Correlation between Preoperative Biometry and Posterior Chamber Phakic Visian Implantable Collamer Lens Vaulting

Effect of anterior segment structure on vault and position after implantable collamer lens implantation

PURPOSE

To evaluate the effect of anterior-segment structure on vault and position after implantable collamer lens (ICL) implantation using ultrasound biomicroscopy.

METHODS

The retrospective case-control study included insufficient vault eyes (<250 µm), ideal vault eyes (250-750 µm), and excessive vault eyes (>750 µm). The preoperative biometric parameters of the anterior-segment structure and basic data between the three groups were analyzed using one-way analysis of variance.

RESULTS

There were significant differences ( P < 0.05) between the three groups in maximum ciliary body thickness (CBT max ), iris-zonule distance (IZD), and trabecular-ciliary angle (TCA). The vault gradually decreased as CBT max decreased and TCA increased. In the pairwise comparison, the CBT max comparison between the insufficient vault (<250 µm) group and the excessive vault (>750 µm) group was statistically significant ( P = 0.024, 95% CI: -0.17-0.017 µm); the TCA comparison between the insufficient vault (<250 µm) group and the excessive vault (>750 µm) group was statistically significant ( P = 0.005, 95% CI: 1.78°-12.15°); The IZD comparison between the insufficient vault (<250 µm) group and the excessive vault (>750 µm) group was statistically significant ( P = 0.037, 95% CI: 0.0027-0.1119 µm). The analysis of 284 ICL haptics locations showed that there were 16.67%, 32.69%, and 70.83% haptics located in the ciliary sulcus in three groups, respectively.

CONCLUSION

The vault and ICL haptics position are related to anterior-segment structure. A thinner and posteriorly positioned ciliary body would increase the risk of low vault and fewer ICL haptics located in the ciliary sulcus after ICL implantation. This provides guidance for the selection of the ICL size and placement position before surgery.

Comparison of Predictability in Vault Using NK Formula and KS Formula for the Implantable Collamer Lens Surgery

Background

This study aims to investigate the agreement between the NK and KS formulas in predicting the vault after implantation of an EVO-implantable collamer lens (ICL).

Methods

This retrospective study included 106 eyes of 57 patients who underwent ICL-V4c implantation. Preoperative vault prediction was conducted by utilizing the NK and KS formulas, with postoperative measurements by anterior segment optical coherence tomography (AS-OCT) at one month. The analysis focused on the consistency between predicted and achieved vaults, as well as the correlation between the achieved vault and various biometric parameters.

Results

The mean achieved vault was 605.25 ± 212.72 µm, which was significantly smaller than the predicted vaults of 710.08 ± 195.08 and 673.80 ± 212.76 µm, using the NK and KS formulas, respectively (P < 0.05). The mean differences between the achieved vault and the predicted vault using the NK formula and KS formula were -104.82 μm (95% LoA: -600.38-391.19 μm) and -68.55 μm (95% LoA: -628.91-491.82 μm), respectively. Anterior chamber depth (ACD), vertical sulcus-to-sulcus (V-STS) diameter, and crystalline lens rise (CLR) were independent factors associated with the achieved vault (P < 0.05). The two formulas showed no statistically significant difference in absolute prediction error (APE).

Conclusion

The NK formula exhibited superior consistency and low predictive error compared to the KS formula in the 12.6 mm ICL group. AS-OCT measurements overestimated the predicted ICL vault, especially in the 13.2 mm ICL size selection. Relying solely on the NK or KS formulas for predicting vaults before ICL surgery is not recommended.

Ocular features in myopic eyes with longer horizontal ciliary sulcus diameters for intended implantable collamer lens surgery

PURPOSE

To assess the ocular anterior segment characteristics in myopic eyes intended for ICL surgery with horizontal ciliary sulcus-to-sulcus (STS) diameters being greater than vertical STS diameters.

METHODS

This retrospective, comparative case study included 1230 eyes of patients who underwent ICL implantation for the treatment of myopia or myopic astigmatism at the Zhongshan Ophthalmic Center from September 2020 to November 2021. The myopic eyes were divided into two groups according to the relatively long diameter of the ciliary sulcus. General parameters and anterior chamber parameters were compared between the two groups.

RESULTS

1230 eyes of 694 patients were included. The proportion of myopic eyes with longer horizontal STS diameters was 4.63%. Horizontal STS distances exceeding vertical meridians in these eyes were mainly attributed to the shortening of vertical STS distances (horizontal STS: P = 0.112; vertical STS: P < 0.001). Eyes with longer horizontal meridians of the ciliary sulcus displayed larger steep keratometry value (P = 0.001), larger corneal volume (P = 0.002), larger corneal astigmatism (P < 0.001), larger ocular residual astigmatism (P = 0.017), worse visual acuity (logMAR UDVA: P = 0.021; logMAR CDVA: P = 0.001), and more iridociliary cysts (P = 0.017) compared to eyes with vertically oval shapes.

CONCLUSION

Myopic eyes with longer horizontal STS diameters are commonly accompanied by a change in corneal morphology and more iridociliary cysts. The anatomical features of the ciliary sulcus should be given sufficient consideration to ICL size and placement selection, contributing to more personalized and precise surgery.

The optimization of the vault-predicting formula based on the anterior segment measurements from artemis insight 100

To optimize and evaluate the accuracy of the vault-predicting formula generated from a very high-frequency digital ultrasound robotic scanner (Artemis Insight 100). The relationship between the achieved lens vault (LVa) at one month after intraocular collamer lens (ICL) implantation surgery and the predicted vault (LVp) was analyzed by a retrospective study, and an optimized formula was built up. Then, the accuracy of the optimized vault-predicting formula was evaluated in a prospective study by comparing the LVa and the predicted vault from the optimized formula (LVop). The retrospective study included 77 patients (133 eyes) while the prospective study enrolled 90 patients (170 eyes). The difference between LVp and LVa at one month after surgery was statistically significant (P < 0.05), and the linear regression analysis of LVa against LVp yielded a good fit (R2 = 0.68). The optimized vault-predicting formula was LVop (μm) = 1.21 × LVp (μm) + 124.73. In the validation study, the difference between LVop and LVa was not statistically significant (P = 0.10), and a good agreement between LVop and LVa was shown by Bland-Altman analysis. The optimized vault-predicting formula could predict the actual LV after ICL implantation surgery, help to select an appropriate ICL size and reduce the need for re-operation.

VAULT: vault accuracy using deep learning technology: new image-based artificial intelligence model for predicting implantable collamer lens postoperative vault

PURPOSE

To develop an accurate deep learning model to predict postoperative vault of phakic implantable collamer lenses (ICLs).

SETTING

Parkhurst NuVision LASIK Eye Surgery, San Antonio, Texas.

DESIGN

Retrospective machine learning study.

METHODS

437 eyes of 221 consecutive patients who underwent ICL implantation were included. A neural network was trained on preoperative very high-frequency digital ultrasound images, patient demographics, and postoperative vault.

RESULTS

3059 images from 437 eyes of 221 patients were used to train the algorithm on individual ICL sizes. The 13.7 mm size was excluded because of insufficient data. A mean absolute error of 66.3 μm, 103 μm, and 91.8 μm were achieved with 100%, 99.0%, and 96.6% of predictions within 500 μm for the 12.1 mm, 12.6 mm, and 13.2 mm sizes, respectively.

CONCLUSIONS

This deep learning model achieved a high level of accuracy of predicting postoperative ICL vault with the overwhelming majority of predictions successfully within a clinically acceptable margin of vault.

Implantable Collamer Lens Procedure Planning: A Review of Global Approaches

More than 2 million implantable collamer lenses (ICLs) have been implanted worldwide. With a central port to improve aqueous flow through the ICL, the latest iteration of this phakic intraocular lens (pIOL) has been shown to have stable outcomes with very low rates of adverse events. However, correct planning and ICL size selection continue to be important to achieve an optimal vault. Shallow or excessive vaults are not complications in and of themselves but may increase the risk of complications. Historically, surgeons have relied on measurements of anterior chamber depth (ACD) and manual, caliper-measured white-to-white (WTW) distance to select the ICL size. New diagnostic and imaging technologies such as optical coherence tomography (OCT) and ultrasound biomicroscopy (UBM) provide additional opportunities for visualization and measurement of the intraocular dimensions involved in phakic intraocular lens implantation, including sulcus-to-sulcus (STS) and angle-to-angle (ATA) diameters. This paper reviews various approaches to ICL planning and sizing that have been published in the peer-reviewed literature, all of which produce acceptable results for predicting vault and size selection. Surgeons may also want to identify a methodology for patient evaluation and ICL size selection that best aligns with their personal preferences, diagnostic technology, and familiarity with analytical optimization tools.

The Distribution of Crystalline Lens Rise in High Myopia Population and Its Influence on Vault After Implanting Intraocular Collamer Lens

INTRODUCTION

As a result of the insufficient ocular anatomical parameters used to customize implantable collamer lens (ICL), many patients still cannot achieve a suitable vault after ICL implantation surgery. This study analyzed the characteristics of a new anatomical parameter crystalline lens rise (CLR) in a population with high myopia and explored the influence of CLR on the vault after ICL implantation.

METHODS

Patients (298 eyes) with high myopia who underwent ICL implantation were enrolled to study CLR characteristics. Postoperatively, patients (159 eyes) were divided into five groups according to the value of CLR (A, CLR ≤ - 150; B, - 150 < CLR ≤ 0; C, 0 < CLR < 150; D, 150 ≤ CLR < 300; E, CLR ≥ 300 μm), and to investigate the correlation between CLR and vault.

RESULTS

In the 298 eyes, the CLR had a normal distribution (P = 0.35) and the mean CLR was 67.93 ± 150.66 μm. Ninety-nine eyes (33.22%) had a CLR ≤ 0 μm, of which 20 eyes (6.71%) had a CLR ≤ - 150 μm; 199 eyes (66.78%) had a CLR > 0 μm, of which 20 eyes (6.71%) had a CLR ≥ 300 μm. In 159 eyes, the CLR was negatively correlated with the vault at 1 day (R = - 0.497, P < 0.001), 3 months (R = - 0.505, P < 0.001), and 6 months (R = - 0.505, P < 0.001) postoperatively. At 6 months, the vault of group A was statistically significantly different compared to groups B-E (all P < 0.05), and that of group E was statistically significantly different compared to groups A-D (all P < 0.001). The remaining groups did not show statistically significant differences (all P > 0.05).

CONCLUSION

The CLR had a normal distribution in the high myopia population, and 13.42% of the CLR values were extreme (CLR ≤ - 150 μm or CLR ≥ 300 μm). A larger ICL diameter than that recommended by the manufacturer should be considered when the CLR is ≥ 300 μm and a smaller ICL diameter should be considered when the CLR is ≤ - 150 μm.

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

Purpose

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.

Methods

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.

Results

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 121.70 µm, 148.87 µm, 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 256.59 µm.

Conclusions

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.

Translational Relevance

Using the proposed machine learning model, surgeons can consider the postoperative vault to reduce the surgical complications.

Comparison of a new implantable collamer lens formula to standards formulas using spectral domain optical coherence tomography

PURPOSE

To use spectral-domain optical coherence tomography (SD-OCT) data to develop a new implantable collamer lens (ICL) sizing formula and compare vault outcomes with the Online Calculation and Ordering System™ (OCOS) and the NK2 formula.

METHODS

Consecutive eyes (n = 237) were evaluated that had undergone ICL/toric ICL implantation. Actual ICL vaults were measured, and a what-if analysis was performed to predict vault values with the NK2 formula using SD-OCT data. To develop a new formula (EPB), multiple regression analysis was performed with different parameters than the NK2 formula. Predicted vaults with NK2 and EPB formulas were compared to the actual vaults.

RESULTS

Parameters that were correlated with optimal ICL size were white-to-white, anterior chamber width, lens rise and desired refractive correction. The mean postoperative vault was 489 ± 258 μm. At last visit, 94.5% of eyes were within the manufacturer's acceptable vault range. Predicted vaults in the acceptable range were 74 and 87% with the NK2 and EPB formulas, respectively. Six percent had a predicted vault less than 100 μm with the EPB formula compared to 1% for actual outcomes. The NK2 formula resulted in a shift toward higher predicted vaults while the EPB formula was similar to the actual postoperative vaults but with slightly more cases with extremely low and high vaults.

CONCLUSION

SD-OCT data with OCOS result in good postoperative vaults. Further refinement is required to the NK2 for use with SD-OCT data. Although the EPB formula provides acceptable predicted vaults, further refinement with a larger sample size is needed.

Predicting Vault and Size of Posterior Chamber Phakic Intraocular Lens Using Sulcus to Sulcus-Optimized Artificial Intelligence Technology

PURPOSE

To investigate the accuracy of posterior chamber phakic intraocular lens (PIOL) vault and size prediction models based on sulcus to sulcus (STS) optimized artificial intelligence and big data analysis technology.

DESIGN

Big data and artificial intelligence prediction model.

METHODS

We included 5873 eyes with posterior chamber PIOL implantation, and the postoperative vault was measured using an anterior segment analyzer (Pentacam AXL) 1 month postoperatively. A random forest regression model and classification model were used to predict the postoperative vault and PIOL size. The postoperative vault and PIOL size were set as output features; other vault-related eye parameters were set as input features. The influence of white to white (WTW), horizontal sulcus to sulcus (STS), and vertical STS on predicting postoperative vault and PIOL size was analyzed and compared.

RESULTS

The mean preoperative WTW diameter was 11.64 ± 0.37 mm, the mean horizontal STS diameter was 11.85 ± 0.47 mm, and the mean vertical STS diameter was 12.39 ± 0.52 mm. In the regression model for numerical prediction of the vault, the combination of WTW, horizontal STS, and vertical STS was the most optimal for vault prediction (R2 = 0.3091, root mean square error [RMSE] = 0.1705); solely relying on WTW was the least optimal (R2 = 0.2849, RMSE = 0.1735). Among the models for classification prediction of the vault, the combination of WTW, horizontal STS, and vertical STS was the most accurate (accuracy, 0.6302; mean area under the curve, 0.8008; and mean precision recall rate, 0.6940). Moreover, the combination of WTW, horizontal STS, and vertical STS exhibited the highest accuracy for classification prediction of PIOL size (accuracy, 0.8170; mean area under the curve, 0.9540; and mean precision recall rate, 0.8864). Whether in the regression prediction models of vault values or in the classification prediction models of vault and PIOL size, the accuracy of STS optimized model was significantly improved compared with the traditional WTW model (P < .001).

CONCLUSION

Artificial intelligence combined with STS optimization contributes to the accuracy of PIOL size and vault prediction models. The random forest machine-learning model optimized by STS is superior to the traditional WTW model.

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

BACKGROUND

This 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.

METHODS

The 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.

RESULTS

There 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).

CONCLUSION

The 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.

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

PURPOSE

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.

METHODS

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.

RESULTS

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).

CONCLUSIONS

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.].

Vault Height Is a Key Predictive Factor for Anterior Segment Measurement Error by IOLMaster 700 in Eyes With Phakic Intraocular Lens

Purpose

To identify risk factors of ocular anterior segment measurement error by the IOLMaster 700 in eyes implanted with an implantable Collamer lens (ICL).

Methods

In total, 152 patients with clear lens (152 eyes, group 1) and another 32 cataract patients (57 eyes, group 2) who underwent ICL implantation were included, and the presence of measurement error by the IOLMaster 700 was determined based on B-scan images. The risk factors for measurement error were evaluated by logistic regression, and the optimal threshold was determined using receiver operating characteristic analysis.

Results

The ICL was misidentified as the anterior surface of the crystalline lens in 51.97% of eyes (79/152) in group 1 and 80.70% of eyes (46/57) in group 2. For every 100-µm decrease in the vault height, a 3.57- and 5.78-fold increase in the risk of measurement error was observed in group 1 and group 2, respectively. We identified an optimal threshold of the vault height at 389.47 µm for predicting biometric measurement error in eyes implanted with ICL, which showed an area under the curve of 0.93 (95% confidence interval, 0.90-0.97), a sensitivity of 0.87, and a specificity of 0.86.

Conclusions

Patients with ICL implantation, particularly those with a vault height less than 389.47 µm, are at a greater risk of anterior segment biometric measurement error by the IOLMaster 700.

Translational Relevance

The threshold of vault height can help to identify high-risk patients and further optimize biometric measurement.

A vault-prediction formula for implantable collamer lens based on preoperative parameters: a retrospective clinical study

OBJECTIVES

The aim of the present study was to predict the vault of implantable collamer lens (ICL) using a formula established based on the preoperative parameters.

METHODS

This retrospective study included data on 226 eyes from 114 patients(the median age and range was 27.5 ± 5.7; 18-46 years) who underwent EVO-ICL surgery between May 2021 and April 2022. Preoperative parameters, such as anterior chamber depth (ACD) horizontal angle-to-angle diameter (ATA), Crystalline lens rise (CLR), and vault (1 week after surgery) were measured by anterior segment optical coherence tomography. The axial length of eyes (AL) and white-to-white (WTW) values were measured using an IOLmaster and calipers under a slit lamp separately.

RESULT

The mean WTW, ACD, horizontal ATA diameter, CLR, AL, and vault 1 week after surgery were 11.42 ± 0.37 mm, 3.25 ± 0.25 mm, 11.72 ± 0.44 mm, 45.78 ± 175.42 μm, 27.61 ± 1.93 mm, and 586.51 ± 254.54 μm respectively. Multivariate regression analysis showed that the ICL-width, ACD (β = 0.293), ATA (β =-0.657), CLR (β =-0.157), and the anterior chamber angle in temporal side (T:ACA) (β=-0.277) were predictors of the vault size (adjusted-R2 = 0.39, P < 0.001).

CONCLUSION

The formula built based on these preoperative parameters could be used to predict the vault before surgery. The predictors indicated that the pre-operative parameters of eye such as ACD, ATA, CLR and T:ACA play an important role in choosing optimal ICL size.

Prediction model of the horizontal trabecular iris angle after phakic posterior chamber implantable intraocular lens surgery

PURPOSE

To determine the predictors of the postoperative horizontal trabecular iris angle (TIA 750 ) after phakic posterior chamber implantable intraocular lens (IOL) surgery.

SETTING

Ophthalmology Clinic Vista Sánchez Trancón, Badajoz, Spain.

DESIGN

Retrospective case series.

METHODS

330 eyes implanted with spherical/toric implantable collamer lens (ICL) were included in this study. From 230 eyes implanted with 13.2 mm ICL, these were divided in modeling (n = 180) and evaluation group (n = 50). Two groups implanted with 12.6 mm and 13.7 mm (n = 50 each) were also used as evaluation. Anterior-segment optical coherence tomography was used preoperatively to perform anterior chamber biometry (angle-to-angle [ATA] distance, crystalline lens rise, anterior chamber depth [ACD], cornea sagittal depth, pupil diameter, nasal/temporal TIA 750 ); postoperatively for measuring the vault, pupil diameter and nasal/temporal TIA 750 . Corneal curvature and horizontal visible iris diameter were measured using optical tomography. Bivariate correlation analysis was used to determine associations between preoperative and postoperative horizontal TIA 750 with anterior chamber biometry, ICL-related parameters and age. Finally, a multivariate linear regression model was constructed for predicting the postoperative TIA 750 .

RESULTS

Horizontal TIA 750 reduced from 42.9 ± 8.0 degrees preoperatively to 24.4 ± 5.6 degrees postoperatively. Postoperative TIA 750 was positively correlated with the preoperative TIA 750 , cornea sagittal depth and ACD, and negatively associated with the vault. The main predictors of the postoperative TIA 750 were the preoperative parameters, TIA 750 , ICLsize - ATA and pupil diameter (adjusted- R2 = 0.39). The limits of agreement between predicted and real TIA 750 were close to ±10 degrees.

CONCLUSIONS

Implantation of a phakic posterior chamber implantable IOL leads to a reduction in TIA 750 and the main factors contributing for this are the preoperative TIA 750 aperture and the vault.

Rotational Stability After Implantation of Two Different Phakic Toric Intraocular Lenses

PURPOSE

To compare clinical outcomes and rotational stability of the toric implantable Collamer lens (TICL) and toric implantable phakic contact lens (TIPCL).

METHODS

Charts were reviewed from January 2011 to January 2023 to identify all TICLs and TIPCLs implanted by a single surgeon. Implant size was generally chosen according to the manufacturer's recommendation, but 15 TIPCLs 0.25 mm larger than recommended to increase vaulting were included.

RESULTS

Eighty-four TICLs and 98 TIPCLs were identified and yielded excellent refractive and visual results in eyes with high myopic astigmatism at the last follow-up visit. No case of acute glaucoma or cataract induction was observed. In total, 15 (8.2%) rotated lenses were recorded; 2 (2.4%) TICLs and 13 (13.3%) TIPCLs (P = .013). Eyes in both groups were similar in preoperative spherical equivalent, cylinder, white-to-white distance, anterior chamber depth (ACD), anterior chamber angle, and mean follow-up times (P = .925, .673, .822, .794, .358, and .873, respectively). Average TICL size was larger than TIPCL size (P < .001). Rotation of the lenses was positively correlated with cylinder and negatively correlated with ACD but not with vaulting (P = .001, r = 0.253; P = .011, r = -0.193; P = .488, r = -0.057; respectively). Vaulting was positively correlated with preoperative ACD (P ≤ .001, r = .329). In eyes with a rotated TIPCL, preoperative cylinder was higher and ACD was shallower than in eyes with a stable TIPCL (P = .001 and .007, respectively). Increasing the implant size had no significant effect on rotation rate (P = .685).

CONCLUSIONS

Although both implants were safe and effective in highly myopic eyes, TICL rotated less frequently than TIPCL and required fewer secondary interventions. Rotation was correlated with preoperative cylinder and ACD but not lens vaulting. [J Refract Surg. 2023;39(7):463-472.].

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

Purpose

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.

Patients and Methods

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.

Results

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.

Conclusion

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.

Predicting post-operative vault and optimal implantable collamer lens size using machine learning based on various ophthalmic device combinations

BACKGROUND

Implantable Collamer Lens (ICL) surgery has been proven to be a safe, effective, and predictable method for correcting myopia and myopic astigmatism. However, predicting the vault and ideal ICL size remains technically challenging. Despite the growing use of artificial intelligence (AI) in ophthalmology, no AI studies have provided available choices of different instruments and combinations for further vault and size predictions. This study aimed to fill this gap and predict post-operative vault and appropriate ICL size utilizing the comparison of numerous AI algorithms, stacking ensemble learning, and data from various ophthalmic devices and combinations.

RESULTS

This retrospective and cross-sectional study included 1941 eyes of 1941 patients from Zhongshan Ophthalmic Center. For both vault prediction and ICL size selection, the combination containing Pentacam, Sirius, and UBM demonstrated the best results in test sets [R² = 0.499 (95% CI 0.470-0.528), mean absolute error = 130.655 (95% CI 128.949-132.111), accuracy = 0.895 (95% CI 0.883-0.907), AUC = 0.928 (95% CI 0.916-0.941)]. Sulcus-to-sulcus (STS), a parameter from UBM, ranked among the top five significant contributors to both post-operative vault and optimal ICL size prediction, consistently outperforming white-to-white (WTW). Moreover, dual-device combinations or single-device parameters could also effectively predict vault and ideal ICL size, and excellent ICL selection prediction was achievable using only UBM parameters.

CONCLUSIONS

Strategies based on multiple machine learning algorithms for different ophthalmic devices and combinations are applicable for vault predicting and ICL sizing, potentially improving the safety of the ICL implantation. Moreover, our findings emphasize the crucial role of UBM in the perioperative period of ICL surgery, as it provides key STS measurements that outperformed WTW measurements in predicting post-operative vault and optimal ICL size, highlighting its potential to enhance ICL implantation safety and accuracy.

Development and validation of a new multivariable prediction model to estimate risk of abnormal vault

PURPOSE

To develop and validate a new multivariable prediction model to estimate risk of abnormal vault after EVO Implantable Collamer Lens (EVO-ICL) implantation using the preoperative parameters.

METHODS

This retrospective study comprised 282 eyes of 143patients who underwent EVO-ICL surgery between May 2021 and April 2022. We measured preoperative parameters before surgery and vaults in 1 week after the operation using swept-source optical coherence tomography (SS-OCT). Risk factors for abnormal vault were determined by univariate and multivariate logistic regression analyses, and a nomogram was developed to forecast the risk of abnormal vault after EVO-ICL implantation. We assessed the performance of nomogram in terms of discrimination and calibration, including concordance index (C-index), receiver operating characteristic curve (ROC), area under the ROC curve (AUC), and decision curve analysis (DCA). Bootstrap resampling was used as an internal verification method.

RESULTS

The logistic regression analysis revealed the independent risk factors for abnormal vault were white-to-white(WTW), anterior chamber angle(ACA), pupil size, and ICL-size, all of them were used to establish a nomogram based on multivariate logistic regression to predict the risk of abnormal vault. The C-indexes and AUC were 0.669 (95%CI, 0.605, 0.733). The calibration curves of the nomogram showed relatively small bias from the reference line, implicating an acceptable degree of confidence. The DCA indicates the potential clinical significance of the nomogram.

CONCLUSIONS

We developed a new multivariable prediction model to estimate risk of abnormal vault. The model shows good prediction effect and can provide assistance for clinical decision of ICL size.

Evaluation of implantable collamer lens sizing developed by reviewing the horizontal compression-vault coefficient

PURPOSE

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.

SETTING

Nagoya Eye Clinic, Nagoya, Japan.

DESIGN

Interventional case series.

METHODS

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 Nakamura-Kojima formula version 3 (NK-formula V3). 85 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 anterior segment optical coherence tomography to validate the NK-formula V3.

RESULTS

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%), 7 (8.2%), and 1 (1.2%) eyes were in the moderate-vault, low-vault, and high-vault categories, respectively. The mean difference between the achieved and predicted vaults was 0.064 ± 0.190 (range: -0.264 to 0.742) mm for the NK-formula V3 and 0.176 ± 0.217 (range: -0.254 to 0.907) mm for the NK-formula V2.

CONCLUSIONS

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.

The Non-uniform Distribution of Horizontal and Vertical Crystalline Lens Rise Using Optical Coherence Tomography

PURPOSE

To observe the crystalline lens rise (CLR) in horizontal and vertical orientations using anterior segment optical coherence tomography (AS-OCT).

METHODS

Non-invasive swept-source AS-OCT was used to measure the lens thickness, CLR, and angle-to-angle distance (ATA) in both the horizontal and vertical orientations. Anterior chamber depth (ACD) and horizontal white-to-white corneal diameter were obtained using the Pentacam HR (Oculus Optikgeräte GmbH). Axial length was obtained using the IOLMaster 700 (Carl Zeiss Meditec AG). The paired t test was used to analyze the difference in CLR between the two orientations. Pearson correlation analysis was performed to investigate the correlations between CLR and other ocular variables.

RESULTS

This prospective observational study comprised 99 eyes (99 patients) that underwent Visian Implantable Collamer Lens (STAAR Surgical) implantation for myopic correction. The mean CLR was 64.29 ± 168.04 and 208.09 ± 173.12 µm in the horizontal and vertical orientations, respectively. The vertical CLR (VCLR) was significantly greater than the horizontal CLR (HCLR) (P < .05). Both the HCLR and VCLR were positively correlated with lens thickness and negatively correlated with ACD (all P < .05). The difference in CLR (VCLR-HCLR) was positively correlated with the axial length and the difference in ATA between the two orientations (P < .05).

CONCLUSIONS

VCLR was greater than HCLR in most patients with myopia, especially in the longer eyes. This nonuniform distribution in CLR implied different placements of the iridocorneal angles in the horizontal and vertical orientations and should be considered for the selection of ICL size and placement position. [J Refract Surg. 2023;39(5):354-359.].

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

PURPOSE

To establish and validate the accuracy of implantable collamer lens (ICL) vault size prediction formula based on preoperative biometric factors and lens parameters.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.].

Artificial intelligence-based refractive error prediction and EVO-implantable collamer lens power calculation for myopia correction

BACKGROUND

Implantable collamer lens (ICL) has been widely accepted for its excellent visual outcomes for myopia correction. It is a new challenge in phakic IOL power calculation, especially for those with low and moderate myopia. This study aimed to establish a novel stacking machine learning (ML) model for predicting postoperative refraction errors and calculating EVO-ICL lens power.

METHODS

We enrolled 2767 eyes of 1678 patients (age: 27.5 ± 6.33 years, 18-54 years) who underwent non-toric (NT)-ICL or toric-ICL (TICL) implantation during 2014 to 2021. The postoperative spherical equivalent (SE) and sphere were predicted using stacking ML models [support vector regression (SVR), LASSO, random forest, and XGBoost] and training based on ocular dimensional parameters from NT-ICL and TICL cases, respectively. The accuracy of the stacking ML models was compared with that of the modified vergence formula (MVF) based on the mean absolute error (MAE), median absolute error (MedAE), and percentages of eyes within ± 0.25, ± 0.50, and ± 0.75 diopters (D) and Bland-Altman analyses. In addition, the recommended spheric lens power was calculated with 0.25 D intervals and targeting emmetropia.

RESULTS

After NT-ICL implantation, the random forest model demonstrated the lowest MAE (0.339 D) for predicting SE. Contrarily, the SVR model showed the lowest MAE (0.386 D) for predicting the sphere. After TICL implantation, the XGBoost model showed the lowest MAE for predicting both SE (0.325 D) and sphere (0.308 D). Compared with MVF, ML models had numerically lower values of standard deviation, MAE, and MedAE and comparable percentages of eyes within ± 0.25 D, ± 0.50 D, and ± 0.75 D prediction errors. The difference between MVF and ML models was larger in eyes with low-to-moderate myopia (preoperative SE >  - 6.00 D). Our final optimal stacking ML models showed strong agreement between the predictive values of MVF by Bland-Altman plots.

CONCLUSION

With various ocular dimensional parameters, ML models demonstrate comparable accuracy than existing MVF models and potential advantages in low-to-moderate myopia, and thus provide a novel nomogram for postoperative refractive error prediction and lens power calculation.

Development of an implantable collamer lens sizing model: a retrospective study using ANTERION swept-source optical coherence tomography and a literature review

BACKGROUND

Optimal sizing for phakic intraocular lens (EVO-ICL with KS-AquaPort) implantation plays an important role in preventing postoperative complications. We aimed to formulate optimal lens sizing using ocular biometric parameters measured with a Heidelberg anterior segment optical coherence tomography (AS-OCT) device.

METHODS

We retrospectively analyzed 892 eyes of 471 healthy subjects treated with an intraocular collamer lens (ICL) and assigned them to either the development (80%) or validation (20%) set. We built vault prediction models using the development set via classic linear regression methods as well as partial least squares and least absolute shrinkage and selection operator (LASSO) regression techniques. We evaluated prediction abilities based on the Bayesian information criterion (BIC) to select the best prediction model. The performance was measured using Pearson's correlation coefficient and the mean squared error (MAE) between the achieved and predicted results.

RESULTS

Measurements of aqueous depth (AQD), anterior chamber volume, anterior chamber angle (ACA) distance, spur-to-spur distance, crystalline lens thickness (LT), and white-to-white distance from ANTERION were highly associated with the ICL vault. The LASSO model using the AQD, ACA distance, and LT showed the best BIC results for postoperative ICL vault prediction. In the validation dataset, the LASSO model showed the strongest correlation (r = 0.582, P < 0.001) and the lowest MAE (104.7 μm).

CONCLUSION

This is the first study to develop a postoperative ICL vault prediction and lens-sizing model based on the ANTERION. As the measurements from ANTERION and other AS-OCT devices are not interchangeable, ANTERION may be used for optimal ICL sizing using our formula. Because our model was developed based on the East Asian population, further studies are needed to explore the role of this prediction model in different populations.

Big-data and artificial-intelligence-assisted vault prediction and EVO-ICL size selection for myopia correction

AIMS

To predict the vault and the EVO-implantable collamer lens (ICL) size by artificial intelligence (AI) and big data analytics.

METHODS

Six thousand two hundred and ninety-seven eyes implanted with an ICL from 3536 patients were included. The vault values were measured by the anterior segment analyzer (Pentacam HR). Permutation importance and Impurity-based feature importance are used to investigate the importance between the vault and input parameters. Regression models and classification models are applied to predict the vault. The ICL size is set as the target of the prediction, and the vault and the other input features are set as the new inputs for the ICL size prediction. Data were collected from 2015 to 2020. Random Forest, Gradient Boosting and XGBoost were demonstrated satisfying accuracy and mean area under the curve (AUC) scores in vault predicting and ICL sizing.

RESULTS

In the prediction of the vault, the Random Forest has the best results in the regression model (R²=0.315), then follows the Gradient Boosting (R²=0.291) and XGBoost (R²=0.285). The maximum classification accuracy is 0.828 in Random Forest, and the mean AUC is 0.765. The Random Forest predicts the ICL size with an accuracy of 82.2% and the Gradient Boosting and XGBoost, which are also compatible with 81.5% and 81.8% accuracy, respectively.

CONCLUSIONS

Random Forest, Gradient Boosting and XGBoost models are applicable for vault predicting and ICL sizing. AI may assist ophthalmologists in improving ICL surgery safety, designing surgical strategies, and predicting clinical outcomes.

EVO/EVO+ Visian Implantable Collamer Lenses for the correction of myopia and myopia with astigmatism

INTRODUCTION

Intraocular lens implantation in phakic eyes for the correction of refractive error is currently a widespread procedure. The EVO and EVO+ Visian Implantable Collamer Lenses (ICL) are two of the most prevalent lenses implanted. They incorporate a central orifice to avoid the need for iridotomy. The main difference between both ICL is the higher optical diameter zone provided by the EVO+, allowing a better quality of vision at night. This review aims to provide an overview of the current ICL models available for correcting myopia and myopic astigmatism.

AREAS COVERED

During the last decade, more than 100 scientific papers analyzing the performance of EVO and EVO+ lenses have been published. This review describes the objective visual performance achieved with the implantation of central hole ICL lenses and the subjective perception of the patients implanted with these lenses. In addition, the safety and the potential complications associated with undergoing an EVO and EVO+ ICL implantation have been addressed.

EXPERT OPINION

Refractive surgeons and candidates to undergo ICL implantation should be aware of the excellent safety and visual outcomes provided by the implantation of central hole ICL lenses. However, future research could address minor issues currently not resolved.

Vault-Correlated Efficacy and Safety of Implantable Collamer Lens V4c Implantation for Myopia in Patients with Shallow Anterior Chamber Depth

INTRODUCTION

The aim of the study was to evaluate efficacy and safety outcomes after implantation of the Visian Implantable Collamer Lens (ICL V4c) in myopia patients with shallow anterior chamber depth (ACD).

METHODS

This retrospective study followed 163 eyes of 94 patients for at least 24 months. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity, intraocular pressure (IOP), manifest refraction, vault, endothelial cell density (ECD), anterior chamber angle (ACA), anterior chamber volume, and the distance from the corneal endothelium to the central ICL (C-ICL) were measured during follow-ups. Spearman's correlation and logistic regression were used to identify variables correlated with changes in ECD and potential risk factors for ineffective outcomes, respectively.

RESULTS

All surgeries were performed safely. High IOP of 9 eyes and anterior capsular opacity of 5 eyes were observed. The last follow-up ACA had a significant difference between the high and normal IOP groups (p = 0.0003). The mean ECD and vault were 2,855.76 ± 270.82 cells/mm2 and 388.01 ± 135.28 μm at the last follow-up, respectively. The vault and C-ICL were significantly associated with ΔECD (all p < 0.05). Furthermore, the vault was most responsible for the ECD loss. Twenty-two eyes had unsatisfactory postoperative UDVA, and the low vault at the last follow-up was a significant risk factor for this ineffective outcome (p < 0.001, OR = 14.739).

CONCLUSIONS

ICL V4c implantation in patients with shallow ACD achieved stable visual outcomes. The vault is related to postoperative visual acuity and ECD loss, which needs to be paid attention during follow-up.

The long-term observation of the rotation of implantable collamer lens as the management of high postoperative vault

Purpose

This study aimed to describe the effectiveness and stability of implantable collamer lens (ICL) rotation in reducing high postoperative vault.

Setting

This study was conducted in the Peking Union Medical College Hospital, Chinese Academy of Medical Sciences.

Design

This is a retrospective case series.

Methods

Twenty-two eyes from 22 patients who had ICL (V4c EVO) implantation with high postoperative vault (>=750 μm) were recruited for our study. All the lenses were rotated from a horizontal to an oblique position. The vault, SSA, AOD500, AOD750, TISA500, and TISA750 at 180° and 0° were measured pre-rotation, 1-week post-rotation, and in the at-least 1-year-follow-up.

Results

Twenty female patients and two male patients were recruited, with a mean age of 28.68 ± 6.08 years. The mean vault had declined significantly from 951.81 ± 154.26 μm pre-rotation to 772.27 ± 119.40 μm 1 week post-rotation (p < 0.001). The SSA, AOD500, AOD750, TISA500, and TISA750 at 180° and 0° pre-rotation and 1-week post-rotation were 30.40 ± 7.91° and 45.14 ± 6.75°, 32.37 ± 7.48° and 46.23 ± 6.39°, 303.27 ± 87.99 and 522.45 ± 122.16 μm, 323.81 ± 89.15 and 536.13 ± 121.66 μm, 387.95 ± 99.43 and 630.81 ± 133.59 μm, 435.68 ± 106.72 and 643.36 ± 132.82 μm, 0.109 ± 0.034 and 0.202 ± 0.053 mm², 0.123 ± 0.034 and 0.212 ± 0.051 mm², 0.194 ± 0.056 and 0.345 ± 0.083 mm², and 0.216 ± 0.055 and 0.358 ± 0.079 mm² (all p < 0.001). The mean vault value had changed from 747.50 ± 116.07 μm 1-week post-rotation to 586.87 ± 132.65 μm in the 1-year follow-up. However, the SSA, AOD500, AOD750, TISA500, and TISA750 at 180° and 0° had remained stable (p > 0.05).

Conclusion

Non-toric ICL rotation is a novel and effective technique in the treatment of high postoperative vault. Our results are more robust given the extended period of follow-up.

Improvement in the ideal range of vault after implantable collamer lens implantation: a new vault prediction formula

Background

To derive and validate a novel vault prediction formula to improve the predictability and safety of implantable collamer lens (ICL) implantation.

Methods

Thirty-five patients (61 eyes) with previous posterior chamber intraocular lens implantation were included. Various parameters, such as horizontal-visible iris diameter (HVID), photopic pupil diameter (PPD), axial length (AL), white-to-white (WTW), anterior chamber width (ACW), angle-to-angle (ATA), crystalline lens rise (CLR), anterior chamber depth (ACD), horizontal sulcus-to-sulcus (HSTS), and ciliary sulcus angle (CSA) were measured. Vault was measured at 3 months after surgery using CASIA2 anterior segment optical coherence tomography. The formula was derived using multiple linear regression analysis and named as WH formula. It was validated in 65 patients (118 eyes) to determine the percentage of the ideal postoperative vault range and to compare the differences between the WH formula and the NK, KS, and STAAR formulas.

Results

Final ICL size, ATA, CSA, and CLR were included in the prediction formula model (adjusted R² = 0.67, p < 0.001). The achieved vault 1 month after the surgery was 556.19 μm ± 166.98 μm in the validation group, and the ideal vault range was 200-800 μm (92%). The difference between the achieved vault and that predicted using the WH formula was not statistically significant (p = 0.165), whereas the difference between the achieved vault and that predicted using the NK and KS formulas was statistically significant (p < 0.001 and p < 0.001, respectively). The 95% agreement limit range of the achieved vault and the vault predicted using the WH formula was narrower than those predicted using the NK and KS formulas (-295.20-258.82 μm).

Conclusion

This study combined the results of optical coherence tomography and ultrasound biomicroscopy measurements of the anterior segment of the eye and incorporated ciliary sulcus morphology quantification into the prediction formula. The study derived a prediction formula for vault by combining ICL size, ATA, and CLR. The derived formula was found to be superior to the currently available formulas.

A Case of a Low Vault after Posterior Chamber Acrylic Phakic Intraocular Lens Implantation

When implanting a posterior chamber phakic intraocular lens (pIOL), it is crucial to maintain a safe distance. The patient was a 29-year-old man with high-degree bilateral myopia. In February 2021, posterior chamber acrylic pIOLs (Eyecryl Phakic TORIC; Biotech Vision Care, Gujarat, India) were implanted in both his eyes. After the surgery, the right eye vault was 6 μm, and the left eye vault was 350 μm. Moreover, the internal anterior chamber depth values were 2,270 and 2,220 μm for the right and left eyes, respectively. In our case, we found a fairly high crystalline lens rise (CLR) in both eyes, but it was greater in the right eye. The CLR value was +455 in the right eye and +350 in the left eye. In our patient, anterior segment anatomical parameters were higher in the right eye than in the left eye, and a greater pIOL length was calculated for the right eye, but the vault was very low. In our opinion, this was associated with the high CLR in the right eye. If an even larger pIOL had been implanted, there would have been a greater narrowing of the anterior chamber angle. This case would be contraindicated if those parameters were considered in selecting the indications and determination of the pIOL length.

Vault differences in eyes implanted with spherical and toric implantable collamer lenses: an inter-eye analysis

Purpose

To determine the influence of implantable collamer lenses (ICL) geometry, i.e. spherical and toric on the vault, and report the refractive and visual outcomes of patients bilaterally implanted with the two ICL geometries.

Methods

This retrospective case series analysed 41 patients implanted with a spherical ICL (sICL) in one eye and an equal sized toric ICL (tICL) in the fellow eye. The anatomical and ICL-related parameters were assessed using anterior-segment optical coherence tomography (AS-OCT Visante, Zeiss Meditec AG) and optical tomography (Pentacam, OCULUS). The influence of the anatomical and ICL-related parameters on the vault was determined using generalised estimating equations (GEE) to incorporate inter-eye correlations.

Results

Postoperative spherical equivalent was within ± 0.50D in 66% and 83% of the eyes, respectively implanted with sICL and tICL. The efficacy index in the sICL group was 1.06 and 1.14 in the tICL group. The mean inter-eye vault difference was -1.46 µm, anatomical and ICL-related parameters showed similar associations with the vault for sICL and tICL. The GEE identified the ICL size minus the anterior chamber width, the ICL spherical power and ICL central thickness as significant factors influencing the vault.

Conclusions

Spherical and toric ICL showed good efficacy for the correction of myopia and astigmatism. Patients implanted bilaterally with sICL and tICL tend to present similar vaults. The vault produced by both types of ICL was mainly regulated by the oversizing of the ICL. This suggests that the ICL geometry (spherical vs toric) is a factor with limited influence on the vault, thus the sizing method of a sICL and tICL should be similar.

Early Assessment of Circumferential Anterior Segment Structures Following Implantable Collamer Lens V4c Implantation Via SS-OCT

Purpose

To explore early changes in circumferential anterior segment structures following Implantable Collamer Lens (ICL) V4c implantation via swept-source optical coherence tomography (SS-OCT).

Methods

In 103 eyes of 56 myopic patients undergoing ICL V4c surgery, anterior segments were measured via SS-OCT to compute local anterior chamber angle (ACA) parameters on the nasal–temporal (0°–180°), superior–inferior (90°–270°), and superior nasal–inferior temporal (80°–260°) meridians, including angle-opening distance at 500 µm (AOD500), trabecular–iris space area at 500 µm (TISA500), trabecular–iris angle at 500 µm (TIA500), and circumferential ACA parameters, including AOD area at 500 µm (AODA500), trabecular–iris circumference volume at 500 µm (TICV500), and the index and area of iris–trabecular contact (ITC). ACA parameters were compared preoperatively and at 1 week, 1 month, and 3 months postoperatively and compared among quadrants. Mixed-effects model was used to evaluate the parameters correlated with the post-ITC parameters.

Results

The mean AOD500, TISA500, TIA500, AODA500, and TICV500 were decreased by 65.4% to 71%, 64.1% to 69.3%, 53.8% to 61.5%, 69.9%, and 69.2%, respectively, at 1 week postoperatively. The ITC index and area values rose from 1.436% ± 4.427% and 0.070 ± 0.254 mm² to 12.343% ± 13.216% and 0.903 ± 1.304 mm² (all P < 0.05). No further decreases in ACA parameters were observed beyond 1 week postoperatively (all P > 0.05). Significant differences were observed among quadrants, with the narrowest in the superior–nasal quadrant, followed by the superior quadrant. The 3-month vault was significantly correlated with the ITC index and area at 3 months postoperatively.

Conclusions

Anterior segment structures were significantly shallow at 1 week with no further decreases thereafter. In light of anatomical variability, we recommend circumferential meridian scan to assess angle status, with special attention to the superior–nasal and superior quadrants.

Translational Relevance

We investigated the early changes in circumferential anterior segment structures following ICL V4c implantation, thus providing a better perspective for understanding anterior segment structural characteristics after ICL V4c surgery.

Corneal diameter measurements by 3 optical biometers and their effect on phakic intraocular lens sizing

PURPOSE

To compare phakic intraocular lens size calculations based on corneal diameter (CD) measurements by 3 instruments.

SETTING

G.B. Bietti Foundation I.R.C.C.S., Rome, Italy.

DESIGN

Retrospective interventional case series.

METHODS

Preoperatively, CD was measured with the Aladdin, IOLMaster 700, and Pentacam AXL Wave. The simulated ICL size was computed by entering CD measurements into the manufacturer's calculator. Postoperatively, vaulting was measured by anterior segment optical coherence tomography. The optimal ICL size (OIS) was calculated and compared with the commercially available OIS (CAOIS).

RESULTS

54 eyes (29 patients) with the implantable collamer lens (ICL) were enrolled. The mean CD was 12.02 ± 0.36 mm with the Aladdin, 12.35 ± 0.39 mm with the IOLMaster 700, and 12.22 ± 0.41 mm with the Pentacam AXL Wave ( P &amp;lt; .0001), with the closest agreement between the Pentacam AXL Wave and IOLMaster 700 (95% limits of agreement: -0.43 to +0.17 mm). Vaulting (mean: 558 ± 261 μm) was within 251 and 1000 μm in 49 eyes (83.3%). The mean difference between the simulated ICL size and OIS ranged between -0.11 ± 0.35 mm and 0.10 ± 0.30 mm ( P &amp;lt; .0001), with no statistically significant difference between the IOLMaster 700 and Pentacam AXL Wave. The simulated ICL size was equal to CAOIS in 38 eyes (70.37%) with the Aladdin, 37 eyes (68.52%) with the IOLMaster 700, and 39 eyes (72.22%) with the Pentacam AXL Wave, without any statistically significant difference.

CONCLUSIONS

CD measurements by the 3 devices lead to similar percentages of eyes with an ICL size equal to the OIS. Agreement is closer between the IOLMaster 700 and Pentacam AXL Wave.

Prediction of excessively low vault after implantable collamer lens implantation using iris morphology

Purpose

To identify the iris morphology-related factors for prediction of outcomes of excessively low vault (< 100 μm) after Implantable Collamer Lens V4c (ICL V4c; STAAR Surgical) implantation.

Methods

This retrospective case-control study included 81 eyes from 2,080 patients who underwent ICL implantation. Twenty-seven eyes of 27 patients with excessively low vault (< 100 μm) constituted the case group (excessively low vault group). Patients with vault (250 to 750 μm) were selected as the optimal vault group by matching anterior chamber depth, white-to-white distance and ICL size with cases with excessive low vault (< 100 μm) at a proportion of 1:2. The preoperative biometric parameters and postoperative vault were recorded. Multiple linear regression analysis was performed to assess the relationship between the postoperative vault and various variables. Conditional logistic regression analysis was used to estimate the risk factors for excessively low vault.

Results

The postoperative vault was associated with preoperative pupil diameter (PD), crystalline lens rise, iris concavity and the ratio of the iris concavity to chord length (P < 0.05). The larger iris concavity increased risk of excessively low postoperative vault (< 100 μm) (OR = 81.10; 95%CI = 2.87 to 2296.58; P = 0.01).

Conclusions

Eyes with obviously concave iris were associated with a higher rate of excessively low vault (< 100 μm). Evaluation of iris morphology may provide significant information for predicting excessive postoperative vault.

Inter-eye and postoperative prediction of vault after implantation of EVO + Visian phakic implantable collamer lens

PURPOSE

To assess whether the postoperative outcomes of the implantation of an EVO + implantable collamer lens (ICL) in one eye can be used as a predictor of the vault of the fellow eye, and to evaluate the vault changes of the implantation in both eyes during the postoperative period.

METHODS

A prospective study including 40 eyes of 20 patients with a bilateral EVO + ICL implantation was performed. Subjects were evaluated before the surgery and 1 day, 1 week and 1, 3 and 6 months postoperatively. Central vault was assessed using spectral-domain optical coherence tomography. The inter-eye and follow-up analyses were performed using lineal models and the Bland-Altman method.

RESULTS

The vault of the first implanted eye at the 1-day visit highly predicts the vault of the second eye (R² = .87; P < .001); the mean inter-eye difference was - 0.95 μm, and the superior and inferior limits of agreement were -50.27 μm and 148.37 μm, respectively. This relationship was maintained during the medium-term follow-up, not finding differences in the slopes among visits (P ≥ .09). A progressive decrease of vault was found during the follow-up (P < .001). Larger vault change 6 months after the surgery was associated with higher vault 1 day after the ICL implantation (R² = .19;P = .005).

CONCLUSION

One-day postoperative vault in the first eye can help to predict the optimal ICL sizing in the second eye. Vault tends to decrease during the first 6 months after EVO + ICL implantation. Eyes with higher initial vaults will also show larger reductions during the medium-term follow-up.

Implantable collamer lens sizing based on measurement of the sulcus-to-sulcus distance in ultrasound biomicroscopy video clips and ZZ ICL formula

BACKGROUND

To evaluate a new method of implantable collamer lens (ICL) sizing based on ultrasound biomicroscopy (UBM) video clips.

METHODS

This observational study included consecutive patients with myopia and myopic astigmatism scheduled for V4c toric ICL (TICL) implantation (STAAR) at Hangzhou MSK Eye Hospital (October 2020 to November 2020). Sulcus-to-sulcus (STS) distance, lens thickness (LT), and clinical refraction were measured preoperatively. The ZZ ICL formula (provides the predicted vault height and refraction based on TICL size, intraocular meridian, power, and eye parameters, including STS distance and LT) was used to select TICL size and predict vault height and residual refraction, which was also compared with the STAAR software recommended. Vault and residual refraction were measured at 3 months postoperatively.

RESULTS

The analysis included 168 eyes in 84 patients. Postoperative vault size was comparable to that predicted by the ZZ ICL formula (528 ± 193 vs. 545 ± 156 μm, P = 0.227). Vault prediction error (PE) by the ZZ ICL formula was within 100, 300, and 500 μm in 40.48%, 88.10%, and 100% of eyes, respectively. Spherical equivalent (SE) and absolute cylindrical refractive error were 0.36 ± 0.48 and 0.40 ± 0.31 D at 3 months postoperatively. The SE PE, absolute cylindrical PE, and percentages of eyes with an absolute cylindrical PE within ± 0.50 D and ± 1.00 D were lower for the ZZ ICL formula than for the STAAR software (P < 0.01).

CONCLUSIONS

Combining measurements obtained in UBM video clips with the ZZ ICL formula provides an effective method of sizing TICLs and predicting vault height and residual refractive error.

A prediction model for sulcus-to-sulcus diameter in myopic eyes: a 1466-sample retrospective study

Background

To establish and verify the accuracy and reliability of a sulcus-to-sulcus diameter (STS) prediction model.

Methods

In this retrospective study, the prediction formula was established with the data from 1466 eyes from 733 subjects from July 2020 to April 2021 and verified with the data from 278 eyes from 139 subjects between May 2021 and June 2021. Each subject was measured with a Pentacam, IOLMaster 700, OPD-Scan III, and ultrasound biomicroscope. The prediction formulas were established with multiple linear regression, and intergroup correlation coefficients (ICCs) and Bland–Altman tests were used to assess the agreement between the predicted and actual STS (actual STS was measured by UBM).

Results

The explanatory variables relevant to the horizontal STS (STSH) were the Pentacam white-to-white diameter (WTWP; standardized partial regression coefficient [β] = 0.330; p < 0.001), the flat K value (β = -0.211; p < 0.001), and the anterior corneal diameter (ACD) (β = 0.178; p < 0.001). The corresponding multiple regression equation was : STSH (mm) = 8.061 + 0.510 × WTWP − 0.090 × Flat K value + 0.430 × ACD. The explanatory variables relevant to the vertical STS (STSV) were the WTWP (β = 0.435; p < 0.001), the steep K value (β = -0.271; p < 0.001), and the ACD (β = 0.187; p < 0.001). The corresponding multiple regression equation was : STSV (mm) = 8.540 + 0.492 × WTWP − 0.075 × Steep K value + 0.329 × ACD. The bias of the predicted to the actual STSH was − 0.021, with 95% limits of agreement (95% LoA) from − 0.499 to 0.457. The bias of the predicted to the actual STSV was 0.057, with 95% LoA from − 0.462 to 0.575. The ICC was 0.883 between the predicted and actual STSH and 0.859 between the predicted and actual STSV.

Conclusions

The Pentacam-measured WTW, the K value and the ACD are important for predicting the STS diameter. The prediction model has good accuracy and reliability.

Trial registration

Not applicable.

Clinical Prediction of Inadequate Vault in Eyes With Thick Lens After Implantable Collamer Lens Implantation Using Iris Morphology

Background

Obtaining an ideal vault is crucial in the implantable collamer lens (ICL) surgery. Prediction of the vault value is difficult since it requires the integration of multiple factors. The purpose of this study was to investigate the association between the iris shape and vault value in eyes with thick lens.

Methods

The study was conducted in Peking Union Medical College Hospital. Patients who received ICL V4c between 2017 and 2021 were screened. Eyes with thick lens (>4.0 mm) and abnormal iris shape (concave or convex) were included. The preoperative biometric parameters and postoperative vault value were compared between eyes with concave shape group and convex shape group. The relationship between various factors and vault was assessed by spearman rank analysis and multiple linear regression analysis. Representative cases our strategies to deal with the abnormal vault were demonstrated.

Results

Twenty eight eyes of 14 patients with thick lens and concave or convex shape iris were eventually included, with 14 eyes of 7 patients in group 1 (concave shape iris) and the other 14 eyes of 7 patients in group 2 (convex shape iris). The mean vault of group 1 was (0.16 ± 0.07) mm, which was significantly lower than (0.88 ± 0.13) mm in group 2. Multiple linear regression analysis showed iris shape (P < 0.001) was only the explanatory variables associated with the postoperative vault. In group1, 4 eyes showed extremely large ACA, requiring a secondary surgical intervention. So all of them underwent ICL exchange for a larger ICL. In group2, the ICL was implanted in a vertical or oblique position to avoid or rescue an extremely large vault.

Conclusion

Concave shape iris had a higher risk of low vault and convex shape iris were more likely to demonstrate high vault in eyes with thick lens. Exchanging ICL for the larger size and adjusting ICL to the vertical or oblique orientation are good option to rescue the low or high vault, respectively.

Comparison of Vault Measurements Using a Swept-Source OCT-Based Optical Biometer and Anterior Segment OCT

Background

To newly describe the vault measurement by using a widely used swept-source OCT-based optical biometer (IOLMaster700) and accessd the accuracy of vault measurement.

Methods

This was a retrospective, cross-sectional study. All patients underwent implantable Collamer lens (ICL) implantation surgery without complications. IOLMaster700 and AS-OCT analyses were conducted for each eye on the same day in the same condition. Measurements of anterior chamber depth (ACD), corneal-ICL (C-ICL), and vault values were made and recorded. The repeatability of the IOL Master700 measurements was quantified based upon intraclass correlation coefficient (ICC) values. Correlations between IOL Master700 and AS-OCT measurements made with these different analytical approaches were assessed. The agreement of instruments was evaluated using Bland-Altman plots.

Results

The IOLMaster700 instrument yielded highly reliable measurements of vault, C-ICL, and ACD (ICC = 0.996, 0.995, 0.995, respectively). Vault, C-ICL and ACD values as measured using the IOLMaster700, was slightly smaller than that measured via AS-OCT, but these differences were not significant (p = 0.652, p = 0.121 and p = 0.091, respectively). The vault, C-ICL, and ACD measurements by these two instruments were strongly correlated (r = 0.971, r = 0.944, and r = 0.963, respectively; all p &lt; 0.001). The 95% limits of agreement for vault, C-ICL, and ACD measurements between the two devices were−0.08 to 0.08 mm,−0.14 to 0.11 mm, and−0.13 to 0.10 mm, respectively.

Conclusions

The IOLMasrer700 can measure implanted ICL vault with a high degree of accuracy and repeatability. Good correlations and agreement were observed between IOLMaster700 and AS-OCT in measuring vault, C-ICL, and ACD measurements.

Imaging of the Ciliary Body: A Major Review

PURPOSE

We conducted a systematic search of literature to understand the various methods of imaging of the ciliary body.

METHODS

PubMed, Science Direct, Cochrane Library and Google Scholar were searched comprehensively and systematically to find studies related to the various modalities of ciliary body imaging.

RESULTS

The various ciliary body parameters that have been described are Ciliary body thickness, Ciliary body length, ciliary muscle thickness, ciliary process length, ciliary muscle length, ciliary muscle anterior length, trabecular ciliary process distance and Iris ciliary process distance. The various angles which have been measured, which mostly have a significance in Primary angle closure glaucoma (PACG) are Iris ciliary angle, Trabecular ciliary angle, scleral ciliary process angle. Various authors have defined them in various ways with subtle differences. Plateau iris and PACG mechanisms, not forgetting malignant glaucoma are better understood with imaging of the ciliary body using the ultrasound biomicroscopy (UBM). The anterior segment optical coherence tomography (ASOCT) imaging of the ciliary body has been described albeit with its own disadvantages. A few other fields dependant on the importance of ciliary body imaging are intravitreal injections, pars plana vitrectomy, measurements for implantable collamer lens (ICL) and of utmost importance, the differentiating features of ciliary body masses.

CONCLUSION

The UBM is still preferred over the ASOCT for imaging of the ciliary body. A lot of lacunae of knowledge still exists and consensus has to be reached on defining all the parameters universally. Future studies will be able to shed more light on the role of the ciliary body in the many ocular disorders mentioned in this review.

Outcomes of the EVO ICL Using a Customized Non-horizontal or Horizontal Implanting Orientation Based on UBM Measurement: A Pilot Study

Introduction

To evaluate the short-term safety and efficacy of the EVO implantable collamer lens (ICL) using a customized implanting orientation design based on ultrasound biomicroscope (UBM) measurement.

Methods

The prospective case series included 310 eyes of 158 patients treated with ICL. To achieve an optimal vault, an ICL of specific size was chosen and implanted in a customized orientation according to assessment of sulcus-to-sulcus (STS) diameters, distance between STS plane and crystalline lens (STSL), the morphology of ciliary sulcus (MCS), anterior chamber depth (ACD), and white-to-white (WTW). With the new design, there were 138 eyes with a non-horizontal orientation and 172 eyes with a horizontal orientation of the ICL. Refractive and ICL vault statuses were followed up for 1 day and 1 month postoperatively.

Results

The safety index at 1 month was 1.34 ± 0.17 for the non-horizontally implanted group and 1.33 ± 0.16 for the horizontally implanted group; the efficacy index was 1.21 ± 0.18 for the non-horizontally implanted group and 1.18 ± 0.16 for the horizontally implanted group. All eyes achieved an uncorrected distance visual acuity of 0.10 logMAR or better. No significant difference in endothelial cell density was observed between the preoperative value (2792.6 ± 247.6 cells/mm²) and value at 1 month postoperatively (2744.2 ± 243.3 cells/mm²), and no cataract or anterior subcapsular opacification was observed. Ideal vault (250–750 μm) was achieved in 84% of eyes (260/310).

Conclusion

The customized ICL design of implanting orientation based on UBM measurement provides good safety, efficacy, and vault predictability.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40123-022-00498-8.

Agreement of implantable collamer lens sizes using parameters from different devices

Objective

To assess agreement and repeatability of white-to-white (WTW) and anterior chamber depth (ACD), and agreement of implantable collamer lens (ICL) size using these measurements from different devices.

Methods and analysis

A retrospective review of 83 eyes with ICL implantation (42 patients) was conducted. The agreement of WTW (measured with WaveLight Topolyzer and Orbscan IIz) and ACD (measured with WaveLight Oculyzer and Orbscan IIz) was analysed. Correlation of ICL sizes and difference of eyes with unacceptable vaults between two data sets (WaveLight platform; Topolyzer and Oculyzer and Orbscan IIz) were assessed.

Results

Average WTW measured by Orbscan IIz and Topolyzer demonstrated good agreement (Ρ 0.884) with low systematic bias (−0.03±0.1 mm) and narrow 95% limits of agreement (LoA) of −0.28 to 0.22. Average ACD measured by Orbscan IIz and Oculyzer also showed good agreement (Ρ 0.903) with low systematic bias (−0.04±0.1 mm) and relatively narrow 95% LoA (0.2 to 0.12). ICL size selected according to two data sets showed moderate to strong level of agreement (Kappa=0.81). There was a statistically significant difference (p<0.001) in the proportion of eyes with unacceptable postoperative vaults when using the Wavelight platform data set (five eyes, 6.02%) and the Orbscan IIz data set (12 eyes, 14.46%).

Conclusion

Although the agreement of WTW and ACD between devices was good, there was a significant difference in proportion of eyes with unacceptable postoperative vaults when using two data sets. Therefore, Topolyzer and Oculyzer might not be suitable for operating interchangeably with Orbscan IIz for ICL size selection.

Correlation between intraoperative and postoperative vaulting of the EVO implantable Collamer lens: a retrospective study of real-time observations of vaulting using the RESCAN 700 system

Background

Implantable Collamer lens (ICL) vaulting is one of the most important parameters for the safety, aqueous humor circulation, and lens transparency after ICL implantation. This study aimed to investigate the factors associated with the actual vaulting after refractive EVO-ICL surgery.

Methods

This retrospective study included patients who underwent EVO-ICL surgery at a tertiary eye hospital between October and December 2019. A RESCAN 700 was used for the intraoperative and CIRRUS HD-OCT was used for postoperative observation of vaulting. Subjective and objective refractions, anterior ocular segment, corneal morphology, intraocular pressure (IOP), anterior chamber volume (ACV), crystalline lens rise (CLR), white-to-white distance (WTW), anterior chamber depth (ACD), axial length, corneal endothelial cell density (ECD), and fundoscopy were examined. A multivariable analysis was performed to determine the factors independently associated with 1-month postoperative vaulting.

Results

Fifty-one patients (102 eyes) were included. Compared with the eyes with normal vaulting, those with high vaulting had higher preoperative diopter values (P = 0.039), lower preoperative corrected visual acuity (P = 0.006), lower preoperative IOP (P = 0.029), higher preoperative ACD (P = 0.004), lower preoperative CLR (P = 0.046), higher ICL spherical equivalent (P = 0.030), higher intraoperative vaulting (P < 0.001), and lower IOP at 1 month (P = 0.045). The multivariable analysis showed that the only factor independently associated with high vaulting at 1 month after surgery was the intraoperative vaulting value (odds ratio = 1.005, 95% confidence interval: 1.002–1.007, P < 0.001). The intraoperative and 1-month postoperative vaulting values were positively correlated (R² = 0.562).

Conclusions

The RESCAN700 system can be used to perform intraoperative optical coherence tomography to predict the vaulting value of ICL at 1 month.

Indications for exchange or explantation of phakic implantable collamer lens with central port in patients with and without keratoconus

AIM

To evaluate the causes of phakic implantable collamer lens (ICL) exchange/explantation in patients with and without keratoconus (KC) at two tertiary hospitals in Riyadh, Saudi Arabia.

METHODS

A retrospective chart review of all patients who underwent ICL (model V4c with central port) exchange/explantation was performed using the electronic medical record systems. All available preoperative and postoperative data were documented for each patient.

RESULTS

Over 7y, 2283 ICL implantation procedures were performed; 46 implants (2%) required exchange (21 implants)/explantation (25 implants), of which 14 cases (30.4%) were patients with KC. Indications for ICL exchange/explantation in non-KC group were vault measurement, cataract formation, increased intraocular pressure, inaccurate refraction, and patient dissatisfaction in 22 (68.75%), 4 (12.5%), 3 (9.37%), 2 (6.25%), and 1 (3.12%) case, respectively. The most common indication for ICL exchange/explantation in the KC group was inaccurate vault sizing in 11 patients (78.57%), inaccurate refraction in 2 patients (14.28%), and patient dissatisfaction postoperatively in 1 (7.14%) case.

CONCLUSION

ICL implantation results in predictable refractive outcomes over the long term with exchange/explantation rates comparable to previous literature. Improper vault size is the most common cause of ICL exchange/explantation among patients with or without KC.

Consecutive contralateral comparison of toric and non-toric implantable collamer lenses V4c in vault after implantation for myopia and astigmatism

AIMS

To compare the vault performance between implantable collamer lens (ICL) V4c and Toric ICL (TICL) V4c after implantation and to investigate the affecting factors.

METHODS

Sixty-eight eyes from 34 patients with myopia or myopia astigmatism who underwent implantation of TICL in one eye (group A) and identically sized ICL (group B) in the contralateral eye were included. Mean follow-up time were 7.58 ± 1.63 months (range: 6-10 months). Vault was compared between the two groups and correlations between vault and age, preoperative ocular biometric measurements were analysed. Generalized estimating equation (GEE) model of postoperative vault adjusting for within-patient intereye correlations was performed.

RESULTS

The safety indices were 1.27 and 1.35, and the efficacy indices were 1.20 and 1.24 for groups A and B, respectively. Vault of TICL was significantly higher than that of ICL (554.11 ± 219.36 μm vs 449.70 ± 172.47 μm, P < 0.001). The difference between ICL/TICL size and WTW (size-WTW) and STS (size-STS), anterior chamber depth and pupil diameter (PD) were positively correlated with vault. Patient age and clear lens rise measured by Pentacam were negatively correlated with vault. Results of GEE model showed preoperative PD, age, cylindrical power of TICL and size-WTW were influencing factors for postoperative vault.

CONCLUSIONS

Vault after TICL implantation is higher than that with ICL. PD, age, cylindrical power of TICL and size-WTW could affect postoperative vault.

Effect of the Difference Between the White-to-White and Sulcus-to-Sulcus on Vault and the Related Factors After ICL Implantation

INTRODUCTION

To assess the differences between the horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements, their related factors, and their effects on vault after implantable Collamer lens (ICL) implantation.

METHODS

This retrospective study included 429 eyes of 429 patients (145 men and 284 women with a mean age of 29.22 ± 8.06 years) who underwent ICL implantation. The choice of the ICL size depended on the WTW diameter and anterior chamber depth (ACD). The information of WTW diameter, STS diameters, ACD, and their relationships on vault were analyzed.

RESULTS

Horizontal STS and WTW diameters were correlated (r = 0.71, P < 0.001). The mean difference between the STS and WTW diameters was -0.02 ± 0.33 (-1.36 to 1.11) mm. The average vaults of the ^△STS-WTW < -0.1 group, - 0.1 ≤ ^△STS-WTW ≤ 0.1 group, and ^△STS-WTW > 0.1 group were 558.36 ± 163.58 (250-1100) μm, 513.10 ± 121.42 (190-850) μm, and 469.01 ± 133.23 (120-750) μm, respectively. There were significant differences between these groups (P < 0.05). ^△STS-WTW was correlated with the horizontal STS diameter (r = 0.30, P < 0.001), the WTW diameter (r = -0.17, P = 0.001), and the ACD (r = 0.17, P < 0.001). When the WTW diameter was further away from 11.08 to 12.51 mm or the ACD was further away from 2.81 to 3.74 mm, the difference between the STS and WTW diameters was larger and the correlation between the STS and WTW diameters was weaker.

CONCLUSIONS

The difference between the WTW and STS diameters was larger for cases with a WTW diameter or anterior chamber depth outside a certain range; this may be associated with an undesirable vault after ICL implantation. Special attention should be paid to these patients.

Clinical results of Visian implantable collamer lens implantation according to various sizes and implantation angles

PURPOSE

To investigate the clinical outcomes of Visian implantable collamer lens (ICL) implantation according to lens size and implantation angle.

SETTING

Onnuri Smile Eye Clinic, Seoul, Republic of Korea.

DESIGN

Retrospective case series.

METHODS

This study included 566 eyes of 283 patients treated with ICL implantation. Patients were divided into three groups: horizontally implanted same-sized ICL (group A), horizontally implanted different sized-ICL (group B: large ICL and small ICL) and same sized-ICL implanted with a different implantation angle (group C: horizontal and vertical).

RESULTS

At 12-month follow-up, the mean vault was 0.78 ± 17, 0.48 ± 0.13, 0.71 ± 0.18 and 0.44 ± 0.16 mm when large and small sized ICL was used in group B (p < 0.001), and when ICL was horizontally and vertically implanted in group C (p = 0.021), respectively. And the mean SE was -0.11 ± 0.30, -0.34 ± 0.42, -0.3 ± 0.56 and -0.64 ± 0.66 dioptres (D), when the large and the small sized ICL was used group B (p = 0.039), and when the ICL was horizontally and vertically implanted in group C (p = 0.036), respectively. No significant difference in UDVA, IOP and ECD between both eyes in groups B and C was observed. No statistical difference was found in the vault between both eyes for groups B and C.

CONCLUSIONS

The vault was significantly higher and the SE was significantly more hyperopic when a larger-sized ICL was used or the ICL was horizontally implanted compared to when the ICL was vertically implanted.

Use of neural networks to predict vault values after implantable collamer lens surgery

Background

Appropriate sizing of the implantable collamer lens (ICL) and accurate prediction of the vault are crucial prior to surgery. However, sometimes, the vault value is higher or lower than predicted, necessitating reoperation. The present study aimed to develop neural networks for improving predictions of vault values following ICL implantation based on preoperative biometric data.

Methods

This retrospective study included 137 eyes of 74 patients with ICLs. Linear regression and neural network analyses were used to examine the relationship between vault values at the 6-month follow-up and preoperative parameters (e.g., ICL characteristics and biometrics).

Results

Linear regression analysis revealed that vault values were correlated with five variables: ICL size, anterior chamber depth (ACD), angle-to-angle (ATA), white-to-white (WTW), and lens thickness (LT) (adjusted R² = 0.411). Inclusion of more input variables was associated with better performance in the neural network analysis. The degree of fit when all 11 variables were included in the neural network model was close to 1 (R² = 0.98). R² values for the quaternary neural network model enrolling four input variables (ICL size, ATA, ACD, and LT) reached 0.90.

Conclusions

A neural network equation including the ICL size and biometric parameters of the anterior segment (ATA, ACD, and LT) can be used to predict the postoperative vault, aiding in the selection of an appropriate ICL size and reducing the need for reoperation after surgery.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05294-x.

Determining vault size in implantable collamer lenses: preoperative anatomy and lens parameters

PURPOSE

To determine patient preoperative anatomical features and the parameters of implantable collamer lenses (ICLs) relevant in explaining vault variability.

SETTING

Ophthalmology Clinic Vista Sánchez Trancón, Badajoz, Spain.

DESIGN

Retrospective case series.

METHODS

This study comprised 360 eyes of 360 patients implanted with myopic or toric ICLs. Pentacam imaging was used for assessing white-to-white (WTW) diameter, central keratometry, and central corneal thickness. Anterior-segment optical coherence tomography was used to measure the horizontal anterior chamber angle distance (ATA), internal anterior chamber (ACQ), crystalline lens rise (CLR), anterior chamber angle (ACA), and vault. The sample was divided according to the implanted lens size (12.6 mm, 13.2 mm, and 13.7 mm). Vault predictors were identified from the variables above using multivariate regression analysis.

RESULTS

The groups showed significant statistical differences for WTW, ATA, ACQ, ACA, and vault (P < .007 for all). In general, bigger lenses were implanted in eyes with larger transverse sizes (WTW and ATA) and deeper ACQ. Also, larger ICL diameters were associated with higher vaults. Multivariate regression analysis identified the lens size (13.2 mm as reference; 12.6 mm: β [standardized coefficients] = -0.33; 13.7 mm: β = 0.42), ATA (β = -0.42), and CLR (β = -0.25), ICL spherical equivalent (β = -0.22) and patient age (β = -0.12) as predictors of the vault size (adjusted-R = 0.34 P < .001).

CONCLUSIONS

The multivariate model explained 34% of vault variability. The predictors indicated the presence of different mechanisms regulating the vault. These involved the difference between the transverse size of the eye and the ICL, the crystalline lens protrusion, and the ICL properties, such as power and size.