Intraocular lenses (IOLs) are central to restoring vision after cataract surgery, but selecting the right lens in complex eyes requires precision, experience and the correct tools. In this Q&A, Professor Andrzej Grzybowski shares his expert practice pearls on achieving the best possible refractive outcomes in challenging cases.

In challenging cases such as those with post-refractive surgery corneas, irregular astigmatism, keratoconus, extreme axial lengths (AL), paediatric and vitrectomized eyes, I rely on a multimodal diagnostic approach. No single device or metric is sufficient to ensure refractive accuracy in these complex scenarios.

The difficulty in obtaining precise IOL power calculation in children contributes to several issues. First, compared to adults, paediatric eyes have a short­er AL, steeper corneal curvature, higher K value and shal­lower anterior chamber depth (ACD). Second, inaccurate biometric measurements can be caused by the poor cooperation and eye

ELP prediction is particularly difficult in eyes that have undergone corneal refractive surgery. Difficulty in obtaining precise corneal power contributes to inaccurate ELP estimation. Incorrect measurement of anterior corneal curvature, changes in posterior corneal curvature and aberration of corneal refractive index can also cause difficulties in achieving accurate corneal power.

Axial length and anterior chamber depth are foundational measurements, and I prefer using swept-source optical coherence tomography (OCT) biometry such as the IOLMaster^® 700 (ZEISS, Oberkochen, Germany), Lenstar LS 900^® (Haag-Streit, Bishop’s Stortford, UK), or Argos® (Alcon, Camberley, UK). These platforms are reliable even in long and short eyes, where small errors can significantly impact postoperative outcomes.

Corneal measurements are equally critical. I routinely use Scheimpflug-based tomography (e.g., Pentacam^® [OCULUS, Wetzlar, Germany], Galilei G6 [Ziemer Ophthalmic Systems AG, Port, Switzerland]) and wavefront-based topography to assess both anterior and posterior corneal surfaces. This is particularly helpful for detecting irregularities in post- laser-assisted in situ keratomileusis (LASIK) or keratoconic eyes.

To account for posterior corneal curvature and avoid over- or under-correcting astigmatism, I incorporate total corneal power assessments and use calculators such as the Barrett Toric and Barrett True-K formulas. These tools integrate posterior corneal data for better toric alignment and spherical power selection. For keratoconus eyes, I use the Barrett True-K KC and Kance KC formulas.

I also validate measurements across multiple devices, comparing optical biometry with manual keratometry and ultrasound when needed. If discrepancies in astigmatism magnitude or axis exceed 0.25 D, I repeat or delay measurements to ensure reliability before selecting an IOL.

The choice hinges on three key factors: corneal regularity, stability of astigmatism and presence of higher-order aberrations.

For eyes with regular, stable astigmatism, even in post-LASIK cases, a toric IOL can be considered, provided that the axis is consistent across measurement platforms and posterior corneal curvature is incorporated into planning. However, if the astigmatism is irregular or the axis is unstable, as in advanced keratoconus, post-RK, or decentered ablations, I avoid toric lenses. These cases are better suited for monofocal lenses with planned visual rehabilitation postoperatively.

In post-myopic LASIK or photorefractive keratectomy (PRK), I typically select monofocal or neutral aspheric IOLs to reduce the risk of hyperopic refractive surprises and to avoid amplifying existing spherical aberrations. Multifocal lenses are generally avoided due to the corneal aberration profile and reduced contrast sensitivity.

A neutral aspheric IOL (with zero spherical aberration) is particularly beneficial in eyes with negative or irregular corneal spherical aberration, such as post-myopic LASIK. These lenses help avoid compounding higher-order aberrations and provide better contrast sensitivity.

Overall, IOL selection is guided by topography, aberrometry and wavefront analysis. When aberrations dominate the visual symptoms, simpler optics, like monofocal or neutral aspheric lenses, tend to yield better functional outcomes.

Material choice is crucial in eyes with ocular comorbidities, as it can significantly impact inflammation, fibrosis and lens stability.

In uveitic eyes, I prefer hydrophobic acrylic IOLs. They are less reactive, exhibit lower rates of posterior capsular opacification (PCO) and have better biocompatibility. Their chemically inert surfaces reduce cellular adhesion and minimize inflammatory responses. I avoid hydrophilic IOLs, which are more prone to deposits, calcification and exacerbated inflammation. One-piece, square-edged hydrophobic lenses are my go-to in these cases.

In patients with diabetes, the risk of capsular contraction and PCO is higher due to blood–aqueous barrier breakdown. Again, hydrophobic acrylic lenses perform better, providing more stability and clarity in the long term. These lenses also resist opacification better than hydrophilic options, especially in patients with poor glycaemic control.

When managing eyes with weak zonular support, whether from trauma, pseudoexfoliation, or systemic conditions like Marfan syndrome, the IOL design becomes paramount. I typically select a three-piece hydrophobic acrylic IOL, which can be sutured or placed in the sulcus if needed. I also frequently use a capsular tension ring (CTR) to stabilize the bag. Hydrophilic lenses are generally avoided in these situations due to increased risk of decentration, fibrosis, or calcification in unstable capsular environments.

It is known that the major risk for IOL decentration is YAG (yttrium aluminum garnet) capsulotomy, and this is in turn related with PCO and hydrophilic IOLS.

Managing expectations is a critical, often underestimated part of refractive surgery planning. I follow a structured approach that emphasizes patient education, individualized counselling and clinical transparency.

I begin with open-ended questions to understand the patient’s visual goals: are they hoping to reduce their need for glasses? Do they prioritize reading, driving, or computer work? These insights help align IOL selection with the patient’s lifestyle and expectations.

Next, I clearly explain IOL options –monofocal, toric, multifocal, or EDOF –highlighting both the benefits and the trade-offs. For example, I describe multifocal lenses as potentially offering greater spectacle independence, but I emphasize the need for neuroadaptation and the possibility of halos or glare. Visual models or diagrams often help patients grasp these complex concepts.

I always cross-reference the clinical findings with IOL options. For instance, if macular OCT reveals an epiretinal membrane or if corneal topography shows irregular astigmatism, I advise against multifocal or premium lenses and prioritize clarity over spectacle freedom.

Setting realistic expectations is essential. I reinforce that visual outcomes can take time to stabilize and that no IOL guarantees total spectacle independence. I often use phrases like:

• “We’re aiming for excellent clarity, but you may still use glasses in some situations.”
• “Because of your eye’s history, we’re prioritizing quality of vision over convenience.”

Finally, I document the counselling discussion thoroughly and provide customized informed consent based on the chosen IOL type. During follow-up, I validate any concerns and reinforce earlier guidance, managing dissatisfaction proactively if needed.

The latest report indicates that, following cataract surgery, 74.54% of eyes achieved a prediction error within ±0.50 D, and 94.86% were within ±1.00 D.

One practice that has consistently improved my refractive outcomes is the validation of biometry and keratometry using at least two independent modalities.

Even minimal discrepancies in K-readings or axial length (particularly in post-refractive surgery eyes or those receiving premium or toric IOLs) can result in significant postoperative refractive errors. That is why I always compare data from swept-source biometry (like the IOLMaster 700 or Argos) with manual keratometry, topography or tomography (e.g. Pentacam, Galilei or Atlas).

If there is a difference greater than 0.25 D in astigmatism magnitude or axis, I either remeasure or postpone IOL planning until the measurements converge. This strategy has reduced the incidence of toric misalignment and improved the accuracy of refractive targets.

For additional reassurance, I input the validated data into multiple IOL power calculation formulas such as Barrett Universal II, SRK/T and Hill-RBF 3.0 and look for a consensus. In complex cases, this redundancy has proven invaluable. The recently introduced calculation formulas based on artificial intelligence, like Kane, Hoffer QST and PEARL DGS, also give very good results.

References

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About Prof. Grzybowski

Prof. Grzybowski is Professor of Ophthalmology at the University of Warmia and Mazury, Olsztyn, Poland, and Head of the Institute for Research in Ophthalmology, Foundation for Ophthalmology Development, Poznan, Poland. He is an internationally recognized expert in ophthalmology and artificial intelligence, with active roles in leading scientific societies, including serving as President of the European Vision and Eye Research Association (EVER, 2023–2024) and as a lifelong member and Treasurer of the European Academy of Ophthalmology.

Prof. Grzybowski is also the founder of the AI in Ophthalmology Society, a member of Academia Europaea, and has held positions within Euretina, ESCRS, ISRS, and other international organizations. He has received numerous awards and recognitions, most recently being named to The Ophthalmologist’s prestigious Power List 2025. His latest book, Artificial Intelligence in Ophthalmology, reviews current and emerging applications of AI in ophthalmic healthcare, co-authored by world-leading experts in the field.

Disclosures: Prof. Grzybowski has nothing to disclose in relation to this article. No fees or funding were associated with this article.

Citation: Expert pearls on selecting the optimal IOL. touchOPHTHALMOLOGY.com. 3 September 2025.

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