In recent years, various models of presbyopia-correcting IOLs have emerged, enhancing intermediate vision beyond monofocal and multifocal IOLs with fewer dysphotopsias and minimal loss of contrast sensitivity compared to conventional multifocal IOLs [11]. Our study assesses the visual performance and optical quality of a segmental refractive EDoF IOL.

The Acunex Vario IOL qualifies as an EDoF-IOL extending far focus to include the intermediate range, delivering satisfactory distance and intermediate vision [5]. We found favorable unaided monocular and binocular UDVA and corrected CDVA. To our knowledge, there is no literature comparing the AN6V with other monofocal or multifocal IOLs.

Comparable distance monocular VA was achieved from our study group with monofocal IOLs such as Tecnis ZCB00 (-0.05 ± 0.06 logMAR and − 0.14 ± 0.09 logMAR) and Mini 4 IOL (-0.06 ± 0.06 logMAR) [12,13,14]. The hydrophilic Lentis Comfort LS-313 MF15 IOL, similar in design to the Acunex Vario, demonstrated equivalent visual performance, with Kretz et al. reporting UDVA of 0.00 logMAR and CVDA of -0.08 logMAR in 60 eyes of 30 patients [15]. The diffractive EDoF Tecnis Symfony ZXR00 shows UDVA ranging from 0.08 to 0.01 logMAR and our group found UDVA of -0.02 logMAR with this lens [12, 16]. Greve et al. reported UDVA of 0.04 logMAR and CDVA of -0.02 logMAR with the nondiffractive EDoF IOL Mini Well, noting superior CDVA in the monofocal IOL Mini 4 [13].

The + 1.50 D addition of the AN6V IOL provides favorable intermediate vision outcomes and effective near functional UNVA. Corrected distance VA is preferred for comparing IOL visual function due to refractive error [17]. Song et al. found no significant difference in DCIVA between Tecnis Symfony ZXR00 and LS-313 MF15 at 80 cm [18]. In our study, UNVA was better than DCNVA due to a minimal residual myopic error. Despite the better near visual performance, similar refractive mIOLs with + 3.0 D addition power show remarkably poorer intermediate VA than AN6V [19, 20]. Reducing add power improves intermediate VA, enabling functional near vision < 0.50 logMAR, enough to read bigger print sizes [15, 21]. The ANV6 IOL´s defocus curve demonstrated commendable VA across a broad spectrum, covering intermediate vision without discontinuities. Binocularly, a visual acuity of 0.20 logMAR or better was achieved within + 1.50 to -2.45 D (monocularly, from + 1.33 to -2.32 D), covering a range of 3.95 D (or monocularly, 3.65 D).

The contrast sensitivity results were comparable to those of monofocal lenses studied by our group [12,13,14]. Several studies highlight the exceptional contrast vision of refractive segmental IOLs, establishing their equivalence with monofocal IOLs [22]. In contrast, diffractive EDoF designs reduce effective light energy reaching each focal plane, resulting in loss in contrast sensitivity [5, 23].

Slightly higher residual coma aberrations could be attributed to the IOL’s asymmetric refractive power distribution. Alió et al. found similar increases with the Lentis Mplus LS-312, a segmental refractive mIOL with + 3 D add, showing nearly 0.500 μm of coma aberrations [22]. Elevated primary coma, although causing optical blur, can paradoxically extend the depth of focus, enhancing near VA [24]. Internal SA were nearly neutral, resulting in slightly positive ocular SA, which can increase depth of focus without impairing the distance vision [25].

Our objective VA outcomes aligned with high spectacle independence scores in the NEI-RQL-42 questionnaire. Subjective performance of the IOL was over 90% for distance and above 80% for near vision. However, 70% of the patients had at least some difficulty reading small print and 85% wore spectacles at least occasionally or prolonged reading. Comparisons between trifocal and bifocal IOLs reveal similar quality of life and satisfaction outcomes, with trifocal lenses generally providing better near VA [11, 26,27,28]. General satisfaction appears to correlate more with intermediate vision than with near vision, suggesting that intermediate distances are crucial for modern tasks like using computers, mobile phones and tablets [28].

Patient-reported photopic phenomena, including halos and glare, were comparable to our previous reports with monocular IOLs. The AN6V achieved a 80% of positive rating in the glare category, compared to 60–65% with the Tecnis ZCB00 and 70% with the Mini 4 IOL [12,13,14]. Dysphotopsia is an inherent challenge with mIOLs due to the overlap of multiple images on the retina caused by redirection of light to various focal points [29]. Diffractive technology, like the ZXR00 IOL, have higher disturbances [30]. Our study with this IOL reached only 50% patient satisfaction for glare [12]. Nondiffractive EDOFs, such as the Alcon Vivity DFT015 and Mini Well IOL show similar patterns to aspheric monofocal IOLs [31, 32]. As the Acunex Vario also lacks diffractive optics, it might cause fewer dysphotopsias. Song et al. found milder photopic symptoms with segmental refractive LS-313 MF15 IOL compared to the the ZXR00 IOL [18]. Despite slightly higher residual coma aberrations, our patients did not report increased perception of glare or halos in the dark, with 80% of patients experiencing no difficulties driving at night.

The study´s limitations include a limited sample size and potential selection bias due to the COVID-19 pandemic. The 3-month follow-up period, although common in studies, does not provide insights into long-term outcomes, especially regarding neuroadaptation. Studies suggest that while optical phenomena might be detectible after years, the subjective perception of visual disturbances tends to decrease over time [33].

When selecting an IOL, thorough preoperative assessments and discussions about potential advantages and disadvantages are essential [6]. A blended vision approach, such as targeting slight myopia in the non-dominant eye, can enhance binocular visual outcomes and reduce the risk of dysphotopsias compared to multifocal IOLs [34]. For small deviations from emmetropia, such as -0.50 D, the mini monovision approach has been successful with EDoF IOLs like Tecnis Symfony [4, 35]. Breyer at al. showed improved binocular UNVA and UIVA without impairment of UDVA using the LENTIS Comfort LS-313 MF 15 with a target of -1.50 D in the nondominant eye [3]. These findings suggest that blended vision with EDoF IOLs, such as AN6V, is an effective alternative to trifocal IOL implantation.

In conclusion, the Acunex Vario AN6V demonstrated an extensive range of vision up to 60 cm, with high postoperative satisfaction and minimal visual disturbances. This EDoF IOL is a promising choice for patients seeking freedom from spectacles for both distant and intermediate distances. However, its suitability for eyes that have undergone previous refractive surgery should be considered, and a preoperative assessment of HOAs is recommended.