Understanding Tecnis PureSee IOL
- Mar 26, 2025
- 10 min read
Attention: The Tecnis PureSee IOL DFU clearly states the following: 'The posterior optic of the IOL has a proprietary refractive surface designed to extend range of vision'(TECNIS PureSeeâ„¢ IOL, Model ZEN00V).
Per the company website the following is quoted under technical specification (last accessed 9th Sept, 2025) 'Shape: Biconvex, wavefront-designed anterior aspheric surface, proprietary refractive surface to increase the depth of focus'.
The following are the interpretation of Tecnis PureSee IOL optical principle. The article also explains where PureSee may differ from Eyhance design.
This is a brief explanation of Tecnis PureSee IOL that has been launched in 2024. The official description of the lens from Johnson & Johnson (J&J) is that it is based on proprietary refractive technology that enables continuous changes in power(1). Beyond this the company claims a monofocal like dysphotopsia profile. For those who follow this blog and are interested in science, surely would seek more information to satiate their curiosity. Therefore, here I try to break in a simple language what this may mean to an user beyond the carefully scripted company message.
In the picture on the left are two circles, one big and the other small. The radius of curvature of the bigger circle will be higher than the smaller circle, naturally. However, the smaller radius of curvature (smaller circle) will be associated with a steeper curvature. In this case, the orange circle will have a steeper curvature and associated with a higher power. The opposite is true for the larger (blue) circle. If you design a convex lens with radius of curvature of the two circles, then the posterior curvature of the lens will be flatter than the anterior curvature.
Next let us see what happens if we play with the anterior and posterior radius of curvature of the lens/IOL. In image 2, the lens on the above has an equal radius of curvature on both sides of the lens. Note the depth of focus is limited for this equiconvex IOL. In the below, as we increase the posterior radius of curvature of the lens, the depth of focus increases. Thus a continuous change in refractive surface from the center of the lens to the periphery will introduce some depth of focus. In this case a positive spherical aberration is generated, that is the peripheral rays of light are falling before the focal point generated through refraction of the paraxial rays ( rays that go close to the optical axis of a lens).
Unlike positive spherical aberration, with negative spherical aberration, the marginal rays of light fall posterior or behind the paraxial rays of light (image 3). Thus a prolate surface ( steeper in the center and flatter in the periphery) will generate negative spherical aberration.
It is important to note that if the eye is emmetropic, that is the paraxial rays of light fall on the retina, negative spherical aberration may not help gain depth of focus, as the depth of focus generated will be in a hyperopic direction. Thus IOLs that provide depth of focus (EDOF) generally provide positive primary spherical aberration. If negative spherical aberration is generated it must either be associated with a secondary positive spherical aberration to bring the depth of focus on the myopic side, or the surgeons must target myopia in controlled amount.
Let us now put our focus on Tecnis PureSee IOL.
The company talks about proprietary refractive changes, which could be interpreted as a controlled refractive power change by modifying the curvature of the lens posterior surface (the PureSee IOL has negative asphericity in the anterior surface to negate corneal positive spherical aberration). Thus, like image 2, a steeper curvature, of the posterior surface will induce depth of focus by creating a strum's conoid ( an area ) between the paraxial rays and the marginal rays that pass through these refractive curvature changes. Any change in curvature away from the monofocal base power of lens ( Tecnis monofocal for example ) will thus induce primary spherical aberration (defined here as the area between the focal point on the retina for an emmetropic eye and the rays of light falling anterior/posterior due to positive/negative spherical aberration). Thus Ruediger Schmid and Andreas F Borkenstein (2) in their paper has listed a primary spherical aberration value of negative .65 micron and a secondary spherical aberration value of .2 with the Tecnis PureSee IOL.
Update December 2025 -
