This study compares two types of artificial lens (intraocular lens, or IOL) used during cataract surgery. Both are extended depth-of-focus (EDOF) lenses, designed to give clear vision across a range of distances - far and intermediate - so that people depend less on glasses after surgery. The two lenses, the Tecnis PureSee and the 1stQ Comfort Z-EDOF, use different optical designs, and it is not yet known whether one provides a wider range of clear vision than the other.

Adults having cataract surgery in both eyes may take part. Each participant is randomly assigned to receive one of the two lens types, and the same lens type is implanted in both eyes. Neither the participant nor the staff measuring vision knows which lens was used until the main 6-month assessment is complete.

After surgery, participants attend check-ups at 1, 3, and 6 months. The study measures how wide a range of distances each person can see clearly, along with vision at different distances, quality of vision, side effects such as glare or halos, and overall satisfaction. The results will help doctors and patients choose between these lens types.

Background and rationale: Extended depth-of-focus (EDOF) intraocular lenses (IOLs) extend the range of functional vision beyond that of conventional monofocal IOLs by modifying the eye's wavefront to create an elongated focal range, while aiming to limit the photic phenomena (halos, glare, starbursts) often associated with multifocal IOLs. Different EDOF platforms use fundamentally different optical strategies, yet direct comparative evidence between EDOF designs from prospective randomized trials is limited; most published studies compare an EDOF IOL with monofocal or multifocal lenses rather than with another EDOF design. This trial provides a head-to-head comparison of two purely refractive EDOF platforms that employ different optical principles: the Tecnis PureSee (Johnson & Johnson Vision), a refractive EDOF design with a continuous power profile and negative spherical aberration, and the 1stQ Comfort Z-EDOF (1stQ GmbH), a refractive aspheric EDOF design with a modified spherical aberration profile.

Design: This is a single-center, prospective, randomized, parallel-group comparative study conducted at the Department of Ophthalmology, Klinik Hietzing, Vienna, Austria. Patients undergoing bilateral cataract surgery are randomized 1:1 to receive one of the two EDOF IOL platforms, implanted bilaterally (the same platform in both eyes). Randomization uses permuted blocks and is stratified by toric versus non-toric IOL variant; patients with preoperative corneal astigmatism greater than 0.75 D receive the toric version of the assigned platform. Target refraction is emmetropia in the dominant eye and approximately -0.50 D in the non-dominant eye. Participants and outcome assessors are masked to lens allocation until the 6-month primary endpoint assessment is complete; the operating surgeon cannot be masked.

The study compares monocular (eye-level) and binocular (patient-level) outcomes between the two platforms. The primary endpoint is the monocular distance-corrected defocus range at the 0.2 logMAR threshold, measured 6 months after surgery from a standardized defocus curve (4-meter ETDRS chart, defocus +1.0 D to -3.5 D in 0.5 D steps). Secondary assessments include visual acuity at multiple distances, the complete defocus curve, manifest refraction and astigmatic vector components, higher-order wavefront aberrations, rotational stability of the toric variants, patient-reported visual function and quality of vision (including halos, glare, and starbursts), spectacle independence, satisfaction, and surgical safety.

Assessments are performed preoperatively and at 1, 3, and 6 months postoperatively. The primary analysis compares the mean monocular defocus range between groups using one eye per patient (the first-operated eye), with sensitivity analyses using both eyes and appropriate adjustment for within-patient correlation. The study is regulated as a post-market clinical follow-up (PMCF) investigation under Article 74(1) of Regulation (EU) 2017/745; both lenses are CE-marked and used within their approved intended purpose.

Inclusion Criteria:

• Age ≥40 years, able to understand the study and give written informed consent
• Clinically significant bilateral age-related cataract suitable for phacoemulsification with posterior chamber IOL implantation
• Expected postoperative best-corrected visual acuity ≤0.2 logMAR in both eyes
• Regular corneal astigmatism ≤4.5 D in both eyes (IOLMaster 700)
• Axial length 21.5-26.5 mm in both eyes
• Clear cornea without clinically significant opacities, scars, or stromal dystrophies
• Normal pupil function; no significant anisocoria (≥1 mm) and no afferent pupillary defect
• Acceptance of the target refraction strategy: emmetropia in the dominant eye and -0.50 D in the non-dominant eye
• Willing and able to attend all follow-up visits (Month 1, 3, and 6)
• Written informed consent obtained before any study-related procedure

Exclusion Criteria:

• Prior corneal refractive surgery, corneal transplantation, glaucoma filtering surgery, or vitreoretinal surgery in either eye (uncomplicated intravitreal injections allowed)
• Irregular astigmatism, keratoconus, forme fruste keratoconus, corneal ectasia, significant corneal opacities or scars, or endothelial dystrophy
• Keratometric astigmatism >4.5 D in either eye
• Axial length <21.5 mm or >26.5 mm in either eye
• Calculated IOL power outside the available range of either study lens
• Macular pathology expected to limit visual acuity (e.g., age-related macular degeneration, diabetic maculopathy, epiretinal membrane, macular hole)
• Advanced glaucoma with central visual field involvement, or IOP not controlled on ≤2 topical medications
• Optic neuropathy expected to limit visual potential
• Pre-existing amblyopia in either eye
• Significant anisocoria, afferent pupillary defect, non-dilating pupil, or iris abnormalities affecting IOL function or measurement
• Endothelial cell density <1500 cells/mm²
• Uncontrolled diabetes mellitus (HbA1c >9%) or autoimmune disease with active ocular involvement
• Systemic medications affecting pupil size that cannot be discontinued (e.g., tamsulosin)
• Pregnancy or breastfeeding
• Intraoperative complication precluding safe in-the-bag IOL implantation (affected eyes withdrawn)
• Cognitive impairment, language barrier, or other factors preventing reliable participation
• Current enrollment in another interventional clinical study affecting visual outcomes