Art and science of presbyopia correction

Today’s patients are not only well informed—many arriving at consultations with anecdotal comparisons and lofty goals—but also diverse in their visual needs, lifestyle demands, and ocular anatomy. At the same time, the availability of advanced diagnostics such as iTrace, OPD-Scan III, and ray-tracing aberrometers has given clinicians a more refined understanding of corneal aberrations, dysfunctional lens indices, and visual performance metrics. This precision enables a more personalized approach to IOL selection but also requires thoughtful integration of biometric data, ocular comorbidities, patient psychology, and even personality traits.

In an in-depth interview with Ophthalmology Times, Zach R. Balest, MD, a staff ophthalmologist at North Georgia Eye Associates, and Lisa K. Feulner, MD, PhD, chief medical officer and founder of Advanced Eye Care and Aesthetics in Bel Air, Maryland, provide a candid look at how leading cataract surgeons approach IOL counseling, manage expectation gaps, and tailor premium lens strategies to the unique anatomy and goals of each patient. From technology utilization to the role of artificial intelligence (AI) to the clinical red flags that influence lens selection, this discussion explores both the art and science of modern presbyopia correction.

Note: This interview has been edited for length and clarity.

Ophthalmology Times: Presbyopia-correcting IOLs have come a long way in recent years. How have patient expectations changed?

Zach R. Balest, MD: Patient expectations with cataract surgery have never been higher. It seems every patient knows someone who has had surgery and no longer needs any correction, and many walk in the door with that expectation. Although this outcome is not realistic for everyone, we have a great deal of technology at our disposal that can help achieve great outcomes with varying levels of spectacle independence. In my experience, the most vital part to ensuring a happy patient is setting realistic expectations prior to surgery based on each patient’s individual case.

Lisa K. Feulner, MD, PhD: Cataract surgery has become more of a refractive procedure these days due to increased patient expectations for spectacle-independence. Presbyopia-correcting IOLs can provide patients with near spectacle-free vision; however, not all patients are ideal candidates for such IOLs. For instance, presbyopia-correcting IOLs are not recommended for patients with coexisting corneal comorbidities due to the increased risk of reduced contrast sensitivity and increased photic phenomena owing to the presence of increased corneal higher-order aberrations (HOAs). Also, inaccurate IOL power calculations due to altered anterior-to-posterior corneal curvature ratio can lead to refractive surprises after cataract surgery. Newer IOL technologies that can extend the depth of focus and reduce the impact of corneal aberrations are now available for patients with compromised corneas.

When you meet a patient interested in lens surgery for presbyopia, what’s your overall approach to evaluating their candidacy and setting the tone for that discussion?

Balest: I start the process with all IOL categories on the table and remove individual options as we go. Given the significant number of IOLs available, it is important to narrow down the options, so the patient is not overwhelmed. I use the exam and preoperative testing, which includes biometry, corneal topography/tomography, and retinal optical coherence tomography, to remove options that will not work well for that individual patient.

Then I have a discussion with the patient, with the goal of narrowing the list down to only a couple of options. I discuss the patient’s hobbies and visual goals for after surgery. I like to know at what distances they are using correction currently and what they are willing to do after surgery. I also determine whether their priority is to achieve the highest-quality vision with less nighttime symptoms or as much spectacle independence as possible. I then present the remaining options to the patient, making sure to explain the pros and cons of each option.

Feulner: Standard monofocal IOLs only restore vision at 1 focal point and can be used in most patients, resulting in excellent vision with or without glasses. To address the limitation of needing glasses for other focal points, newer IOLs utilizing different technologies have been developed to reduce spectacle dependence, extend the depth of focus, and improve uncorrected intermediate and near vision. Previously, patients with comorbid corneal disease have been limited to monofocal options, often resulting in total dependence on spectacle correction, but newer IOL options to improve spectacle independence are now available to a broader subset of these patients.

I start with a standard lifestyle questionnaire, which I review prior to meeting the patient. The questionnaire gives me clues to the patient’s visual difficulties, lifestyle, and expectations before I enter the room. It’s important to assess the patient’s personality, visual goals, health and ocular history, and exam to match the right lens choice to the patient. Based on this, I am already considering whether the patient would be best suited for a monofocal with distance or near, monovision with an enhanced monofocal, or mini-monovision. Are they suited for a multifocal, trifocal, or EDOF for more spectacle independence, or do they have a history of prior refractive surgery or corneal abnormalities that make them a better candidate for a small-aperture IOL or a light-adjustable lens?

Advanced technology lenses work best in pristine eyes. Problems with ocular alignment, pupil size, ocular surface disease, irregular astigmatism, corneal dystrophies, scarring, and diseases of the retina and optic nerve limit successful utilization of these technologies

Once I have reviewed the lifestyle questionnaire, past medical history, and ocular history, I review the data collected by an OPD-Scan III and an iTrace. Both technologies help me quickly assess a patient’s candidacy for a lens beyond a monofocal. I work off an iPad and often review this data quickly before I enter the room. With the OPD III I’m looking at:

• Placido rings: clear, sharp, concentric
• Corneal total coma HOA: < 0.32
• Astigmatism: regular vs irregular
• Angle κ (the angular distance between the pupillary axis and visual axis): < 0.6
• Chord mu (the 2-dimensional linear distance between the center of the pupil and the cornel light reflex; often used to approximate angle κ
• Angle α (the angle between the visual axis and the optical center, ie, how much the visual axis is offset from the geometric center): < 0.5
• Photopic and mesopic pupils: > 3 mm photopic and < 6 mm mesopic
• Root mean square value: higher than 0.43 at the 3-mm zone (ie, HOAs are influencing the visual system)

The iTrace lets me evaluate their corneal quality (corneal performance index) both in photopic and mesopic settings and the impact of their cataract (illustrated by the dysfunctional lens index), and then it concisely combines the two to give me a Quality of Vision Index score. This is helpful to quickly determine whether the degree of cataract is consistent with their visual complaints and visual acuity or whether I should be looking for other pathologies. The iTrace also gives me an excellent evaluation of their tear film and ocular surface. I can evaluate the data generated by these 2 technologies in less than a minute. This really cuts down on the time I spend with patients discussing lenses that they are not candidates for while giving me an opportunity to visually show the patient how different IOLs can meet their expectations. Then, of course, I examine the patient and evaluate the ocular surface, cornea, optic nerve, and retina.

How do you explain the differences between monofocal, multifocal, EDOF, light-adjustable, accommodating, and small-aperture IOLs to patients?

Balest: For patients with lower amounts of corneal astigmatism, I let them know that a monofocal IOL provides very high-quality vision at 1 distance but that it has the least amount of range out of our options. I tell them that the trifocal is going to provide the greatest range of vision but that it does come with some trade-offs such as halos/glare at night and the potential of slightly reduced quality of vision. I like to describe EDOF lenses as hybrid lenses that provide some extra range of vision but with adverse effects similar to a monofocal; I also let them know that the near vision is a little less predictable in that category, with some patients having better near than others.

More recently, we have had the benefit of small-aperture IOLs, which I explain work differently and are able to provide a good range of vision, with the downside being some patients notice dimness in the treated eye compared with the other eye. I also utilize a lot of blended/mini-monovision in my practice and discuss that option when warranted.