Trifocal IOLs show greater paracentral and peripheral visual field sensitivity than monofocal, bifocal lenses

Cataract remains the leading cause of blindness worldwide, and cataract surgery has increasingly become a refractive procedure, with IOL selection now shaping a substantial share of a patient's postoperative visual experience.^1,2 Monofocal IOLs remain the default for reliable distance vision, but a growing proportion of patients now receive bifocal or trifocal designs to reduce spectacle dependence at intermediate and near distances. This is a shift that has been building since multifocal optics first began challenging monofocal lenses as the standard of care.³ As presbyopia-correcting IOLs become more common, questions about their downstream effects on functional testing, such as standard automated perimetry, the workhorse of glaucoma and neuro-ophthalmic follow-up, have taken on more clinical weight.

A new prospective, non-randomized controlled study from Shandong Eye Hospital in Jinan, China, offers one of the more tightly controlled looks yet at how VF outcomes differ across monofocal, bifocal, and trifocal IOL designs.¹ The study addresses a limitation the authors say has muddied prior literature: earlier comparisons often pooled IOLs from different manufacturers and optical platforms, making it difficult to isolate the effect of focal design itself from differences in material, diffractive architecture, or edge design.

A platform-controlled comparison

The study enrolled 102 patients (123 eyes) with age-related cataract (Lens Opacities Classification System III grade II–IV) who underwent phacoemulsification with implantation of 1 of 3 Carl Zeiss Meditec IOLs: the monofocal CT ASPHINA 409MP (38 eyes), the diffractive bifocal AT LISA 809M with a +3.75 D near addition (42 eyes), or the diffractive trifocal AT LISA tri 839MP, which splits light across distance, intermediate (+1.66 D), and near (+3.33 D) foci (43 eyes). Because all 3 lenses share a manufacturer and optical platform, the design controls for a variable that has complicated cross-study comparisons in the past.

Patients underwent best-corrected visual acuity (BCVA) testing, refraction, defocus curve assessment, and Humphrey Field Analyzer 3 perimetry (30-2 SITA Standard, white size III stimulus) preoperatively and at 3 months postoperatively.¹ Beyond the standard global indices—VF index (VFI), mean deviation (MD), and pattern standard deviation (PSD)—the investigators calculated regional mean sensitivity (MS) across 3 predefined eccentricity zones: central (0°–5°), paracentral (6°–15°), and peripheral (16°–30°), using 74 of the 76 standard 30-2 test points after excluding the 2 points adjacent to the physiologic blind spot.¹

Global indices improve equally across lens types

All 3 groups showed statistically significant improvements from baseline in BCVA, VFI, MD, and PSD, and in MS across all 3 zones, at 3 months (P < .001 for most comparisons). When the groups were compared against each other, there were no significant differences in postoperative BCVA, VFI, MD, or PSD—the global metrics clinicians typically scan first on a printed field.

That equivalence held for central MS as well: in zone I, adjusted pairwise regression (controlling for age and sex, with cluster-robust standard errors for patients contributing both eyes) showed no significant difference among the 3 IOL types.¹

Zone-by-zone differences emerge outside the center

In the paracentral zone (zone II), MS was significantly higher in both the bifocal group (β = 1.06 dB; 95% CI, 0.11–2.02; P = .031) and the trifocal group (β = 1.62 dB; 95% CI, 0.75–2.49; P < .001) compared with the monofocal group, though bifocal and trifocal MS did not differ significantly from each other (P = .089).

In the peripheral zone (zone III), the trifocal IOL separated from both other designs: MS was significantly higher than monofocal (β = 2.38 dB; 95% CI, 1.21–3.54; P < .001) and significantly higher than bifocal (β = 0.94 dB; 95% CI, 0.07–1.82; P = .035), with bifocal also outperforming monofocal (β = 1.44 dB; 95% CI, 0.09–2.78; P = .037). Analysis of the magnitude of change from baseline (ΔMS) followed a similar pattern—no intergroup difference centrally, greater paracentral gains with both multifocal designs, and the largest peripheral gain specifically with the trifocal lens versus monofocal (β = 1.50 dB; 95% CI, 0.13–2.86; P = .032).

Defocus curve testing added functional context: the monofocal group showed the expected steady decline in acuity with increasing defocus, the bifocal group produced a bimodal curve favoring distance and near, and the trifocal group produced a flatter overall curve with better intermediate acuity—consistent with its 3-point light distribution.¹

What might explain the pattern

The authors propose that the broader light distribution built into multifocal optics—splitting energy across 2 or 3 foci rather than concentrating it at one—may enhance detection of para-foveal and peripheral stimuli even as it introduces the halos and reduced contrast sensitivity documented in other multifocal IOL literature. They're careful to frame this as platform-specific: results center on the Zeiss AT LISA diffractive architecture, and lenses with different optical designs, such as PanOptix (Alcon), may not behave the same way. The finding also runs against some earlier reports describing reduced central VF sensitivity with multifocal IOLs, a discrepancy the study authors attribute partly to those studies' use of 10-2 perimetry and mixed-platform lens comparisons rather than the zonal 30-2 approach used here.

The authors are also careful not to overstate the clinical read: absolute intergroup MS differences were modest, within the range of known SAP test-retest variability, and the study excluded eyes with glaucoma or other conditions affecting VF. They stop short of recommending trifocal IOLs specifically for patients with glaucoma, framing the takeaway instead as a call for clinicians to factor IOL focal design into how they interpret postoperative perimetry—particularly in patients likely to need years of serial VF follow-up, a population in whom IOL implantation is already known to alter VF measurements in eyes with comorbid glaucoma.⁴

Limitations

The study's prospective but non-randomized design carries a risk of selection bias, and the sample—35 to 43 eyes per group—was powered for the study's primary MS comparison but remains modest for subgroup work. Follow-up was limited to 3 months, VF testing was monocular even though real-world visual function is binocular, and the analysis did not incorporate contrast sensitivity, higher-order aberrations, or patient-reported visual quality measures. The authors call for larger, randomized, longer-term studies with binocular VF testing to confirm whether the regional pattern they observed holds up and translates into meaningful differences in glaucoma detection or monitoring.

References

1. Yao, S., Li, F., Shi, J., Zhong, X., Ding, R., Niu, M., Zhang, Y., Sun, J., Pei, L., He, X., Wang, J., Zeng, M., Shi, W., Wang, T., & Zhao, C. (2026). Comparison of Visual Field Outcomes After Monofocal, Bifocal, and Trifocal Intraocular Lens ImplantationJournal of Cataract & Refractive Surgery https://doi.org/10.1097/j.jcrs.0000000000002041

2. Liu YC, Wilkins M, Kim T, Malyugin B, Mehta JS. Cataracts. Lancet. 2017;390(10094):600-612. doi:10.1016/S0140-6736(17)30544-5

3. Leyland M, Zinicola E. Multifocal versus monofocal intraocular lenses in cataract surgery: a systematic review. Ophthalmology. 2003;110(9):1789-1798. doi:10.1016/S0161-6420(03)00722-X

4. Zhao C, Cun Q, Tao YJ, Yang WY, Zhong H, Li FJ, Tighe S, Zhu YT, Wang T. Effect of intraocular lens implantation on visual field in glaucoma and comorbid cataracts. Int J Ophthalmol. 2020;13(4):580-586. doi:10.18240/ijo.2020.04.08