Implantable Collamer Lens V4c Research Articles

Clinical Observation of Posterior-Chamber Phakic Implantable Collamer Lens V4c Implantation in Myopic Patients with Shallow Anterior Chamber Depth: A Retrospective, Consecutive Observational Study.

The reference range for the preoperative anterior chamber angle width for ICL surgery is unclear. Our objective was to assess the clinical effect and the range of anterior chamber angle width of posterior-chamber implantable collamer lens V4c (ICL V4c) implantation in patients with anterior chamber depth (ACD) < 2.8 mm. Patients who underwent ICL V4c implantation with shallow ACD were included in this retrospective study. The patients' uncorrected and corrected distance visual acuity, angle of trabecular-iris (TIA), angle-opening distance (AOD500), trabecular-iris space area (TISA500), corneal endothelial cell density, vault, retinal nerve fiber layer thickness, intraocular pressure, visual field, and complications were analyzed. Forty-one patients (68 eyes) completed at least 12 months of follow-up (median follow-up, 30 months). The effectiveness and safety indices were 1.09 ± 0.13 and 1.04 ± 0.21, respectively. The preoperative TIA values on the nasal and temporal sides were 39.78 ± 7.68 degree (range, 25.8-65.1 degree) and 41.54 ± 8.03 degree (range, 28.5-63.00 degree). Forty-seven eyes had uncorrected distance visual acuity ≥1.0, and 55 had corrected distance visual acuity ≥1.0 at the last follow-up visit. The TIA, AOD500, and TISA500 on the nasal and temporal sides were significantly reduced compared to those before surgery (all P < 0.01); no eye had an angle closure or elevated intraocular pressure. The ICL V4c vault was 290.88 ± 153.36 μm (range, 60.0-880.0 μm). No severe complications occurred in any patient. In patients with myopia with shallow ACD (2.55-2.79 mm), a preoperative TIA >25.8° is safe and effective for a relatively long time after surgery; however, an extended long-term close follow-up is needed.

Ten-year follow-up of posterior chamber phakic intraocular lens with central port design in patients with low and normal vault.

To assess the clinical outcomes and postoperative complications of the implantable collamer lens (ICL) with a central port throughout 10 years of follow-up in patients with low and normal vault. Fernández-Vega Ophthalmological Institute, Oviedo, Spain. Retrospective and comparative case series. This study included eyes that underwent a V4c ICL implantation with 10 years of follow-up. The eyes were divided into 2 groups according to the vault at 1 year postoperatively: vault <250 μm and between 250 μm and 800 μm. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), intraocular pressure (IOP), endothelial cell density (ECD), vault, complications, and secondary surgeries were analyzed. 37 and 90 eyes were enrolled in the low and normal-vault groups, respectively. No differences in UDVA, CDVA, and refraction were found between the groups over 10 years of follow-up. No cases developed ICL-induced anterior subcapsular opacity over the follow-up period. 2 (5.4%) and 8 (8.9%) eyes in the low and normal-vault groups, respectively, required ICL exchange. 1 (2.8%) and 2 (2.2%) eyes in the low and normal-vault groups, respectively, required excimer laser to correct residual refractive error. The IOP remained stable throughout the 10-year follow-up. The loss in ECD from that preoperatively to 10 years postoperatively was 3.8% and 4.5% in the low and normal-vault groups, respectively ( P = .4). No pigment dispersion glaucoma or other vision-threatening complications were reported. This study shows good long-term outcomes of the V4c ICL, supporting that the central hole provides safety to the procedure and prevents the potential risk associated with low vault.

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.

Predictability comparison of sizing parameters for postoperative vault after implantable Collamer lens implantation.

This study aims to assess the accuracy of three parameters (white-to-white distance [WTW], angle-to-angle [ATA], and sulcus-to-sulcus [STS]) in predicting postoperative vault and to formulate an optimized predictive model. In this retrospective study, a cohort of 465 patients (comprising 769 eyes) who underwent the implantation of the V4c implantable Collamer lens with a central port (ICL) for myopia correction was examined. Least absolute shrinkage and selection operator (LASSO) regression and classification models were used to predict postoperative vault. The influences of WTW, ATA, and STS on predicting the postoperative vault and ICL size were analyzed and compared. The dataset was randomly divided into training (80%) and test (20%) sets, with no significant differences observed between them. The screened variables included only seven variables which conferred the largest signal in the model, namely, lens thickness (LT, estimated coefficients for logistic least absolute shrinkage of -0.20), STS (-0.04), size (0.08), flat K (-0.006), anterior chamber depth (0.15), spherical error (-0.006), and cylindrical error (-0.0008). The optimal prediction model depended on STS (R2=0.419, RMSE=0.139), whereas the least effective prediction model relied on WTW (R2=0.395, RMSE=0.142). In the classified prediction models of the vault, classification prediction of the vault based on STS exhibited superior accuracy compared to ATA or WTW. This study compared the capabilities of WTW, ATA, and STS in predicting postoperative vault, demonstrating that STS exhibits a stronger correlation than the other two parameters.

Mesopic pupil indices as potential risk factors for glare disability after intraocular implantable collamer lens implantation: prospective study.

To explore the influence of preoperative factors, including varying pupil sizes and refractive attributes, on postoperative glare disability in patients undergoing implantable collamer lens (ICL) implantation. Second Affiliated Hospital, Nanchang University, Nanchang, Jiangxi, China. Prospective observational study. The preoperative ocular characteristics and 6-month postoperative glare status in eligible patients who underwent EVO-Visian ICL V4c (VICMO) implantation were analyzed. The glare disability criteria encompassed a glare symptom score >6 and glare sensitivity exceeding 1:2.7. Logistic regression analysis was used to explore the relationship between the preoperative ocular parameters and post-ICL glare. The study included 95 patients (mean age, 26.04 ± 6.29 years), comprising 30 men (58 eyes) and 65 women (129 eyes). Multivariate analysis revealed a significant correlation between postoperative glare disability and increased spherical power in preoperative mesopic pupils (β = -0.124, P = .039), as well as elevated cylinder power in preoperative mesopic (β = -0.412, P = .009) and photopic pupils (β = -0.430, P = .007). Moreover, a larger preoperative mesopic pupil diameter (β = 0.561, P = .005) demonstrated a significant correlation with glare disability. Preoperative mesopic pupil dimensions and associated refractive parameters, such as sphere and cylinder, were correlated with glare disability, including the cylinder aspect in photopic pupils, which can assist clinicians in optimizing preoperative selection for ICL implantation, aiding in the anticipation of potential glare disability risks.

Predicting Implantable Collamer Lens Vault Using Machine Learning Based on Various Preoperative Biometric Factors.

To predict the vault size after Implantable Collamer Lens (ICL) V4c implantation using machine learning methods and to compare the predicted vault with the conventional manufacturer's nomogram. This study included 707 patients (707 eyes) who underwent ICL V4c implantation at the Department of Ophthalmology, Peking Union Medical College Hospital, from September 2019 to January 2022. Random Forest Regression (RFR), XGBoost, and linear regression (LR) were used to predict the vault size 1 week after ICL V4c implantation. The mean absolute error (MAE), median absolute error (MedAE), root mean square error (RMSE), symmetric mean absolute percentage error (SMAPE), and Bland-Altman plot were utilized to compare the prediction performance of these machine learning methods. The dataset was divided into a training set of 180 patients (180 eyes) and a test set of 527 patients (527 eyes). XGBoost had the lowest prediction error, with mean MAE, RMSE, and SMAPE values of 121.70µm, 148.87µm, and 19.13%, respectively. The Bland‒Altman plots of RFR and XGBoost showed better prediction consistency than LR. However, XGBoost showed narrower 95% limits of agreement (LoA) than RFR, ranging from -307.12 to 256.59µm. XGBoost demonstrated better predictive performance than RFR and LR, as it had the lowest prediction error and the narrowest 95% LoA. Machine learning may be applicable for vault prediction, and it might be helpful for reducing the complications and the secondary surgery rate. Using the proposed machine learning model, surgeons can consider the postoperative vault to reduce the surgical complications.

The influence of iris -ciliary angle (ICA) on the vault after implantation of V4c implantable collamer lens: a chain mediation model of ICL haptic related factors

BackgroundThis study aims to identify the relationship between iris -ciliary angle (ICA) and the vault. Additionally, we also seek to investigate the chain mediating effects of the ICL haptic related factors on this relationship.MethodsThe participants were categorized into three groups according to the ICA value as follows: low ICA group (< 35°); moderate ICA group (35°-70°); high ICA group (> 70°). We compared the preoperative ocular characteristics and postoperative examinations among the three groups. Multiple variable stepwise regression was performed to establish the vault prediction formula. The Process V4.0 in SPSS and Hayes’s PROCESS model 6 was conducted to further elucidate the mediating effects of the final tip point of ICL haptic and the ICL arc-lens arc on the relationship between the ICA and vault.ResultsThere was a significant difference in the positions of the ICL haptic among three ICA groups. The regression vault equation was Vault = 679.42–7.26*TCA + 192.30*ACD-196.37*CLR + 73.21* STS(horizontal).A significant negative correlation was found between the ICA and vault (P < 0.01).The chain mediation model revealed that the final tip point of ICL haptic and the ICL arc-Lens arc were sequential mediators between ICA and vault (effect = -1.63, 95% CI = -2.72–-0.73).ConclusionThe ICA was associated with vault via the mediation effect of the final tip point of the ICL haptic and the ICL arc -lens arc. Assessment of ICL haptic related parameters adds significant information to interpret the vault after surgery.

Implantable Collamer Lens in Management of Unilateral High Myopia After Pseudophakia for Traumatic Cataract: Piggybacking With Two Lenses in the Sulcus

Purpose: To describe the management of unilateral high myopia after pseudophakia for traumatic cataract by piggybacking an Implantable Collamer Lens (ICL) (V4C ICL; STAAR Surgical) along with a primary intraocular lens (IOL) in the sulcus. Methods: A 24-year-old woman underwent lens aspiration with non-foldable IOL implantation in the sulcus at 5 years of age for post-traumatic cataract. She had regular follow-up for 21 years and developed unilateral high myopia. She was using contact lenses and wanted laser vision correction. An Implantable Collamer Lens in the sulcus was used to manage the unilateral high myopia in this pseudophakic patient with a rigid IOL in the sulcus. Results: Her corneal thickness was less than 500 µm. Except for raised intraocular pressure in the immediate postoperative period, she had uneventful postoperative recovery. Her uncorrected distance visual acuity (UDVA) at 4 weeks improved to 6/9. The patient was followed up for 7 months and had a UDVA of 6/9, intraocular pressure on Goldmann applanation tonometry of 14 mm Hg, adequate vault height (1.057 mm), good anterior chamber depth (1.739 mm), and no deposits on either of the lenses. Conclusions: An ICL can be used over a primary IOL in the sulcus for the correction of ametropia, although additional cases need to be evaluated for the proper sizing and results in similar patients. [ Journal of Refractive Surgery Case Reports. 2023;3(4):e42–e46.]

Efficacy and Safety of Implantable Collamer Lens V4c Implantation in 1,834 Myopic Eyes for 1 Year of Follow-up.

To evaluate visual outcomes of patients with myopia after EVO Implantable Collamer Lens (ICL) (STAAR Surgical) implantation and predict risk factors of postoperative vault abnormalities. In this single-center, retrospective analysis, 1,834 eyes of 926 patients with myopia who underwent EVO ICL implantation were recruited between 2020 and 2021. Patients were followed up for 1 year, during which surgery outcomes were evaluated. In addition, 31 eyes with vault abnormalities who underwent secondary surgery were enrolled to form a generalized linear model, which aimed to predict risk factors contributing to vault abnormalities. At the final follow-up visit, safety and efficacy indexes were 1.12 ± 0.17 and 1.10 ± 0.19, respectively, and there was no statistical significance between the low and high myopia groups. Furthermore, 79.18% of eyes achieved a residual spherical equivalent within ±0.50 diopters. Except for the temporary elevation of intraocular pressure at 1 week postoperatively, IOP and endothelial cell density remained stable during follow-up visits. The rate of postoperative adverse events was 21.97% and most adverse events were transient. Vault abnormalities accounted for the majority of complications (9.54%). Results of generalized linear model showed that age was a risk factor for postoperative vault abnormalities, and the anterior chamber depth served as a protective factor (P < .05). Visual outcomes of EVO ICL implantation were satisfactory in safety and efficacy indexes in both the low and high myopia groups for 1 year of follow-up, with acceptable stability in postoperative spherical equivalent, intraocular pressure, and endothelial cell density. This study emphasized cautious ICL size selection for older patients and those with shallow anterior chamber depth. [J Refract Surg. 2023;39(10):694-704.].

Retinal and Choroidal Changes Following Implantable Collamer Lens V4c Implantation in High Myopia Patients-A 1-Year Follow-Up Study.

This prospective study aimed to evaluate the impact of Visian Implantable Collamer Lens (ICL) V4c implantation on retinal and choroidal morphology in patients with high myopia. A total of 97 eyes from 52 high myopic patients who underwent ICL V4c implantation were followed up for 12 months. Preoperative and postoperative evaluations included comprehensive ophthalmic assessments and enhanced depth imaging optical coherence tomography (EDI-OCT) to analyze changes in central retinal thickness (CRT), retinal volume (CRV), choroidal thickness (ChT), total choroidal area (TCA), luminal area (LA), and choroidal vascular index (CVI). Repeated measures mixed-effects models were used for comparing pre- and postoperative measurement variables and exploring relationships among age, axial length (AL), spherical equivalent refraction (SER), and postoperative retinal and choroidal changes, with statistical significance set at p < 0.05. Follow-up assessments were conducted at various time points, with participation rates ranging from 21% to 98%. Baseline characteristics showed a median age of 26.7 years, -10.14 diopters of SER, and an AL of 27.44 mm. Throughout the 12-month follow-up, CRT and 3.0 mm CRV consistently increased compared to the baseline, with statistically significant rises observed at postoperative day 1, week 1, and month 12. Most ChT measurements, including subfoveal ChT, declined over the 12 months, except at postoperative 6 months. Horizontal and vertical TCA and LA values significantly increased throughout the follow-up, except for month 6. After surgery, both horizontal and vertical CVI parameters exhibited an increase compared to the baseline, with some changes reaching statistical significance. Correlation analysis performed by repeated measures mixed-effects models showed that no relationship was found between age, AL, and SER and changes in postoperative retinal parameters and CVI parameters. However, postoperative changes in ChT and choroidal area parameters showed a negative correlation with AL and a positive correlation with SER. Our research demonstrated that ICL V4c implantation resulted in noteworthy alterations in retinal and choroidal morphology over a 1-year follow-up period. Moreover, in patients with high myopia, individuals with longer AL and higher degrees of myopia exhibited more pronounced postoperative changes in the choroid and retina. Further studies with extended follow-up durations are necessary to comprehensively understand the long-term effects of ICL implantation on retinal and choroidal morphology and function.

Four-year visual outcomes and optical quality of SMILE and implantable collamer lens V4c (EVO-ICL) implantation for high myopia: a retrospective study

BackgroundTo compare the 4-year visual outcomes of implantable collamer lens V4c (EVO-ICL) implantation and small incision lenticule extraction (SMILE) for high myopia and astigmatism.MethodsThis retrospective case study included 64 eyes of 40 patients. These patients with preoperative manifest refraction spherical equivalent (SE) between − 6.00 and − 10.00 diopters (D) were screened from the database of SMILE and EVO-ICL implantation procedures in 2015. The ICL group [32 eyes of 19 patients (mean age, 29.6 ± 6.3 years); mean SE, -8.71 ± 1.06 D] and SMILE group [32 eyes of 21 patients (mean age, 27.7 ± 5.6 years); mean SE, -8.35 ± 0.65D] were compared. All patients were then prospectively examined at a four-year follow-up for routine postoperative examinations, higher-order ocular aberrations, retinal image quality and a questionnaire.ResultsThe safety indexes were 1.15 ± 0.14 and 1.22 ± 0.21 (P = 0.36) for the SMILE and ICL groups, respectively. No eyes lost two or more lines of CDVA in either group. The efficacy indexes were 0.97 ± 0.16 and 0.96 ± 0.19 (P = 0.87), respectively. Twenty-three eyes (72%) in ICL and 26 eyes (81%) in SMILE groups were within ± 0.5 D of the attempted SE (P < 0.01). ICL-treated eyes had significantly less spherical aberration and coma (P < 0.01 and < 0.05, respectively) postoperatively. Halos were the prevalent visual disturbance in both groups.ConclusionSMILE and EVO-ICL implantation provided safe and effective correction of high myopia. SMILE showed slightly better long-term predictability. Mild postoperative visual disturbances were observed after ICL and SMILE at 4-year follow-up.

Changes of dysfunctional lens index before and after implantable collamer lens V4c implantation in patients with moderate-to-high myopia

BackgroundDysfunctional lens index (DLI) changing is rarely reported after implantable collamer lens (ICL) implantation. In the current research, we hope to investigate the changes of DLI by ray-tracing aberrometry before and after implantation of the posterior chamber phakic implantable collamer lens with a central artificial hole for patients with moderate-to-high myopia.MethodsThis retrospective, observational case series included 206 eyes of 104 patients with moderate-to-high myopia who underwent ICL V4c implantation. Data were collected on ocular indicators preoperatively and at 1 day, 1, 3, and 6 months postoperatively. The i-Trace Visual Functional Analyzer was used to assess the DLI measurement.ResultsThe overall values of safety index and efficacy index were both more than 1. Preoperatively, the mean spherical equivalent (SE) of included 206 eyes was − 10.77 ± 3.46 diopter (D). Then at 1-day postoperation, the mean SE was − 0.22 ± 0.55 D, and barely changed from 1 day to 6 months postoperatively. Although the endothelial parameters had no significant differences between preoperation and postoperation, the mean loss of endothelial cells was 0.74 ± 0.98% at 6 months. Regarding the vault, there was a significant difference between each time of follow-up (P < 0.001). The mean of the vault decreased 109.6 ± 13.5 µm from 1-day post-op to 6 months post-op. The DLI values were 3.70, 9.26, 10.00, and 9.68 at baseline, 1, 3, and 6 months, respectively (P < 0.001), but no significant differences were found between 1, 3, and 6 months postoperatively (P > 0.05). The preoperative lnDLI showed a significant positive linear correlation (r = 0.621, P < 0.001) with the preoperative spherical equivalent (SE). The lnDLI was negatively correlated with the axial length (r = − 0.462, P < 0.001), corneal thickness (r = − 0.207, P = 0.003), preoperative LogMAR UDVA (r = − 0.189, P = 0.006), and preoperative LogMAR CDVA (r = − 0.306, P < 0.001).ConclusionsThe postoperative refractive parameters were confirmed excellent in efficacy, predictability, and stability in half a year. The DLI was significantly improved after the ICL V4c implantation in patients with moderate-to-high myopia and showed good stability during the follow-up periods. The DLI deserves a more comprehensive understanding and application in clinical services.

Anterior segment structure changes caused by different luminance light after implantable collamer lens surgery

BackgroundsTo investigate the changes of anterior eye segment with implantable collamer lens (ICL) under mesopic and photopic conditions.MethodForty-seven eyes of myopic patients who underwent ICL V4c implantation were included. Three months after surgery, the pupil diameter (PD), dynamic vault, ACD (distance from the posterior corneal surface to the anterior lens surface), ACD-ICL (distance from the posterior corneal surface to the anterior ICL surface), and anterior chamber angle parameters were measured using the anterior segment optical coherence tomography (AS-OCT, Carl Zeiss AG, Germany) under completely mesopic (0 lx) and photopic (5290 lx) lighting conditions.ResultsCompared with mesopic conditions, a significant decreased vault was detected in photopic conditions (486.7 ± 186.1 μm versus 643.5 ± 191.2 μm, p < 0.001), while the ACD-ICL increased significantly (2.54 ± 0.24 mm versus 2.37 ± 0.23 mm, p < 0.001). The pupil was smaller in photopic condition (2.66 ± 0.23 mm versus 5.62 ± 0.55 mm, p < 0.001). ACD didn’t change(3.32 ± 0.24 mm versus 3.31 ± 0.22 mm, p = 0.079). The change of the vault was positively related to the changes of the PD (r2 = 0.301, p = 0.04). There were no statistical difference between the change of vault and the change of ACD-ICL (158.0 ± 58.1 μm versus 165.9 ± 65.3 μm, p = 0.320).ConclusionWhen exposed to high intensity light after ICL surgery, the pupil constricted, vault decreased, ACA widened and ACD-ICL increased. All these changes were caused by the change of iris not the crystalline lens.

Binocular imbalance in patients after implantable collamer lens V4c implantation or femtosecond laser-assisted in situ keratomileusis for myopia with presbyopia.

To investigate the long-term safety, efficacy, and binocular balance of monovision surgery using Implantable Collamer Lens (ICL) V4c implantation and Femtosecond Laser-Assisted in situ Keratomileusis (FS-LASIK) for the treatment of myopic patients with presbyopia. This case series study involved 90 eyes of 45 patients (male/female = 19/26; average age:46.27 ± 5.54 years; average follow-up time:48.73 ± 14.65 months) who underwent the aforementioned surgery to treat myopic presbyopes. Data on manifest refraction, corrected distance visual acuity, dominant eye, presbyopic addition, intraocular pressure, and anterior segment biometric parameters were collected. The visual outcomes and binocular balance at 0.4 m, 0.8 m, and 5 m were documented. The safety index for the ICL V4c and FS-LASIK groups were 1.24 ± 0.27 and 1.04 ± 0.20 (p = 0.125), respectively. Binocular visual acuity (logmar) for 0.4 m, 0.8 m, and 5 m were -0.03 ± 0.05, -0.03 ± 0.02, and 0.10 ± 0.03 for the ICL V4c group, and -0.02 ± 0.09, -0.01 ± 0.02, and 0.06 ± 0.04 for the FS-LASIK group, respectively. The proportions of all patients with imbalanced vision at 0.4 m, 0.8 m, and 5 m distances were 68.89, 71.11, and 82.22%, respectively (all p > 0.05 between the two groups). There were significant differences in refraction between the balanced and imbalanced vision for patients at 0.4 m distance (for non-dominant eye spherical equivalent [SE]: -1.14 ± 0.17D and -1.47 ± 0.13D, p < 0.001), 0.8 m distance (for preoperative ADD:0.90 ± 0.17D and 1.05 ± 0.11D, p = 0.041), and 5 m distance (for non-dominant SE: -1.13 ± 0.33D and -1.42 ± 0.11D, p < 0.001). ICL V4c implantation and FS-LASIK monovision treatment demonstrated good long-term safety and binocular visual acuity at various distances. After the procedure, the imbalanced patients' vision is primarily related to the age-related presbyopia and anisometropia progression caused by the monovision design.

Analysis of Inter-Eye Vault Differences After Implantable Collamer Lens (V4c) Implantation.

The safety and stability of implantable collamer lens (ICL) implantation are closely related to the vault. We aimed to assess clinical data from patients with similar anterior segment anatomy who received ICL of the same model placed in the same position and analyze common range and factors affecting the vault inter-eye difference. A prospective study was performed, including 162 eyes of 81 patients with a bilateral ICL (V4c) implantation. Subjects were evaluated before the surgery and 1 day, 1 week, and 1 month postoperatively, and they were divided into 4 groups based on the ICL size. Bivariate correlation and multiple linear regression (stepwise) analyzed associations between vault inter-eye differences and horizontal sulcus-to-sulcus diameter, anterior chamber depth, lens thickness, ICL size, spherical equivalent, and vault. One month after surgery, mean vault inter-eye differences were 74.59 ± 55.59 µm. Nearly 70% of patients presented with vault inter-eye differences lower than 100 µm. The second eye vault variance of 69% was attributed to the first eye vault. Vault inter-eye differences were positively correlated with ICL spherical equivalent (regression equation: vault inter-eye differences (μm) = 139.415 + 6.295 × ICL spherical equivalent). Vaults after ICL implantation were similar in fellow eyes, with some considerable differences. The 95% confidence interval of the vault inter-eye difference was -34.4 ~ 183.6 μm. In eyes with similar anterior segment anatomy, there is a 95% probability that the vault will vary from -34.4 μm to -183.6 μm when a similar ICL is implanted. These results can help surgeons to select an appropriate ICL size to achieve an ideal vault. The smaller the spherical equivalent, the larger the difference between the two vaults, which provides a reference for size in moderate myopia. ICL spherical equivalent affects and predicts vault inter-eye differences after ICL implantation.

Comparison of higher-order aberrations between implantable collamer lens V4c implantation and simulated spectacle correction in patients with high myopia

To investigate the differences in higher-order aberrations between non-toric or toric implantable collamer lens (ICL or TICL) V4c implantation and simulated spectacle correction. Patients with high myopia who underwent ICL/TICL V4c implantation were enrolled. The "total no defocus" pattern of iTrace aberrometry to simulate the condition of spectacle correction was measured before ICL/TICL implantation, and higher-order aberrations in this condition were compared to those 3 months after surgery. Related factors with changes in coma were comprehensively analyzed. A total of 89 right eyes of 89 patients were included. Compared to simulated spectacle correction, total-eye coma (P<0.0001 ICL, P<0.0001 TICL) and internal coma (P<0.0001 ICL, P<0.001 TICL) decreased in the ICL- and TICL-treated groups after surgery. Total-eye secondary astigmatism (P<0.0001 ICL, P=0.007 TICL) and internal secondary astigmatism (P<0.0001 ICL, P=0.009 TICL) were also decreased in both groups postoperatively. Spherical error showed positive correlations with variation in total-eye coma (r=0.37, P=0.004 ICL; r=0.56, P=0.001 TICL) and internal coma (r=0.30, P=0.02 ICL and r=0.45, P=0.01 TICL). Axial length revealed negative correlations with changes in total-eye coma (r=-0.45, P<0.001 ICL; r=-0.39, P=0.03 TICL) and internal coma (r=-0.28, P=0.03 ICL and r=-0.42, P=0.02 TICL). Both ICL- and TICL-treated groups demonstrated a decrease in coma and secondary astigmatism after 3 months, postoperatively. ICL/TICL may confer a compensatory effect on coma aberration and secondary astigmatism. Patients with a higher myopia achieved a greater improvement in coma and may benefit more from ICL/TICL implantation than from spectacle correction implantation than from spectacle correction.

Prediction of Implantable Collamer Lens Vault Based on Preoperative Biometric Factors and Lens Parameters.

To establish and validate the accuracy of implantable collamer lens (ICL) vault size prediction formula based on preoperative biometric factors and lens parameters. This study included 300 patients (300 eyes) with Visian ICL V4c (STAAR Surgical) implantation. They were randomly divided into the formula establishment group and formula validation group. Anterior segment measurements, ICL V4c size and power, and vault 1 week postoperatively were collected from all patients. Multiple linear regression analysis was performed to establish the prediction formula. Mean absolute error (MAE), median absolute error (MedAE), root mean square error (RMSE), and Bland-Altman diagrams were used to evaluate the prediction formula. Anterior chamber depth (ACD) had the greatest influence on vault 1 week after ICL V4c implantation, followed by ICL V4c size and angle-to-angle distance (ATA). The prediction formula was obtained according to the partial regression coefficient, which was vault (mm) = -1.279 + 0.291 × ACD (mm) + 0.210 × ICL V4c size (mm) - 0.144 × ATA (mm) (R2 = 0.661). In the formula validation group, the mean predictive vault, MAE, MedAE, and RMSE were 628.10, 135.09, 130.42, and 150.46 µm, respectively. The Bland-Altman diagram showed the predictive vault was in good agreement with the actual vault. A novel ICL V4c vault prediction formula was developed and shown to be an effective method for predicting the vault to reduce surgical complications. [J Refract Surg. 2023;39(5):332-339.].

Evaluation of Implantable Collamer Lens Sizing Developed by Reviewing the Horizontal Compression-vault Coefficient.

To evaluate the implantable collamer lens (ICL) sizing method using the partial regression coefficient of the implanted ICL size to review the conventional horizontal compression coefficient and match the results of clinical observation. Nagoya Eye Clinic, Nagoya, Japan. Interventional case series. Patients who underwent ICL V4c implantation to correct myopia and myopic astigmatism were enrolled. The stepwise multiple regression analysis used achieved vault as a dependent variable and preoperative biometric parameters as explanatory variables. The partial regression coefficient of the implanted ICL size was obtained to develop the optimal ICL-sizing formula, the NK-formula version 3 (NK-formula V3). Eighty-five eyes of 45 patients were implanted with an ICL size recommended by the NK-formula V3. At 3 months postoperatively, the achieved vault was measured using AS-OCT to validate the NK-formula V3. The study enrolled 174 patients (174 eyes). The partial regression coefficient of the implanted ICL size adopted as the compression-vault coefficient in the multiple regression equation predicting the vault was 0.729. To validate the NK-formula V3, 77 (90.6%), seven (8.2%), and one (1.2%) eye were in the moderate, low, and high vault categories, respectively. The mean difference between the achieved and predicted vault was 0.064±0.190 (range: -0.264-0.742) mm for the NK-formula V3 and 0.176±0.217 (range: -0.254-0.907) mm for the NK-formula V2. As in vivo coefficient measurement experiments are not possible, the partial regression coefficient is the best option for developing a formula to predict the optimal ICL size.

Efficacy Comparison Between Steep-Meridian Incision and Non-Steep-Meridian Incision in Implantable Collamer Lens Surgery with Low-to-Moderate Astigmatism.

To compare the visual outcomes of astigmatism correction with implantable collamer lens (ICL) surgery with low-to-moderate astigmatism through a steep-meridian corneal relaxing incision (SM-CRI) and non-steep-meridian corneal relaxing incision (NSM-CRI). Seventy eyes of 70 patients with myopia and myopic astigmatism who underwent ICL V4c implantation were classified into two groups: SM-CRI and NSM-CRI. Refractive outcomes and vector analysis were evaluated preoperatively and 6months postoperatively. At the postoperative 6month visit, all participants in both groups achieved an uncorrected distance visual acuity (UDVA) of 20/20 or better. The difference vector (DV) showed that the residual astigmatism in the SM-CRI group was much smaller than that in the NSM-CRI group (P = 0.021), and the correction index (CI) was 0.84 ± 0.30 and 0.67 ± 0.35 for the SM-CRI and NSM-CRI groups, respectively, with a significant statistical difference (P = 0.013). Approximately 71% of eyes in the SM-CRI group had an angle of error (AE) within ± 15°, whereas 55% of eyes in the NSM-CRI group were within that range. The absolute mean AE was 10.13 ± 14.57° in the SM-CRI group, compared with 23.88 ± 28.22° in the NSM-CRI group (P = 0.038). SM-CRI can alleviate corneal astigmatism and decrease the cylindrical diopter of the ICL, thus improving postoperative visual quality compared with NSM-CRI.

Characteristics and factors associated with the position of the haptic after ICL V4C implantation.

To assess the position of implantable collamer lens (ICL) haptic after ICL V4C implantation using standardized panoramic ultrasound bimicroscopy (UBM), to analyze its characteristics, associated factors, and the relationship with the clinical vault quantitatively. Hankou Aier Eye Hospital, Wuhan, Hubei, China. Cross-sectional study. 167 subjects (323 eyes) implanted with ICL V4C who had a 3-month follow-up with UBM examination were included in this study. The relative position of ICL to the adjacent structure and ICL haptic-related parameters (the final tip point of ICL haptic [ftICL haptic], measured from the scleral spur to the final tip of the ICL haptic, the posterior of the ICL to ICL haptic [ICL arc], measured from the posterior surface of the ICL to the ICL haptic plane, and the height of the crystalline lens from the ICL haptic (lens arc), measured from the anterior surface of the crystalline lens to the ICL haptic plane and other parameters), were estimated on the UBM image. Eyes were divided into 3 subgroups according to the ftICL haptic (Group 1: ≤0.5 mm; Group 2: 0.5 to 1.0 mm; and Group 3:≥1.0 mm, respectively), and the factors associated with the ICL haptic-related parameters and their impact on the clinical vault were evaluated. The haptics could be imaged in the ciliary sulcus, on the ciliary body, and under the ciliary body in 629 (48.7%), 525 (40.6%), and 138 (10.7%) eyes, respectively. The ftICL haptic and the summation of ICL arc and lens arc showed a correlation with the clinical vault ( r = -0.34, P = .00; r = 0.87, P = .00). When the ftICL haptic results were divided into 3 groups, the percentage of eyes that exhibited clinical vault >750 μm were lowest in Group 3. Multivariate regression analysis showed spherical equivalent, white-to-white (WTW), anterior chamber volume (ACV) and iris-ciliary angle (ICA); the difference between the implanted ICL size and horizontal sulcus-to-sulcus (ICL size-STS) were associated with the ftICL haptic. The IOP, WTW, ACV, and the ICL size-STS were significantly associated with ICL arc, while the ICA and lens rise were associated with lens arc. The position of ICL haptic was associated with the clinical vault. Its quantitative evaluation may provide valuable information to help clinicians to select the best ICL size before surgery and understand the formation of clinical vault after surgery.