Long-term Clinical Outcomes of a Hydrofilic Extended Depth-of-focus Intraocular Lens After Bilateral Cataract Surgery

Technical Summary: Long-term Clinical Outcomes of a Hydrophilic Extended Depth-of-Focus Intraocular Lens

Problem Statement
Extended depth-of-focus (EDOF) intraocular lenses (IOLs) are designed to provide a continuous range of functional vision while minimizing photic phenomena (such as glare and halos) often associated with multifocal designs. While established EDOF platforms utilizing diffractive optics (e.g., Tecnis Symfony) or non-diffractive wavefront shaping (e.g., AcrySof IQ Vivity) have been extensively studied, long-term clinical data regarding newer aberration-based EDOF designs remain limited. Specifically, there is a need to evaluate the long-term refractive stability, visual performance, and safety profile of hydrophilic acrylic EDOF IOLs that utilize controlled induction of spherical aberrations rather than diffractive structures.

Methodology
This prospective, observational, single-center study was conducted at the Gemini Eye Clinic in the Czech Republic between January 2021 and November 2025. The study cohort consisted of 20 patients (40 eyes) with age-related cataracts who underwent bilateral phacoemulsification and implantation of the Synthesis Plus EDOF IOL (Cutting Edge, France).

• Lens Characteristics: The Synthesis Plus is a hydrophilic acrylic IOL featuring a blue-light filter. Its optical design incorporates a central 2-mm EDOF zone created by inducing fourth- and sixth-order spherical aberrations with opposite polarity to elongate the focal area without diffractive elements.
• Study Protocol: Patients were evaluated at 1 week, 1 month, 3 months, 6 months, and 3 years postoperatively.
• Measured Parameters:
  • Refractive: Manifest refraction and spherical equivalent (MRSE).
  • Visual Acuity: Uncorrected and corrected distance visual acuity (UDVA, CDVA); uncorrected and distance-corrected intermediate visual acuity (UIVA, DCIVA) at 66 cm and 80 cm; near visual acuity.
  • Functional: Defocus curves and contrast sensitivity under photopic and mesopic conditions.
  • Safety: Slit-lamp biomicroscopy, endothelial cell density (ECD), intraocular pressure (IOP), and adverse events.
• Statistical Analysis: Nonparametric methods (Wilcoxon signed-rank test) were used to analyze changes over time, with a significance threshold of p < 0.05.

Key Contributions and Results
The study provides a comprehensive 3-year longitudinal assessment of the Synthesis Plus IOL, highlighting the following outcomes:

1. Refractive Stability: The lens demonstrated high predictability and long-term stability. The mean spherical equivalent (MRSE) shifted slightly toward myopia post-surgery but remained stable between 6 months (-0.15 ± 0.27 D) and 3 years (-0.05 ± 0.19 D). At 3 years, 95% of eyes were within ±0.50 D of emmetropia. Residual astigmatism was minimal, with 95% of eyes having a cylinder ≤ 0.50 D at the 3-year mark.
2. Visual Acuity:
   • Distance: Mean CDVA was excellent, reaching -0.02 ± 0.07 logMAR at 6 months and -0.01 ± 0.08 logMAR at 3 years. 95% of eyes achieved CDVA of 0.2 logMAR or better at 3 years.
   • Intermediate: Visual acuity was favorable at both 66 cm and 80 cm. Notably, intermediate vision was consistently slightly better at 80 cm. At 3 years, 92% of eyes achieved UIVA of 0.2 logMAR or better at 66 cm, and 95% at 80 cm. Binocular intermediate vision was particularly strong, with 100% of eyes achieving 0.1 logMAR or better at 80 cm.
3. Defocus Curve: The defocus curve showed a continuous functional range. At 3 years, visual acuity of 0.2 logMAR or better was maintained from +0.5 D to -1.5 D of defocus, with peak performance between 0.0 D and -0.5 D.
4. Contrast Sensitivity: Contrast sensitivity remained stable over the 3-year period under both photopic and mesopic conditions. While values were near the lower limit of normal at higher spatial frequencies (particularly under mesopic conditions), no clinically significant deterioration was observed between the 6-month and 3-year visits.
5. Safety and Complications: No intraoperative complications or serious postoperative adverse events (e.g., retinal complications, cystoid macular edema, IOL dislocation) occurred. All IOLs remained well-centered.
   • Posterior Capsule Opacification (PCO): The most significant finding regarding safety was a high rate of PCO. Nd:YAG laser capsulotomy was required in 28 of 40 eyes (70.0%) due to clinically significant PCO. 20 of these treatments occurred after the 6-month mark. The authors attribute this to the hydrophilic acrylic material, which is associated with increased lens epithelial cell proliferation compared to hydrophobic materials.
   • Photic Phenomena: While not systematically quantified, patients generally reported good visual satisfaction, and no significant glare or halos were systematically noted as a primary complaint.

Significance and Claims
The authors claim that the Synthesis Plus EDOF IOL offers stable long-term refractive results and very good distance and intermediate visual acuity over a 3-year period. The study highlights that the lens's non-diffractive, aberration-based optical design successfully extends the depth of focus while preserving contrast sensitivity, avoiding the light-splitting issues common in diffractive multifocal lenses.

The paper modestly acknowledges its limitations, including a small sample size (20 patients), the lack of a control group, and the absence of systematic patient-reported outcome measures for dysphotopsia. However, the authors emphasize the value of the 3-year follow-up, noting that long-term data on this specific hydrophilic, aberration-based EDOF platform is scarce. They conclude that while the optical performance is favorable, the relatively high rate of posterior capsule opacification associated with the hydrophilic material must be considered during long-term clinical management.