This prospective observational study included 104 eyes from 104 subjects who underwent cataract surgery combined with implantation of IOLs at the First Affiliated Hospital of Guangzhou Medical University, Guangzhou, China, from May 2022 to May 2023. Subjects selected the IOL according to their preferences, and were divided into 4 groups: Mon IOLs, 24 subjects; SegRef IOLs, 25 subjects; Dif IOLs, 29 subjects; and EDoF IOLs, 26 subjects. The inclusion criteria included age ranging from 50 to 80 years, axial length ranging from 21.0 mm to 26.0 mm, corneal astigmatism less than 1.0 D, corneal endothelial cell density greater than 2000/mm2, and no pupillary abnormalities. Subjects with a history of severe dry eye, corneal pathologies, glaucoma, uveitis, retinal abnormalities, ocular trauma, previous corneal or intraocular surgery, high myopia, or connective tissue disease were excluded from the study. All participants signed informed consent prior to the study. The study followed the Declaration of Helsinki tenets of 1975 and received approval from the First Affiliated Hospital of Guangzhou Medical University Ethical Review Board (No. 50 2022).

The NS-60YG (Nidek Co. Ltd., Japan) is a modified C-loop Mon IOL with an aspheric optical side manufactured from hydrophobic acrylic. The total diameter of the IOLs is 13.0 mm, with an optic size of 6.0 mm [13].

The SBL-3 (Lenstec, Christ Church, Barbados) is a SegRef IOL manufactured from hydrophilic acrylic material with two distinct zones. One zone is for distance vision, and the other is for near vision, with a near addition of + 3.0 D (+ 2.5 D on the spectacle plane) in the inferior anterior optic. The distance zone is separated from the near addition zone by using a small wedge-shaped transition zone. The total diameter of the multifocal IOLs is 11.0 mm, with an optic size of 5.75 mm [14].

Tecnis Symfony ZXR00 (Johnson & Johnson Vision, Santa Ana, California, USA) is an EDoF IOL with a biconvex hydrophobic UV-filtering C-loop manufactured from hydrophilic acrylic material. It has a negative spherical aberration of 0.27 μm on the anterior surface. To expand the field of vision, the posterior surface has an achromatic design and an echelette, which is a type of diffraction grating. Within the 9 rings of the diffractive zone, the refractive area has a diameter of 1.7 mm. The total diameter of the multifocal IOLs is 13.0 mm, with an optic diameter of 6.0 mm [15, 16].

The Tecnis ZMB00 (Johnson & Johnson Vision, Santa Ana, California, USA) is a Dif IOL that uses a material and structure similar to that of ZXR00. The main difference between these two IOLs is that the back surface of ZMB00 consists of 22 concentric diffractive rings with a near addition of + 4.0 D (+ 3.0 D on the spectacle plane). The diffractive zone has a refractive area of 1.0 mm in diameter and a 1:1 distribution between two foci [16, 17].

Preoperative assessment: All subjects underwent a standardized ophthalmic examination, including preoperative uncorrected visual acuity (UCVA), manifest refraction, intraocular pressure (IOP), corneal topography (Pentacam, Oculus, Wetzlar, Germany), endothelial cell count (SP 2000P specular microscope, Topcon, Norway, Europe BV), slit-lamp examination (SL115; Carl Zeiss, Oberkochen, Germany), dilated fundus examination, and retinal optical coherence tomography (OCT, Carl Zeiss Meditec AG, Jena, Germany). In addition, the axial length (AL), anterior chamber depth (ACD), and corneal curvature were measured by an IOL Master (Carl Zeiss Meditec AG, Jena, Germany).

Postoperative assessment: BCDVA and optical metrics were collected 6 months after surgery. BCDVA was evaluated using logarithm of the minimum angle of resolution (logMAR) charts at a distance of 5 m. An OQAS II device (Visiometrics, Terrassa, Spain) was used to collect OQAS optical metrics, including the objective scattering index (OSI), Strehl ratio (SR), modulation transfer function (MTF) cut-off frequency (c/deg), and predicted visual acuity (PVA) at contrasts of 100%, 20%, and 9%. Before statistical analysis, all PVA data were converted into logMAR format. An iTrace device (Tracey Technology, Houston, Texas) was used to collect the wavefront aberrations [18, 19] and iTrace optical metrics of the subjects. The iTrace optical metrics included blur/double vision, glare/halo, starburst, mixed focus, night myopia, and night hyperopia. Through its built-in calculation formula, the iTrace device simulated the morphology of the point spread function (PSF) (Fig. 1) and presented the type and degree of the iTrace optical metrics (Fig. 2) when wavefront aberrations occurred. For instance, when a coma aberration occurred alone, a comet tail appeared in the image, which was described as “blur” or “double vision” (Fig. 1A). When a spherical aberration occurred alone, concentric circles appeared in the image, which were described as “glare” or “halo” (Fig. 1B). When a trefoil aberration occurred alone, the image seemed to be a star, which was described as “starburst” (Fig. 1C). When a second-order astigmatism aberration occurred alone, multiple focal points appeared in the image, which was described as “mixed focus” (Fig. 1D). The severity of the iTrace optical metrics was classified into four grades: none (-), mild (+), moderate (++), and severe (+++). All the examinations were completed by the same technicians.

The simulative morphology of the point spread function (PSF) when wavefront aberration presented in the iTrace device. (A): blur/double vision; (B): glare/halo; (C): starburst; (D): mixed focus

Optical metrics collected through the iTrace device. (red frames)

All surgeries were performed by the same experienced surgeon under topical anaesthesia. The Centurion Vision System (Alcon, Fort Worth, TX, USA) was used to obtain a clear corneal phacoemulsification through a 2.2 mm main incision and a 1 mm lateral incision in all subjects. The Verion Image Guided System (Alcon, Fort Worth, TX, USA) was used to demonstrate a capsulorhexis diameter of 5.0 mm and the centre of the IOLs.

The Kolmogorov‒Smirnov test was applied to assess the normality of the data. Numbers are presented as counts (percentage) for categorical variables, mean (standard deviation, SD) for normally distributed continuous variables, and median (interquartile range, IQR) for nonnormally distributed continuous variables. Comparisons between groups of categorical variables were performed using a chi-square test or Fisher’s exact test. Normally distributed continuous data were compared by analysis of variance (ANOVA): the least significant difference (LSD) t test was applied when the assumption of homogeneity of variance was satisfied; otherwise, Tamhane’s T2 test was used. Nonnormally distributed continuous data and grade data were compared by the Kruskal‒Wallis H test, and multiple comparisons were performed using the Bonferroni correction. To evaluate the associations among the iTrace optical metrics, OQAS optical metrics and BCDVA, Spearman rank correlation tests were performed. The power of postoperative comparison analysis among groups and correlation analyses were tested using PASS software 2021 (NCSS, Kaysville, UT, USA), and a value of power above 80% was considered credible. P < 0.05 was considered to indicate statistical significance. SPSS Statistics v26.0 (IBM, Chicago, IL) was used for all the statistical analyses.