As IOL technology has diversified, there have been advancements in IOL materials, particularly in the context of multifocal IOLs. TFNT (Acrysof PanOptix, Alcon), a globally used IOL, is the trifocal diffractive IOL based on SN-60WF (Acrysof IQ, Alcon). However, it is known that long-term issues such as glistening and surface scattering are more associated with multifocal lenses, particularly those made of the Acrysof material [
8]. Glistening refers to small, fluid-filled vacuoles that can scatter light, leading to visual disturbances like glare and halos. To address this, CNA0T0 (Clareon, Alcon) is an advanced IOL that incorporates improved material technology, transitioning from phenylethyl methacrylate (PEMA) to hydroxyethyl methacrylate (HEMA) [
9]. A new diffractive hydrophobic multifocal IOL, CNWT (Clareon PanOptix, Alcon), aims to improve near and intermediate VA while minimizing the risk of glistening [
10].
This study aims to evaluate the visual performances and patient satisfaction of individuals who underwent bilateral implantation of Clareon PanOptix IOLs, through a comprehensive analysis of monocular and binocular visual outcomes, defocus curves, and patient-reported experiences.
Materials and Methods
This study was approved by the Institutional Review Board of Kangbuk Samsung Hospital (No. 2022-10-033-003). Informed consent was obtained from all participants before enrollment. The study adhered to the principles outlined in the Declaration of Helsinki
This prospective study enrolled patients with age-related cataracts who underwent bilateral cataract extraction via phacoemulsification and received bilateral implantation of the trifocal CNWT IOL. All participants, aged 50 years or older, consented to undergo surgery for the second eye within a week following the initial surgery. Inclusion criteria comprised individuals with a postoperative visual potential of 20/25 or higher and preoperative corneal astigmatism of 0.75 diopters (D) or less. Exclusion criteria were the same as in a previous study [
11]: (1) pregnant and lactating women; (2) patients with a history of retinal disease, ocular trauma, or ocular surgery with evidence of keratoconus or significant irregular astigmatism; (3) patients who had worn rigid contact lenses within the past 6 months, gas-permeable lenses within the past month, or longer wearing times or daily soft contact lenses within 7 days of scheduled surgery; (4) patients with other diseases affecting capsule stability such as pseudoexfoliation syndrome, glaucoma, traumatic cataract, or Marfan syndrome; and (5) patients who were not able to read or understand the informed consent.
For preoperative assessment, all patients received ophthalmic examinations including uncorrected distance VA (UDVA), corrected distance VA (CDVA), uncorrected intermediate VA (UIVA) at 66 cm, uncorrected near VA (UNVA) at 40 and 33 cm, topography (Galilei G6, Ziemer Ophthalmic Systems AG), corneal aberration (OPD SCAN, NIDEK Inc), optical biometry and keratometry (IOLMaster 700, Carl Zeiss Meditec), slit-lamp examination, and funduscopy. All visual acuities were checked using ETDRS (Early Treatment Diabetic Retinopathy Study) charts (Vector Vision Ltd).
All surgeries were performed by two operators (CYC, KT) in two institutions, involved a 2.2-mm corneal incision, manual capsulorhexis, and phacoemulsification under topical anesthesia, with IOLs implanted in the bag. Postoperative refraction aimed at the nearest negative value from emmetropia using the Haigis formula for IOL power calculation.
Follow-up examinations were conducted at 1 week, 1 month, and 3 months after fellow eye IOL implantation. Main outcomes included VA, monocular and binocular defocus curves, and patient questionnaires. UDVA, CDVA, UIVA at 66 cm, and UNVA at 40 and 33 cm were measured. Uncorrected monocular and binocular defocus curves ranged from +1.00 to −4.00 D in 0.50 spherical D intervals. A questionnaire assessed subjective satisfaction, spectacle independence, spectacle-free vision satisfaction, and subjective photic phenomena. During the subjective assessment of photic phenomena, simulation images were given to the patients representing various types and degrees of photic phenomena (
Fig. 1A-1D). Subsequently, they were instructed to indicate the severity level on a scale consisting of four options: none, mild, moderate, and severe.
Statistical analyses used IBM SPSS ver. 24.0 (IBM Corp), presenting continuous variables as means ± standard deviations. The Wilcoxon signed rank test analyzed preoperative and postoperative variables, considering a p-value less than 0.05 as statistically significant.
Discussion
This study analyzed the outcomes of binocular implantation of the CNWT IOL, exploring monocular and binocular visual performance at diverse distances (4 m, 1.5 m, 40 cm, 33 cm), defocus curves, photic phenomena, and spectacle independence. Previous research indicates that multifocal IOL implantation extends the range of vision and enhances spectacle independence compared to monofocal IOLs [
12-
15].
In previous studies, some authors reported that Acrysof material is associated with glistening [
16]. Tognetto et al. [
17] showed higher percentage and greater density of glistening in Acrysof group compared to other intraocular lenses. Other study reported SN60WF showed mean glistening density (microvacuole [MV] per square millimeter) of 264.4 ± 110.3 MV/mm
2 and mean Miyata grading of 2.6
in vitro glistening formation [
18]. Another study detected mean number of microvacuoles of Acysof model (47-650 MV/mm
2), in contrast to the Clareon model group (1 ± 1 MV/mm
2), showing Clareon materials greater resistance to glistenings compared to the Acrysof model [
19]. In addition, long-term clinical observation study showed glistenings and surface light scattering did not develop with Clareon IOLs during 9-year observation [
20].
To address the issue of glistening, CNA0T0, a novel IOL replacing material of PEMA to HEMA, was introduced. HEMA is a hydrophilic polymer that may contain 1.5% increased water content. Therefore, lens clarity with less glistening is gained [
10]. According to this point, CNWT was released recently which is made of CNA0T0 material with optical structure of TFNT. The objective of this study is to assess the updated clinical results and gauge patient satisfaction among individuals receiving the trifocal IOL with new IOL material, providing valuable insights for ophthalmic clinicians and surgeons.
Patients with bilateral CNWT IOL implantation showcased enhanced visual acuities at far, intermediate, and near distances. The mean intermediate VA, illustrated in
Fig. 2, exceeded 0.1 logMAR for all patients, indicating proficient vision for tasks like computer work. These findings align with previous studies reporting good VA at all distances, particularly excellent intermediate vision with TFNT IOL [
14]. Additionally, trifocal IOLs, especially TFNT IOLs, exhibited superior intermediate performance compared to bifocal and other trifocal IOLs [
15]. In terms of mean near VA at 33 cm distance, 85% and 90% of patients achieved monocular and binocular UNVA of 0.1 log-MAR or better, respectively, indicating the common ability to read J2 letter size at near distances without glasses.
The study included an assessment of the uncorrected defocus curve, recognizing the limitation of the corrected defocus curve in representing real-life scenarios [
21]. VA results were supported by the outcome of the binocular defocus curve which showed that the lens provided consistently excellent vision of approximately 0.1 logMAR or better between +0.50 and −2.50 D, from distance to near. The binocular uncorrected defocus curve showed a plateau without clearly evident peak in range between +1.00 and −3.00 D (corresponding in distance to the interval between 100 and 33 cm), suggesting stable intermediate vision. On the contrary, as the defocus diopter decreased (−3.00 to −4.00 D, corresponding to visual distances of 33 and 25 cm), a progressive decrease of the curve was observed, while the VA at near distance was remained between 0.07 and 0.27 logMAR. Previous studies have shown similar defocus curves to the ones obtained in our study [
22]. Also, in previous studies, −2.50 to −3.00 D (corresponding to 40 to 33 cm) are often used as the near range in the defocus curve [
23,
24]. However, in this study, we assessed the patient’s functional vision at even closer distances by expanding the range of defocus curves to encompass up to −4.00 D (corresponding to 25 cm). We can speculate that our result of progressive decay of VA at near distance (−3.50 to −4.00 D) occurred due to the difference measuring range of near distance in this study compared to previous studies.
This broad range of good VA is important in reducing patients’ reliance on glasses for daily activities. Spectacle independence at intermediate distances was achieved in all patients, while the rate of spectacle independence was just slightly lower at the near distance (95.0%) and far distance (97.5%) in this study. Out of 40 patients only two (5.0%) and one (2.5%) reported that they required glasses for near and far vision, respectively. In a previous study, over 80% of patients with Acrysof PanOptix IOL reported never needing eyeglasses to see [
23]. In other study, 90% or more of subjects reported never wearing glasses or wearing them only a little [
25]. Kohnen et al. [
14] reported complete spectacle independence in 96% of patients. In line with previous studies, Clareon PanOptix IOL in our study exhibited a high level of spectacle independency.
A Cochrane review about multifocal IOLs found that photic phenomena are 3.5 times more likely with multifocal IOLs than with monofocal IOLs [
13]. In this study, we evaluated the patients’ experiences with optic phenomena to better understand their satisfaction in their real life. Mild optic phenomenon (43%) was the most common by the respondents in this study. The proportion of patients who did not experience photic phenomena was 20%. Nevertheless, patient satisfaction of spectacle-free remains high in all distances.
In prior studies, reported outcomes on photic phenomena have varied significantly. Kohnen et al. [
14] found that 93% of patients experienced optic phenomena, whereas Ramamurthy et al. [
24] reported 86.6% of patients indicating “none” to “only some of the time” for optic phenomena. Galvis et al. [
22] noted 6.1% of participants expressing “some difficulties in daily life” related to photic phenomena. It is important to note that differences in question wording and discomfort level categorization among studies make direct comparisons challenging. In a study conducted in Germany by Kohnen et al. [
14], may have yielded a higher proportion of bothersome responses due to factors like lighter iris color and larger scotopic pupil size. Additionally, the studies did not analyze the duration of optic phenomena; only their presence and frequency were assessed. Prior research suggests that neuroadaptation after multifocal IOL surgery could alleviate these optical phenomena over time. Typically, this process takes a minimum of 3 months and up to 1 year. However, our study’s last follow-up was at 3 months, during the ongoing neuroadaptation process. It could be assumed that challenges related to optical phenomena might decrease over time; hence, further research with an extended follow-up is necessary. Subsequent studies should also investigate other visual disturbances linked with multifocal IOLs, including halo, glare, starbursts, hazy vision, blurred vision, distortion, and multiple images, providing a more comprehensive understanding of their impact on both vision quality and overall quality of life.
This study has several limitations, including a relatively short follow-up period, a small sample size, and a homogeneous Korean population. The absence of measurements for contrast sensitivity and reading speed, common limitations of multifocal IOL studies, is another drawback. Additionally, restricted patient participation in certain tests, with only 20 patients undergoing VA tests and a defocus curve, further limits the generalizability of the findings. As the follow-up period was short, confirming the long-term stability and superiority of the new material was not clearly feasible. Consequently, further follow-up observations and investigations are needed.
Prior studies on Clareon material IOLs have demonstrated reduced susceptibility to complications like glistening. Likewise, research on PanOptix IOLs has underscored the lens’s ability to provide VA with wide range of distances. Our study demonstrated good uncorrected far and intermediate visual acuities. Our results show that the Clareon PanOptix IOL’s new composition, which combines the optical characteristics of Clareon material IOLs and the multifocal characteristics of PanOptix trifocal IOLs, demonstrates outcomes consistent with prior investigations conducted using each individual composition [
11,
22,
24,
26].
In conclusion, bilateral implantation of Clareon PanOptix CNWT IOL demonstrated excellent visual outcomes at distance, intermediate and near. Spectacle independence was high at all distances. Thus, these IOLs can offer patients a good option for cataract surgery that aligns with their visual needs and expectations seeking to reduce their dependence on spectacles across a wide range of vision especially a specific visual quality for near tasks.