The objective of this study was to evaluate the effect of intraocular lens (IOL) selection on visual acuity and refractive outcomes, to assess the impact of IOL type on postoperative contrast sensitivity, and to investigate whether IOL choice influences the induction and dynamics of higher-order ocular aberrations following cataract surgery/refractive lens exchange surgery in hyperopic patients.

A prospective randomized interventional clinical study was conducted in its entirety at the Department of Refractive Surgery, University Eye Hospital Svjetlost, Zagreb, Croatia. Participant enrolment occurred between January 1, 2018, and October 31, 2020. Each participant was followed prospectively for a period of 12 months.

The study was designed to include 4 groups, each comprising 50 participants. Eligible participants were those aged 45 years or older and present with hyperopia ranging from +0.50 dioptres (D) to +5.00 D, and astigmatism of up to +1.00 D. Participants with refractive errors must exhibit a best-corrected visual acuity (BCVA) of ≥0.05 Logarithm of the Minimum Angle of Resolution (LogMAR). For those with cataracts, inclusion requires a BCVA of ≥0.7 LogMAR, contingent upon cataract severity. Participants with BCVA <0.05 LogMAR were enrolled only after the exclusion of low vision, as confirmed by prior ophthalmological records.

All patients underwent a comprehensive preoperative ophthalmologic evaluation. This included slit-lamp bio microscopy of the anterior segment and dilated fundus examination. Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), as well as manifest and cycloplegic refractions were recorded. Corneal tomography was performed to assess the topography of both the anterior and posterior corneal surfaces, as well as corneal thickness. Wavefront aberrometry (Luneau Visionix L80 Wave+, Visionix, Prunay-le-Gillon, France), was conducted to evaluate higher-order aberrations. Pupil size was measured under photopic, mesopic, and scotopic conditions using a pupillometer (Peramis, CSO, Italy). Specular microscopy (Perseus specular microscope, CSO, Firenze, Italy), was employed to determine corneal endothelial cell density. Additional assessments included determination of ocular dominance, evaluation of ocular motility, and assessment of tear film stability using the Schirmer test and Tear Break-Up Time (TBUT) test. Contrast sensitivity (CS) at 10% and 25% illumination was also measured.

Phacoemulsification was performed using the Infinity Vision System (Abbott Medical Optics, WhiteStar Signature Phacoemulsification System). Surgical parameters, including phaco power, vacuum level, pulse mode, oscillation, and infusion bottle height, were adjusted according to the specific phase of the procedure. All surgeries were performed by a single experienced surgeon employing a standardized micro coaxial technique. Corneal incisions measuring 2.7 mm were created along the steepest meridian; in rare cases where intraoperative challenges were encountered, the incision was extended.

Following successful completion of anterior capsulorhexis and lens phacoemulsification, a foldable intraocular lens (IOL) was implanted into the capsular bag via the main incision using the Acrijet Blue injector (VSY Biotechnology, Amsterdam, Netherlands). Residual viscoelastic material was thoroughly removed by irrigation and aspiration. All corneal incisions were self-sealing and did not require suturing. At the conclusion of the procedure, an antibiotic drop was instilled intraocularly, and antibiotic ointment was applied to the conjunctival sac. Maxitrol eyedrops (Alcon, Fort Worth, Texas), a neomycin, polymyxin B sulphates, and dexamethasone ophthalmic suspension were prescribed for application after the surgery. At first postoperative day drops were administered every hour, then four times per days in first postoperative week, and then gradually tapered for next three weeks.

Patients underwent follow-up evaluations at 1 week, 1, 6, and 12 months postoperatively. During each examination, the anterior eye segment was thoroughly assessed and documented. Uncorrected and corrected visual acuity was measured at multiple working distances (6m, 80 cm and 35 cm). Additionally, refractive status was evaluated by quantifying spherical and cylindrical corrections. Contrast sensitivity was assessed under illumination levels of 10% and 25%, and higher-order aberrations of coma and SA (spherical aberration) were measured to determine optical quality.

Data from treated eyes were analysed. Details of visual acuities, sphere and cylinder refraction, contrast sensitivity at 10% and 25% illumination, and higher-order aberrations were recorded and stored on Excel spreadsheets (Microsoft, Redmond, WA) during the monitoring of the subjects. Descriptive statistics, including minimum and maximum values, means, standard deviations, medians, and interquartile ranges, were used for preliminary variable characterization by groups. Prior to inferential analyses, the Kolmogorov-Smirnov test was applied to assess the normality of variable distributions, which is a prerequisite for parametric tests such as ANOVA and the t-test. As the Kolmogorov-Smirnov test indicated non-normal distribution for the variables, nonparametric statistical methods were employed throughout subsequent analyses. Specifically, the Friedman test was utilized to evaluate differences across multiple measurement time points within groups. When the Friedman test revealed statistically significant differences, pairwise comparisons were conducted using the Wilcoxon signed-rank test to identify specific time points exhibiting significant changes. For comparisons between the two independent groups-patients implanted with a new generation multifocal intraocular lens and those receiving a monofocal lens implant-the Mann-Whitney U test was applied. All statistical tests were performed at a significance level of 0.05 (95% confidence interval).

Inclusion Criteria:

• Age of ≥ 45 years
• Hyperopic correction ranging from +0.50 D to +5.00 D, and astigmatism of up to +1.00 D
• Best corrected visual acuity of ≥0.05 LogMAR

Exclusion Criteria:

• Previously performed eye surgical procedures or eye injuries
• Glaucoma
• Fuchs' endothelial dystrophy or other corneal diseases (corneal degeneration and dystrophy)
• Zonular weakness or subluxated lens
• Systemic autoimmune and rheumatic disease
• Insulin dependent diabetes