved an error of less than 0.5 D and 97.06% would achieve an error less than 1.0 D.

Quality of life

A significant improvement (p < 0.05) was observed in all domains of the NEI-VFQ 25 Questionnaire 30 days after BIOS Trifocal implant, in comparison to the preoperative evaluation. The overall quality of life score increased from 67.9 to 94.1%. General vision scores improved from 10.8 to 73.9%, near activities scores from 57.2 to 91.4% and driving scores from 57.2 to 95.5%. All individual domain improvements are presented in Fig. 6. Seventeen patients reported driving at night, from which 15 (88.2%) reported 75% or better functionality according to NEI-VFQ 25 scores.

Fig. 6.

NEI-VFQ 25 Score Improvements. Chart showing improvements in NEI-VFQ 25 scores, with preoperative scores depicted in red on the left and postoperative scores in green on the right. A significant increase was observed in all domains of the NEI-VFQ 25.

Chart showing improvements in NEI-VFQ 25 scores, with preoperative scores depicted in red on the left and postoperative scores in green on the right. A significant increase was observed in all domains of the NEI-VFQ 25.

Complications

There were no intraoperative complications. A total of 9 eyes (6.7%) developed posterior capsule opacity at day 90 after surgery. Those individuals were treated with Nd: YAG laser capsulotomy without any further complications. We also had one case of persistent macular edema at day 90 after surgery and one case of epiretinal membrane affecting visual acuity, none of which were IOL-related. No cases of IOL decentration were observed.

Discussion

The BIOS Trifocal IOL proposes to meet the current need of an intraocular lens capable of providing good visual function for distant, intermediate and near foci, causing minimal photic disturbances.

In the present study a non-randomized clinical trial was performed, which aimed to evaluate the visual, clinical and quality of life outcomes of the BIOS Trifocal IOL for treatment of cataract and presbyopia, translated as visual acuity in different distances, defocus curves, quality of life questionnaire results, and frequency of complications. Our observations demonstrate improvements in visual acuity, quality of life, and spectacle independence in near, intermediate and far distances, whilst presenting a low number of complications, none of which were apparently IOL-related.

Visual acuity and defocus curve

Trifocal IOLs exhibit superior capacity to generate spectacle independence in comparison to bifocal IOLs due to an improved intermediate visual acuity and wider range of functional vision [13, 14]. Patients implanted with the BIOS Trifocal IOL showed significant improvement in visual acuity, achieving 0.2 LogMAR or more in the monocular defocus curve range from + 1.5 to −1.00 D and in the bilateral defocus curve from + 1.5 to −2.50 D, a result that is comparable to other presbyopia-correcting IOL studies, such as the FineVision (PhysIOL, Liège, Belgium) [13], AT LISA Tri (Carl Zeiss Meditec., Jena, Germany) [15], PanOptix (Alcon Laboratories, Texas, USA) [16], RayOne Trifocal (Rayner, Worthing, UK) [17] trifocal IOLs and Tecnis Synergy (Johnson & Johnson Vision, California, USA) [18], Tecnis Symfony (Johnson & Johnson Vision, California, USA) [19], and AT LARA (Carl Zeiss Meditec., Jena, Germany) [20] EDoF IOLs.

A study by Gil et al. [19] compared visual acuity and defocus curves between six different multifocal IOLs. Binocular defocus curves revealed a general tendency towards a “valley” on defocus steps representing intermediate vision (−1.00 to −2.00 D) and “peaks” on far (0.00 D) and near (−2.00 to −3.00) distances. The main exception was the Tecnis Symfony ZXR00 model, presenting a superior performance on intermediate vision, albeit sacrificing performance in defocus steps that represent closer distances. Even though direct comparisons cannot be made due to methodological restraints, the findings of the current study show that the BIOS Trifocal IOL presented a similar behavior to the one from the Tecnis Symfony ZXR00 model in the study by Gil et al., with a drop in visual acuity for near distances, although the BIOS Trifocal still maintained a functional visual acuity in this range.

It is noteworthy that the BIOS Trifocal provided satisfactory uncorrected visual acuity levels across different distances in both monocular and binocular defocus curves, even though the A constant used during IOL power calculation was not optimized, creating a significant myopic shift. Another bias involved in visual acuity evaluation was the residual astigmatism, which was not corrected in this study, since no toric lenses were implanted. Residual astigmatism might affect both visual acuityhe permitted use, you will need to obtain permission directly IOL may have good tolerance to residual refractive errors, although additional studies are necessary to confirm this. Considering the tolerance to myopic shifts, the BIOS Trifocal IOL might be able to tolerate different refractive strategies that are not usual in trifocal IOLs, such as micromonovision or monovision. Further studies should be conducted to evaluate the tolerability of these strategies, visual results and incidence of adverse effects, such as photic phenomena.

Quality of life

Currently, there is no standardized method for quantification of quality of life and vision after cataract surgery. Some of the studies used a self-developed or adapted questionnaire to evaluate the level of difficulty in performing some vision related tasks after IOL implantation [21, 22], while others use questionnaires aimed at subjective perception of quality of life, vision and health [23, 24]. In our study, we used a translated validated Visual Function Index Questionnaire (NEI-VFQ 25) for the subjective assessment of visual function and patient satisfaction. There was significant improvement in all domains of the test. Other studies of trifocal IOL implants also observed a significant improvement in quality of life [21–25]. One point that deserves attention is the fact that 88.2% of all patients that drove at night reported no significant difficulties associated with this activity, which is usually affected by the loss of contrast sensitivity and increased halos and glare associated with multifocal IOLs.

Limitations

Among the limitations of this study, it is possible to mention the lack of randomization, masking, and controls. Also, no comparative measurement was made with another IOL as a benchmark, and the A constant used in this study was not optimized yet. Additionally, significant topics such as reading speed and contrast sensitivity were not measured in this study. This study also did not include pupil size analysis, which can interfere in the results due to its effect in photic phenomena, depth of focus and exposition of the diffractive grating. Therefore, we suggest a randomized, blinded, and controlled clinical trial, comparing the BIOS Trifocal IOL, after constant optimization, to other IOL models, including contrast sensitivity, pupil size, reading speed analyses, and pupil size measurement, granting a better capacity of generalization of the findings of this study [12].

Conclusions

The BIOS Trifocal IOL appears to be an effective device for the correction of cataract and presbyopia, being capable of enhancing visual acuity for far, intermediate and near distances, improving quality of life, and generatingspectacle independence, while also tolerating some degree of refractive error, with subjects reporting little interference in low-contrast activities such as driving at night. We suggest using an A constant of 118.0 for BIOS Trifocal power calculation in future studies. Further randomized clinical trials are needed to allow generalization of the findings of this study.

Authors’ contributions

JMAGL contributed in the conceptualization, methodology, validation, investigation, supervision, project administration, funding acquisition, and writing (reviewing and editing) of this study. MSGA contributed in the conceptualization, methodology, validation, investigation, project administration, and writing (reviewing and editing) of this study. LABL and LOS contributed in the methodology and investigation of this study. MLS contributed in the validation, data curation, formal analysis and writing (both original draft and reviewing/editing) of this study. JAPMC contributed in the validation, data curation, formal analysis and writing (reviewing and editing) of this study.

Funding

Financiadora de Estudos e Projetos (Finep), a brazilian governamental company, funded the development of the BIOS Trifocal IOL, but had no interference in the collection or analysis of data, nor provided any type of direct funding for this study.

Data availability

The datasets used and/or analyzed during the current study are available from the corresponding author upon reasonable request.

Declarations

Ethics approval and consent to participate

This study was approved by a certified Institutional Review Board (Universidade Estadual de Ciências da Saúde de Alagoas, UTN: U1111-1252-4994) and followed the tenets of the Declaration of Helsinki. All participants included had to sign a written informed consent form after careful and extensive explanation of the study and their rights.

Consent for publication

Not applicable.

Competing interests

The authors declare that they have no affiliations with or involvement in any organization or entity with any financial interest in the subject matter or materials discussed in this manuscript. Mediphacos Indústrias Médicas SA, as a sponsor of this study, manufactured and provided the IOLs, but had no interference in the collection or analysis of data.