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

Optimization of implantable collamer lens sizing based on swept-source anterior segment optical coherence tomography

PURPOSE

To optimize the implantable collamer lens (ICL) sizing method using anterior segment optical coherence tomography (AS-OCT).

SETTING

Nagoya Eye Clinic, Nagoya, Japan.

DESIGN

Interventional case series.

METHODS

A stepwise multiple regression analysis was performed using the optimal ICL size as a dependent variable and preoperative AS-OCT parameters as explanatory variables for 81 eyes of 41 patients, and the NK-formula version 2 (NK-formula V2) was obtained. Thereafter, 68 eyes of 42 patients were implanted with the ICLs selected as closest to the optimal ICL size calculated by the NK-formula V2. At 3 months postoperatively, the achieved vault was measured by AS-OCT to evaluate the optimization of the sizing method.

RESULTS

The anterior chamber width (ACW) and crystalline lens rise were selected as significant parameters for the regression model (R = 0.61, P < .001), as with the previous NK-formula. Of the 68 eyes, 36 patients/62 eyes (91.2%), 5 patients/5 eyes (7.3%), and 1 patient/1 eye (1.5%) were in the moderate, high, and low vault categories, respectively. In the 68 eyes, the vault showed no correlation with the optimal ICL size (R = 0.0185, P = .269), whereas the vault showed a negative correlation with the optimal ICL size in both the 12.6 mm ICL subgroup (R = -0.409, P = .0088) and the 13.2 mm ICL subgroup (R = -0.818, P = .0013).

CONCLUSIONS

This optimization approach showed excellent ability to select an appropriate ICL to be implanted regardless of the value of other ocular parameters and age, except ACW.

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.

Intraoperative Versus Postoperative Vault Measurement After Implantable Collamer Lens Implantation in a Large Cohort of Patients

PURPOSE

To compare intraoperative and postoperative central vault measurement after implantable Collamer lens (ICL; STAAR Surgical) implantation using optical coherence tomography (OCT).

METHODS

A total of 574 eyes of 338 consecutive patients undergoing myopic ICL implantation were evaluated (mean age of 30.8 ± 5.7 years, 117 men and 221 women). Central ICL vault was measured both intraoperatively using the microscope-integrated iOCT (Optomedical Technologies GmbH) mounted on a standard surgical microscope (HS Hi-R NEO 900A; Haag-Streit Surgical GmbH), and postoperatively using the CASIA2 swept-source OCT (Tomey GmbH) at 4 and 24 hours.

RESULTS

Mean differences between intraoperative and postoperative vault values were 11.5 ± 29.0% of the mean value 4 hours postoperatively (P < .001) and 2.7 ± 33.5% of the mean value 24 hours postoperatively (P < .001). Correlation analysis shows significant agreement between vault values obtained intraoperatively and at the two postoperative times, 4 hours (Spearman Rho = 0.850, P < .001) and 24 hours (Spearman Rho = 0.745, P < .001). In 73% of cases, postoperative vault values 4 hours after the surgery could be predicted from intraoperative vault values, and so were 56% of vault values 1 day after surgery. Significant differences in vault were found at the different times, grouping cases by ICL size (Kruskal-Wallis, P = .028 for intraoperative vault, and P < .001 for both postoperative vault times), with smaller vault values for the smaller ICL size.

CONCLUSIONS

Intraoperative determination of ICL vault using iOCT is an effective method for predicting postoperative ICL vault and minimizing postoperative vault surprises that could require surgical retouching. [J Refract Surg. 2021;37(7):477-483.].

Development of a Web-Based Ensemble Machine Learning Application to Select the Optimal Size of Posterior Chamber Phakic Intraocular Lens

Purpose

Selecting the optimal lens size by predicting the postoperative vault can reduce complications after implantation of an implantable collamer lens with a central-hole (ICL with KS-aquaport). We built a web-based machine learning application that incorporated clinical measurements to predict the postoperative ICL vault and select the optimal ICL size.

Methods

We applied the stacking ensemble technique based on eXtreme Gradient Boosting (XGBoost) and a light gradient boosting machine to pre-operative ocular data from two eye centers to predict the postoperative vault. We assigned the Korean patient data to a training (N = 2756 eyes) and internal validation (N = 693 eyes) datasets (prospective validation). Japanese patient data (N = 290 eyes) were used as an independent external dataset from different centers to validate the model.

Results

We developed an ensemble model that showed statistically better performance with a lower mean absolute error for ICL vault prediction (106.88 µm and 143.69 µm in the internal and external validation, respectively) than the other machine learning techniques and the classic ICL sizing methods did when applied to both validation datasets. Considering the lens size selection accuracy, our proposed method showed the best performance for both reference datasets (75.9% and 67.4% in the internal and external validation, respectively).

Conclusions

Applying the ensemble approach to a large dataset of patients who underwent ICL implantation resulted in a more accurate prediction of vault size and selection of the optimal ICL size.

Translational Relevance

We developed a web-based application for ICL sizing to facilitate the use of machine learning calculators for clinicians.

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.].

Peripheral Anterior Chamber Depth and Angle Measurements Using Pentacam After Implantation of Toric and Non-toric Implantable Collamer Lenses

Purpose: To evaluate the characteristics of peripheral anterior chamber measurements by Pentacam after posterior implantable collamer lenses (ICL) and toric ICL (TICL) with central hole (V4c) implantation.

Methods: Prospective, non-randomized consecutive case series. Forty-six patients undergoing ICL implantation in one eye (Group A) and identically sized TICL in the contralateral eye (Group B) in the Refractive Surgery Center of Eye and ENT Hospital of Fudan University were prospectively included. According to ICL/TICL size, these eyes were further divided into four subgroups. Peripheral anterior chamber depth (PACD) and angle (ACA) in nasal and temporal sides were measured using Pentacam pre-operatively and 12-month post-operatively.

Results: The safety indices were 1.34 ± 0.32 and 1.25 ± 0.16 and the efficacy indices were 1.20 ± 0.24 and 1.19 ± 0.19 for ICL and TICL groups, respectively. There was no significant difference in pre-operative PACD or ACA between the two groups. Post-operative PACD and ACA were significantly lower than pre-operative values. Variations of PACD and ACA of TICL group were significantly larger than those of ICL group. The change of ACA for 13.2 mm lenses was significantly larger than that of 12.6 mm lenses. Pre-operative CACD and vault were significantly associated with post-operative PACD, while pre-operative ACA and vault were significantly associated with post-operative ACA.

Conclusions: Variations of PACD and ACA were greater in eyes after TICL (V4c) implantation compared with identically sized ICL (V4c) implantation and with larger size than smaller size lens implantation. Pre-operative anterior chamber structure and vault affect post-operative PACD and ACA.

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.

Vault changes after cyclopentolate instillation in eyes with posterior chamber phakic intraocular lens

Posterior chamber phakic intraocular lens (pIOL) implantation is a common option for correcting moderate-to-high ocular refractive defects. Because this pIOL is implanted on ciliary sulcus, the distance between the back surface of the pIOL and the anterior surface of the crystalline lens, that it is known as vault, should be measured in different conditions to ensure the technique's safety. Cyclopentolate is a drug that dilates the pupil and relaxes accommodation (cycloplegia). It is often used for different ocular examinations and for other medical purposes. However, there is no evidence of the effect of this drug on vault. This study quantified central vault changes associated with cyclopentolate instillation. We measured the vault under normal conditions (pre-cycloplegic instillation) and after instilling cyclopentolate on 39 eyes of 39 patients with implanted pIOL. Our results suggest that cyclopentolate instillation may induce changes to vault in eyes with implanted pIOL. These changes seem safe and are mainly associated with vault under normal conditions, but also with anterior chamber depth, pupillary diameter and pIOL size.

Rotational Stability of a New Posterior Chamber Toric Phakic Intraocular Lens

PURPOSE

To evaluate the refractive results and rotational stability of Eyecryl toric phakic intraocular lens (pIOL).

METHODS

In this retrospective single-surgeon case series, manifest refraction, visual acuities, endothelial cell density (ECD), and pIOL rotation were evaluated over 6 months.

RESULTS

43 eyes from 23 patients were included. At 6 months, the SE was within ±0.50  D of emmetropia in 30 (70%) eyes and within ±1.00  D of emmetropia in 39 (91%) eyes. The efficacy and safety indices were 1.25 ± 0.38 and 1.41 ± 0.34, respectively. Mean ECD was 2719 ± 296 cells/mm2 at the preoperative visit and 2779.42 ± 422 cells/mm2 at the 6-month visit (p > 0.05). The mean value of absolute axis orientation error was 4.95 ± 5.28°. Mean absolute change in axis orientation between visits was less than 3° for all visit intervals. Ninety percent or more of lenses were found to rotate 5° or less between all visit intervals. None of the patients experienced a vision-threatening complication, and no patient required secondary IOL repositioning.

CONCLUSION

The pIOL appears to effectively reduce subjective manifest astigmatism and provide good visual acuity. Its position was found to be stable throughout the follow-up.

Confounding sizing in posterior chamber phakic lens selection due to white-to-white measurement bias

Purpose:

To assess the agreement in the white-to-white (WTW) measurement with two different devices, the reproducibility and the probability of confusing sizing (PCS) in selecting a different implantable collamer lens (ICL).

Study Design:

Retrospective observational case series.

Methods:

Images of 192 eyes were captured with both devices. The WTW was measured automatically (OA) and manually (OM) with the Orbscan and Keratograph (KA and KM) by one examiner who repeated a total of four measures. A second examiner conducted a single manual measure for each device over the same image. The ICL sizing was computed for each measure of WTW and the PCS was calculated as the percentage of cases for which the confronted or repeated measure resulted in a different size of the ICL. The critical WTWs with highest PCS were identified.

Results:

KM overestimated the WTW versus OM in 0.13 ± 0.18 mm (P < 0.001) but not in the automated method comparison, 0.01 ± 0.19 mm (P = 0.58). Inter-examiner reproducibility (R) was higher with OM than with KM, and the intra-examiner R decreased with the average of two measures in both cases. The PCS was higher with the increase of mean differences, the limits of agreement (LoAs), and R. WTWs from 11.1 to 11.2 mm, 11.6 to 11.7 mm, and 12.3 to 12.4 mm resulted in higher PCS.

Conclusion:

The mean difference is not enough to apply conversions between devices and the LoAs and R should be considered. Special attention should be taken for WTWs with higher PCS.

Optimization of the lens sizing for the second eye based on the vault obtained in the first eye in bilateral myopic collamer phakic intraocular lens surgery

PURPOSE

To assess vault and the decision-making process involved in selecting the size of the lens for the fellow eye in a series of patients who received bilateral phakic collamer intraocular lens (pIOL) implants with central hole for correction of myopia.

METHODS

The study sample included all patients who underwent bilateral insertion of a different size pIOL from a pool of 269 patients who underwent sequential bilateral insertion of a pIOL from March 2012 to May 2015 in our institution. Procedures were separated in time to assess the value of the vault and select the pIOL size in second eyes. Vault was analysed objectively using optical coherence tomography.

RESULTS

The decision to change the size of the pIOL in the fellow eye was taken in 25 patients. A smaller pIOL was implanted in the second eye in 9 patients, whereas a lens that was 1 size larger was necessary in 16 patients. Implantation of a larger lens led to a mean increase in vault of 251 ± 180 microns; implantation of a smaller size lens led to a mean decrease in vault of 542 ± 187 microns. In 5 patients, the pIOL implanted in first eye was rotated vertically to reduce lens vault. No lenses had to be explanted.

CONCLUSIONS

Vault in fellow eyes can be improved in patients receiving bilateral myopic pIOL implants by modifying the pIOL size based on the vault value obtained in the first eyes.

Intraoperative Optical Coherence Tomography Vault Measurement in Posterior Chamber Phakic Intraocular Lens Implantation

PURPOSE

To describe the use of intraoperative optical coherence tomography (OCT) vault measurement in 5 cases of posterior chamber phakic intraocular lens (IOL) implantation.

METHODS

This case series included 5 eyes in 3 consecutive patients undergoing phakic IOL implantation. RTVue OCT (Optovue, Inc., Fremont, CA) was used to obtain intraoperative vault measurements after pupil constriction. Visante OCT (Carl Zeiss Meditec, Jena, Germany) was used to obtain postoperative vault measurements.

RESULTS

Intraoperative vault measurements ranged from 228 to 1,060 µm. There were no postoperative complications. Postoperative OCT vault measurements ranged from 230 to 670 µm.

CONCLUSIONS

Intraoperative OCT can be a useful tool in phakic IOL implantation to provide real-time intraoperative vault measurements. This may help to confirm appropriate phakic IOL sizing and guide decision-making at the time of surgery. [J Refract Surg. 2017;33(4):274-277.].

Implanting a posterior chamber phakic intraocular lens in highly myopic eyes with peripheral primary iris and ciliary body cysts

PURPOSE:

To investigate the safety and efficacy of implanting a posterior chamber implantable collamer lens with a central hole in cases of high myopia with peripheral primary iris or ciliary body cysts.

METHODS:

A total of 37 eyes of 19 patients with primary iris or ciliary body cysts detected by ultrasonic biological microscope were included, with spherical powers of -10.26 ± 3.28 D and cylinder powers of -1.71 ± 1.18 D. Each patient received ultrasonic biological microscope and a routine examination before implantation of the implantable collamer lens. A routine postoperative follow-up was performed to observe changes in the iris or ciliary body cyst, ranging from 3 to 18 months.

RESULTS:

There were no complications. At the last follow-up, 56.8% (21/37) of eyes achieved the same corrected distance visual acuity as their preoperative measurements, 43.2% of eyes were enhanced by ≥1 line, and no patients' corrected distance visual acuity declined. The efficacy index and safety index were 0.95 and 1.11, respectively. After 18 months, 66.7% of the spherical equivalents were between ±0.5 D with 100% between ±1.0 D. The postoperative mean spherical equivalents at 1, 3, 6, 12, and 18 months were -0.45 ± 0.31 D, -0.39 ± 0.29 D, -0.36 ± 0.30 D, -0.39 ± 0.38 D, and -0.48 ± 0.23 D (p = 0.789). The vaults were 516 ± 140, 548 ± 124, 498 ± 133, 582 ± 161, and 557 ± 110 μm (p = 0.355). There were no changes in size (p > 0.05), number, or position of the iris or ciliary body cysts.

CONCLUSION:

Implantable collamer lens implantation is safe and effective for highly myopic patients with peripheral primary iris and ciliary body cysts. The cysts did not change after operation in this study.

Conjunctival Flap with Biodegradable Collagen Matrix Implantation for the Treatment of Scleromalacia after Periocular Surgery

Purpose: To report a new surgical procedure using biodegradable collagen matrix (Ologen) implantation with conjunctival flap for reconstruction of scleromalacia after periocular surgery. Methods: A total of 26 areas of 25 eyes in 25 patients were included. We divided all eyes according to the preoperative extent of calcified plaque or scleral defect as follows: small, large, and large and severe. Morphologic outcomes were graded from 0 to 7, with higher scores indicating worse cosmetic outcomes. Results: Mean follow-up period was 8.3 ± 5.6 months. No eyes showed recurrence or specific complications related to Ologen such as implant extrusion or allergic reaction. Minor complications such as flap vessel engorgement and flap hypertrophy were easily treated. Mean morphologic outcome scores were 1.8, 2.4, and 5.3 in groups 1, 2, and 3, respectively. Discussion: The combined surgery may be an effective and safe procedure for the treatment of scleromalacia after periocular surgeries.

Buffering zone of implantable Collamer lens sizing in V4c

Background

The purpose of this study was to identify factors related to the unexpected vault in V4c implantable collamer lens (ICL; STAAR Surgical) implantation.

Methods

V4c ICLs were implanted in 43 eyes of 43 patients for the correction of myopia. The implanted V4c ICL sizes were determined individually with our previous V4 ICL sizing nomogram based on the sulcus-to-sulcus diameter (STS), and the V4 ICL sizes were then converted to V4c ICL sizes with a size-converting table. We defined the “normal-sizing group” as having a pre-converted ICL size larger than the STS, and the “under-sizing group” as having a pre-converted ICL size smaller than the STS. Refractive outcomes, safety and parameters related to postoperative vault were compared between the two groups.

Results

The value of “actual ICL size – STS” differed significantly between the normal-sizing and under-sizing groups (p < 0.001), but postoperative vault did not differ significantly (p = 0.442). The demographics, implanted ICL characteristics, effectiveness indexes, safety indexes, and parameters related to postoperative vault did not differ significantly between the two groups (p > 0.05). Two patients in the normal-sizing group exhibited over-vaulting; these patients had shallow anterior chambers and were implanted with high-dioptric-power ICLs.

Conclusions

The achievement of acceptable vault in both normal-sizing and under-sizing groups indicates the existence of a buffering zone in V4c ICL sizing. The smaller size of V4c ICLs should be considered in patients susceptible to over-vaulting, such as those with shallow anterior chambers and high-dioptric-power ICLs.

Adjustment formulae to improve the correlation of white-to-white measurement with direct measurement of the ciliary sulcus diameter by ultrasound biomicroscopy

Purpose

This study evaluates the correlation between horizontal white-to-white (WTW) distance using Caliper and Orbscan IIz with the ciliary sulcus diameter measured by high frequency ultrasound biomicroscopy (UBM) and presents an adjustment formula to improve the correlation.

Methods

We measured horizontal sulcus-to-sulcus (STS) dimension of 273 right eyes of 273 high myopic patients with 35 MHz UBM and horizontal WTW using Orbscan IIz and Caliper. Mean WTW diameter, differences, and the correlation of measurement methods were evaluated.

Results

The mean spherical equivalent was −8.79 ± 4.87 diopters. Mean horizontal STS dimension with UBM was 12.13 ± 0.45 mm (range, 10.81–13.42 mm). Mean WTW diameter in the Caliper method was 11.70 ± 0.40 mm (range, 10.6–12.8 mm) and 11.70 ± 0.40 mm (range, 10.5–13.1 mm) in the Orbscan method. Mean difference of UBM STS and WTW with Caliper was 0.48 ± 0.28 mm (range, −0.19 to 1.37 mm). Mean difference of UBM STS diameter and Orbscan WTW was 0.38 ± 0.31 mm (range, −0.64 to 1.29 mm). The Pearson correlations of WTW diameter measured by Caliper and Orbscan with UBM's STS diameter were 0.778 and 0.773, respectively. This difference diminished after adjustment. The 95% limit of agreement was almost the same in Caliper and Orbscan (−0.07 to 1.03 compared with −0.23 to 0.99).

Conclusion

There is a significant difference in measurements between STS diameter using UBM and WTW diameter utilizing Caliper and Orbscan. This difference diminished after our recommended adjustment.

A Rare Case of Pupillary Block Glaucoma Following CentraFLOW Implantable Collamer Lens Surgery

A 28-year-old lady with a refractive error of -11.0 D sphere/-1.50 D cylinder at 160 degrees in the right eye underwent an uneventful Implantable Collamer Lens surgery (ICL) with a V4c model, which uses a central Aquaport. This ICL does not require preoperative laser iridotomy or surgical iridectomy, as the centraflow opening is designed to prevent pupillary block. At postoperative day 1, her visual acuity in the right eye was 20/400, with diffuse microcystic corneal edema with fixed, dilated pupil and high intraocular pressure. Following intravenous mannitol, the corneal edema resolved. It was then noted that the ICL was anteriorly displaced, creating acute pupillary block, presumably due to obstruction of the central Aquaport with viscoelastic and inflammatory debris. She underwent AC wash the same day that helped in IOP control; however, the pupil remained permanently dilated and fixed because of extensive sphincter atrophy as a result of acute pupillary block. By 1 month, the visual acuity was 20/30 with an IOP of 14 mm Hg, which was maintained at 1-year follow-up. We report the first case of pupillary block glaucoma with this particular ICL design, suggesting the need for careful attention to complete removal of viscoelastic in the anterior chamber and behind the ICL, to prevent such complications and their cosmetically unacceptable sequelae.

A comparison of visual outcome and rotational stability of two types of toric implantable collamer lenses (TICL) : V4 versus V4c

PURPOSE

To compare the efficacy and rotational stability after implantation of two types of toric implantable collamer lenses (Toric ICL™(TICL);V4 and V4c, STAAR Surgical Co.).

STUDY DESIGN

Retrospective case series.

METHODS

This retrospective study evaluated total 48 eyes of 48 patients who underwent the implantation with V4 and V4c TICL with a central hole; A twenty-four eyes of 24 patients with V4 TICL and 24 eyes of 24 patients with V4c TICL with a central hole. Visual acuity, manifest refraction, and intraocular pressure were evaluated before and after surgery. Rotational stability (disparity between the intended axis and achieved axis) was assessed in both groups using digital anterior segment photographs, and vector analysis was also performed.

RESULTS

Uncorrected visual acuity improved in both groups without significant difference (P = .111). There were no statistical differences between two groups in postoperative SE and cylindrical errors (P = .067 and .384, respectively). The mean value of rotation was 4.17±3.31° and 3.39±2.36° in the V4 and V4c TICL groups, respectively without significant difference (P = .364). Vector analysis of astigmatic correction showed no significant diffrence between two groups.

CONCLUSION

V4 and V4c TICL have similar efficacy with regard to visual acuity and refractive outcomes and rotational stability.

Anterior segment optical coherence tomography angle and vault analysis after toric and non-toric implantable collamer lens V4c implantation in patients with high myopia

OBJECTIVE

To assess anterior segment changes, including iridocorneal angle and vault, after toric and non-toric implantable collamer lens (ICL) V4c (STAAR Surgical AG) implantation under different lighting conditions.

METHODS

Longitudinal, prospective, case series. Patients with high myopia (>6 dioptres) underwent toric and non-toric ICL V4c implantation. Optical coherence tomography measurements were taken under different lighting conditions preoperatively and at 1 week and 1, 6 and 12 months of follow-up.

RESULTS

Seventy-six eyes of 42 patients underwent ICL V4c implantation. Mean age was 27.4 years (±5.14 years, range 20 to 39 years). The average iridocorneal angle showed a statistically significant decrease (p<0.05) in all mesopic, scotopic and photopic conditions after 1 week of surgery compared with the preoperative measurements; in mesopic conditions, it decreased 14.1°, in photopic conditions 14.8° and scotopic conditions 13.2°. The angle measurement had a statistically significant change only in mesopic conditions (p=0.01) over the 1-year follow-up. The average vault under mesopic conditions was 0.661±0.21 mm at week 1. The vault measurement change was statistically significant over the 1-year follow-up in mesopic conditions (p=0.01). Refractive results showed a significant improvement in both uncorrected and corrected distance visual acuity (p<0.001).

CONCLUSION

There is a significant reduction in the iridocorneal angle after ICL V4c implantation. Furthermore, there is a change under mesopic conditions in both the iridocorneal angle and vault during long-term follow-up.

Etiology and Management of Raised Intraocular Pressure following Posterior Chamber Phakic Intraocular Lens Implantation in Myopic Eyes

AIM

To evaluate the etiology and management of elevated intraocular pressure (IOP) following posterior chamber phakic implantable collamer lens (ICL) surgery.

METHODS

Between 2009 and 2015, 638 eyes of 359 subjects with refractive myopia, underwent V4b and V4c (CentraFLOW) model ICL implantation. Ocular hypertension (OHT) was defined as IOP of ≥ 22 mm Hg on two separate occasions and elevated IOP with corresponding optic disc or visual field damage was defined as glaucoma.

RESULTS

Elevated IOP ≥ 22 mm Hg was noted in 33 eyes of 30 subjects (33/638; 5.17%). Median age of subjects with raised IOP was 26 years (Inter quartile range (IQR):22, 29) and median refarctive error was -16 diopters (-19.5, -13). The median follow up was 7.8 months (IQR:0.3, 17.6) and median time for postoperative IOP rise was 12 days, (IQR:2, 24). The various etiologies for elevated IOP were steroid response in 21 eyes (64%; 10 eyes with V4b, 11 eyes with V4c), retained viscoelastic in 5 eyes (15%) (3 with V4b, 2 with V4c), pupillary block in four eyes (12%; 3 with V4b, 1 with V4c), malignant glaucoma in one eye (3%, V4b), and missed pre-existing Juvenile open angle glaucoma (JOAG) in two eyes (6% with V4b). Elevated IOP in 31 eyes resolved with conservative management. One eye (centraFLOW design) with central aquaport block by viscoelastic, needed AC wash and one eye with malignant glaucoma needed parsplana vitrectomy and hyaloidotomy. Ten eyes required longterm (>2 months) antiglaucoma medications (AGM) for IOP control. Except the two eyes with JOAG, none had disc and field damage.

CONCLUSION

In our series, OHT was seen in 4.85% and glaucoma in 0.3% eyes that underwent V4b and V4c model ICL implantation. Multiple etiologies were noted and steroid induced ocular hypertension was the most common cause of elevated IOP followed by retained viscoelastic and pupillary block. One third of these eyes required longterm AGM for IOP control.

Comparison of early changes in and factors affecting vault following posterior chamber phakic Implantable Collamer Lens implantation without and with a central hole (ICL V4 and ICL V4c)

Background

To objectively compare the early changes in vault over time following implantation of an Implantable Collamer Lens without (ICL V4) and with (ICL V4c) a central hole and the respective factors affecting vault change in moderate to high myopia.

Methods

This prospective study comprised of 38 eyes of 38 patients implanted with ICL V4 and 39 eyes of 39 patients implanted with ICL V4c intraocular lenses. We quantitatively assessed the postoperative values of vault and pupil size at 1 day, 1 week, and 1 month following implantation using a rotating Scheimpflug camera (Pentacam). We compared these postoperative values within and between the two groups and identified the factors affecting vault change.

Results

The mean vaults at 1 day, 1 week, and 1 month following ICL V4 implantation were 303.68 ± 185.11, 517.89 ± 160.07 and 521.32 ± 155.72 μm respectively, and those following ICL V4c were 316.67 ± 186.89, 495.13 ± 180.84 and 510.77 ± 175.51 μm, respectively. There was a significant difference in vault between 1 day and 1 week postoperatively. There was a significant association between the vault change and the pupil size change in both groups from 1 day to 1 month postoperatively (Pearman correlation coefficient; ICL V4: r = 0.585, P = 0.001; ICL V4c: r = 0.588, P <0.001). The vault value 1 month after implantation of ICL V4 and ICL V4c was associated with the preoperative anterior chamber depth, horizontal corneal diameter, horizontal and vertical sulcus-to-sulcus.

Conclusions

Pupil movement is a critical factor in vault change, with increasing vault observed postoperatively from 1 day to 1 week associated with the declining effects of pharmacological miosis and increasing pupil size. The anterior chamber depth, horizontal corneal diameter, horizontal and vertical sulcus-to-sulcus show some correlation with vault.

Electronic supplementary material

The online version of this article (doi:10.1186/s12886-016-0336-8) contains supplementary material, which is available to authorized users.

Real-time assessment of intraoperative vaulting in implantable collamer lens and correlation with postoperative vaulting

PURPOSE

To assess the intraoperative vaulting in patients undergoing implantable collamer lens (ICL) implantation with microscope-integrated intraoperative optical coherence tomography (iOCT) and correlate it with the postoperative vaulting.

METHODS

Forty eyes of 22 consecutive patients undergoing ICL implantation were prospectively evaluated. Vaulting was measured intraoperatively using microscope-integrated iOCT. The ICL-lenticular relationship was dynamically assessed throughout the surgery. Postoperative vaulting was measured using anterior segment optical coherence tomography on the first postoperative day and after 1 month and compared with the intraoperative vaulting. Uncorrected and best-corrected Snellen visual acuity, intraocular pressure (IOP), and anterior and posterior segments were assessed in all cases.

RESULTS

The mean central vaulting noted intraoperatively was 558.4 ± 122.8 µm. Postoperative mean vaulting was 576.0 ± 131.2 µm on day 1 and 551.1 ± 122.5 µm on day 30. There was a significant correlation between the intraoperative and the postoperative day 1 vaulting (paired samples correlation: 0.969, p&lt;0.001) and day 30 vaulting (paired samples correlation: 0.945, p&lt;0.001). An ICL-lenticular touch was not noted at any time during the surgery. The postoperative course was uneventful and no patient developed raised IOP or lenticular changes by the last follow-up.

CONCLUSIONS

Intraoperative vaulting correlates well with postoperative vaulting and can aid in on-table detection of extremes of vaulting and decision-making. It enhances the safety of the surgical procedure by providing a real-time display of the intraoperative manipulations.

Meta-analysis and review: effectiveness, safety, and central port design of the intraocular collamer lens

The purpose of this review is to summarize relevant data from publications appearing in the peer-reviewed scientific literature over the past decade since US Food and Drug Administration approval of the implantable collamer lens (ICL), and, in particular, to review studies relating to sizing methodology, safety, and effectiveness, as well as more recent studies reporting clinical outcomes of the V4c Visian ICL with KS Aquaport, VICMO. A literature search was conducted using two databases, PubMed.gov and Science.gov, to identify all articles published after 2005 related to the Visian ICL (STAAR Surgical, Inc.). Articles were examined for their relevance to sizing methodology, clinical safety, and effectiveness, and the references cited in each article were also searched for additional relevant publications. The literature review revealed that all currently reported methods of determining the best-fit size of the ICL achieve similarly satisfactory results in terms of vault, the safe distance between the crystalline lens and the ICL. Specifically, meta-analysis demonstrated that sulcus-to-sulcus and white-to-white measurement-based sizing methods do not result in clinically meaningful nor statistically significant differences in vault (two-sample two-sided t-test using pooled mean and standard deviations; t (2,594)=1.33; P=0.18). The reported rates of complications related to vault are very low, except in two case series where additional risk factors such as higher levels of myopia and older age impacted the incidence of cataract. On the basis of preclinical studies and initial clinical reports, with up to 5 years of follow-up, the new VICMO central port design holds promise for further reduction of complications. Given its safety record and the significant improvement in vision and quality of life that the ICL makes possible, the benefits of ICL implantation outweigh the risks.

Long-term clinical results of posterior chamber phakic intraocular lens implantation to correct myopia

BACKGROUND

The aim of this study was to determine whether implantable collamer lens (ICL) implantation to correct myopia is an effective and safe surgical option even after long-term follow up.

DESIGN

A retrospective observational study was carried out.

PARTICIPANTS

A total of 281 eyes of 145 myopic patients were included in the study.

METHODS

Patients underwent ICL implantation and had the follow-up period of at least 5 years (87 ± 18.9 months).

MAIN OUTCOME MEASURES

Outcome measures included uncorrected and corrected distance visual acuities, refraction for the evaluation of efficacy, safety, stability and predictability, ICL vault and adverse events.

RESULTS

The final mean logMAR uncorrected and corrected distance visual acuities were 0.02 ± 0.19 and -0.12 ± 0.13, respectively. The mean efficacy and safety indices were 1.04 ± 0.32 and 1.20 ± 0.26. The mean spherical equivalent decreased from -8.74 ± 2.27 diopter (D) to -0.58 ± 0.72 D, and there was high predictability with 69.8% and 87.2% having a postoperative refraction within 0.5 D and 1.0 D, respectively. The mean postoperative vault was changed from 2.53 ± 0.6 to 2.00 ± 0.7. Six (2.1%) eyes developed cataract, and the mean endothelial cell loss was 7.8 ± 8.3%. Increased intraocular pressure was found in two (0.7%) eyes that required the exchange of lenses with different sizes.

CONCLUSIONS

Implantable collamer lens implantation to correct myopia was an effective and safe surgery with high predictability and stability during long-term follow up. Slight myopic shift and cataract formation related with change in vault should be further evaluated.

Correcting Interdevice Bias of Horizontal White-to-White and Sulcus-to-Sulcus Measures Used for Implantable Collamer Lens Sizing

PURPOSE

To assess the agreement and repeatability of horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements and use these data in combination with available literature to correct for interdevice bias in preoperative implantable collamer lens (ICL) size selection.

DESIGN

Interinstrument reliability and bias assessment study.

METHODS

A total of 107 eyes from 56 patients assessed for ICL implantation at our institution were included in the study. This was a consecutive series of all patients with suitable available data. The agreement and bias between WTW (measured with the Pentacam and BioGraph devices) and STS (measured with the HiScan device) were estimated.

RESULTS

The mean spherical equivalent was -8.93 ± 5.69 diopters. The BioGraph measures of WTW were wider than those taken with the Pentacam (bias = 0.26 mm, P < .01), and both horizontal WTW measures were wider than the horizontal STS measures (bias >0.91 mm, P < .01). The repeatability (Sr) of STS measured with the HiScan was 0.39 mm, which was significantly reduced (Sr = 0.15 mm) when the average of 2 measures was used. Agreement between the horizontal WTW measures and horizontal STS estimates when bias was accounted for was г = 0.54 with the Pentacam and г = 0.64 with the BioGraph.

CONCLUSIONS

Large interdevice bias was observed for WTW and STS measures. STS measures demonstrated poor repeatability, but the average of repeated measures significantly improved repeatability. In order to conform to the US Food and Drug Administration's accepted guidelines for ICL sizing, clinicians should be aware of and account for the inconsistencies between devices.

Prevention and management of collagen copolymer phakic intraocular lens exchange: causes and surgical techniques

PURPOSE

To analyze causes leading to explantation and exchange of Implantable Collamer Lens phakic intraocular lenses (pIOLs) and examine the surgical techniques of pIOL exchange.

SETTING

Wuhan Aier Eye Hospital, Wuhan, China.

DESIGN

Retrospective analysis of prospectively collected data.

METHODS

Different techniques were used to explant the pIOLs based on the amount of vaulting. Preoperative and postoperative data were collected to evaluate possible causes leading to pIOL exchange and the safety of pIOL exchange.

RESULTS

Of 616 myopic eyes with previous pIOL implantation, 16 eyes of 15 patients having pIOL exchange were reviewed. Eight surgeries (50%) were performed because of low vaulting (≤100 μm) and another 8 (50%) because of too high vaulting (≥1000 μm). The causes leading to low vaulting included increased crystalline lens thickness (≥4.0 mm), low anterior chamber depth (ACD) (<3.1 mm), and a too-small pIOL (<12.0 mm). The high vaulting was primarily the result of oversized white-to-white (WTW) measurements with Scheimpflug pachymetry (Pentacam) or the use of a digital caliper by an unskilled examiner and of ciliary body cysts. Six months after pIOL exchange, the vaulting ranged from 162 to 715 μm. No anterior subcapsular cataracts or other complications occurred during the observation period.

CONCLUSIONS

The main causes of abnormal vaulting and subsequent pIOL exchange included a thick crystalline lens, low ACD, too-small pIOL, WTW measurement error, and ciliary body cysts. Phakic IOL explantations were individually designed based on the vaulting to achieve proper safety and efficacy.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Clinical results of posterior chamber phakic intraocular lens implantation in eyes with low anterior chamber depth

PURPOSE

To investigate visual outcomes of Visian implantable Collamer lens (ICL) implantation in eyes with a shallow anterior chamber depth (ACD).

DESIGN

Retrospective, noncomparative, interventional case series.

METHODS

Medical charts of the patients with a low ACD of 2.8 mm or less who underwent implantable Collamer lens implantation were reviewed. To evaluate efficacy and safety, preoperative and postoperative uncorrected visual acuity, manifest refractive spherical equivalent (MRSE), endothelial cell count, intraocular pressure, angle opening distance at 500 μm from the scleral spur, trabecular-iris angle, and postoperative central vault were analyzed.

RESULTS

The mean follow-up period for 18 eyes of 10 patients was 24.67 ± 15.09 months (range, 10 to 51 months). The preoperative ACD was 2.71 ± 0.08 mm (range, 2.42 to 2.79 mm). There was no postoperative endothelial cell count reduction to less than 2000 cells/mm(2) or intraocular pressure elevation to more than 21 mm Hg. The differences between preoperative and postoperative angle opening distance at 500 μm from the scleral spur and trabecular-iris angle were statistically significant (P = .000, both). The mean postoperative central vault was 331.83 ± 181.28 μm (range, 174 to 811 μm), which was significantly less than expected (P = .000). Anterior subcapsular cataract was observed in 2 eyes (11.1%).

CONCLUSIONS

Implantable Collamer lens implantation in shallow ACD eyes exhibited good visual outcomes. Severe complications did not develop over relatively long periods. Two cases of anterior subcapsular cataract developed in older aged patients, suggesting the need for thorough preoperative warning about the risk of cataract. In addition, a postoperative vault less than expected should be taken into account when determining implantable Collamer lens size in lower ACD eyes.

Comparison of postoperative vault height predictability using white-to-white or sulcus diameter-based sizing for the visian implantable collamer lens

PURPOSE

To compare vault height predictability of Implantable Collamer Lens (ICL; Staar Surgical) sizing using a sulcus diameter-based formula or the manufacturer-recommended white-to-white-based method.

METHODS

In 50 myopic eyes, ICL size was calculated using both a formula including sulcus diameter and the traditional formula based on white-to-white diameter. Sulcus diameter was measured using Artemis 2 very high-frequency (VHF) digital ultrasound (ArcScan Inc). Implantation was based on the sulcus diameter derived size. Actual postoperative vault height achieved was measured by VHF digital ultrasound scanning. Circle segment trigonometry was used to calculate the vault height that would have resulted had lens sizing been based on the white-to-white formula.

RESULTS

The same lens size would have been used in 60% of eyes, a smaller lens would have been used in 34% of eyes and a larger lens in 6% of eyes had lens sizing been based on the white-to-white formula. Mean vault for eyes with lenses sized using the sulcus diameter formula was 0.37±0.16 mm (range: 0.08 to 0.92 mm), with 2% <0.09 mm, the recognized low-vault height for risk of cataract. Circle segment trigonometry predicted that the vault height would have been 0.24±0.28 mm (range: -0.31 to 0.92 mm), with 26% <0.09 mm had lens sizing been based on the white-to-white formula.

CONCLUSIONS

Significantly better predictability of postoperative vault height was achieved by including sulcus diameter into the ICL sizing formula compared with using the traditional white-to-white-based formula.