Trifocal IOL – Cataract implant

Trifocal Intraocular Lenses: History, Design, and Clinical Outcomes

The development of trifocal intraocular lenses (IOLs) has revolutionized cataract surgery by enabling patients to achieve clear vision at near, intermediate, and far distances without the need for additional corrective lenses. For more than 15 years, trifocal implants have been the most commonly used intraocular lenses when one of the key goals of cataract surgery is to minimize dependence on corrective glasses. This allows the patient to enjoy clear vision without glasses for distance, near (reading), and intermediate distances (working on a computer). This segment of so-called « presbyopia-correcting » lenses accounts for approximately 11% of the total intraocular lens market for cataract surgery. Trifocal implants make up half of this market in Europe (see clinical trends, ESCRS). This page is dedicated to the technical aspects of pioneering trifocal diffractive IOLs.

1. History of Trifocal IOLs

I played a pioneering role in this development, driven by the lack of intermediate vision in patients implanted with bifocal lenses in the mid-2000s. As a cataract surgeon, I had been using bifocal lenses in patients seeking some spectacle independence during the years 2005-2007. These patients would often come back to me satisfied with their distance and near vision, but asking for some « screen reading glasses, » as they could not really work on their computer, which was about 70 cm from their eyes. This was seminal to the project of developing a multifocal IOL that would provide the patients with distance, near, AND intermediate vision.

As early as 2007, I began research in collaboration with the research and development team of the Physiol laboratory in Liège, Belgium, headed by Christophe Pagnoulle, with whom I had already worked on determining the optimal asphericity of the manufacturer’s soft monofocal lenses. By applying optimized diffraction principles, we developed a design that is both simple and elegant, and it has since become the standard.

In 2010, the company Physiol (Belgium) released the first-ever designed trifocal intraocular lens (IOL) for the replacement of the crystalline lens during cataract surgery. This new generation of multifocal IOL is based on a proprietary diffractive profile and is named « FineVision. » FINE stands for an acronym for « Far, Intermediate and NEar. » This IOL has been implanted in hundreds of thousands of eyes worldwide and delivers satisfying, predictable visual performance by enabling spectacle-free near, distant, and intermediate vision, unlike previous bifocal multifocal IOLs that did not provide satisfactory intermediate vision.

Read: The Best of Ophthalmology…Testing a Trifocal IOL – EyeWorld News Magazine

2. Justification of Trifocality

Bifocal diffractive IOLs provide patients with some spectacle independence for distant (more than 2 meters) and near (35-40 cm) vision. These lenses, however, have not been shown to provide satisfactory intermediate vision.

Intermediate vision relates to activities such as computer work, car driving (instrument panel), music playing (musical chart), etc. In these activities for which good uncorrected vision is required for distances between 60 and 80 cm, glasses may be required despite satisfactory near and distance uncorrected vision. Interestingly, the commercial release of the FineVision IOL was concomitant with the introduction of the iPad in the USA (March 2010). Tablets are heavier than books, and readers usually hold them on their laps, which increases the reading distance to the intermediate vision range (60-70 cm).

The benefit of trifocal vs. bifocal IOL technology helps patients to better recover a full range of useful spectacle-free vision.

This was seminal to the pioneering solution represented by the design and introduction of the first trifocal diffractive lens (FineVision). This lens aims to be more than a bifocal, providing distance and near correction only. The FineVision lens has an additional focus for intermediate vision, to provide treated patients with a full range of correction: hence, it is a true trifocal IOL (the « FineVision » commercial designation stands for an acronym: Far – Intermediate – NEar Vision).

📺 Video: The following video relates to the reasons and steps incurred for the development of a trifocal IOL:

📺 Video: Fundamentals for diffractive IOL design:

3. Designing a Trifocal Diffractive IOL

The IOL theoretical profile was first designed from theoretical computational equations. Its effect on an incident wavefront was simulated with MathCAD software (PTC Inc., Needham, Massachusetts, USA). The original idea was to combine two independent diffractive bifocal profiles, yielding a single diffractive pattern (this concept was patented in 2010).

3.1 From a Fresnel Lighthouse Lens to Diffractive Optics

Augustin Fresnel was a 19th-century French scientist who first developed the concept that bears his name, the « Fresnel optic, » for lighthouse lamps.

The profile of a multifocal diffractive IOL derives from the Fresnel zone plate.

Zone plates are not efficient, mainly because they block part of the incident light. By applying Fermat’s principle, progressive modifications to the zone plate can be made to achieve higher efficiency and reduce the number of foci. The plate can be made transparent, and the blocking zones replaced by « phase-shifting » zones that selectively modify the optical path to cancel the half-wavelength phase shifts, allowing more light to interfere constructively at the desired focal distance. These zones look like little grooves, which can be made using microlithographic techniques on transparent lens materials.

Before going further, it is important to review some theory and recall some important properties of diffractive IOLs. To understand how to achieve clinically efficient trifocality, it is mandatory to know the basic principles of diffraction for the realization of bifocal optics. At this stage, it is important to realize that diffractive elements are very sensitive to wavelength.

3.2 Basics of a Bifocal Diffractive IOL

Bifocality can be achieved by combining a conventional monofocal optic with a « kinoform zone plate, » whose profile results from applying Fermat’s principle (which states that light will always take the shortest path in time between two points). In gross approximation, the profile of the kinoform resembles that of an asymmetric « saw-tooth » profile. In practice, the height of these steps is on the order of a few microns. This is somewhat expected, as this scale is of the same order as that of the wavelength of incoming light (the visible light average wavelength is close to half of a micron, i.e., 500 nanometers).

3.3 Mathematical Design

(This section can be skipped by non-specialists)

The phase shift created by a diffractive surface is proportional to the height h(r) of the surface profile and the wavelength of light λ. The equation governing the phase shift φ(r) at a radial distance r from the optical axis is given by:

Where:

• h(r) is the height of the lens surface at radius r,
• n₁ and n₂ are the refractive indices of the surrounding medium and the IOL material, respectively,
• λ is the wavelength of light, typically 550 nm.

This equation forms the foundation for designing the diffractive profiles used in the FineVision IOL.

Kinoform Profile

The FineVision IOL leverages kinoform profiles, which are diffractive surfaces with continuous phase modulation. Kinoform profiles are designed to reduce the energy lost to higher diffraction orders, making them more efficient than traditional diffractive surfaces.

The general equation for the height profile H(r) of a kinoform diffractive lens, as described in patent WO2011092169A1, is:

Where:

• a is the amplitude parameter specific to the lens design,
• R is the radial distance from the optical axis to the edge of the lens,
• λ is the wavelength of light,
• n₁ and n₂ are the refractive indices,
• F is the focal length associated with the diffractive order.

This equation looks rather complicated, but it explains the classic « saw-tooth » aspect of diffractive IOLs.

The FineVision IOL combines multiple such diffractive profiles to create a trifocal effect, balancing light between near, intermediate, and far distances.

Optical Design of the FineVision Trifocal IOL

Calculating Focal Lengths

In the FineVision IOL, the diffractive structure is designed to focus light at three distinct focal points: near, intermediate, and far. The focal lengths for near and intermediate vision are determined by the following vergence formula:

Where:

• P is the lens power in diopters,
• n₁ is the refractive index of the surrounding medium.

For a near vision power of +3.50D and an intermediate power of +1.75D, the focal lengths are calculated as follows:

• F₁ = 1.334 / 3.50 ≈ 0.3811 m (near focus)
• F₂ = 1.334 / 1.75 ≈ 0.7623 m (intermediate focus)

These focal lengths are used to design the diffractive profiles H₁(r) and H₂(r), which manage the light distribution to the near and intermediate foci, respectively.

Optimizing Light Distribution

The FineVision lens is designed to distribute light efficiently among the three focal points, allocating roughly 42% of light to far vision, 36% to near vision, and 22% to intermediate vision. This allocation ensures that patients can function across a wide range of activities without the need for additional corrective lenses.

In addition to optimizing light distribution, the FineVision design also addresses chromatic aberrations by adjusting the height of the diffractive zones. This reduces chromatic aberration across varying lighting conditions, enhancing clarity at all distances.

3.4 General Properties of Kinoforms for Bifocal IOLs

Here we will return to a simpler and more visual approach. The following illustration represents schematically the behavior of light waves diffracted through a kinoform.

When properly designed, the kinoform can split incident light into several foci. This occurs when the optical path represented by the height of the steps is not an even multiple of the considered wavelength in the lens material. Some percentage of the incident light may not be deviated by the kinoform (0th order), while another percentage may go to the near focus (1st order). Some calculation shows that approximately 20% of incident light energy is diffracted in orders other than the 0th (non-deviated) and the 1st (near focus) when the kinoform is designed to be « bifocal » for a specific wavelength.

Effects of the Width of the Diffraction Steps

The width of the steps determines the distance at which the 1st (and subsequent) orders come into focus.

Apodization: Reducing the Height of the Diffractive Steps

The height of the steps is controlled by the design wavelength: optical designers may choose 550 nm, as it is the wavelength to which foveal (precise) vision is most sensitive. If the steps have a constant height value throughout the IOL, the distribution of incident light energy between the various diffraction orders will also be constant. A progressive reduction in step height can modulate the distribution of incoming light energy across the different diffraction orders as the pupil diameter increases. This reduction is called « apodization. »

Vergence of Higher Diffractive Orders

It has been mentioned previously that the kinoform diffracts light into several orders beyond the 0th and the 1st order; these represent 20% of the initial light energy, provided 40% is diffracted toward the 1st order and another 40% is diffracted (but not optically deviated) toward the 0th order. The 0th order contributes to distance vision, the first order contributes to near vision, and the second and superior orders are lost for vision, as their vergences (the distance of the foci) are not useful.

Interestingly, with such a design, the second diffractive order has double the vergence of the first order.

4. Achieving Trifocality

The combination of two specific diffractive kinoform patterns makes the envisioned asymmetric distribution of light energy among the 3 foci possible.

The final FineVision trifocal IOL profile (patented) is a combination of two apodized profiles. It displays a full diffractive area with a specific diffractive pattern comprising alternating diffractive steps of different heights.

This diffractive area extends throughout the anterior side of the IOL. The zeroth (0th) order of the two profiles is used for far vision.

5. Apodization and Convolution

The IOL diffractive profile is also gradually attenuated throughout the entire optic (apodization), resulting in a continuous modulation of the light energy distribution directed to the three primary foci. The larger the considered zone, the more light is proportionally directed to the distance focus.

This profile is lathed on the surface of a monofocal aspherical optic. The asphericity of the monofocal lens is intended to optimize image quality by balancing physiological levels of corneal positive spherical aberration.

Apodization of the Trifocal Profile

As the step height decreases toward the periphery (apodization), the peripheral steps are progressively exposed as the pupil aperture becomes larger. This results in an increasing amount of light dedicated to the distance vision focus. Hence, less light is recruited for the near and intermediate focal points. This gradual decrease of the step height from center to periphery has been shown to reduce halos, which are generated by defocused light under dim conditions.

In contrast to non-apodized IOLs, apodization provides some degree of customization for pupil movements: near reading tasks trigger pupil constriction, while mesopic distance vision (e.g., night driving) triggers pupil dilation. Apodization allows more light to be directed to the distance focus (0th order) when the pupil is dilated, thereby uncovering a larger IOL surface. This warrants superior optical performance in mesopic conditions.

Convolution of the Trifocal Profile

Diffraction can occur when light waves encounter any « abrupt » change in their path. The sharp edges of each step can cause unwanted diffraction, leading to a slight dispersion of incoming light energy. The light scattering on the edges of the steps can be decreased by their smoothing. Theoretically, this can be simulated by adding a mathematical smoothing function called « convolution. » This function was optimized to match the lens profile as manufactured, based on the cutting tool geometry, since in practice it is not possible to achieve abrupt steps with current lathing technology.

6. Optical Bench Results of the FineVision Trifocal IOL

The optical bench evaluation (through-focus and through-frequency MTF) has been conducted in accordance with ISO quality standards. These optical bench results echo the theoretical results. In addition to the two major foci at 0 and +3.5D, which provide add power for far and near vision, respectively, the FineVision multifocal IOL also provides a focus at +1.75D, which corresponds to intermediate vision. This characteristic should, therefore, offer enhanced visual performance for intermediate vision relative to that obtained by conventional bifocal multifocal IOLs.

The diffractive profile test has been designed to extend throughout the entire optical surface of the FineVision trifocal IOL. The gradual decrease in step height toward the periphery reinforces distance vision under mesopic conditions, when human pupils dilate. Without this gradual reduction, the contribution to far, intermediate, and near vision would be constant across the entire optical surface for any pupil size: this would not be optimal as all human pupils tend to dilate when ambient light reduces and to constrict when attempting to perform near visual tasks such as reading.

The variations of the through-focus MTF curve of the IOL for different pupil apertures confirm that the FineVision IOL is pupil-dependent and designed to favor distance vision under dim light conditions. This change of energy balance with pupil size mimics the natural pupil’s response to various lighting conditions. It is a function of the required distance (near or far vision). It is consistent with the accommodation reflex, in which the pupil tends to constrict for near vision. To decrease the risk of glare at night, only 9% of the energy is devoted to intermediate vision at a 4.5 mm pupil aperture.

The FineVision Physiol trifocal IOL was the first IOL ever designed to display a useful additional focus for intermediate vision at +1.75D. This IOL improves intermediate vision relative to standard bifocal IOLs while maintaining near and far visual performance owing to its advanced optical features: apodization, convolution, and aspherization.

The risk (for the patient) associated with this intermediate focus seems limited relative to the offered benefit, as the diffractive structure of this trifocal IOL was designed to allocate less energy to intermediate vision than to far and near vision. Regardless of pupil size, the limited energy allocated to intermediate vision reduces the risk of monocular diplopia at intermediate focus.

7. Current Trifocal IOL Market (2024-2025)

Since the introduction of the first trifocal IOL (FineVision) in 2010, several manufacturers have developed their own trifocal designs. The current market includes:

8. Trifocal vs. EDOF IOLs: Superior Near Vision

Extended Depth of Focus (EDOF) IOLs represent an alternative approach to presbyopia correction. Unlike trifocal IOLs that create three distinct focal points, EDOF lenses produce a single elongated focal zone, aiming to provide continuous vision from distance to intermediate without the « peaks and valleys » of traditional multifocal designs. While this approach may reduce photic phenomena (halos, glare), clinical evidence consistently demonstrates that trifocal IOLs provide significantly better near vision than EDOF lenses.

Key Differences Explained

The fundamental difference lies in the optical design philosophy:

Clinical Implications

For patients who prioritize reading and close-up tasks (smartphones, books, detailed work), trifocal IOLs remain the better choice. The higher near addition power (+3.25D to +3.50D) provides a true near focus at typical reading distances (35-40 cm), whereas EDOF lenses with their lower addition (+1.50D to +1.75D) may leave patients dependent on reading glasses for fine print.

As noted at the ESCRS Winter Meeting debates, « There is no ideal IOL. However, EDOF lenses have the advantage in intermediate vision, while trifocals clearly excel in near vision. » The choice should be individualized based on the patient’s lifestyle and visual priorities.

9. Online IOL Simulation: AIOL Sci

Today, IOL power formulas are well established. The real challenge comes after power selection: how do you decide which IOL design will benefit your patient the most? In an industry full of players competing for attention, there is now an objective, patient-specific way to answer that question.

AIOL Sci bridges lab physics and clinical decision-making by combining measured IOL wavefronts with a personalized aspheric cornea model (R, Q). The platform computes through-focus MTF to quantify how a specific IOL will perform in your patient’s eye—not in an average eye.

Why Patient-Specific Simulation Matters

Every eye is unique. Corneal curvature (K) and asphericity (Q) govern spherical aberration, which can reshape through-focus image quality dramatically. Standard models assume an « average » cornea, but this leads to suboptimal outcomes—especially after refractive surgery, where aberrations shift significantly. AIOL Sci enables you to model potential IOL selections for each patient’s corneal optics, for modern, personalized care.

Choosing a lens without considering the cornea’s actual optics is like tailoring a suit without measurements: it may look fine on paper, but it fails in practice.

Empirical IOL Data vs. Manufacturer Datasheets

The AIOL Sci lens catalogue is built entirely on proprietary optical bench measurements. Using a validated method, the platform captures the true optical effects of each IOL model, including asphericity, refractive profiles, diffractive steps, and manufacturing tolerances and defects. This ensures that the simulator reflects the true manufactured performance of the lens—not the idealized design described in marketing datasheets.

Manufacturer-Neutral & Device-Agnostic

AIOL Sci works seamlessly with any commonly available biometers and topographers, without locking users into a specific hardware platform or IOL manufacturer. The expanding IOL library spans multiple manufacturers, giving you the flexibility to balance performance and cost transparently.

The platform provides objective, manufacturer-independent data on lens performance, transformed into patient-specific visual outcome predictions. Results are delivered in plain language and intuitive graphics, focusing on what matters most in the clinic: clarity at distance and near, and the depth of field that a given lens delivers in that individual eye.

What You See

AIOL Sci reports through-focus Modulation Transfer Function (TF-MTF) at several spatial frequencies (10, 30, 50, 100 lp/mm and average) at common pupil sizes (3.0 mm and 4.5 mm). These outputs make it clear how contrast shifts across focus, enabling:

• Contrast curves that condense performance into an easy-to-interpret metric
• In vitro depth of field estimates based on published thresholds
• Direct design comparisons so you can evaluate different monofocal, EDOF, and multifocal options side by side for the same eye

Why It Matters

The number of available IOL designs continues to grow, while patient expectations are higher than ever. The expanding range of options—enhanced monofocals, EDOF, multifocals, and novel profiles—makes apples-to-apples comparisons difficult. Bench-measured metrics such as standardized MTF at 50 lp/mm or TF-MTF curves published by manufacturers on an « average cornea » provide useful reference points, but they only describe average performance.

By combining bench-measured IOL optics with patient-specific corneal modeling, AIOL Sci equips surgeons with an intuitive, science-based foundation for lens selection—ensuring each IOL choice is tailored to the individual patient rather than the statistical mean.

10. References

See also: Cataract Surgery | IOL Power Calculation | Presbyopia

Page updated: January 2026

3 réponses à “Trifocal IOL – Cataract implant”

1. JC Kim dit :

   24 décembre 2024 à 2 h 06 min

   Hello Dr Gatinel. I am a South Korean opthalomolgist who is a big fan of your works.
   Starting from this page, I have tried to understand the mathematical principles behind diffractive bifocal IOLs. However, combining two bifocal diffractive designs to achieve trifocality remains still elusive to me.
   Specifically, in the above image titled « TRIFOCAL IOL DESIGN, » the lower trifocal design, if we ignore apodization, appears similar to a bifocal design. In this design, each triangle seems to have the same width corresponding to +3.5D. The only difference is the alternating heights, controlling the light distribution.
   As shown in the image, if the initially wider triangle for +1.75D is cut in half and the base half is removed to incorporate the narrower +3.5D triangle, how can the remaining apex half still function to provide a +1.75D power with only half the original width?
   Thank you.

2. Dr Damien Gatinel dit :

   17 mars 2018 à 0 h 48 min

   Thanks, it appears to me that Kappa angle and pupil size do not really affect the performance of trifocal IOLs. It is important to perform an uneventful surgery, and control for astigmatism. If the cornea is irregular (trefoil and coma like aberration), the indication can be reconsidered. But otherwise the precautions and recommendations of these IOLs are the usual ones when it deals with cataract surgery and premimum multifocal implantation.

3. Mahmoud Ebadi dit :

   9 mars 2018 à 14 h 52 min

   Congratulations Dr. Gatinel on a very comprehensive and detailed presentation. I was wondering if you could comment on your recommendations for pupil size, Coma, Angle Kappa and any other parameters that you feel are necessary to consider in chosing the pts. for this trifocal IOL.
   Thank you,