Innovative IOL designs – like multifocal intraocular lenses (MIOLs) – have emerged over the past decade to provide better outcomes in the correction of presbyopia for many patients. And now, technological progress is pushing the frontiers of research and development into IOLs that are better adapted to patients’ needs.
Still, unwanted optical effects may occur depending on the patient’s eye anatomy. There are two key aspects of eye anatomy that affect patient outcomes:
- The degree of misalignment between the pupil and the visual axis of the eye (angle κ); and
- The misalignment between the optical axis of the cornea and the visual axis (angle α).
In cases where physiological κ or α is relatively large, specific parameters of MIOL geometry can greatly impact the results of the visual acuity of the implanted IOL and subsequently, patient satisfaction.
Therefore, care should be used to select an MIOL insensitive to decentration of the visual axis and MIOL center.
For this reason, the Precizon Presbyopic NVA (Ophtec, Groningen, The Netherlands) has a geometry that limits dependence on angle κ, with a central zone 1.4 mm in diameter in one direction, and 2.6 mm in diameter in the perpendicular direction (“butterfly” shaped). For angle κ with visual axis decentration up to 0.7 mm, the visual axis passes through the smooth central part of the lens regardless of MIOL orientation. And for large angle κ patients, the MIOL can be oriented so that the visual axis passes through the wider part of the central segment, which can then accommodate a decentration of up to 1.3 mm at the extreme.
The innovative design of the Precizon Presbyopic NVA integrates a CTF (Continuous Transitional Focus) optical system, with an anterior surface with multiple segments
for far and near vision. The entire anterior and posterior lens surfaces are shaped by computer-guided patented Transitional Conic technology, which is capable of producing an aberration-neutral aspheric IOL with a plus power of 2.75D or an aspherical negative aberration lens of -0.11μm depending on the patient’s needs.
Additionally, regular MIOLs cause positive dysphotopsia due to concentric rings, however CTF uses segments to avoid that problem, as they are designed to produce a lens more tolerant to halos and glares.
Having conducted extensive research into presbyopic IOLs and with decades of clinical experience, Dr. Rahman Korkmaz from the Visus Oogkliniek in Rotterdam, The Netherlands, shared his experience with Precizon Presbyobic NVA IOLs.
“I started with the first version of this IOL during the pre-commercial testing when it wasn’t in the market yet,” recalled Dr. Korkmaz. “I got a lot of insight into the best kinds of patients to use this IOL with. The design of the Precizon Presbyopic IOL is a disruptive design with segments instead
of rings, which is a totally new approach. Therefore, it is not in the same class with existing products.”
“Positive aberrations are natural,” he emphasized. “And you might want to compensate for these with a negative aberration lens like the Natural Visual Acuity (NVA) model.”
Furthermore, Dr. Korkmaz noted that “angle κ [angle kappa] and angle α [angle alpha] are important considerations in the use of MIOLs”.
“For surgeons, this [the NVA model] is an excellent lens to work with and is highly indicated in patients where we want to eliminate glare or halos,” he said. “The Precizon Presbyopic NVA IOL is designed to give cataract patients excellent far vision. I have used this lens in more than 40 patients bilaterally and most were patients with difficult eyes (high angle alphas and kappas) with excellent results.”
According to Dr. Korkmaz, he would also suggest this lens for tall patients because reading distance with presbyopia is less.
Furthermore, Dr. Korkmaz explained: “As the eye’s anatomical structure is very patient-dependent, I would like to recommend that in order to achieve the best possible outcome for the patient, an evaluation should be performed prior to implantation of any IOL to ensure it is the right one for the specific individual. For patients with larger than normal angle κ values, MIOLs with a wider central segment such as in Precizon Presbyopic NVA, should be considered to allow for accommodation of decentration that arises from the natural misalignment of the eye itself, and the implantation procedure.”
“This IOL [Precizon Presbyopic NVA] does not have the traditional dips associated with trifocal lenses,” noted Dr. Korkmaz. “In particular, this lens provides a more fluid transition of focus from a nearby to a faraway object. This has been the experience reported by majority of my patients, who have attested to the smooth transition when they try to focus from far to a near object. This smooth transition has been a remarkable change in their quality of vision and overall quality of life,” he concluded.
CAKE Magazine Issue 03: The ebook version (The 'Haute Couture' Issue, ESCRS 2019 Edition)
CAKE (Cataract – Anterior Segment – Kudos – Enlightenment) is The World’s Second Funky Ophthalmology Magazine, and Asia-Pacific’s Most Delicious Magazine on the Anterior Segment. CAKE Magazine is published by Media MICE Pte Ltd (Singapore).