HM is an increasing ocular disease worldwide. In China, it has become and is a cause for concern. With the increase in HM patients that also have cataracts, the challenge is how to improve the postoperative visual quality of these patients. It is, therefore, important for ophthalmologists to investigate how to choose the ideal IOLs for HM patients combined with cataract.

Alignment of the IOL is the most important factor affecting visual quality after cataract surgery. Tilt and decentration are the indicators most frequently used to evaluate IOL alignment. Previous literature speculates that long axial length might decrease the position stability of the intraocular lens, resulting in more rotation as well as poorer zonule stability [14, 15], which are the causes of postoperative IOL displacement. However, our study shows that there was no significant correlation between AL and the degree of postoperative IOL displacement, and the position of postoperative IOL depends more on the position of the preoperative CLL. We speculate that different operating habits as well as phacoemulsification energy using habits of different surgeons may affect the IOL position of in HM eyes following cataract surgery.

In this study, the preoperative and postoperative lens position characteristics of patients with HM combined with cataract were recorded by AS-OCT and compared with those of the normal AL population. The position misalignment of IOLs in cataract patients with high myopia mainly depends on the position misalignment of the CLLs; tilt was not affected by the length of the AL, and even showed a decrease with the growth of AL. It has been consistently believed that the AL has a strong positive relationship with IOL’s tilt compared to CLL’s, which has not been observed in our study. This may be due to the fact that the longer AL concentrates on the elongation of the posterior pole of the eye and has little or no effect on the stretching of the anterior face of the eye [18]. Decentration of the IOLs is greater than preoperatively, which may be due to the fact that the transverse diameter of the IOL tends to be smaller than of the CLLs, so that the IOL becomes more mobile in the capsular bag. Zhu et al. also point out that longer ALs have an effect on capsule size, which means the incompatibility between IOLs and capsule size should not be underestimated in HM eyes [19]. Tokuhisa et al. suppose that the IOLs often have a larger space for movement compared to CLLs [20,21,22].

Our research has many limitations. First, the limited number of participants. It needs to be expanded to make the data more independent in subsequent research. In this study, we focused on the comparison between the EM and HM groups. Our observations show that the mean age of the HM group in this study was significantly younger than of the EM group. Upon reviewing the ophthalmological examination results, we hypothesize that this discrepancy arises from the fact that the HM participants predominantly underwent cataract surgery due to severe nuclear lens opacity causing visual impairment, whereas the EM participants primarily experienced vision problems associated with age-related cortical lens opacity. These objective findings should be systematically documented in subsequent research using the Emery-Little classification to elucidate the underlying mechanisms contributing to the observed age differences between these distinct cohorts. Second, our current research remains primarily focused on the processing and analysis of examination data, with a notable absence of objective evidence regarding patients' visual quality assessment. Numerous factors could influence the postoperative visual quality of patients, necessitating further refinement and supplementation in subsequent research. Moreover, due to the methodological constraints of AS-OCT's bilateral eye measurements conducted separately, the obtained results exhibit slight discrepancies from the patient's binocular visual results. Nevertheless, it remains one of the most accurate diagnostic approaches currently available for assessing patients' visual conditions.

Notwithstanding the aforementioned limitations, the position-stable result of IOLs in the HM group is rarely mentioned in the existing literature, this structural characteristic as well as the mechanism that makes the alignment of IOLs stable need to be further studied and explained. Our research indicates that while the magnitude of IOLs decentration in the HM group significantly increased following cataract surgery, the magnitude remains insufficient to induce visual quality impairment. Consequently, a longer AL does not contribute to an additional risk of visual quality issues associated with IOLs decentration post-cataract surgery. Since HM has greater variability in decentration compared to EM, it is recommended to examine the detailed parameters of CLLs using AS-OCT before inserting multifocal intraocular lenses. The decentration and tilt of IOLs are the most frequently observed indicators after the wide application of AS-OCT. The magnitude of decentration or tilt is considered an important factor affecting visual quality. It cannot be denied that the tilt of IOL is naturally accompanied by decentration, to a greater or lesser extent. However, as two sets of data that can be independently quantified by the AS-OCT, they have been widely used in existing studies to discuss and research the position of IOLs. Perhaps with the continuous development of inspection technology, there will be more rigorous measurement indicators for research and discussion in the future. One crucial aspect that cannot be overlooked is that the measurement and collection of parameters mentioned in this paper depend on AS-OCT, a new measuring method that will contribute to better understanding of ocular conditions.

In this study, AS-OCT was used to further explore the influencing factors of IOL location in patients with high myopia complicated with cataract. The study reveals that the relationship between the magnitude of tilt and decentration of IOLs and the AL was determined, the alignment of CLL determines IOL position in HM eyes, filling the current research blind spot.