From advanced extended-depth-of-focus technologies to toric intraocular lenses, leading ophthalmologists offered valuable insights to optimize cataract surgery outcomes during the 36th Annual Meeting of the Asia-Pacific Society of Cataract and Refractive Surgeons (APACRS 2024).
Spoiled for choice? Expert views on choosing the right IOL
With the variety of intraocular lens (IOL) designs available today, how can we choose the right one for our patients?
According to Dr. Florian Kretz (Germany), selecting the appropriate IOL for a patient involves considering several factors, including the patient’s suitability for diffractive optics (considering their tolerance for halos) and the amount of corneal defocus already present.
“Not every patient needs complete spectacle independence. If you want overall vision, an extended-depth-of-focus (EDoF) and multifocal intraocular lens (MIOL) mix-and-match is a really good option. If you want to minimize dysphotopsia (visual disturbances such as halos and glare), it’s best to stay away from diffractive lenses. For patients who are comfortable using reading glasses and primarily need good intermediate to distance vision, EDOF lenses providing emmetropic vision are likely the perfect option,” explained Dr. Kretz.
Next, Dr. Lee Mun Wai (Malaysia) emphasized the importance of understanding the patient’s needs when selecting the appropriate IOL. This involves considering factors such as occupation, reading requirements, driving needs, personality and informing them about potential visual disturbances (dysphotopsias). “Utilizing a visual simulator to demonstrate dysphotopsia can effectively communicate postoperative visual experiences to the patient,” he shared.
Furthermore, Dr. Lee highlighted the significance of evaluating surgical outcomes to ensure optimal patient care. To do so, one would require continuous self-improvement, thorough examination of refractive outcomes, assessment of IOL performance and refinement of surgical techniques, he noted.
Meanwhile, Dr. Guo Haike (China) shared insights on the personalization of multifocal IOLs. He noted that eyes with a short axial length necessitate a high base refractive power, short posterior focal distance and a large depth of focus. Suitable lens options include monofocal, EDoF and trifocal lenses. Conversely, eyes with a normal axial length typically exhibit normal near vision of about 2.5 diopters (40 cm), making them suitable for bifocal, trifocal and EDoF lenses with slight monovision adjustment.
For mild myopia ranging from 15 to 19 diopters, characterized by a slightly long posterior focal distance, an additional +3 to +3.5 diopters is recommended, with bifocal or trifocal lenses being suitable choices. Conversely, in cases of high myopia with a long axial length and a small depth of field, near vision heavily relies on additional correction exceeding +3.5 diopters, warranting the use of multifocal lenses.
Patients who have undergone corneal refractive surgery require thorough evaluation, with EDoF and trifocal lenses being potential options for optimal visual outcomes, he emphasized.
Advanced EDoF technologies
Sharing insights into the latest EDoF technologies, Dr. Sheetal Brar (India) highlighted several notable options. Among them is the small aperture lens IC-8 Apthera (Bausch+Lomb), featuring a 6-mm optic with a central donut filter ring that capitalizes on the pinhole effect to effectively reduce pupil size in various lighting conditions.
Dr. Brar also mentioned diffractive ring EDoF IOLs like the TECNIS Symfony (J&J Vision), known for their track record in reducing reliance on reading glasses, especially for the intermediate range of 67 mm. “Successive diffractive rings split incoming light into a broader range, enhancing depth of focus, but may induce glare/halos,” she explained.
Another EDoF technology is the beam-shaping EDoF IOLs (Alcon Vivity) with a central 2.2 mm beam-shaping element on the optic in order to elongate the depth of focus. “It is more dependent on the patient’s pupil size. While there is no typical night glare/halos, it may result in loss in contrast, particularly at night,” explained Dr. Brar.
The question arises: can we have better EDoF lenses that not only reduce halos but also minimize the loss of light and contrast?
Dr. Brar suggested that the solution may lie in enhanced monofocal IOLs, citing examples such as the TECNIS Eyhance (J&J Vision), Isopure (BVI Medical), and Vivinex Impress (Hoya Surgical Optics). These lenses have shown statistically significant improvements in intermediate vision (60-66 mm) compared to aspheric monofocal IOLs. Additionally, distance vision is comparable to aspheric monofocal IOLs, and the photic phenomena profile is similar. Furthermore, there were no statistically significant differences in contrast sensitivity at 6 months compared to a monofocal IOL, she noted.
“EDoF IOLs, along with other newcomers like enhanced monofocal IOLs, offer exciting options for patients, enabling surgeons to customize lenses for individual needs. These advancements may likely replace standard monofocal IOLs in the future,” Dr. Brar concluded.
Meanwhile, focusing on small aperture IOLs, Dr. Robert Ang (Philippines) highlighted their efficacy in enhancing the range of vision when placed in the cornea. This concept has been extended to intraocular lenses (IOLs) to develop a non-diffractive, EDoF IOL.
He noted that the IC-8 small aperture lens offers comparable distance vision and superior intermediate and near vision compared to monofocal IOLs. It demonstrates consistent performance in eyes with 1.5 D or less astigmatism (serving as a low toric alternative) and is forgiving of refractive surprises. Moreover, it effectively filters out unwanted aberrations, rendering it an ideal choice for post-refractive surgery eyes and complex corneas.
Optimizing cataract surgery with toric IOLs
Last but not least, Dr. Chitra Ramamurthy (India) emphasized the importance of performing biometry and checking for toricity when evaluating a patient for cataract surgery. This enables informed discussions regarding the suitability of a toric IOL implant for the patient. “Also, we need to understand whether the patient has against the rule astigmatism or with the rule astigmatism,” she said.
She highlighted that planning for the worst is by doing the best before surgery. “It’s necessary to have good equipment, dedicated staff, accurate axial length and keratomy measurements and a reliable formula,” she said.
Keratometry has the potential to be one of the least accurate parts of the measurement process, due to variations in the ocular surface. Hence, Dr. Ramamurthy recommended the comparison of data from more than one modality when doing keratometry (K).
Additionally, she noted that it is very important to be able to differentiate between accurate and inaccurate data. “For example, if there’s a difference in the axial length of more than 0.3 mm, a K value difference of more than 1 D, or an IOL power difference between the two eyes of more than 1 D, repeat the measurements,” she asserted.
Editor’s Note: Reporting for this event took place during the 36th Annual Meeting of the Asia-Pacific Association of Cataract and Refractive Surgeons (APACRS 2024), held from May 30 to June 1, 2024 in Chengdu, China. The 36th APACRS annual meeting is jointly organized with the 24th CSCRS (Chinese Society of Cataract & Refractive Surgery) annual meeting.