Purpose: Accurate alignment of Toric Intraocular Lens (T-IOLs) in cataract surgery is crucial for good visual outcomes. The purpose of this study was to evaluate the influence of rotation, axial shift and their combined effects on the refractive error and image quality of a wide range of T-IOL powers (from +1.50 D to +6.00 D cylinder) and two pupil diameters (3.34 and 4.44 mm). Methods: Numerical ray tracing was utilized to quantify the residual error. Simulated retinal images and Visual Strehl (VS) ratios were calculated to evaluate image quality. Results: First, T-IOL rotation showed better agreement with Holladay’s formula than 3.33% rule. Second, axial displacement resulted in acceptable residual cylinder (<0.50 D) across all examined cylinder powers. Third, concerning the combined effects, the influence of axial shift on residual cylinder becomes negligible when rotation errors exceed 2.5°. Fourth, a pupil-dependent nonlinear relationship was noted for image quality caused by both types of misalignment factors. Conclusions: The 3.33% rule was confirmed as a reasonable approximation for the residual astigmatism caused by rotation of T-IOLs. The influence of axial shift on residual astigmatism becomes insignificant when there is also rotation. Image quality studies confirm that 30° of rotation are enough invalidate the compensation benefits of a T-IOLs in comparison with a Spherical Intraocular lens.

A new, to the best of our knowledge, optical element designed to compensate regular astigmatism while exhibiting increased tolerance to rotational misalignment is introduced. The element incorporates an optical design based on concentric annular regions with slightly different cylindrical axis angular positions. To assess visual quality performance as a function of rotation, retinal image simulation and clinical assessments with an adaptive optics visual simulator were carried out. The results demonstrate the superior performance of the newly proposed element in the presence of rotational errors when compared to traditional solutions.

(1) Background: This study compares the effective lens position (ELP) and intraocular lens power (IOLP) derived from SRK/T, Hoffer Q, Holladay I, and Haigis formulas with the actual lens position (ALP) and the implanted IOLP after cataract surgery. Additionally, it aims to optimize ALP using a ray-tracing-based simulated optical model to achieve emmetropia. (2) Methods: A retrospective observational study was conducted on 43 eyes implanted with the same monofocal intraocular lens (IOL). Preoperative and postoperative biometric data were collected using the Lenstar LS900. Postoperative measurements included ALP, subjective refraction, and refraction error (RE). Optical simulations (OSLO EDU 6.6.0) were utilized to optimize ALP for emmetropia (ALP_IDEAL). (3) Results: Paired t-test results between RE_OSLO-RE_OBJ (p-value = 0.660) and RE_OSLO-RE_SUB (p-value = 0.789) indicated no significant statistical differences. However, statistically significant differences were found between ALP and ALP_IDEAL (p < 0.05), with a difference of −0.04 ± 0.45 mm [ranging from −1.00 to 1.20 mm]. A significant correlation was observed between ΔALP (ΔALP = ALP − ALP_IDEAL) and RE_SUBJ. (4) Conclusions: This customized ray-tracing eye model effectively achieves refractive outcomes similar to those obtained both subjectively and objectively post-surgery. Additionally, it has enabled optical simulations to optimize the IOL position and achieve emmetropia.

To assess the feasibility of a novel method for simulating a Rigid Gas Permeable Contact Lenses (RGP-CL) fitting using 3-D printed sclero-corneal surfaces (SCSs). The experiment involved the fabrication of two resin SCSs with biconic corneal geometry and the participation of 22 optician-optometrists as observers. Participants compared the fluorescein patterns of three RGP-CL fitted on each SCS with theoretical patterns generated through computer simulation. To standardize visualization, comparisons were conducted through a multiple-choice questionnaire composed of 6 questions. Each question presented one main fluorescein pattern (either theoretical or experimental) and four additional patterns obtained using the other technique. Optometrists were required to select the fluorescein pattern more similar to the main pattern. A statistical analysis was performed to evaluate the accuracy of the comparison between the two methods. The surface quality of the printed SCSs was sufficient to produce consistent and interpretable fluorescein patterns. In all questions, at least 70 % of optometrists selected the correct pattern. In four questions, more than 90 % identified the correct pattern, and in one question accuracy reached 100 %. The correct option was always the most frequently chosen, with a significantly higher rate than the second most selected option (p = 0.05). The ability of most optometrists to correctly identify patterns suggests that, even without polishing, 3-D printed SCSs can simulate fluorescein patterns closely resembling theoretical ones. This approach shows promise as a supportive tool for training in RGP-CL fitting.

Geometric optics constitutes a cornerstone of the physics curriculum, yet its instruction is frequently hindered by persistent misconceptions regarding light propagation, image formation, and the visual process. This study details a pedagogical intervention that integrates an educational escape room within a Service-Learning framework to mitigate these conceptual barriers. To address the scarcity of experimental resources, we designed 3D-printed structural components (including optical benches, lens holders, and an eye model) to complement commercial optical element. The activity, anchored in a forensic crime-solving narrative, was facilitated by undergraduate optics students acting as mentors for a cohort of fifteen 12th-grade students. Qualitatively, initial student sketches exposed significant gaps in their grasp of ray tracing and physiological optics. Data from a pretest–posttest design indicated a substantial improvement in conceptual understanding, with mean knowledge scores rising from 35.1% to 77.6% ( p < 0.001). Beyond student gains, undergraduate mentors reported enhanced scientific communication skills, while high school teachers emphasised the kit’s high replicability. By disseminating the open-access 3D-printing files and pedagogical guide, this project offers a sustainable and engaging model to foster STEM interest and enhance optics education.

Purpose: Achieving good visual quality with a conventional spherocylindrical (CSC) lens requires precise alignment with the principal meridians of the astigmatism to be corrected. Despite advancements in stabilisation, current contact lens and intraocular lens designs face limitations on this regard. This study introduces different trizonal multi-toric (TMT) lens designs endowed with three concentric zones to provide 3.50 D of astigmatic correction, with increased tolerance to rotational errors. Experimental results using low-contrast optotypes are also presented for the best purposed design. Methods: First, several variants of 3.50 D astigmatic TMT designs were created and evaluated by means of retinal image simulation. The optical TMT design was then selected based on its Visual Strehl Ratio (VSR) performance and simulated image quality. Subsequently, a double-blind clinical study was conducted using an adaptive optics visual simulator and low-contrast optotypes. The study compared the maximum low-contrast visual acuity (LCVA) achieved with the best TMT design to that of a conventional spherocylindrical (CSC) design under varying degrees of rotational error. Results: Numerical image simulations confirmed the superior rotational tolerance of the TMT designs, compared with CSC lenses, maintaining acceptable image quality up to ±7.50°, particularly with a 40% central zone. Clinical evaluation showed that the 3.50 D astigmatic CSC design provided better LCVA than the best TMT design when properly aligned; however, this advantage decreased quickly with increasing rotational error. At ±7.50°, the CSC suffered a nearly two-line loss (+0.19 logMAR) compared with a one-line loss (+0.07 logMAR) achieved for the best TMT design tested here. Conclusions: Retinal image simulations have shown that TMT designs with a 40% central zone exhibit superior tolerance to rotational errors than CSC lenses. Moreover, the LCVA of the TMT design used in this study remained more stable under rotational errors than that of a CSC lens.