Visual Outcomes and Quality of Life After Vivity EDOF IOL Implantation in Early-Stage Keratoconus

Background and Rationale Keratoconus (KC) is a progressive, non-inflammatory corneal ectasia characterized by stromal thinning and irregular astigmatism, often resulting in significant higher-order aberrations (HOAs) that impair visual quality. Due to these optical limitations, the use of premium intraocular lenses (pIOLs) has traditionally been considered contraindicated in these patients. However, in patients with early-stage keratoconus, corneal shape and optical quality can be relatively well preserved, with HOAs remaining within acceptable limits. These patients may thus benefit from carefully selected premium IOL technologies.

Extended-depth-of-focus (EDOF) IOLs, in contrast to traditional multifocal lenses, not only provide significantly fewer visual disturbances but, thanks to their elongated focus, they could mitigate HOAs and coma-like distortions characteristic of early keratoconus. Unlike monofocal or multifocal lenses, which rely on a single, sharp focal point or discrete focal planes, EDOF lenses are inherently designed to maintain functional retinal image quality across an extended focal range, offering greater tolerance to minor defocus and wavefront aberrations. While EDOF lenses do not correct such aberrations, their extended focal range may reduce the impact of this distortion on functional vision. This is especially true for non-diffractive EDOF lenses, which preserve high levels of contrast sensitivity by not splitting light energy into multiple focal points.

The AcrySof IQ Vivity IOL (Alcon, Fort Worth, TX, USA) is a non-diffractive EDOF IOL that uses wavefront-shaping technology to elongate the focal range. Previous studies have already demonstrated good outcomes in patients with other challenging ocular conditions such as glaucoma, macular degeneration, and epiretinal membrane. The present pilot study aims to evaluate the visual performance, tolerance, and optical quality outcomes following implantation of the Vivity IOL in patients with cataract and stable, early-stage keratoconus. This investigation explores the clinical viability of premium IOLs in a population traditionally excluded from such refractive options.

Study Design This is a prospective, interventional, single-center pilot study conducted in Italy. The study has been approved by the local ethics committee (protocol number 22546) and adheres to the principles of the Declaration of Helsinki. A total of 10 patients (20 eyes) with cataracts and mild bilateral keratoconus will be enrolled and followed for 3 months after bilateral implantation of the AcrySof IQ Vivity EDOF IOL.

Study Objectives

Primary Objective:

• To evaluate monocular distance-corrected visual acuity (DCVA) in the dominant eye at 3 months after surgery.

Secondary Objectives:

• To assess monocular and binocular uncorrected and distance-corrected visual acuity at distance (4 meters), intermediate (66 cm), and near (40 cm)
• To evaluate binocular defocus curves from +1.50 D to -3.50 D in 0.50 D increments;
• To measure monocular and binocular contrast sensitivity under photopic (80 cd/m²), mesopic (6 cd/m²), and scotopic (3 cd/m²) lighting conditions;
• To assess ocular optical quality including root mean square (RMS) wavefront error and point spread function (PSF) Strehl ratio at 3 mm and 4 mm pupil diameters;
• To evaluate binocular halo perception using standardized halometry;
• To assess patient-reported quality of life using the National Eye Institute Refractive Error Quality of Life Instrument-42 (NEI-RQL-42) questionnaire;
• To evaluate the safety profile including intra- and postoperative complications and adverse events;
• To assess toric IOL rotational stability in eyes receiving the toric version.

Eligibility criteria such as inclusion and exclusion criteria are reported separately.

Preoperative Assessment:

All patients will receive a comprehensive ophthalmologic evaluation prior to surgery, including:

• Measurement of monocular and binocular uncorrected and corrected visual acuity for distance (4 meters) and near (40 cm) using CSO Vision Charts software version 14.0
• Corneal tomography using MS-39 anterior segment optical coherence tomography (CSO, Florence, Italy)
• Ocular optical quality analysis using Pyramidal WaveFront-based sensor aberrometer (Osiris T Aberrometer, CSO, Florence, Italy) to assess higher-order aberrations including coma and coma-like aberrations
• Optical biometry using Lenstar 900 (Haag-Streit Diagnostics, Koeniz, Switzerland) for axial length and IOL power calculation
• Intraocular pressure measurement
• Slit-lamp examination of the anterior segment
• Dilated fundoscopy
• Macular evaluation through spectral-domain optical coherence tomography (Spectralis OCT, Heidelberg Engineering GmbH, Germany)
• Ocular dominance determination using the Miles test

Surgical Procedure:

All patients will undergo standard phacoemulsification cataract surgery performed by the same experienced surgeon using a 2.2 mm phaco probe under topical anesthesia. The AcrySof IQ Vivity EDOF IOL will be implanted in the capsular bag with a target of emmetropia bilaterally. IOL power calculation will be performed using the Kane formula. In eyes with regular corneal astigmatism equal to or greater than 1.00 diopter, the toric version of the Vivity IOL (AcrySof IQ Vivity Toric) will be implanted to optimize postoperative refractive outcomes. The second eye will be operated within 7 days of the first eye surgery.

Postoperative Follow-up:

Toric IOL rotational stability will be assessed on postoperative days 1 and 7 to account for early positional shifts and to allow for re-centering if necessary. The IOL will be deemed stable if the angular deviation is less than 5 degrees and if it induces a residual cylindrical error of 0.75 diopters or less, as estimated using the Toric IOL Assistant feature of the Osiris T Aberrometer.

Complete ophthalmological examination will be performed at the 3-month follow-up visit and outcome measures are measured as explained in the outcome measures section.

The Vivity IOL Technology The AcrySof IQ Vivity is a single-piece, hydrophobic acrylic EDOF IOL that utilizes a non-diffractive wavefront-shaping mechanism to enhance intermediate and near vision. The optic is 6.0 mm in diameter with an overall length of 13.0 mm and features a C-loop haptic design. The lens material incorporates both ultraviolet and blue light-filtering chromophores and has a refractive index of 1.55 at 35°C.

The lens design is based on a monofocal aspheric platform with an aberration-neutral anterior surface. The central optical zone incorporates X-WAVE technology, which integrates two subtle anterior surface transition elements: a slightly elevated central plateau (approximately 1 micrometer) that stretches the wavefront to extend the focus, and a surrounding curvature modulation that shifts the wavefront, ensuring efficient retinal energy delivery across the extended range.

The spherical model is available in powers ranging from +15.0 diopters to +25.0 diopters in 0.5 diopter increments, with additional availability up to +30.0 diopters in selected markets. The toric version, AcrySof IQ Vivity Toric, incorporates the same non-diffractive EDOF design and is offered in cylinder powers from 1.03 diopters to 4.11 diopters at the IOL plane.

Statistical Analysis All statistical analyses will be performed using STATA software, version 13.0 (StataCorp, College Station, TX, USA). The distribution of continuous variables will be assessed with the Shapiro-Wilk test. When data are normally distributed, results will be reported as mean ± standard deviation.

To evaluate the safety profile of the implanted IOL, both absolute and relative frequencies of intra- and postoperative complications, as well as any adverse events, will be recorded and analyzed at each follow-up. Paired t-tests will be conducted between preoperative and postoperative DCVA, DCNVA, UDVA, UNVA, and total RMS to assess postoperative functional improvement.

The primary endpoint is the evaluation of DCVA in the dominant eye at 3 months. A formal sample-size calculation was performed based on a previous pilot series reporting a standard deviation of 0.01 logMAR for monocular DCVA in eyes with stable keratoconus and cataract implanted with a premium IOL. A single-group design was used to estimate a 95% confidence interval for one standard deviation via the chi-square method. Assuming a standard deviation of 0.017 logMAR, 10 subjects (10 eyes) are required to yield a confidence interval half-width no greater than 0.02 logMAR (equivalent to one ETDRS letter). Sample-size calculations were carried out with PASS 2023, version 23.0.2.

Safety Considerations All participants will be carefully monitored for any adverse events or complications related to the surgical procedure or the implanted IOL. Standard cataract surgery risks include infection (endophthalmitis), inflammation, bleeding, increased intraocular pressure, lens dislocation, posterior capsule rupture, cystoid macular edema, and retinal detachment. Additional considerations specific to premium IOLs include the potential for visual disturbances such as glare, halos, starbursts, reduced contrast sensitivity, and in rare cases, dissatisfaction requiring IOL exchange.

In the specific context of keratoconus patients, there is theoretical concern that residual corneal irregularities and higher-order aberrations might interact with the IOL optics in unpredictable ways, potentially limiting visual quality or increasing photic phenomena. However, by carefully selecting only patients with early-stage, stable keratoconus and relatively preserved corneal morphology, this study aims to minimize these risks while exploring the potential benefits of EDOF technology in this population.

Any serious adverse events will be immediately reported to the ethics committee and appropriate medical management will be provided. Participants are free to withdraw from the study at any time without affecting their medical care.

Expected Outcomes and Significance This pilot study will provide preliminary evidence regarding the safety, efficacy, and patient satisfaction associated with Vivity EDOF IOL implantation in patients with early-stage keratoconus. If successful, the results may challenge the traditional view that premium IOLs are contraindicated in keratoconus and open new treatment options for carefully selected patients who wish to reduce spectacle dependence after cataract surgery.

The non-diffractive EDOF design of the Vivity lens, with its extended focal range and preserved contrast sensitivity, may be particularly well-suited to tolerating the mild corneal irregularities present in early keratoconus. By extending the depth of focus rather than creating discrete focal points, the lens may maintain functional vision despite minor wavefront aberrations.

Results from this study will inform larger, multicenter, randomized controlled trials and may ultimately contribute to updated clinical guidelines for IOL selection in keratoconus patients