In this real-life study, we reported an original 3-year overview of the refractive stability and safety of the Clareon® IOL. In the immediate postoperative time, the mean UDVA (≥ 0.097 logMAR or 20/25 Snellen equivalent) allowed spectacle independence in at least three quarters of the patients for activities at far distances such as driving. This result remained stable over time. The UDVA is poorly described in the literature unlike the CDVA. Nevertheless, this result should be considered when planning refractive cataract surgery, especially in elderly patients who may lose their spectacles and thus experience difficulties. Indeed, Knudtson et al. have reported an association between poorer VAs and an increased risk of falls [9]. For example, some elderly patients may wake up and get up during the night with no need to immediately find their spectacles.

Moreover, at the time of refractive cataract surgery, the UDVA is one of the best biomarkers for efficacy and well-being. Our results are consistent with those of Lehman et al. [10], Stanojcic et al. [11], and Titiyal et al. [12] who have assessed the Clareon® IOL but their follow-up was reduced to 1 year. Regarding the CDVA, a high VA (mean: 0.003 LogMAR) was also maintained at 3 years. Other teams have published similar results with a follow-up ≤ 1 year [13], [14], [5], [10]. Very recently, Nuijts et al. reported similar functional results in a prospective study with a three years follow up [6].

This result highlighted the good tolerance of the Clareon® IOL since it is well known that a PCO can impair the vision in the years following cataract surgery. This point was discussed below.

The subgroup analyzes performed according to the AL were reassuring. No significant differences were found between the short, normal and long ALs, except for the UDVA at 3 years between the short and normal ALs. This difference was not observed for the CDVA. This finding could indicate that short eyes could be more prone to refractive changes at 3 years. Nevertheless, the size of the subgroup was limited, and this specific isolated result needs to be confirmed in a larger sample. The absence of difference in UDVA regardless of the subgroup suggested that, even in small capsular bags (i.e., in case of short AL), the Clareon® IOL was stable and no axial displacement led to refractive errors.

In the three subgroups, the VA was also remarkably stable during the follow-up.

Regarding capsular transparency, no clinically significant PCO was observed in 95.3% of patients at 3 years. In other words, Nd:YAG capsulotomy was only required in 4.7% of patients, in line with the Nd:YAG rate of 4.7% reported by Ursell et al. with the AcrySof IOL in their British large data study [3] and by Nuijts et al. in their international and prospective study assessing the Clareon® material [6]. Maxwell et al. have described a lower capsulotomy rate of 1.4% at 3 years in 138 patients but the design of their study was different, and they have used a three-piece IOL composed of the same Clareon material [15]. These results in terms of transparency are encouraging knowing that a recent register study that has assessed over 6,000 thousand surgical procedures has identified that 4.2% of PCO required Nd:YAG treatment at 3 years for hydrophobis IOLs [16]. This is in contrast with a recent national study based on the claims of 6,210 patients which has recently reported that a third of the patients required Nd:YAG capsulotomy within the 2 years following surgery for all IOLs grouped [17]. The impact of Nd:YAG capsulotomy has been highlighted in this study, reporting that early post-cataract capsulotomy was a main driver for adverse event occurrence, especially for ocular hypertension and macula edema. Thus, the use of Nd:YAG capsulotomy should be reduced and delayed as much as possible in our daily practice. PCO occurrence is multifactorial and the IOL material is known as one of the key triggering factors. Indeed, Ursell et al. have reported that the rate of capsulotomy was 2–3 times higher when hydrophilic materials were used [3]. The good safety of the recent Clareon hydrophobic IOL was confirmed in our study with a low rate of capsulotomy; in addition, no capsulotomy was performed before the third year.

Among the 9 patients who needed Nd:YAG treatment, two were under the age of 60 and five presented with systemic or ophthalmological conditions for which local or general medication was needed such as open-angle glaucoma, epiretinal membrane, branch retinal vein occlusion. A young age and a history of vitrectomy are known risk factors for PCO [18]. Glaucoma has also been recently described as a factor contributing to fibrosis development by Dot et al [17]. Proinflammatory profiles have also been described as a risk factor for PCO [19].

Regarding Clareon lens ageing, no surface haze was noted during the follow-up as recently reported by Titiyal et al [12]. Very few and asymptomatic patients presented with low-grade glistening at 3 years, supporting a safe evolution of the yellow Clareon material. This result is in line with the findings of experimental studies that have shown the superiority of the Clareon IOL over hydrophobic IOLs in terms of glistening rate [2], [20]. This is also in line with the results of Stanojcic et al. who have described only 4 out of 68 eyes implanted with Clareon IOLs experiencing glistening < 10 nanovacuoles per mm2 at 1 year [11]. Nuijts et al. have recently reported a grade 0 glistenings in 100% of the cases at three years [6]. We have also used the Miyata classification in which Grade 0 corresponds to very few microvacuoles (0–25/mm2), a data that has been interpreted as glistening free in the recent papers including ours [6].

The resistance of the Clareon IOL to PCO and glistening could be explained by the modified HEMA material. This material binds less to the proteins of the extracellular matrix. The edge design is quite similar to that of the AcrySof IOL in order to block proliferation [21].

There are other complications that a surgeon must face in the long term (related or not to the IOL), mainly retinal detachment [17], which was not described in our cohort on the 191 eyes analyzed at 3 years (including the patient who experienced the capsular rupture). Post-operative macular edema should also be screened, as its early resolution generally does not impair visual acuity, as in the 2 patients in our study. We cannot rule out that postoperative macular oedema may have been overlooked due to the decrease in the cohort over time.

Our study has some limitations, including its retrospective design. Analyses at 3 years were performed on 59% of operated patients. The design did not allow achieving a stable efficacy over time for all the patients and the samples could not be paired, nevertheless this was not the primary endpoint. Also, the monocular VA was only assessed as usually performed in our daily practice. Binocular results would be interesting and could increase the rate of spectacle independence, which is already high. The 3-year visit was performed at the patients’ discretion as suggested immediately after surgery, and this could have induced a bias that increased the rate of Nd:YAG capsulotomy.

The strengths of this study were its long follow-up and the 3-year collection of data on the Clareon® IOL in a real-life setting with less stringent patient selection and more representative of daily practice compared to prospective and randomized studies. The UDVA was systematically assessed and showed the good refractive outcome of this IOL at the time of refractive cataract surgery, and it confirmed the accuracy of the chosen A constant. Only two senior MD performed the postoperative visits to grade PCO and glistening the same day with a double-blind lecture, according to the Miyata’s classification.

This study reports high-performance long-term refractive and functional outcomes of the Clareon® IOL with good safety in terms of PCO and glistening. These findings suggest that the Clareon® IOL and its material could be an interesting and performing choice for upcoming premium IOLs to be implanted in cataract surgery.