All patients underwent a comprehensive preoperative ophthalmologic evaluation, including visual acuity assessment with the Nidek ARK-1 autorefractor-keratometer (Nidek Co), ocular biometry using the IOL Master 700 (Carl Zeiss Meditec AG), AS-OCT imaging under miotic and mydriatic conditions using the Casia 2 (Tomey Corporation), corneal tomography using the MS-39, and macular imaging performed with the Cirrus HD-OCT 5000 (Carl Zeiss Meditec AG). Additional examinations included slit-lamp examination, intraocular pressure measurement, and pupil diameter evaluation under mydriasis. Measurements of aqueous depth, lens thickness, and equatorial lens diameter were obtained under mydriatic conditions with the Casia 2 AS-OCT.

The SE was determined using the Barrett TK Universal II (total keratometry) with the IOL Master 700. The cylindrical power was calculated using Rayner’s IOL online calculator (Rayner Intraocular Lenses Ltd), based on MS-39 total keratometry within the 4.5-mm optical zone, with surgically induced astigmatism (SIA) set to zero. The quality of the measurement was assessed with special attention to the tear film stability during the combined Placido/OCT acquisition. Notably, Rayner’s IOL calculator underwent a version update between 2024 and 2025. Accordingly, patients included before 2025 were planned using the earlier version, while those enrolled in 2025 were calculated with the updated version.

The RayOne EMV Toric is a single-piece, aspheric, hydrophilic acrylic IOL with an overall length of 12.5 mm and an optic diameter of 6.0 mm, featuring nonangulated C-loop haptics. The lens is available in SE powers from +10.0 D to +25.0 D in 0.5 D increments, and in cylindrical powers ranging from +0.75 D to +4.50 D in 0.75 D steps at IOL plane.

Cataract surgeries were performed by four highly experienced surgeons (D.S., M.S., C.A.-F., C.L.). All surgeries were performed using topical anesthesia and the Opmi Lumera 700 surgical microscope (Carl Zeiss Meditec AG). A 2.2 to 2.4 mm temporal postero-limbal corneal incision was created, followed by one or two paracenteses according to the surgeons’ preference. A continuous curvilinear capsulorhexis measuring approximately 5.0 to 5.5 mm was performed. Phacoemulsification was followed by irrigation and aspiration of residual cortex material. For IOL implantation, the capsular bag was expanded with strictly cohesive ophthalmic viscoelastic device only (Provisc, Alcon). The TIOL was then rotated to the dedicated axis using the markerless Callisto Eye System (Carl Zeiss Meditec AG). This system allows visualization of the target axis, corresponding to the steep axis determined by the MS-39 measurement, relative to the horizontal reference axis obtained preoperatively in the sitting position. Intraoperatively, the live microscope image from the OPMI Lumera 700 is automatically matched with the reference image from the IOL Master 700, thereby accounting for potential cyclorotational changes on the surgical table. After implantation, the ophthalmic viscoelastic device was carefully removed, with particular attention paid to the capsular bag fornices and the retrolental space. After confirming alignment, stromal hydration was performed to seal the incisions, and cefuroxime (1 mg/0.1 mL) was injected into the anterior chamber. At the EOS, with the patient still supine at the operating table, a video was recorded where the conjunctiva was gently moved by using a sterile swab to distinguish movable conjunctival from nonmovable episcleral or scleral landmarks, using a well-established method previously described by our study group.

Postoperative medication included ketorolac-trometamol and lubricating eye drops for three weeks, as well as dexamethasone and gentamicin for one week.

Postoperative follow-up visits were scheduled at 1 hour (1 h), 1 week (1 w), 1 month (1 m), and between 4 and 6 months (4 m) after surgery.

At each visit, retroillumination pictures under full pharmacological pupil dilation were captured using a high-resolution digital camera (D70s, Nikon Corporation). For optimal visualization of the sclera, the upper eyelid was gently lifted with a cotton swab, while the lower eyelid was carefully retracted using the examiner’s thumb, without applying pressure to the bulbus. Refraction and visual acuity were assessed with the Nidek ARK-1, alongside slit-lamp examination, intraocular pressure measurement, and a dilated fundus examination.

At 1 h, 1 w, and 6 m, AS-OCT imaging with the Casia 2 was performed under miotic conditions for corneal analysis and under mydriatic conditions for lens analysis.

At the final follow-up visit (6 m), manifest subjective refraction, corrected and uncorrected distance visual acuity were assessed using Snellen charts at a distance of 6 meters. Uncorrected intermediate visual acuity (UIVA) was evaluated using ETDRS charts with 100% contrast at a distance of 66 cm (Good-Lite Company) in logMAR. Additionally, the strength of anterior capsule fibrosis was graded on a scale from 0 to 3 and classified by type as diffuse, rhexis-edge, on-growth, or involving the IOL edge.

To evaluate rotational stability, a screenshot from the EOS video, as well as the retroillumination pictures obtained at the follow-up visits, were imported into the semiautomated Rotix software. This software enables the drawing of two axes: one connecting two fixed anatomical landmarks clearly visible at each follow-up visit, and another connecting the TIOL marking dots. The software then automatically calculates the TIOL axis deviation between follow-up visits. Figure 1 illustrates the TIOL rotation assessment in a right eye with a counterclockwise rotation of 0.46° from EOS to 6 m.

Image series of a right eye showing a counterclockwise rotation of 0.53° from end of surgery to 1 hour, followed by a clockwise rotation of 0.07° from 1 hour to 1 week, then a counterclockwise rotation of 0.15° between 1 week and 1 month, and finally a clockwise rotation of 0.15° from 1 to 6 months, resulting in a counterclockwise rotation of 0.46° from end of surgery to 6 months.

For sample size determination, the ISO criteria of the American National Standards Institute for TIOLs were applied, which require a minimum of 100 eyes for analysis. Rotational stability is defined as a change of less than 10° in 90% of the cases and less than 20° in 95% of the cases between visits spaced a minimum of three months apart. In addition, 90% of the TIOLs in the treated eyes should rotate less than or equal to five degrees between the final two consecutive visits. To account for an anticipated dropout rate of 20%, due to loss to follow-up, and cases in which scleral landmarks may be not visible, the target enrolment was set at 120 eyes.

Exploratory data analysis was performed to evaluate TIOL rotational stability across all follow-up visits. Data is presented as mean ± SD and median (range). Preoperative corneal astigmatism, postoperative refractive astigmatism, and SIA are visualized using double-angle plots, following the method described by Kan-Tor et al. Left eyes were mirrored to standardize axis orientation and permit pooled analysis of both eyes. Secondary outcomes included correlations between axial length, lens thickness, and equatorial lens diameter assessed using Spearman’s rank correlation coefficient (rho). Group differences for continuous variables were assessed using one-way analysis of variance (ANOVA) for normally distributed data and the Kruskal–Wallis test for non-normally distributed data, with appropriate post hoc comparisons (Bonferroni or Dunn–Bonferroni). A multivariable linear regression analysis was performed, and residuals were examined for normality. For all statistical analyses, a P value <.05 was considered statistically significant.

For the main outcome, TIOL rotation from EOS to 6 m, 114 from the 119 eyes were available for analysis. Detailed results of absolute TIOL rotation for the intervals EOS to 1 h, 1 h to 1 w, 1 w to 1 m, 1 m to 6 m, and EOS to 6 m are summarized in Table 2 and illustrated graphically in Figure 2 . From EOS to 6 m, 85 TIOLs (74.6%) rotated clockwise and 29 (25.4%) rotated counterclockwise ( P <.01). TIOL rotation differed significantly between astigmatism subtypes between 1 w to 1 m postoperatively ( P =.001). Posthoc analysis revealed greater rotation in eyes with ATR astigmatism compared with WTR astigmatism (adjusted P =.002), whereas comparisons involving oblique astigmatism were not significant (ATR vs oblique P =.114; WTR vs oblique P =.000). TIOL rotation did not differ significantly between astigmatism subtypes during the intervals EOS to 1 h, 1 h to 1 w, 1 to 6 m, or EOS to 6 m ( P =.077, 0.919, 0.471, and 0.230, respectively). No secondary intervention for TIOL rerotation was required in any patient.

TABLE 2

Detailed Toric Intraocular Lens Rotation Results

Timeframe	Number of Eyes	Mean ± SD	(Min; Max)	Median	IOLs Rotating
					>5°	>10°	>15°	Clock-Wise	Counterclockwise	No Rotation
EOS to 1 h	116	0.89 ± 1.10	(0.00; 8.37)	0.57	2	0	0	48	67	1
1 h to 1 w	115	0.58 ± 0.49	(0.00; 2.76)	0.49	0	0	0	87	27	1
1 w to 1 m	112	1.19 ± 1.45	(0.02; 7.17)	0.62	4	0	0	83	29	0
1 m to 6 m	111	1.11 ± 1.41	(0.00; 7.96)	0.59	4	0	0	69	40	2
EOS to 6 m	114	2.44 ± 2.34	(0.04; 10.60)	1.59	19	1	0	85	29	0

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