Journal of Refractive Surgery

Original Article Supplemental Data

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

Qian Chen, MD; Weina Tan, MD; Xiaohua Lei, MD; Chao Pan, MD; Lina Jin, MD; Qingyan Zeng, MD; Zheng Wang, MD

Abstract

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.]

Abstract

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.]

Implantation of the Implantable Collamer Lens (Visian ICL; STAAR Surgical) for correction of myopia and myopic astigmatism has been conducted in clinical practice for approximately two decades since the U.S. Food and Drug Administration first approved the ICL.1 It is currently a more popular refractive surgical procedure than corneal laser surgery owing to its superiority in visual quality and corneal biomechanics.2,3

Obtaining an ideal vault is crucial to ensure safety after ICL implantation. Insufficient vault or excessive vault increases the risk of adverse events such as anterior subcapsular opacities, pigment dispersion, and secondary glaucoma.4,5 With the advent of the central hole design of the ICL V4C (STAAR Surgical), which largely preserves the natural circulation of the aqueous and the nutrition of the patient's own crystalline lens, the incidence of anterior subcapsular opacities has decreased significantly.3 Excessive vault greater than 1,000 µm should raise more concern due to its severe consequences, which may require emergency treatment or even early secondary surgical intervention.6

The incidence of excessive vault was reported to be approximately 0.4% to 11.1%.3,7 Previous studies have identified oversized white-to-white (WTW) distance, shallow anterior chamber depth (ACD), and high dioptric power of the ICL as being relevant to excessive vault after ICL implantation.6,8 Considering that the ICL is placed in the ciliary sulcus of the posterior chamber, attempts have been made to employ the sulcus-to-sulcus (STS) diameter to determine the ICL size.9 Although this approach partly improved postoperative vault prediction performance, excessively high vault still occurs in some cases.7 Therefore, some authors hypothesized that the unexpected excessive vault may result from unmeasurable posterior chamber anatomic factors such as the ciliary body.3

With the wide application of ultrasound biomicroscopy (UBM) in clinical practice, which facilitates objective and quantitative estimation of the ciliary body anatomy, many parameters were developed to characterize the ciliary body morphology. Based on these measurements, researchers have identified various shapes and positions of the ciliary body generally classified as neutrally positioned and anteriorly positioned,10 in which the latter was confirmed as a risk factor for plateau iris and angle closure.11,12 In normal eyes with open angles, a study has also observed an anteriorly positioned ciliary body often accompanied by an absence of ciliary sulcus.13

We designed and conducted this study to test the above-mentioned hypothesis. To the best of our knowledge, there has been no published study to explain the possible relationship between the ciliary body measurement and clinical outcomes of excessive vault.

Patients and Methods

This retrospective, 1:2 case-control study was performed in Hankou Aier Eye Hospital and approved by the institutional review board. The study adhered to the ethical principles outlined in the Declaration of Helsinki. All patients signed written informed consents before being enrolled in the current study.

A total of 81 eyes of 81 patients (only the left eye was enrolled) who underwent Visian ICL V4C implantation to correct myopia and myopic astigmatism from January 2016 to June 2019 were analyzed, of which 27 eyes of 27 patients with postoperative vault of 1,000 µm or greater in the early postoperative period were selected as the excessive vault group. For each eye in the excessive vault group, two matched control eyes with postoperative vault of between 250 and 1,000 µm were randomly selected from the database within the same observational period. These eyes were matched for WTW distance (±0.1 mm), ACD (±0.2 mm), and the size of the ICL (±0) and defined as the normal vault group.

Inclusion criteria were as follows: (1) age between 18 and 45 years; (2) spectacle spherical power ranging from −0.50 to −18.00 diopters (D); cylindrical power between 0.00 and −6.00 D, stable refractive state for at least 1 year; (3) ACD no less than 2.8 mm; (4) corneal endothelial cell density greater than 2,000 cells/mm2; (5) open angle on gonioscopy; (6) UBM image with high quality; and (7) the implanted ICL size was determined strictly based on the manufacturer's recommendations. The exclusion criteria included any history of ocular pathologies, trauma, previous ocular surgeries, or chronic systemic diseases.

All participants received a complete ophthalmic examination preoperatively, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity, manifest and cycloplegic refraction, non-contact tonometry, slit-lamp microscopy, gonioscopy, funduscopic examination, and endothelial cell density measurement. In addition, the axial length and lens thickness were recorded from A-scan ultrasound measurement, the horizontal WTW distance was obtained using an electronic digital caliper under the microscope by two experienced physicians (QC and WT), and ACD (measured from the corneal endothelium to the anterior lens), anterior chamber angle (ACA), anterior chamber volume (ACV), and pupil diameter were assessed by a Scheimpflug camera (Pentacam HR; Oculus Optikgeräte GmbH). UBM with a 50-MHz producer (Model SW-3200L; Tianjin Suowei Electonic Technology Co, Ltd) was performed to measure the horizontal and vertical STS diameter, the crystalline lens rise (CLR), and parameters related to the ciliary body.

Patients were followed up on postoperative 1 day, 1 week, and 1, 3, 6, and 12 months. UDVA, intraocular pressure measurements, and slit-lamp examination for subjective vault and any adverse effects were obtained on each visit. The Pentacam HR and anterior segment optical coherence tomography (Triton; Topcon Corporation) used to assess the vaulting were performed only at 1 month after surgery.

The UBM measurements were performed by one of two experienced operators (LJ and another operator). The patients were asked to lie down in a supine position after use of a drop of topical anesthesia. The plastic eye cup was gently placed into the conjunctival sac, and then it was filled with an artificial tea formulation as a coupling agent. To control the influence of accommodation, patients were asked to fixate on a ceiling target using the contralateral eye. A full view scan of the anterior segment was obtained at the 3- to 9-o'clock and 6- to 12-o'clock positions with the probe held perpendicular to the eyes. Radial scans of the limbus area through a typical process in the 2-, 4-, 8-, and 10-o'clock quadrants were also acquired by asking the patients to turn their eyes to the opposite side. Several scans were repeated until the images displayed a clear reflectivity of scleral spur, angle, half full chord of the iris, ciliary body, and anterior surface of the lens.

All UBM images were imported into a personal computer and measured manually using ImageJ software (National Institutes of Health) by another well-trained examiner (CP) who had been masked to the clinical data. The following parameters were measured at the 2-, 4-, 8-, and 10-o'clock positions (Figure A, available in the online version of this article): (1) iris-ciliary angle (ICA): the angle between the posterior iris surface and the anterior surface of the ciliary body; (2) trabecular-ciliary angle (TCA): the angle measured by the scleral spur as the apex and the corneal endothelium and the anterior surface of the ciliary body as the arms; (3) trabecular ciliary process distance (TCPD): the length of the line extending from the corneal endothelium 500 µm from the scleral spur perpendicularly to the line passing through the innermost point of the ciliary body and parallel to the iris; (4) maximum ciliary body thickness (CBTmax): the distance from the innermost point of the ciliary body to the inner wall of the sclera or its extended line; and (5) ciliary process length (CPlength): the distance from the innermost point of the ciliary body to the intersection point of the iris and ciliary body. The CLR, which was defined as the perpendicular distance from the anterior pole of the lens to the horizontal line between STS distance, was measured on a full view scan from the 3-to 9-o'clock positions (Figure B, available in the online version of this article). Each measurement was repeated three times and the mean values were calculated. The final values averaged from the parameters at the four quadrants were obtained for statistical analysis.

Diagrammatic representation of the ultrasound biomicroscopy measurements of ciliary body parameters. Iris-ciliary angle (ICA) is the angle between the posterior iris surface and the anterior surface of the ciliary body; trabecular-ciliary angle (TCA) is measured with the scleral spur as the apex and the corneal endothelium and the anterior surface of the ciliary body as the arms of the angle; trabecular ciliary process distance (TCPD) is defined as the length of the line extending from the corneal endothelium 500 μm from the scleral spur perpendicularly to the line passing through the innermost point of ciliary body and parallel to the iris; maximum ciliary body thickness (CBTmax) is the distance from the innermost point of the ciliary body to the inner wall of the sclera or its extended line; ciliary process length (CPlength) is the distance from the innermost point of the ciliary body to the intersection point of the iris and ciliary body.

Figure A.

Diagrammatic representation of the ultrasound biomicroscopy measurements of ciliary body parameters. Iris-ciliary angle (ICA) is the angle between the posterior iris surface and the anterior surface of the ciliary body; trabecular-ciliary angle (TCA) is measured with the scleral spur as the apex and the corneal endothelium and the anterior surface of the ciliary body as the arms of the angle; trabecular ciliary process distance (TCPD) is defined as the length of the line extending from the corneal endothelium 500 μm from the scleral spur perpendicularly to the line passing through the innermost point of ciliary body and parallel to the iris; maximum ciliary body thickness (CBTmax) is the distance from the innermost point of the ciliary body to the inner wall of the sclera or its extended line; ciliary process length (CPlength) is the distance from the innermost point of the ciliary body to the intersection point of the iris and ciliary body.

Ultrasound biomicroscopy image showing the measurement of the sulcus-to-sulcus (STS) distance and the crystalline lens rise (CLR). The CLR was defined as the distance from the anterior pole of the lens to the STS plane.

Figure B.

Ultrasound biomicroscopy image showing the measurement of the sulcus-to-sulcus (STS) distance and the crystalline lens rise (CLR). The CLR was defined as the distance from the anterior pole of the lens to the STS plane.

The ciliary body was classified as anteriorly or neutrally positioned. The characteristic of a long ciliary process with no ciliary sulcus (ICA = 0°) was based on Sakata et al's13 definition of the anteriorly positioned ciliary body as exhibiting at least two quadrants of the ciliary body (Figure 1). The neutrally positioned ciliary body was defined as the iris and the ciliary body did not touch much with an obvious ciliary sulcus observed in at least three quadrants (Figure 2).

The determination of an anteriorly positioned ciliary body according to the definition of Sakata et al.13 The ciliary process length crosses the line C and the ciliary sulcus disappears at the intersection of this line (C) with the ciliary process. The line C is drawn from the point (B) located at the corneal endothelium 750 μm from the scleral spur (A) perpendicularly through the posterior surface of the iris.

Figure 1.

The determination of an anteriorly positioned ciliary body according to the definition of Sakata et al.13 The ciliary process length crosses the line C and the ciliary sulcus disappears at the intersection of this line (C) with the ciliary process. The line C is drawn from the point (B) located at the corneal endothelium 750 μm from the scleral spur (A) perpendicularly through the posterior surface of the iris.

The determination of a neutrally positioned ciliary body. Features show the iris and the ciliary body do not touch much and an obvious ciliary sulcus can be seen.

Figure 2.

The determination of a neutrally positioned ciliary body. Features show the iris and the ciliary body do not touch much and an obvious ciliary sulcus can be seen.

Statistical Analysis

Statistical analyses were performed with SPSS software version 25.0 (SPSS, Inc). The normality assumption of the data was assessed by the Kolmogorov-Smirnov test. The continuous variables with a normal distribution between groups were compared using the independent t test, and data with a non-normal distribution were analyzed using the Mann-Whitney U test. For the comparison of the categorical variables, the chi-square test was used. The relationship between the vault values and biometric parameters was evaluated using multiple linear regression analysis. Conditional logistic regression analysis was applied to identify independent risk factors for the presence of vault greater than 1,000 µm. A P value of less than .05 was considered statistically significant.

Results

The demographic and clinical baseline characteristics of the study participants in the two groups are summarized in Table 1. Male gender accounted for 22.2% in the excessive vault group and 46.3% in the normal vault group. There were no significant differences between the two groups except for sex, STS-WTW distance, ICA, TCA, TCPD, and CPlength. Eyes in the excessive vault group displayed a larger difference of the STS-WTW distance compared with the normal vault group. Among parameters related to the ciliary body measured by UBM, ICA, TCA, and TCPD were significantly lower in the excessive vault group and eyes in the normal vault group had a smaller CPlength (P < .05).

Comparison of Demographics and Ocular Characteristics of Patients Between the Excessive Vault and Normal Vault Groups

Table 1:

Comparison of Demographics and Ocular Characteristics of Patients Between the Excessive Vault and Normal Vault Groups

Table 2 depicts the comparison of postoperative clinical features and outcomes between the excessive vault and normal vault groups. No significant differences were noted in mean UDVA and intraocular pressure between the two groups (P > .05). The mean value of the vault was 1,204.56 ± 230.66 µm in the excessive vault group versus 683.87 ± 142.72 µm in the normal vault group. In the early postoperative period, a greater decrease in ACD and ACA was found in the excessive vault group compared with the normal vault group (P < .05). Four eyes in the excessive vault group exhibited extremely shallow ACD, with angle closure in any quadrant requiring a secondary surgical intervention, of which 1 eye underwent ICL extraction and 3 eyes required ICL exchange for a smaller ICL. After the ICL exchange, the mean value of the postoperative vault decreased from 1,525.67 ± 468.22 to 810.33 ± 254.92 µm.

Comparison of Changes in Anterior Chamber Parameters 1 Month Postoperatively Between the Excessive Vault and Normal Vault Groups

Table 2:

Comparison of Changes in Anterior Chamber Parameters 1 Month Postoperatively Between the Excessive Vault and Normal Vault Groups

All variables were strictly selected before being included in the regression model using simple linear regression. If the correlation coefficient of the two variables was greater than 0.6, only one variable was selected in the analysis; 10 variables were finally selected. Multiple linear regression analysis showed ACV (P = .01), ICA (P < .001), and CLR (P = .01) were the three explanatory variables associated with the postoperative vault (Table 3). A conditional logistic regression analysis (Table 4) was completed to identify the predictive factors for the presence of vault greater than 1,000 µm after ICL implantation in the early postoperative period. The ICA was found to be the only independent factor for prediction of excessive vault (odds ratio [OR] = 0.96; 95% CI = 0.93 to 0.99; P < .001). After further analysis by classifying the ciliary morphology as anteriorly positioned or neutrally positioned according to the parameters related to the ciliary body, we found eyes with an anteriorly positioned ciliary body were associated with 3.75 times increased odds of excessive vault after ICL implantation (OR = 3.57; 95% CI = 1.67 to 7.63; P < .001).

Results of Multiple Linear Regression Analysis Evaluating the Association Between Preoperative Biometric Parameters and Central Vaulting After ICL Implantation

Table 3:

Results of Multiple Linear Regression Analysis Evaluating the Association Between Preoperative Biometric Parameters and Central Vaulting After ICL Implantation

Results of Conditional Logistic Regression Analysis Assessing the Risk Factors Associated With Excessive Vault (>, 1000 µm) After ICL Implantation

Table 4:

Results of Conditional Logistic Regression Analysis Assessing the Risk Factors Associated With Excessive Vault (>, 1000 µm) After ICL Implantation

Discussion

The accurate predictability of postoperative vault remains a challenge for refractive experts. Many studies have tried to solve the problem by exploring more influencing factors and using different ICL sizing methodologies. However, unexpected excessive vault still occurs occasionally, leading to shallow ACD, which is a risk factor for angle closure and glaucoma.3,8 It raises doubts about whether some occult factors (eg, the structure of the posterior chamber) exist that have been ignored previously. Because the ciliary body is the major tissue composing the posterior chamber and ciliary sulcus, it remains unclear whether the morphology of the ciliary body has an association with excessive vault after ICL implantation. To the best of our knowledge, this is the first study attempting to assess the prediction power of preoperative biometrics, especially the characteristics of the ciliary body in detecting excessive vault (> 1,000 µm) after ICL implantation.

In the current study, UBM parameters including ICA, TCA, TCPD, CBTmax, and CPlength14,15 were measured to assess the shape and position of the ciliary body. We observed a strong correlation among these parameters, with a correlation coefficient greater than 0.6 between ICA and CPlength and CPlength and CBTmax. Our findings are in agreement with previous studies that described a longer ciliary process usually accompanied by a more anteriorly located ciliary body.13 Similarly, Smith et al16 mapped the characteristics of the ciliary body using electron microscopy, revealing that the ciliary body would be anteriorly positioned if these characteristics were thick or numerous. Based on these results, ICA was finally selected to represent the morphology of the ciliary body in the regression model. Sugiura et al15 reported the mean average values for the ICA were 66.3° in normal eyes. In the current study, similar values (48.23° ± 16.15°) for ICA were found in the normal vault group, whereas the excessive vault group tended to have significantly lower mean values (26.18° ± 16.32°). Further analysis using the conditional logistic regression analysis disclosed that every 1° reduction in ICA was associated with a 4% increased likelihood of vault greater than 1,000 µm.

ICA can also reflect the degree of the ciliary sulcus, in which ICA with a value of “zero” means no ciliary sulcus. Sakata et al13 first defined this “special” ciliary body structure as the anteriorly positioned ciliary body. Previously published reports12,13 have clarified that an anteriorly positioned ciliary body is associated with occurrence of plateau iris and acute angle closure. On the contrary, Jiang et al10 found there were no significant differences in the ciliary body size and position after comparing the qualitative grading of UBM images between eyes with primary angle-closure suspect and wide-angle glaucoma, demonstrating that the anteriorly positioned ciliary body is also common in eyes with wide-angle glaucoma. This is consistent with our study and reports by Sakata et al13 with a prevalence of 32% in eyes with open-angle glaucoma in Brazilian patients exhibiting an anteriorly positioned ciliary body.

Considering the ICL is placed in the ciliary sulcus, we further analyzed the relationship between an anteriorly positioned ciliary body and excessive postoperative vault. The results revealed that eyes with an anteriorly positioned ciliary body were linked strongly to an increased incidence of excessive vault after ICL implantation. The possible mechanism underlying this phenomenon might be that the anteriorly positioned ciliary body may lead to an actual smaller diameter of STS distance and overcrowding of the posterior chamber segment. Although we did not find a significant correlation between the horizontal STS distance and ICA, the P value (P = .06) was close to significance. Lee et al17 demonstrated the difference between the ICL size and horizontal STS distance was one determining factor for postoperative ICL vault. In our practice, the ICL size was selected based on the WTW distance and ACD. Thus, we speculated that overestimation of the ICL size and consequently a risk of overvaulting may happen when the WTW distance method is used in eyes with an anteriorly positioned ciliary body after ICL implantation because of larger variance among the differences of WTW-STS distance.

Reinstein et al9 found a larger lens may have been used in 6% of eyes based on the WTW diameter formula when comparing the postoperative vault with sizing based on STS distance to the theoretical vault that would have been achieved with WTW-based sizing. However, Packer3 revealed there was no meaningful significant difference between the achieved vault using sizing methodologies based on WTW and STS distance. We suggested that the characteristics of the ciliary body should be taken into account carefully in these comparisons to detect a possible influence on postoperative vault prediction variations obtained with different ICL size calculation methods. In the excessive vault group, three ICLs were replaced for a smaller size lens. Although the postoperative vault decreased significantly after replacement, two patients still exhibited a relatively high vault that approached 1,000 µm. It reminds us that the influence of the actual smaller diameter of sizing methodologies on the postoperative vault in these cases sometimes may amplify or even exceed the change of vault brought about by a smaller ICL size.

The absence of ciliary sulcus in the anteriorly positioned ciliary body may possibly hinder the unfolding of the ICL haptic or induce inappropriate ICL haptic location during the ICL placement. Shi et al18 reported significant varying degrees of ICL decentration in excessive vault cases. Consistently, Zhang et al19 observed eyes that had excessive vault after ICL implantation with various positions of the ICL haptic, in which 3 eyes with the haptics on the top of the ciliary body definitely exhibited excessive vault. They speculated that the varied positions of the ICL haptic were mainly due to the blindly performed surgery. However, we hypothesized the inside characteristic of the posterior segment, especially the ciliary body, may be an important factor that should be considered. Unfortunately, we did not measure the position of the ICL haptic in the current study, which will need to be done in the future to confirm the possible relationship between the position of the ICL haptic and the shape and the location of the ciliary body.

In addition to ICA, CRL and ACV were the other two parameters associated with postoperative vaulting in the current study. Gonzalez-Lopez et al20 found a negative correlation between CRL and postoperative vaulting using an anterior segment optical coherence tomography device. Kojima et al7 developed a novel ICL sizing method based on the UBM data, in which CLR proved to be a candidate for predicting the vault after ICL implantation. We also demonstrated similar outcomes identifying CLR as an important factor that may affect the vault.

Considering ACD was an important parameter influencing the ICL size selection, we matched the ACD values in the two groups. However, multiple linear regression analysis in our study still showed ACV was correlated with postoperative vaulting. We could deduce that ACV may be a more sensitive parameter in the prediction of postoperative vault than ACD. A possible explanation would be that ACV reflects a more comprehensive anterior segment assessment, taking into account the corneal endothelium, peripheral ACA, and anterior surface of the iris and crystalline lens relative to the ACD.

There are several limitations in our study. All enrolled participants were Chinese. A previous study21 detected that the shape and location of the ciliary body were affected by ethnicity. The ciliary body in Chinese patients tends to be located more anteriorly, so the current results should be carefully applied in different populations. Second, the parameters of the ciliary body were measured semi-automatically in the software by only one examiner, which could induce a potential bias. Third, to be consistent with the position of the ICL haptic, the quantitative measurements of UBM images were performed at the 2-, 4-, 8-, and 10-o'clock positions, and it is not possible to control the influence of accommodation on the measurements in these quadrants. Variation of the ciliary body in the quadrants is another factor that should be considered.

Eyes with an anteriorly positioned ciliary body presented higher risk of excessive vault after ICL implantation in the early postoperative period. These findings offer new insight about ICL preoperative management and support the role of parameters related to the ciliary body as an important factor to be considered in the assessment of the vault after ICL implantation surgery and the selection of ICL size.

References

  1. Sanders DR, Doney K, Poco MICL in Treatment of Myopia Study Group. United States Food and Drug Administration clinical trial of the Implantable Collamer Lens (ICL) for moderate to high myopia: three-year follow-up. Ophthalmology. 2004;111(9):1683–1692. doi:10.1016/j.ophtha.2004.03.026 [CrossRef]
  2. Chen X, Guo L, Han T, Wu L, Wang X, Zhou X. Contralateral eye comparison of the long-term visual quality and stability between implantable collamer lens and laser refractive surgery for myopia. Acta Ophthalmol. 2019;97(3):e471–e478. doi:10.1111/aos.13846 [CrossRef]
  3. Packer M. Meta-analysis and review: effectiveness, safety, and central port design of the intraocular collamer lens. Clin Ophthalmol. 2016;10:1059–1077. doi:10.2147/OPTH.S111620 [CrossRef]
  4. Gonvers M, Bornet C, Othenin-Girard P. Implantable contact lens for moderate to high myopia: relationship of vaulting to cataract formation. J Cataract Refract Surg. 2003;29(5):918–924. doi:10.1016/S0886-3350(03)00065-8 [CrossRef]
  5. Apel A, Stephensen D. Surgical management of acute angle-closure glaucoma after toric ICL implantation. J Cataract Refract Surg. 2007;33(10):1672. doi:10.1016/j.jcrs.2007.05.043 [CrossRef]
  6. Zeng QY, Xie XL, Chen Q. Prevention and management of collagen copolymer phakic intraocular lens exchange: causes and surgical techniques. J Cataract Refract Surg. 2015;41(3):576–584. doi:10.1016/j.jcrs.2014.06.036 [CrossRef]
  7. Kojima T, Yokoyama S, Ito M, et al. Optimization of an implantable collamer lens sizing method using high-frequency ultrasound biomicroscopy. Am J Ophthalmol. 2012;153(4):632–637. doi:10.1016/j.ajo.2011.06.031 [CrossRef]
  8. Nam SW, Lim DH, Hyun J, Chung ES, Chung TY. Buffering zone of implantable Collamer lens sizing in V4c. BMC Ophthalmol. 2017;17(1):260. doi:10.1186/s12886-017-0663-4 [CrossRef]
  9. Reinstein DZ, Lovisolo CF, Archer TJ, Gobbe M. Comparison of postoperative vault height predictability using white-to-white or sulcus diameter-based sizing for the Visian implantable collamer lens. J Refract Surg. 2013;29(1):30–35. doi:10.3928/1081 597X-20121210-02 [CrossRef]
  10. Jiang Y, He M, Huang W, Huang Q, Zhang J, Foster PJ. Qualitative assessment of ultrasound biomicroscopic images using standard photographs: the Liwan Eye Study. Invest Ophthalmol Vis Sci. 2010;51(4):2035–2042. doi:10.1167/iovs.09-4145 [CrossRef]
  11. Wand M, Pavlin CJ, Foster FS. Plateau iris syndrome: ultrasound biomicroscopic and histologic study. Ophthalmic Surg. 1993;24(2):129–131.
  12. Yao BQ, Wu LL, Zhang C, et al. Ultrasound biomicroscopic features associated with angle closure in fellow eyes of acute primary angle closure after laser iridotomy. Ophthalmology. 2009;116(3):444–448. doi:10.1016/j.ophtha.2008.10.019 [CrossRef]
  13. Sakata LM, Sakata K, Susanna R Jr, et al. Long ciliary processes with no ciliary sulcus and appositional angle closure assessed by ultrasound biomicroscopy. J Glaucoma. 2006;15(5):371–379. doi:10.1097/01.ijg.0000212251.72207.19 [CrossRef]
  14. Henzan IM, Tomidokoro A, Uejo C, et al. Ultrasound biomicroscopic configurations of the anterior ocular segment in a population-based study the Kumejima Study. Ophthalmology. 2010;117(9):1720–1728. doi:10.1016/j.ophtha.2010.01.045 [CrossRef]
  15. Sugiura T, Kaji Y, Tanaka Y. Anatomy of the ciliary sulcus and the optimum site of needle passage for intraocular lens suture fixation in the living eye. J Cataract Refract Surg. 2018;44(10):1247–1253. doi:10.1016/j.jcrs.2018.07.017 [CrossRef]
  16. Smith SG, Snowden F, Lamprecht EG. Topographical anatomy of the ciliary sulcus. J Cataract Refract Surg. 1987;13(5):543–547. doi:10.1016/S0886-3350(87)80110-4 [CrossRef]
  17. Lee DH, Choi SH, Chung ES, Chung TY. Correlation between preoperative biometry and posterior chamber phakic Visian Implantable Collamer Lens vaulting. Ophthalmology. 2012;119(2):272–277. doi:10.1016/j.ophtha.2011.07.047 [CrossRef]
  18. Shi M, Kong J, Li X, Yan Q, Zhang J. Observing implantable collamer lens dislocation by panoramic ultrasound biomicroscopy. Eye (Lond). 2015;29(4):499–504. doi:10.1038/eye.2014.336 [CrossRef]
  19. Zhang X, Chen X, Wang X, Yuan F, Zhou X. Analysis of intraocular positions of posterior implantable collamer lens by full-scale ultrasound biomicroscopy. BMC Ophthalmol. 2018;18(1):114. doi:10.1186/s12886-018-0783-5 [CrossRef]
  20. Gonzalez-Lopez F, Bilbao-Calabuig R, Mompean B, Luezas J, Ortega-Usobiaga J, Druchkiv V. Determining the potential role of crystalline lens rise in vaulting in posterior chamber phakic collamer lens surgery for correction of myopia. J Refract Surg. 2019;35(3):177–183. doi:10.3928/1081597X-20190204-01 [CrossRef]
  21. He N, Wu L, Qi M, et al. Comparison of ciliary body anatomy between American Caucasians and ethnic Chinese using ultra-sound biomicroscopy. Curr Eye Res. 2016;41(4):485–491. doi:10.3109/02713683.2015.1024869 [CrossRef]

Comparison of Demographics and Ocular Characteristics of Patients Between the Excessive Vault and Normal Vault Groups

ParameterExcessive Vault (n = 27)Normal Vault (n = 54)P
Age (y)25.12 ± 6.2425.13 ± 4.81.99a
Sex (male, %)22.246.3.04b,c
T/I (%)10/1711/43.10b
IOP (mm Hg)13.74 ± 1.9513.77 ± 2.90.96a
SE (D)−8.11 ± 3.27−7.30 ± 3.43.38d
WTW (mm)11.61 ± 0.2611.63 ± 0.26.70d
ACD (mm)3.33 ± 0.253.34 ± 0.22.89a
ACA (°)39.26 ± 4.9739.60 ± 5.50.79a
ACV (mm3)203.15 ± 31.63217.00 ± 28.60.05a
LT (mm)3.79 ± 0.223.80 ± 0.24.84a
PD (mm)3.56 ± 1.003.38 ± 0.59.31a
AL (mm)26.06 ± 1.6726.58 ± 1.35.13a
STS horizontal (mm)11.42 ± 0.6111.67 ± 0.48.09a
STS vertical (mm)11.74 ± 0.5611.97 ± 0.49.10c
ICL diameter (mm)12.95 ± 0.3012.95 ± 0.301.00a
STS-WTW (mm)−0.19 ± 0.490.04 ± 0.41.03a,c
ICA (°)26.18 ± 16.3248.23 ± 16.15< .001a,c
TCA (°)111.76 ± 10.18117.10 ± 11.44.04a,c
TCPD (mm)1.31 ± 0.121.40 ± 0.14.01a,c
CBTmax (mm)1.22 ± 0.151.17 ± 0.11.07a
CPlength (mm)0.79 ± 0.110.69 ± 0.09< .001a,c
CLR (µm)0.35 ± 0.170.45 ± 0.24.16d

Comparison of Changes in Anterior Chamber Parameters 1 Month Postoperatively Between the Excessive Vault and Normal Vault Groups

ParameterExcessive Vault (n = 27)Normal Vault (n = 54)P
UDVA (logMAR)−0.04 ± 0.08−0.07 ± 0.07.06a
IOP (mm Hg)13.02 ± 2.3412.43 ± 2.93.40a
Delta ACD (mm)0.29 ± 0.250.18 ± 0.23.04b,c
Delta ACA (°)21.12 ± 7.7014.93 ± 6.12< .001a,c
Delta ACV (mm3)102.48 ± 24.7592.74 ± 18.58.05a
Delta PD (mm)−0.11 ± 0.600.12 ± 0.57.08a
Vault (µm)1,204.56 ± 230.66683.87 ± 142.72.00b,c
ICL removal1/270/54.15d
ICL exchange3/270/54.01c,d

Results of Multiple Linear Regression Analysis Evaluating the Association Between Preoperative Biometric Parameters and Central Vaulting After ICL Implantation

ParameterUnstandardized CoefficientStandardized CoefficientP95% CI
Age (years)7.690.14.14−2.63 to 18.02
Sex (male, %)68.50.11.25−50.45 to 187.45
SE (D)−13.38−0.15.10−29.56 to 2.80
IOP (mm Hg)−0.70−0.01.95−21.65 to 20.24
ACV (mm3)−2.50−0.25.01a−4.38 to −0.60
STS-WTW (mm)−123.00−0.18.06−247.34 to 1.33
LT (mm)37.320.03.76−203.09 to 277.75
PD (mm)52.190.13.19−26.31 to 130.70
ICA (°)−7.76−0.50< .001a−10.67 to −4.87
CLR (µm)−446.34−0.33.01a−697.4 to −195.31

Results of Conditional Logistic Regression Analysis Assessing the Risk Factors Associated With Excessive Vault (>, 1000 µm) After ICL Implantation

ParameterOR95% CIP
Age (years)1.020.93 to 1.11.63
Sex (male, %)1.670.61 to 4.55.32
SE (D)0.920.79 to 1.07.29
IOP (mm Hg)0.910.74 to 1.12.39
ACV (mm3)0.980.97 to 1.00.08
STS-WTW (mm)0.670.24 to 1.85.44
LT (mm)1.440.23 to 8.78.69
PD (mm)1.170.71 to 1.93.55
ICA (°)0.960.93 to 0.99< .001a
CLR (µm)0.120.01 to 1.12.06
Authors

From Aier Eye Hospital of Wuhan University, Wuhan, Hubei Province, People's Republic of China (QC, WT, XL, CP, LJ, QZ); Hankou Aier Eye Hospital, Wuhan, Hubei Province, People's Republic of China (QC, WT, XL, CP, LJ, QZ); and Aier Institute of Refractive Surgery, Guangzhou, Guangdong Province, People's Republic of China (ZW).

Supported in part by the research project of the Science Research Foundation of Aier Eye Hospital Group (Grant Nos. AF1909D2 and AR1909D1).

The authors have no financial or proprietary interest in the materials presented herein.

Drs. Chen and Tan contributed equally to this work and should be considered as equal first authors.

AUTHOR CONTRIBUTIONS

Study concept and design (QC, WT, QZ, ZW); data collection (QC, WT, XL, CP, LJ, QZ, ZW); analysis and interpretation of data (QC, WT, XL, CP, LJ, QZ, ZW); writing the manuscript (QC, WT, CP, QZ, ZW); critical revision of the manuscript (QC, WT, XL, LJ, QZ, ZW); administrative, technical, or material support (QC, WT, XL, CP, LJ, QZ, ZW); supervision (QZ, ZW)

Correspondence: Zheng Wang, MD ( gzstwang@gmail.com), and Qingyan Zeng, MD ( zengqingyan1972@163.com), Hankou Aier Eye Hospital, Wuhan, Hubei, People's Republic of China.

Received: November 08, 2019
Accepted: May 13, 2020

10.3928/1081597X-20200513-02

Sign up to receive

Journal E-contents