Analysis of intraocular positions of posterior implantable collamer lens by full-scale ultrasound biomicroscopy

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.

Reverse pupillary block with pigment dispersion and elevated intraocular pressure following bilateral phakic intraocular lens implantation

The authors describe a case of reverse pupillary block with pigment dispersion following sequential phakic intraocular lens (pIOL) implantation for high myopia, in a young female patient. The intraocular pressure (IOP) elevation began 3 weeks postoperatively, for which Nd-YAG laser peripheral iridotomies (PIs) were attempted elsewhere. Despite maximum medical therapy, the IOP was uncontrolled. She was referred to our institute for further management. Examination showed anteriorly displaced iris-pIOL diaphragm, iris pigment dispersion and raised IOP. The PIs were incomplete. Based on clinical evaluation and investigations, we concluded that the excess area of contact of the posterior iris over the pIOL caused a reverse pupillary block and pigment dispersion. The IOPs were controlled by repeating laser iridotomies and with medical therapy. Subsequently, the patient developed a low lens vault leading to bilateral cataract. Sequential explantation of the pIOL along with cataract extraction was performed and her vision was restored.

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.

Effects of Decentration of Implantable Collamer Lens V4c on Visual Quality With the OPD-Scan III Aberrometer

PURPOSE

This study aimed to analyze the relationship between visual quality and implantable collamer lenses (ICL) decentration.

DESIGN

Prospective treatment evaluation clinical study METHODS: This prospective study included 119 eyes with ICL implantation. Refractive parameters and ocular aberrations were examined pre- and postoperatively. ICL decentration and higher-order aberrations (HOAs) were evaluated using the OPD-Scan III aberrometer.

RESULTS

At the 1-month follow-up, the mean values for decentration were 0.38 ± 0.19 mm (0.02-0.78). Regarding the position of decentration in right and left eyes, 22.8% and 17.7% were located in the superior nasal section, 0% and 6.5% in the inferior nasal section, 50.9% and 53.2% in the superior temporal section, and 26.3% and 22.6% in the inferior temporal section, respectively. The root mean square values of whole-eye total HOAs, coma, and trefoil had significantly increased. Decentration had a significant negative correlation with variation in the pre- and postoperative trefoils of the whole eye.

CONCLUSIONS

ICL decentration had a slightly negative correlation with trefoil and slightly affected visual quality.

Risk factors associated with haptic malposition in eyes implanted with implantable collamer lenses

PURPOSE

To examine the risk factors for haptic malposition in eyes with implantable collamer lens (ICL).

SETTING

Eye and ENT Hospital, Fudan University, Shanghai, China.

DESIGN

Prospective nonrandomized observational study.

METHODS

This study included 134 (77.9%) of 172 initially enrolled patients who underwent ICL implantation and completed a 1-year follow-up. The extent of haptics present in the ciliary sulcus (ICS) was measured. Patients were categorized based on ICS count (0 to 4). The position of the haptics was quantified as the distance between the iris root and the terminal tip of ICL haptics (iris root to haptic tip, IRH). The related factors to the ICS count and its correlation with the central vault were analyzed.

RESULTS

ICS distribution was 0 ICS in 19 eyes (14.2%), 1 in 22 eyes (16.4%), 2 in 32 eyes (23.9%), 3 in 29 eyes (21.6%), and 4 in 32 eyes (23.9%). Parameters like maximum ciliary body thickness (CBTmax, P = .008), iris-ciliary process distance (ICPD, P < .001), and ciliary process length ( P = .034) varied significantly across ICS groups. A multiple linear regression analysis revealed that the iris-ciliary angle ( P = .006), CBTmax ( P = .007), the distance between the sulcus-to-sulcus plane and the anterior crystalline lens surface (STSL, P = .035), and ICL size ( P = .015) were significantly associated with IRH. Spherical equivalents ( P = .042), STSL ( P = .001), and ICS count ( P = .020) significantly correlated with the central vault.

CONCLUSIONS

Shortened ciliary process is a primary risk for haptic malposition. The ICS count significantly relates to the central vault.

Vault changes in eyes with a vertically implanted implantable collamer lens

Sulcus-to-sulcus vertical diameter is longer than the horizontal. However, the effect of vertical positioning of the implantable collamer lens (ICL) on the vault compared to preoperative prediction is unclear. This prospective consecutive case series aimed to examine postoperative and preoperative predicted vaults during vertical ICL fixation. This study assessed 180 right eyes in 180 patients with myopic astigmatism. For the 90 eyes in 90 patients who underwent horizontal fixation (horizontal group) and 90 eyes in 90 patients who underwent vertical fixation (vertical group), biometrics by three-dimensional tomography of the anterior segment optical coherence tomography (A-OCT) was performed before surgery and 2 h, 1 day, 1 week, 1 month and 3 months after surgery. The anterior chamber depth did not change over time in both groups, and there was no significant difference from preoperative values. The postoperative vault values were significantly lower in the vertical group than in horizontal group over time. The difference between vault measurements and preoperative predictions at all postoperative time points was significantly greater in the vertical group than in horizontal group. Vertical fixation of the ICL reduced the vault by > 100 μm compared with horizontal fixation, which was different from the A-OCT preoperative predicted value.

Effect of ciliary sulcus angle on the prediction of the vault for phakic implantable collamer lens in the KS formula

PURPOSE

We aimed to explore the effects of the ciliary sulcus angle (CSA) on accurate prediction of the vault after phakic implantable collamer lens (EVO ICL Model V4c) using the KS formula.

METHODS

Patients were classified according to the size of CSA: group A, narrow angle (CSA < 30°); group B, normal angle (CSA = 30-90°); and group C, wide angle (CSA > 90°). Further, differences between the actual vault dimensions at 3 months postoperatively and the preoperatively predicted vault dimensions in the three groups were analyzed.

RESULTS

This study included 223 eyes of 223 individuals. In groups A-C, the difference in the preoperative vault dimensions of the three groups predicted with the KS formula was not statistically significant (P = 0.056). The actual vault dimensions at 3 months postoperatively were significantly different between the three groups (P < 0.001). Moreover, the difference between the actual and predicted vaults by the KS formula was statistically significant (P < 0.001). In the 3 months, after surgery, the percentages of patients with a low vault (< 250 μm) were 0%, 3%, and 29% in groups A, B, and C, respectively. Further, the percentages of patients with an ideal vault (250-750 μm) in the postoperative period were 66%, 84%, and 71% in groups A, B, and C, respectively. Finally, the percentages of patients with a high vault (> 750 μm) in the postoperative period were 34%, 13%, and 0% in groups A, B, and C, respectively. Notably, the distribution of the vault among the three groups was statistically significant (P < 0.001).

CONCLUSION

The size of CSA significantly affects the predictiveness of the vault by the KS formula, with the most pronounced effect on the angles < 30° and > 90°. Therefore, CSA should be considered when selecting the lens size using the KS formula preoperatively.

CLINICAL TRIAL REGISTRATION NUMBER

ChiCTR2200065501.

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.

Evaluation of ciliary body morphology and position of the implantable collamer lens in low-vault eyes using ultrasound biomicroscopy

PURPOSE

To investigate the ciliary body anatomy and position of the implantable collamer lens (ICL) in low-vault eyes and analyze factors related to insufficient vault.

SETTING

Zhongshan Ophthalmic Center, Guangzhou, China.

DESIGN

Retrospective case-control observational study.

METHODS

In this study, 73 eyes of 73 patients with an insufficient vault (<250 μm) were matched with 73 eyes with an ideal vault (250 to 750 μm). Ultrasound biomicroscopy was used to determine the ciliary body morphology and ICL position. The biometric parameters acquired by Scheimpflug tomography were compared. The correlation between the vault and these factors was analyzed, and the least absolute shrinkage and selection operator method was used to screen the risk factors for low vault.

RESULTS

The low-vault group had a steeper corneal curvature, thicker lens thickness (LT), higher crystalline lens rise, and shorter axial length (AL) (all P < .005). The ciliary process length (CPL) and maximum ciliary body thickness (CBTmax) were significantly smaller, and the trabecular-ciliary angle (TCA), iris-ciliary angle (ICA), and ciliary sulcus width (CSW) were significantly greater in the low-vault eyes (all P < .005). The low-vault group had more ICL haptics below the ciliary process, and TCA, ICA, CPL, CBTmax, CSW, and haptic position were related to the postoperative vault (all P < .05). CPL, AL, and LT were identified as predictors of a low vault.

CONCLUSIONS

Malposition of ICL haptics behind the ciliary process is a risk factor for low vault. A shorter CPL, thicker LT, and shorter AL are significant risk factors for the postoperative low vault.

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.

A new formula based on new parameters for predicting postoperative vault after posterior chamber intraocular lens implantation: a retrospective study

Background

To investigate the parameters influencing vault after posterior chamber intraocular lens implantation, thereby establishing a formula to predict the vault after operation.

Methods

In this retrospective study, 61 patients (122 eyes) who underwent implantable collamer lens (ICL) implantation were enrolled consecutively from the Qingdao Eye Hospital of Shandong First Medical University, China, between August 2020 and October 2021. Comprehensive optometry, axial length, curvature, anterior chamber depth (ACD), lens thickness (LT), white-to-white distance (WTW), corneal thickness, sulcus-to-sulcus distance (STS), the distance between the sulcus-to-sulcus plane and the anterior crystalline lens surface (STSL), ciliary-to-ciliary distance (CTC) and the distance between the ciliary-to-ciliary plane and the anterior crystalline lens surface (CTCL) were recorded preoperatively. The vault was measured by ultrasound biomicroscopy at 1 month after operation. The correlation among vault, preoperative parameters and ICL size was analyzed. The accuracy and reliability of the prediction formula were verified by analyzing the postoperative correlation coefficient of actual and predicted vaults of the contralateral eye and through the Bland-Altman consistency test.

Results

Parameters significantly influencing the vault at 1 month after operation are ACD (r=0.260, P=0.004), LT (r=-0.338, P<0.001), WTW (r=0.240, P=0.03), STSL (r=-0.394, P<0.001), CTC (r=-0.199, P=0.03), CTCL (r=-0.328, P<0.001), ICL size (r=0.224, P=0.01) and ICL power (r=-0.231, P=0.01). The regression formula was as follows: vault (mm) = -2.179 - 0.227 * CTC (vertical) - 0.783 * CTCL (mean) + 0.472 * ICL size (fitting R=0.853, R2=0.727, adjusted R2=0.705). The predicted vault was 0.50±0.18 mm, and the actual vault was 0.56±0.24 mm. The Bland-Altman scatter plot showed a satisfactory agreement between actual and predicted vaults (-0.06 mm, 95% limits of agreement: -0.45 to 0.32 mm).

Conclusions

ACD, LT, WTW, STSL, CTC, CTCL, ICL size and ICL power were the factors affecting vault after ICL implantation. The prediction formula with the new parameter CTCL was accurate and reliable.

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.

Three-Dimensional Quantitative Description of the Implantable Collamer Lens in the Ocular Anterior Segment of Patients With Myopia

PURPOSE

To describe the 3-dimensional (3D) location of the implantable collamer lens (ICL) quantitatively in the posterior ocular chamber of patients with myopia.

DESIGN

Cross-sectional study.

METHODS

To obtain visualization models before and after mydriasis, an automatic 3D imaging method based on swept-source optical coherence tomography was created. Parameters like the ICL lens volume (ILV), the tilt of the ICL and crystalline lens, the vault distribution index, and topographic maps were evaluated to describe the ICL location. Using a paired sample t test and the Wilcoxon signed rank test, the difference between nonmydriasis and postmydriasis conditions was compared.

RESULTS

The study investigated 32 eyes from 20 patients. The 3D central vault did not differ significantly before (P = .994) or after mydriasis (P = .549) compared with the 2D central vault. After mydriasis, the 5-mm ILV decreased by 0.85 mm2 (P = .016), and the vault distribution index increased significantly (P = .001). The ICL and the crystalline lens exhibited tilt (nonmydriasis: ICL total tilt 3.78 ± 1.85 degrees, lens total tilt 4.03 ± 1.53 degrees; postmydriasis: ICL total tilt 3.84 ± 1.56 degrees, lens total tilt 4.09 ± 1.64 degrees). The phenomenon of asynchronous tilt of the ICL and lens was found in 5 eyes, leading to the spatially asymmetric distribution of the ICL-lens distance.

CONCLUSION

The 3D imaging technique provided exhaustive and reliable data for the anterior segment. The visualization models offered multiple perspectives on the ICL in the posterior chamber. Before and after mydriasis, the intraocular ICL position was described by the 3D parameters.

Predictability of the vault after implantable collamer lens implantation using OCT and artificial intelligence in White patient eyes

PURPOSE

To compare the predicted vault using machine learning with the achieved vault using the online manufacturer's nomogram in patients undergoing posterior chamber implantation with an implantable collamer lens (ICL).

SETTING

Centro Oculistico Bresciano, Brescia, Italy, and I.R.C.C.S.-Bietti Foundation, Rome, Italy.

DESIGN

Retrospective multicenter comparison study.

METHODS

561 eyes from 300 consecutive patients who underwent ICL placement surgery were included in this study. All preoperative and postoperative measurements were obtained by anterior segment optical coherence tomography (AS-OCT; MS-39). The actual vault was quantitatively measured and compared with the predicted vault using machine learning of AS-OCT metrics.

RESULTS

A strong correlation between model predictions and achieved vaulting was detected by random forest regression (RF; R2 = 0.36), extra tree regression (ET; R2 = 0.50), and extreme gradient boosting regression ( R2 = 0.39). Conversely, a high residual difference was observed between achieved vaulting values and those predicted by the multilinear regression ( R2 = 0.33) and ridge regression ( R2 = 0.33). ET and RF regressions showed significantly lower mean absolute errors and higher percentages of eyes within ±250 μm of the intended ICL vault compared with the conventional nomogram (94%, 90%, and 72%, respectively; P < .001). ET classifiers achieved an accuracy (percentage of vault in the range of 250 to 750 μm) of up to 98%.

CONCLUSIONS

Machine learning of preoperative AS-OCT metrics achieved excellent predictability of ICL vault and size, which was significantly higher than the accuracy of the online manufacturer's nomogram, providing the surgeon with a valuable aid for predicting the ICL vault.

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

BACKGROUNDS

To investigate the changes of anterior eye segment with implantable collamer lens (ICL) under mesopic and photopic conditions.

METHOD

Forty-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.

RESULTS

Compared 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).

CONCLUSION

When 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.

Differences Between Angle Configurations in Different Body Positions by Ultrasound Biomicroscopy in Patients with Cortical Age-Related Cataract

Purpose

To investigate the differences in parameters related to angle configuration and lens position in patients with cortical age-related cataract by ultrasound biomicroscopy (UBM) in different body positions.

Methods

Prospective study with 55 patients with cortical age-related cataract proposed for phacoemulsification, examined using a Compact Touch STS UBM (Quantel Medical, France). UBM bag/balloon technology was applied to measure the central anterior chamber depth (ACD) and lens vault (LV) in horizontal and vertical orientation in sitting and supine positions, angle opening distance (AOD500), trabecular iris angle (TIA) and iris lens angle (ILA) in four quadrants: superior, inferior, nasal, and temporal.

Results

We found no significant difference in ACD between sitting and supine positions (p = 0.053); LV was significantly greater in the supine position (p < 0.001); AOD500 in superior and inferior quadrants were significantly longer in the sitting position (p = 0.001; p < 0.001); TIA in superior and inferior quadrants was significantly greater in the sitting position (p < 0.001; p < 0.001), and TIAmax-min was significantly smaller in the sitting position (p = 0.001); ILA in temporal quadrant was significantly larger in the sitting position (p = 0.015) and ILAmax-min was significantly smaller in the sitting position (p < 0.001).

Conclusion

The anterior chamber angle was narrower and the lens was positioned more anteriorly in the supine than in the sitting position in cortical age-related cataract. Different positions may affect the angle configuration and the relative space of lens through different directions of mechanics and modes of action.

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

PURPOSE

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.

SETTING

Hankou Aier Eye Hospital, Wuhan, Hubei, China.

DESIGN

Cross-sectional study.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Anterior Segment Characteristics of Eyes with Anterior Chamber Depth Less than 2.8 mm and Axial Length Greater than 25 mm

INTRODUCTION

This study aimed to investigate anterior segment parameters of eyes, with anterior chamber depth (ACD) less than 2.8 mm and axial length greater than 25.0 mm.

METHODS

This cross-sectional study included 180 myopic eyes of 180 consecutive patients with axial length greater than 25.0 mm. Patients were divided into low ACD (ACD < 2.8 mm, n = 56) and normal ACD (ACD ≥ 2.8 mm, n = 124) groups. Anterior segment parameters were measured using Scheimpflug imaging and ultrasound biomicroscopy. A general linear model was used to compare parameters between the two groups, after adjusting for age and spherical equivalent.

RESULTS

Compared with the normal ACD group, the low ACD group had lower values for the following parameters: corneal diameter, trabecular-anterior iris surface angle, angle-opening distance at 500 μm, anterior chamber volume, anterior chamber width, anterior vault, iris thickness at 500 μm, ciliary sulcus-to-sulcus diameter, distance between cornea and sulcus, trabecular-ciliary process distance, maximum ciliary body thickness, ciliary process length, relative anterior vault, relative distance between cornea and sulcus, and relative lens position (general linear model, p < 0.05). In contrast, central corneal thickness, iris curvature, lens thickness, lens vault, and iris-ciliary angle were greater in the low ACD group (general linear model, p < 0.05).

CONCLUSION

A smaller anterior segment, as well as a thicker and more anteriorly positioned lens, may correlate with shallow ACD in eyes with long axial length.

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.

Descriptive Analysis of Footplate Position After Myopic Implantable Collamer Lens Implantation Using a Very High-Frequency Ultrasound Robotic Scanner

Purpose

To assess the position of the haptics of the implantable collamer lens (ICL) in myopic eyes using a high-frequency ultrasound robotic scanner.

Methods

This was a prospective, single-arm, observational study carried out at the Instituto Zaldivar SA (Mendoza, Argentina) in a sample of 52 eyes who have been submitted to successful ICL implantation prior to enrollment. Images of the eyes were obtained using a very-high frequency digital ultrasound robotic scanner (VHFDU) to establish the position of the ICL in the posterior chamber and its relation to the ciliary sulcus. New parameters for lens position analysis were also described.

Results

In 81% of cases (42 eyes), the ICL rests on the ciliary body (CB) in both temporal and nasal sides, being slightly lower than 6% (3 eyes) those that rest on the sulcus in both sides, with significant correlations between ICL position and vault values (p<0.05). Cases in which the ICL position was CB-CB yielded central vault values across the whole range determined within the sample, but most of the eyes where the ICL rests on both the sulcus in one side and the CB in the other yield greater central vault values. Correlation was significant between ICL position and retroposition distance on the temporal side (Spearman's rho -0.487, p<0.001). A significant but weaker correlation was also found between ICL position and retroiridian space (p<0.05).

Conclusion

ICL for myopia footplates tend to locate outside of the sulcus in a significant percentage of patients after successful implantation. VHFDU assessment in eyes implanted with an ICL to properly study the lens footplate position and posterior anatomical relations provides important additional information besides post-surgery vault.

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.

Immediate or Delayed Sequential Bilateral ICL Surgery: a Survey of Chinese Ophthalmologists

INTRODUCTION

In China, the demand for implantable collamer lens (ICL) surgery is booming. Immediate sequential bilateral ICL surgery (ISBICLS) benefits patients and clinics, but it remains controversial and lacks standardization. We aim to investigate the prevalence of, factors for, and surgeon attitudes toward ISBICLS.

METHODS

In this cross-sectional survey study, an electronic questionnaire about the practice and attitudes toward performing ISBICLS or delayed sequential bilateral ICL surgery (DSBICLS) was distributed to 792 qualified ICL surgeons in Mainland China, between 4 April and 22 April 2022.

RESULTS

A total of 531 surgeons (66.79%) from 30 provinces in Mainland China responded. Among them, 374 (67.23%) were currently performing ISBICLS. Fifty-two percent (277) of surgeons reported performing ISBICLS more than 50% of the time, while 85.05% of surgeons chose to perform the second eye surgery 1 day after the first eye surgery. Seventy percent (248) of surgeons performing ISBICLS chose to perform the second eye surgery less than 30 min after the first eye surgery. Surgeons who started ICL surgery earlier (before 2010, OR = 2.772, 95% CI = 1.290-5.957, P = 0.009; 2011-2013, OR = 2.479, 95% CI = 1.060-5.800, P = 0.036), completed one-eye ICL surgery faster (< 3 min, OR = 3.936, 95% CI = 1.505-10.293, P = 0.005) and modified the second eye ICL selection less frequently (1-25%, OR = 0.203, 95% CI = 0.054-0.771, P = 0.019; 26-50%, OR = 0.173, 95% CI = 0.041-0.726, P = 0.017; 51-75%, OR = 0.299, 95% CI = 0.041-0.726, P = 0.123; 76-100%, OR = 0.163, 95% CI = 0.039-0.688, P = 0.014) tended to perform ISBICLS. No significant association was found among clinical settings, preoperative measurement devices, and hospital policies with performing ISBICLS. Regarding their attitudes toward ISBICLS, 54.63% preferred ISBICLS and 45.37% preferred DSBICLS. The main supporting reasons were patient convenience (98.64%), faster vision rehabilitation (73.56%), and improved perioperative compliance (73.22%). The concerns regarding ISBICLS included the risk of endophthalmitis (62.22%), lack of recommendation in expert consensus (61.67%), and decreased vault predictability (60.93%). The most common desires for further adoption were expert consensus on surgical criteria and patient indicators for ISBICLS (82.3%).

CONCLUSIONS

ISBICLS has been gradually adopted in Mainland China, but has not been widely accepted as a routine procedure. Surgeons' experience and skills mainly influence whether ISBICLS is performed. Further research is needed to explore standardized protocols to prevent endophthalmitis, the appropriate time interval of two eye surgery, and requisitions for surgeon skills.

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.

New Sizing Parameters and Model for Predicting Postoperative Vault for the Implantable Collamer Lens Posterior Chamber Phakic Intraocular Lens

PURPOSE

To identify parameters influencing the postoperative vault of the Implantable Collamer Lens (ICL) (STAAR Surgical) using the Artemis Insight 100 very high-frequency (VHF) digital ultrasound robotic scanner (ArcScan, Inc) and develop a model to improve lens vault prediction.

METHODS

This was a retrospective analysis of 147 consecutive V4c EVO and EVO+ ICL implantation procedures performed over three phases in myopic eyes. In the initial phase, lens size was defined by published sulcus-to-sulcus and crystalline lens rise measurements (Kojima formula) from VHF digital ultrasound biometry. From these data, a stepwise multivariate regression analysis was performed to develop a model for predicting central vault including the following variables: ICL size, ICL power, sulcus-to-sulcus (STS), ciliary body inner diameter (CBID), zonule-to-zonule, STS lens rise (STSL), ACD, anterior chamber angle, scotopic pupil diameter (SPD), angle-to-angle, and white-to-white diameter. The resulting regression model was used in coordination with the Kojima formula to select the lens size for the next series of eyes. The regression analysis was then repeated and a further series were treated. The postoperative achieved vault at 1 month was compared to the target vault predicted by the formula. A comparison analysis of the new model was made to previously published lens sizing formulas.

RESULTS

Statistically significant variables were ICL size, ICL power, CBID, STSL, and SPD. The primary 42 eyes (Kojima formula) achieved a mean vault of 506 ± 233 µm, a range of 810 µm (114 to 924 µm), and an interquartile range (IQR) of 391 µm. Using the Reinstein formula v1.0 for the next 36 eyes, the mean vault relative to target was +7 ± 123 µm, range of 569 µm (-278 to +291 µm), and IQR of 169 µm. Using the Reinstein formula v2.0 for the next 69 eyes, the mean vault relative to target was +67 ± 121 µm, range of 573 µm (-219 to +354 µm), and IQR of 131 µm. The achieved vault was within ±100, ±200, and ±300 µm of target in 33%, 50%, and 74% of eyes, respectively, for the training group, 58%, 89%, and 100% for the Reinstein formula v1.0 group, and 62%, 84%, and 94% for the Reinstein formula v2.0 group.

CONCLUSIONS

This is the first report describing the ciliary body inner diameter, which proved to be more highly correlated with vault than STS, and thus CIBD supersedes STS from the previous widely accepted improvement over WTW sizing. The new model also found scotopic pupil size to be a significant predictor, which has not been a part of any previously published model. The significant improvement in vault predictability afforded by these parameters and the new model enables charting attempted versus achieved vault outcomes for the first time. [J Refract Surg. 2022;38(5):272-279.].

Effect of Light Conditions and Accommodation on Implantable Phakic Contact Lens Vault by Anterior Segment Optical Coherence Tomography

Purpose

To investigate the dynamic pupil and vault changes in eyes with implantable phakic contact lens (IPCL) under photopic and scotopic settings, as well as during accommodation using the anterior segment optical coherence tomography (AS-OCT).

Methods

A prospective observational study included consecutive 36 eyes of myopic patients who underwent IPCL V2.0 implantation. Under photopic and scotopic light settings, as well as during accommodation, all patients were scanned using CASIA OCT (CASIA2; TOMEY, Nagoya, Japan). The pupil size, the vault (distance between the back surface of the IPCL and the anterior lens capsule), ACD-lens (distance between the posterior corneal surface and the anterior lens surface), IPCL-lens (distance between the posterior corneal surface and the anterior IPCL surface), and lens thickness (LT) were the study parameters.

Results

The vault was significantly lower under photopic conditions (p-value<0.001). The pupil size was significantly smaller in photopic conditions (p-value<0.001). LT (p-value=0.975) and ACD-lens (p-value=0.917) were not significantly different between scotopic and photopic conditions, while the ACD-IPCL was significantly larger during photopic conditions (p-value=0.013). There were significant changes in all parameters between accommodative and non-accommodative conditions.

Conclusion

The IPCL vault decreased significantly under photopic light conditions and accommodation.

Visual Outcomes, Footplate Position and Vault Achieved with the Visian Implantable Collamer Lens for Myopic Astigmatism

Purpose

Report the outcomes of the implantable collamer lens (ICL) in myopic astigmatism using very high-frequency (VHF) digital ultrasound sizing.

Methods

Analysis of 42 consecutive ICL procedures using EVO and EVO+ (Visian V4c) lenses (STAAR Surgical) was done. ICL size was chosen using the ultrasound-based Kojima Formula with Insight 100 VHF digital ultrasound (VHFDU). Standard visual outcomes analysis was performed using 3-month data, also including contrast sensitivity, refractive and corneal vector analysis, and ECC. Postoperative lens position was evaluated using VHF digital ultrasound.

Results

Attempted SEQ was −10.83±3.39D (−4.40 to −16.98D). Cylinder was −1.46±1.15D (0.00 to −4.25D). One-year follow-up was available in 86% of the eyes and 3 months in 96%. Postoperative UDVA was 20/20 or better in 89% of the eyes, relative to 71% preoperatively. Postoperative SEQ refraction was ±0.50 D in 74% and ±1.00 D in 98% of the eyes. There was a gain of one line of CDVA in 43% of the eyes, 2 or more lines in 10% of the eyes, while there was a one line loss in 7% and no eyes lost 2 or more lines. The vector mean for the corneal SIA was 0.24 D Ax 100. Contrast sensitivity showed a statistically significant increase with a mean of 0.14 log units at 6, 12, and 18 cycles per degree (P<0.01). The mean change in ECC was −153±353 cells/mm². Lens vault was 506±233 µm (114–924 µm). Footplate insertion was in zonular position in 48.3%, ciliary body in 49.2%, and sulcus in 2.5% of locations.

Conclusion

ICL implantation resulted in high safety and efficacy but with an implantation vault range that ideally would be improved upon. VHF digital ultrasound of the lens footplate and posterior anatomical relations may provide essential information for evaluating postoperative vault outliers.

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.

Changes in ocular parameters the crystalline lens after implantation of a collamer lens

CLINICAL RELEVANCE

Understanding changes in ocular anatomical parameters after intraocular lens implantation will allow a more accurate determination of dioptric power prior to surgery.

BACKGROUND

The crystalline lens position might change due to the implantation and removal of an implantable collamer lens (ICL) or toric implantable collamer lens (TICL). This study aimed to assess the effect of ICL implantation on position of the crystalline lens.

METHODS

This retrospective study was conducted on patients who underwent V4c ICL or V4c TICL implantation between March and September, 2018. Preoperative and post-operative (2 weeks, 3 months and 6 months) axial length, central corneal thickness, crystalline lens position, crystalline lens thickness and vault height were analysed. Multivariable linear regression was used to determine the variables associated with 6-month changes in lens position.

RESULTS

This study included 117 eyes of 117 patients. There were decreases in all vertical distance measures from the central corneal endothelium to the anterior and posterior crystalline lens capsule (all p > 0.05). The amount of reduction was related to the crystalline lens position before the operation and crystalline lens thickness after the operation (all p < 0.01). An error in anterior chamber depth and lens thickness may appear when the ICL/TICL is close to the crystalline lens.

CONCLUSION

Phakic intraocular lens implantation resulted in lens thickening and forward movement on day 1 post-operatively, which becomes stable within 6 months. Preoperative lens position and post-operative lens thickness were related to the amount of movement.

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.

Biometric and ICL-related risk factors associated to sub-optimal vaults in eyes implanted with implantable collamer lenses

Background

To identify biometric and implantable collamer lens (ICL)-related risk factors associated with sub-optimal postoperative vault in eyes implanted with phakic ICL.

Methods

This study reports a retrospective case series of the first operated eye in 360 patients implanted with myopic spherical or toric ICL. Preoperatively, white-to-white (WTW), central keratometry (Kc) and central corneal thickness (CCT) were measured using the Pentacam. Anterior-segment optical coherence tomography (AS-OCT, Visante) was applied preoperatively for measuring the horizontal anterior-chamber angle-to-angle distance (ATA), internal anterior chamber depth (ACD), crystalline lens rise (CLR), anterior-chamber angle (ACA) and postoperatively the vault. Eyes were divided into three vault groups: low (LVG: ≤ 250 μm), optimal (OVG: > 250 and < 1000 μm) and high (HVG: ≥ 1000 μm). Multinomial logistic regression (MLR) was used to find the sub-optimal vault predictors.

Results

MLR showed that CLR, ICL size minus the ATA (ICL size-ATA), age, ICL spherical equivalent (ICLSE) and ICL size as contributing factors for sub-optimal vaults (pseudo-R² = 0.40). Increased CLR (OR: 1.01, CI: 1.00–1.01) and less myopic ICLSE (OR: 1.22, CI: 1.07–1.40) were risk factors for low vaults. Larger ICL size-ATA (OR: 41.29, CI: 10.57–161.22) and the 13.7 mm ICL (OR: 7.08, CI: 3.16–15.89) were risk factors for high vaults, whereas less myopic ICLSE (OR: 0.85, CI: 0.76–0.95) and older age (OR: 0.92, CI: 0.88–0.98) were protective factors.

Conclusion

High CLR and low ICLSE were the major risk factors in eyes presenting low vaults. In the opposite direction, ICL size-ATA was the major contributor for high vaults. This relationship was more critical in higher myopic ICLSE, younger eyes and when 13.7 mm ICL were used. The findings show that factors influencing the vault have differentiated weight of influence depending on the type of vault (low, optimal or high).

Supplementary Information

The online version contains supplementary material available at 10.1186/s40662-021-00250-6.

Short-term changes in and preoperative factors affecting vaulting after posterior chamber phakic Implantable Collamer Lens implantation

Background

To describe the very early vault changes in the first month after Implantable Collamer Lens (ICL) implantation and to evaluate the effect of preoperative biometric factors on vault.

Methods

Eighty-three eyes from eighty-three subjects with complete data who met follow-up requirements were recruited in this retrospective study between May 2019 and March 2020. We quantitatively assessed the postoperative vault at 2 h, 1 day, 1 week, and 1 month following implantation. Associations between the postoperative vault and age, ICL size, spherical equivalent (SE), axial length (AL), central corneal thickness (CCT), flat keratometry (K), steep K, mean K, anterior chamber depth (ACD), crystalline lens thickness (LT), white-to-white (WTW) diameter obtained by three devices, horizontal and vertical sulcus-to-sulcus (STS) diameter, bright and dark pupil sizes (BPS and DPS) and DPS-BPS were investigated using Spearman’s correlation analysis and stepwise multiple regression analysis.

Results

The mean vault values at 2 h, 1 day, 1 week, and 1 month after ICL implantation were 672.05 ± 30.72, 389.15 ± 28.33, 517.23 ± 30.76 and 530.12 ± 30.22 μm, respectively. Significant differences were found in the vault values at 2 h, 1 day and 1 week after the operation. The ICL size (β = 0.942; p < 0.001), followed by horizontal STS (β = -0.517; p < 0.001), crystalline LT (β = -0.376; p < 0.001) and vertical STS (β = -0.257; p = 0.017), significantly influenced the vault at 1 month after the operation. The multiple regression equation was expressed as follows: central vault (µm) = -1369.05 + 657.121 × ICL size- 287.408 × horizontal STS − 432.497 × crystalline LT − 137.33 × vertical STS (adjusted R² = 0.643).

Conclusions

After ICL implantation, the vault decreased and then increased, but it did not return to the vault value 2 h after surgery. The ICL size, horizontal and vertical STS and crystalline LT are key factors for predicting postoperative vaulting.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-021-01963-x.

Clinical Prediction of Excessive Vault After Implantable Collamer Lens Implantation Using Ciliary Body Morphology

PURPOSE

To determine the factors related to the ciliary body that are predictive of outcomes of excessive vault (> 1,000 µm) after Implantable Collamer Lens (ICL V4c; STAAR Surgical) implantation.

METHODS

In this retrospective case-control study, 27 eyes of 27 patients who presented with excessive vault (> 1,000 µm) following implantation of an ICL V4c were matched in a 1:2 ratio with those who presented with a normal vault (250 to 1,000 µm) on white-to-white distance, anterior chamber depth, and ICL size. The preoperative biometric parameters and clinical outcomes were compared between the two groups. The relationship between the postoperative vault and various variables was assessed by multiple linear regression analysis. Conditional logistic regression models were used to estimate odds ratios (ORs) and 95% CIs for excessive vault.

RESULTS

The vault value 1 month postoperatively was associated with preoperative anterior chamber volume, iris-ciliary angle, and crystalline lens rise (P < .05). In the conditional regression logistic analysis, every 1° reduction in iris-ciliary angle was associated with 4% increased odds of vault greater than 1,000 µm (OR = 0.96; 95% CI = 0.93 to 0.99; P < .001) and the anteriorly positioned ciliary body was associated with an increased risk of excessive vault after ICL implantation (OR = 3.57; 95% CI = 1.67 to 7.63; P < .001). In the excessive vault group, 1 eye underwent the ICL extraction and 3 eyes had an ICL exchange for a smaller ICL. After the ICL exchange, the mean value of postoperative vault decreased from 1,525.67 ± 468.22 to 810.33 ± 254.92 µm.

CONCLUSIONS

Eyes with an anteriorly positioned ciliary body were associated with a higher rate of excessive vault after ICL implantation, so the size of the ICL may need to be adjusted in these patients. Assessment of ciliary body characteristics adds significant information to the prediction of excessive vault after surgery. [J Refract Surg. 2020;36(6):380-387.].

Phakic intraocular lens: Getting the right size

Phakic intraocular lenses (IOL) are a boon for patients who want spectacle independence but are unable to get refractive correction through laser platforms due to high refractive error or certain corneal contraindications. Phakic IOL's (PIOL) have their own set of complications and challenges, the most important being getting the sizing right. This paper attempts to solve the problem of accurate sizing of PIOL's. Parameters needed for calculating the ideal size of PIOL's have been studied in a step by step manner using all possible tools depending upon the availability and preference of the surgeon. The pros and cons of using a particular tool for measurements have been highlighted along with illustrative case examples to help surgeons who are starting PIOL implantation surgery.

Spontaneous rotation of a toric implantable collamer lens related to abnormal ciliary body morphology: a case report

BACKGROUND

This is a case of spontaneous toric implantable collamer lens (TICL) rotation that occurred twice in the left eye of a patient.

CASE PRESENTATION

A 24-year-old gentleman received TICL implantation for treatment of myopic astigmatism encountered with spontaneous rotation of approximately 90° from its original position. TICL reposition procedure was performed with visual outcome of 20/16. Surprisingly, a re-rotation of TICL occurred. The patient underwent a replacement of non-toric ICL with a larger size after careful re-evaluation with final visual outcome of 20/20. A short and small ciliary process with shallow ciliary sulcus and posteriorly positioned ciliary body was found by Ultrasound Biomicroscopy (UBM).

CONCLUSIONS

The unique morphology of the ciliary body may have a potential association with the vault and instability of implanted ICL. Careful examination of the ciliary body morphology is essential in preoperative evaluation.