How does the ALcon Clareon TruPlus IOL optics work?
While Alcon has not publicly disclosed the exact underlying optical architecture of the Clareon TruPlus intraocular lens (IOL), they describe its proprietary "OptiBalance" technology as providing a slight extension of the depth of focus while maintaining uncompromised distance vision(1). Formally categorized at its launch in ASCRS 2026 as an enhanced monofocal lens, the TruPlus aims to offer extended intermediate functionality without introducing the dysphotopsia profiles typically associated with diffractive multifocal optics.
A review of the FDA pre-market approval record (P190018 and its supplement S047) reveals minimal technical details regarding the precise physical mechanism of action. However, an analysis of a key patent approved just prior to the commercial launch provides a compelling theoretical model for understanding the underlying optical principles of the lens design.
Here is a simplified understanding from the patent of how the Alcon Clareon TruPlus IOL may work from the US patent (2).
The Potential Optical Architecture
Based on publication of US11903819B2 , the underlying mechanism appears to rely on multi-zone refractive profile designed to manipulate wave phase and convergence of light rays. This proposed design breaks the lens surface into four distinct concentric zones (refer image 1):
Zone 1: Inner Power Zone Located at the centre of the optic, Zone 1 features a steeper refractive curvature compared to the rest of the lens. This added central power converges light rays slightly in a myopic direction, creating the initial focus shift necessary to increase the lens's total depth of focus.
Zone 4: Base Curvature Zone: Positioned at the outer perimeter of the optic, Zone 4 represents the standard base curvature responsible for distance vision. It focuses incoming parallel light rays directly onto the retina based on standard patient biometry calculations.
Zones 2 & 3: Transition and Phase Shift Zones
Before I explain the zone 2 which helps in shift of the phase of light, I should explain what a phase shift actually means.
Image 2 no phase shift explanation 
Image 3 negative phase shift Maya falls behind Taking a real world analogy, think of Maya and Devika are running on a track. If they run together (image 2), neither outperforming or reaching ahead of each other, both Maya and Devika reach a given point at the same time. There is no phase difference in this case. However in another example (image 3), if Devika is ahead of Maya, then there is a phase shift or phase difference. In this case Devika reach a given point at an earlier time than Maya. If we take Devika as the reference, we can say there is a negative phase shift, that is while Devika has reached the point at a pace he was suppose to reach, Maya is slightly delayed, to reach the same place.
Relating this analogy, thing of the base curvature of the lens as reference. You have done a biometry and called for a 21 diopter Truplus IOL. The base curvature of the IOL is so designed to reach the distance focal point on the retina. Zone 1, as earlier described has a steeper curvature or higher power to shift the rays of light anterior to the distance focal point. This helps in generating a depth of focus. But if things are left here, the IOL will behave like a bifocal IOL, with distinct peaks on the defocus curve.
Zones 2 and 3 serve to eliminate this gap by progressively shifting the optical phase from the inner power zone (zone 1) to the peripheral distance zone (zone 4). Zone 2 helps bring a negative phase shift, that is light that goes through this transition zone 2, will be delayed like Maya running in the track behind Devika, and will by made to converge at a later point of time compared to light rays that pass through zone 1. This would shift the rays of light passing through the transition zone 2 slightly behind the rays of light that pass through zone 1. This is done to extend the focus, filling up the area between light falling at the two discreet focal points between zone 1 and zone 4.
Zone 3 is a transition zone whose importance is more optical than refractive. Zone 3 helps in a smooth transition of the refractive profile from the inner region (zone 1 and 2) to the outer region zone 4. This may eliminate any abrupt transition in the optics and thereby help bring down any ghosting of image or potentially dysphotopsia.
Together, these positive and negative phase shifts blend the light continuously between Zone 1 and Zone 4, creating a smooth transition across intermediate distances without creating discrete focal peaks or severe optical steps.
Clinical Implications and Spherical Aberration
From a clinical standpoint, this proposed multi-zone phase-shifting design translates to predictable performance enhancements over traditional optics:
Defocus Curve Improvement: Practitioners can expect a modest 1 to 1.5 line improvement in intermediate depth of focus compared to a standard monofocal IOL, helping patients with tasks such as viewing dashboard displays, reading tablets, or seeing computer screens.
Refractive EDOF Classification: This design directly aligns with the second primary method of achieving extended depth of focus (EDOF) as outlined on quickguide.org (https://www.quickguide.org/post/edof-optics), optics featuring a higher radius of curvature or added refractive power situated in the central zone.
Spherical Aberration Considerations: Because the central optic carries higher refractive power, the design inherently may introduce a degree of negative spherical aberration. While this negative spherical aberration is beneficial for expanding depth of focus in standard corneas, it requires careful patient selection. It may not be ideal for patients who already possess high pre-existing negative spherical aberration, such as those with corneal ectasias (e.g., keratoconus) or a history of post-hyperopic LASIK/PRK.
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