The best choice for low and moderate myopia patients incapable for corneal refractive surgery: implantation of a posterior chamber phakic intraocular lens

Endothelial cell loss post-implantable collamer lens V4c: meta-analysis

Endothelial cell density (ECD) loss is a noted effect of implantable collamer lens (ICL) V4c surgery. Current literature provides a wide range of values for ECD loss postsurgery, which may not be helpful in advising patients and clinicians. A meta-analysis exploring ECD loss in ICL V4c for myopia correction was undertaken. 18 studies were included in this meta-analysis with 2 subgroup analyses to account for the variability in follow-up lengths. The average ECD loss 3 months, 12 months, and 21.25 (mean) months postsurgery were 1.32% ± 1.28% ( P < .001, 95% CI, -75.158 to -1.19), 1.75% ± 2.17% ( P < .001, 95% CI, -134.09 to 14.52), and 3.84% ± 1.78% ( P < .001, 95% CI, -156.04 to -54.26), respectively. ECD loss is most pronounced 3 months postsurgery, suggesting that acute surgical trauma was the primary contributor rather than long-term lens implantation. Overall, ICL V4c is for myopia correction exhibits similar ECD loss as seen in other ICL models, thereby affirming its safety.

Choice of refractive surgery types for myopia assisted by machine learning based on doctors' surgical selection data

In recent years, corneal refractive surgery has been widely used in clinics as an effective means to restore vision and improve the quality of life. When choosing myopia-refractive surgery, it is necessary to comprehensively consider the differences in equipment and technology as well as the specificity of individual patients, which heavily depend on the experience of ophthalmologists. In our study, we took advantage of machine learning to learn about the experience of ophthalmologists in decision-making and assist them in the choice of corneal refractive surgery in a new case. Our study was based on the clinical data of 7,081 patients who underwent corneal refractive surgery between 2000 and 2017 at the Department of Ophthalmology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences. Due to the long data period, there were data losses and errors in this dataset. First, we cleaned the data and deleted the samples of key data loss. Then, patients were divided into three groups according to the type of surgery, after which we used SMOTE technology to eliminate imbalance between groups. Six statistical machine learning models, including NBM, RF, AdaBoost, XGBoost, BP neural network, and DBN were selected, and a ten-fold cross-validation and grid search were used to determine the optimal hyperparameters for better performance. When tested on the dataset, the multi-class RF model showed the best performance, with agreement with ophthalmologist decisions as high as 0.8775 and Macro F1 as high as 0.8019. Furthermore, the results of the feature importance analysis based on the SHAP technique were consistent with an ophthalmologist's practical experience. Our research will assist ophthalmologists in choosing appropriate types of refractive surgery and will have beneficial clinical effects.

Visual Acuity Improvement in Low, Moderate and High Myopia After Posterior-Chamber Phakic Implantable Collamer Lens Surgery in a Large Patient Cohort

Purpose

To compare best-corrected visual acuity (BCVA) before and after implantable collamer lens (ICL) surgery in patients with low, moderate and high myopia.

Methods

A single-centre, prospective, registry-based study involving patients with myopia who received ICLs between October 2018 and August 2020. The study population was divided into three groups of subjects with low (from 0 to -6 D), moderate (-6 to -10 D) and high myopia (more than -10 D). We analysed uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), spherical equivalent (SE), differences between BCVA pre- and 1-month postoperative, and line gain in BCVA 1 month after surgery.

Results

A total of 770 eyes belonging to 473 patients were surgically intervened during the study period, of which 692 eyes completed 1 month of postoperative follow-up and were included in the study population. At 1-month follow-up, 478 eyes (69%) achieved a BCVA of 20/20, 599 (87%) obtained 20/25 or better, and 663 (96%) had a BCVA of 20/40 or better. We identified a significant improvement in BCVA (baseline 0.15±0.2 logMAR vs follow-up 0.07±0.2 logMAR, p<0.0001) and a significant reduction in SE (baseline -9.23±4.1 D, vs follow-up -0.21±0.8 D, p<0.0001), with a significant relationship between preoperative SE and line gain (r = -0.46, p<0.0001). We identified a significantly higher line gain among eyes with higher degrees of myopia (low myopia 0.22±0.69 lines compared to moderate myopia 0.56±1.1 lines and high myopia 1.51±1.9 lines, p<0.0001). Notably, 99.6% of eyes with a high grade of myopia achieved improvement to a low degree (less than -6 D) at follow-up. The safety and efficacy indexes were 0.083±0.1 and -0.001±0.1, respectively.

Conclusion

In this large patient cohort, ICL surgery was related to a significant line gain in BCVA, particularly among eyes with higher degrees of myopia.