The comparison of white-to-white via triple person-times caliper measuring and machine-measuring in V4c implantable collamer lens implantation.

This study aimed to compare the differences and characteristics of white-to-white (WTW) values obtained before V4c implantation using triple person-times caliper, IOL-Master 700, Pentacam HR, and UBM, and to assess their correlation with vaulting. A total of 930 myopia patients (1842 eyes) who were interested in undergoing ICL surgery were assessed before the procedure using various instruments. The WTW measurements were obtained using a triple person-times caliper, Pentacam HR, and IOL-Master 700, whereas the angle-to-angle (ATA) measurements were obtained using UBM. The size of the ICL was subsequently calculated using triple person-times caliper measurements. The vault of the ICL was assessed using Pentacam HR three months after the surgery. The WTW was determined to be 11.30 ± 0.29 mm, 11.43 ± 0.29 mm, and11.86 ± 0.38 mm, respectively, using the triple person-times caliper, Pentacam HR, and IOL-Master 700. The measurement of ATA was 11.57 ± 0.51 mm, as done by UBM. The ICL vault was measured to be 400.97 ± 198.46 µm when examined with Pentacam HR three monthsafter the procedure. The linear regression analyses of ICL size and WTW of triple person-times caliper, ICL vault and WTW were (R = 0.703, p < 0.001; R = 0.0969, p < 0.001) respectively. The highest correlation was found between IOL-Master and Pentacam HR (r = 0.766, p = 0.000). The lowest correlation was found between UBM and Pentacam HR (r = 0.358, p = 0.002). Bland-Altman analysis showed that the 95% limits of agreement (LoA) were the triple person-times caliper and Pentacam HR (- 0.573, 0.298) and the triple person-times caliper and UBM (- 1.15, - 0.605). This indicated a strong agreement between the triple person-times caliper and Pentacam HR and a lack of agreement between the triple person-times caliper and UBM. Triple person-times caliper measurements offer excellent maneuverability, practicality, and reliable outcomes for determining ICL vaults. Measurements obtained using the triple-person caliper were less differece than those obtained using the Pentacam HR.

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.

Phakic intraocular lenses (pIOLs) are one method for correcting nearsightedness, with or without astigmatism. This category of refractive surgery has been growing rapidly in the US and around the world. Implantation of the implantable collamer lens (ICL), one type of pIOL, is safe and effective, with stable outcomes and low adverse event rates. When complications do occur, they are typically associated with an inappropriate vault, or distance between the implant and the natural lens. Preoperative planning and accurate ICL sizing are required to achieve an optimal vault and varies, depending on the diagnostic technology available to the surgeon. This paper reviews the current approaches to ICL planning and sizing in order to provide guidance to surgeons implanting this pIOL.

Ocular biometrics in eyes with different white-to-white corneal diameter in young myopic adults.

The interactions between white-to-white corneal diameter (WTW) and other ocular biometrics are important for planning of refractive surgery and understanding of ocular structural changes in myopia, but such interactions are rarely investigated in young myopic adults. This is a retrospective study involving 7893 young myopic adults from five centers. WTW and other ocular biometrics were measured by Pentacam. The ocular biometrics included anterior corneal curvature (AK) and posterior corneal curvature (PK), central corneal thickness (CCT) and corneal volume (CV), anterior and corneal eccentricity and asphericity, anterior corneal astigmatism (ACA) and posterior corneal astigmatism, anterior chamber depth (ACD), and anterior chamber volume (ACV). The ocular biometrics were compared among eyes of different WTW quartiles. Multivariate linear regression was used to assess the linear associations between WTW and other ocular biometrics adjusting for age, gender and spherical equivalent. In eyes of different WTW quartiles, other ocular biometrics were also significantly different (all P < 0.05). After adjusting for age, gender and spherical equivalent, WTW was positively correlated to AK (ß = 0.26 to 0.29), ACA (ß = 0.13), anterior corneal asphericity (ß = 0.05), PK (ß = 0.33 to 0.34), posterior corneal asphericity (ß = 0.13), ACD (ß = 0.29), and ACV (ß = 40.69), and was negatively correlated to CCT (ß = - 6.83), CV (ß = - 0.06 to - 0.78), anterior corneal eccentricity (ß = - 0.035), and posterior corneal eccentricity (ß = - 0.14) (all P < 0.001). In conclusion, we found that in young myopic adults, larger WTW was associated with thinner corneal thickness, flatter corneal curvature, more anterior corneal toricity, less corneal eccentricity and asphericity, and broader anterior chamber. Our findings may fill in the gap of literature, and help us better understand how the anterior segment structures interact with the WTW in myopia.

Distribution and determinants of corneal volume among healthy young Chinese adults: a cross-sectional study.

BACKGROUND: Several studies have previously reported the normal values of corneal volume (CV) in various populations, whereas little is known about the CV distribution in healthy young Chinese adults. Our study aimed to investigate the distribution of CV and its relationships with other ocular biometric parameters among healthy young Chinese adults. METHODS: A total of 1645 eyes from 1645 students at Dali University in Yunnan Province, China, were analyzed. Pentacam was used to measure CV. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated by Corvis-ST. Other biometrical parameters, including axial length (AL), keratometry, and white-to-white (WTW) distance, were measured using IOL Master. RESULTS: The mean age of the study population was 19.01 ± 0.92 years, and 68.81% of them were women. The CV was normally distributed in the whole sample, with a mean value of 61.23 ± 3.22 mm3. CV and CCT were significantly smaller in the Yi ethnic group than in the Han ethnic group (p < 0.01). CCT (coefficient: 0.085; p < 0.001) and keratometry (coefficient: 0.422; p < 0.001) were positively correlated with CV, while AL (coefficient: -0.204; p < 0.001), WTW distance (coefficient: -0.236; p < 0.001) and bIOP (coefficient: -0.06; p < 0.001) were inversely associated with CV. CONCLUSIONS: Our study provides an age-specific distribution of CV among healthy young Chinese adults. CCT, keratometry, AL, WTW distance and bIOP were important factors associated with CV.

Central anterior chamber depth correlated with white-to-white distance in normal, long, and short eyes.

PURPOSE: To explore the associations between central anterior chamber depth (CACD) and other anterior segment biometric parameters and to determine the possible determinants of CACD in short, normal, and long eyes. METHODS: The biometric data of pre-operation patients aged 50-80 years with coexisting cataract and primary angle-closure disease or senile cataract were reviewed. Axial length (AL), CACD, lens thickness (LT), central corneal thickness (CCT), and white-to-white distance (WTW) were measured by Lenstar optical biometry (Lenstar 900). The data of 100 normal eyes (AL = 22 to 26 mm), 100 short eyes (AL ≤ 22 mm), and 100 long eyes (AL ≥ 26 mm) were consecutively collected for subsequent analyses. RESULTS: The mean age of the subjects was 66.60 ± 7.85 years, with 25.7% of the sample being men. Both CACD and WTW were found to be smallest in short eyes and were smaller in normal eyes than in long eyes (F = 126.524, P < 0.001; F = 28.458, P < 0.001). The mean LT was significantly thicker in short eyes than in normal and long eyes (4.66 mm versus 4.49 mm versus 4.40 mm; F = 18.099, P < 0.001). No significant differences were observed in CCT between the three AL groups (F = 2.135, P = 0.120). Stepwise regression analysis highlighted AL, LT, and WTW as three independent factors associated with CACD in the normal AL group. In the short AL group and long AL group, LT and WTW were independent factors associated with CACD. CONCLUSIONS: CACD increases as AL elongates and reaches a peak when AL exceeds 26 mm. Furthermore, CACD showed inverse correlation with LT and positive correlation with WTW. A relatively small WTW results in an anteriorly positioned lens, and thus, a decrease in CACD.

Correlation of Ocular Biometry with Axial Length in Elderly Japanese.

Purpose: Ocular parameters are not only useful for diagnosing diseases but also for guiding treatment approaches. A lot of previous studies have reported ocular parameters and its relations before cataract surgery. However, despite ethnic differences in ocular biometry, few reports have dealt with Japanese. Hence, this retrospective cross-sectional study aimed to measure parameters of preoperative cataract patients and examines the correlations between each parameter in Japanese elderly people. Patients and Methods: The 210 subjects had their ocular axial lengths measured with OA-2000. The endpoints were ocular axial length (AL), central corneal thickness (CCT), average anterior corneal radius of curvature (CR), white-to-white (WTW), anterior chamber depth (ACD), and lens thickness (LT). Our analyses utilized the eye with the longer AL in each person. Each parameter was analyzed for correlations in a round-robin manner. Regression analyses were performed on parameters correlated with AL. Results: The parameters correlated with AL were CR (r = 0.33, P < 0.0001), WTW (r = 0.29, P < 0.0001), ACD (r = 0.59, P < 0.0001), and LT (r = -0.30, P < 0.0001). These parameters related to AL in all simple regression equations (CR (P < 0.0001), WTW (P = 0.0002), ACD (P < 0.0001), LT (P = 0.0001)). In multiple regression analyses, CR, ACD, and LT might relate to AL (CR (P = 0.0002), ACD (P < 0.0001), LT (P = 0.018)). LT tended to be thinner as AL increased, while CR, WTW, and ACD tended to increase. Conclusion: This information may be useful in developing strategies for ophthalmic surgery, as it provides information on the location of intraocular tissues. Various parameters have been used in intraocular lens (IOL) power calculations in recent years and knowledge of the interrelationship among parameters may be useful in determining IOL power according to ethnicity in the future.

Characterization of the external limbus on corneoscleral topography with ultrawide-field optical coherence tomography.

PURPOSE: To present a new method for 3-dimensional external limbal demarcation on corneoscleral topography derived from optical coherence tomography (OCT). Limbal shape is investigated and compared to other landmarks. METHODS: Images from the anterior segment were obtained with a ultrawide-field (20 mm) OCT. An automated algorithm was developed to demarcate the topographic limbus based on the transition from corneal to scleral curvature. The internal limbus was manually identified as the scleral spur on the OCT images. The external topographic limbus was fit with a circle on a plane. Ellipticity and ovality were defined by the lateral limbal deviation from the best-fit circle. Toricity was defined by the axial deviation from the best-fit plane. Repeatability was assessed by the within-subject standard deviation from two repeated measurements. For comparison, the white-to-white (WTW) diameter was obtained from Pentacam HR. RESULTS: 18 eyes from 11 subjects were analyzed. The topographic limbal diameter was 12.16 ± 0.68 mm (mean ± standard deviation) horizontally and 11.18 ± 0.65 mm vertically. The repeatability for the topographic limbal diameter was 0.054 mm. The internal and WTW horizontal limbal diameters were significantly smaller (linear mixed-effects model (GLMM), p <.017). The vertical internal limbal diameter was significantly larger (GLMM p <.05). The topographic limbus had significant ellipticity (0.25 ± 0.13 mm, wider horizontally, repeatability of 0.07 mm) and toricity (0.15 ± 0.08 mm, flatter horizontally, repeatability of 0.10 mm). Low coefficients of determination were found for the topographical limbus with the internal limbus (R2=0.021 and R2=0.039, for horizontal and vertical diameters respectively) and with the WTW (R2=0.146 for the horizontal diameter). CONCLUSION: The proposed method to demarcate the 3D external topographical limbus is repeatable. The topographic limbal shape and size cannot be accurately derived from WTW nor internal limbus measures. This new technology may improve the process of scleral lens fitting.

Assessing the efficacy of four methods established by four parameters in ICL size selection and relevant influencing factors: a prospective cohort study.

PURPOSE: To compare the efficacy and relevant influencing factors of four ICL size selection methods established by four different parameters. METHODS: This prospective study included 60 patients (120 eyes) who underwent bilateral ICL implantation. Patients were equally divided into four groups, and each group used the Parkhurst nomogram based on sulcus-to-sulcus (STS), the manufacturer's Online Calculation & Ordering System (OCOS) nomogram based on white-to-white (WTW), the KS formula based on angle-to-angle (ATA) and the NK formula based on anterior chamber width (ACW) to determine the ICL size. Recorded the vault one month after operation and compared the consistency between STS and WTW, ATA and ACW and their effects on the vault of different groups. RESULTS: The Parkhurst nomogram, OCOS nomogram, KS formula and NK formula determined 86.7%, 70.0%, 83.3% and 66.7% of properly sized ICL, respectively. STS and ATA were correlated (P < 0.05). The mean difference between the STS and WTW, ATA and ACW was -0.37 ± 0.62 mm, -0.42 ± 0.53 mm and -0.44 ± 0.52 mm, respectively. The vault in the OCOS group was negatively correlated with △STS-WTW, and the vault in the NK group was negatively correlated with △STS-WTW, △STS-ATA and △STA-ACW. The vault in the Parkhurst group and KS group was not affected by anterior segment biometry variables. CONCLUSION: ATA can be served as an alternative parameter to STS, and STS-based Parkhurst nomogram and ATA-based KS formula determined the most appropriate ICL size. When using OCOS nomogram and NK formula to select ICL size, postoperative abnormal vault was associated with a larger difference between STS and other anterior segment parameters.

Anterior Segment Biometry in a Caucasian Population with Cataracts.

PURPOSE: To investigate biometric factors of the anterior segment of phakic eyes with cataracts. METHODS: This population-based study included Caucasian patients with cataracts in the University Eye Hospital, Goethe University Frankfurt, Germany. Biometric parameters were measured using the swept-source optical coherence tomography method. Patients were grouped into intermediate stages based on decades of life. RESULTS: In total, 6289 eyes of 3615 patients (age: 70.67 ± 8.42 years) were included. Age-related reductions in the anterior chamber depth (mean ± standard deviation) decreased from 3.26 ± 0.42 mm (group A: 55-59 years) to 2.94 ± 0.4 mm (group G: 85-89 years), and those in the axial length decreased from 24.37 ± 1.87 mm (group A) to 23.39 ± 1.07 mm (group G). Likewise, the white-to-white distance decreased from 12.12 ± 0.48 mm (group A) to 11.96 ± 0.47 mm (group G). Lens thickness tended to increase accordingly from 4.39 ± 0.36 µm (group A) to 4.9 ± 0.40 µm (group G). A comparison of the eyes showed no detectable lateral difference regarding the biometric parameters between the groups (axial length: p = 0.26, Rosenthal effect size = 0.03; lens thickness: p = 0.12, R = 0.03; anterior chamber depth: p = 0.63, Rosenthal effect size = 0.01). The axial length and anterior chamber depth differed significantly between sexes (r = 0.22, p < 0.0001 and r = 0.16, p < 0.0001, respectively). Multiple regression analysis of the anterior chamber depth as a function of biometry parameters as well as age and sex additionally indicated a positive correlation of anterior chamber depth with white-to-white distance (b = 0.32, p = 10-5), axial length (b = 0.10, p = 10-5), keratometry (b = 0.07, p = 10-5), and lens thickness (b=-0.05, p = 10-5) with a high effect size (Cohen f2=1.866, p = 10-5) and strong multiple correlation coefficient (Rosenthal effect size = 0.80, p = 10-5). CONCLUSIONS: In the anterior segment, there are age- and sex-dependent changes in biometric parameters. In addition, changes in anterior chamber depth were noted in relation to white-to-white distance, axial length, keratometry, and lens thickness. These data should be considered in lens calculation formulas.

Agreement of Corneal Diameter and Anterior Chamber Depth Measurements with the IOLMaster 500 and the IOLMaster 700 Optical Biometers in Myopic Eyes.

Purpose: To assess the agreement in automated corneal diameter (CD) and anterior chamber depth (ACD, measured from corneal epithelium to lens) distances measurements between the IOLMaster 500 and 700 optical biometers in myopic eyes. Methods: One hundred and sixteen eyes of 116 myopic patients aged between 21 to 60 years were included in this study. Measurements of CD and ACD distances were taken with each biometer for all patients in the same session. A t-test and a p-value less than 0.05 was considered statistically significant when the measurements were compared. The agreement between biometers was studied by applying a Bland-Altman analysis. Results: The mean CD values obtained using the IOLMaster 500 and 700 biometers were 12.26±0.35 mm and 12.13±0.34 mm, respectively. The mean ACD distance values were 3.61±0.29 mm and 3.62±0.31, for the IOLMaster 500 and 700 biometers, respectively. There were statistically significant differences between the two devices only for CD measurements (p<0.001), but not for ACD measurements (p=0.26). The limits of agreement obtained were wide in both types of measurements, being 0.422 mm for the CD distance and 0.389 mm for the ACD distance. Conclusion: There were statistically significant differences between the IOLMaster 500 and 700 biometers regarding CD but not in ACD measurements in healthy myopic eyes. These differences could be clinically significant in some cases. According to these results, medical judgement should be used to assess whether the two devices could be used interchangeably for CD and ACD measurements during the clinical practice.

Evaluation of Ocular Diameter Parameters Using Swept-Source Optical Coherence Tomography.

Purpose: To investigate the iridocorneal angle-to-angle (ATA), sclera spur-to-sclera spur (STS), and white-to-white (WTW) ocular diameters and their potential influence on anterior chamber intraocular lens (ACIOL) and implantable collamer lens (ICL) sizing in Chinese subjects by using a swept-source optical coherence tomography system (SS-OCT). Design: A retrospective, observational, cross-sectional study. Methods: In 60 right eyes (60 subjects), the ATA, STS, and WTW were measured in six axes (0°-180°, 30°-210°, 60°-240°, 90°-270°, 120°-300°, and 150°-330°) using SS-OCT. The ACIOL and ICL sizes were calculated based on horizontal and vertical axes anterior segment data. A paired sample t-test was used to test the differences in each parameter across the six axes, the potential difference between each pair of parameters in a given axis, and the artificial lens size difference between the horizontal and vertical directions. Pearson's correlation analysis was used to determine the potential correlation between age and AL, WTW, STS, and ATA distances. Results: ATA and STS were the longest on the vertical and shortest on the horizontal axis, while WTW was similar on both axes. These three parameters differed only in the vertical axis (F = 4.910, p = 0.008). ATA and STS were by 0.23 ± 0.08 mm (p = 0.005) and 0.21 ± 0.08 mm wider (p = 0.010) than WTW, respectively. ICL size was 0.27 ± 0.23 mm smaller when based on the horizontal than on the vertical axis parameters (p < 0.001), while ACIOL remained similar (p = 0.709). Age correlated negatively and axial length positively with all measured values. ATA, STS, and WTW correlated positively in the same axis (all p < 0.001). Conclusions: ATA and STS were longer in the vertical than in the horizontal direction, while WTW measurements remained similar. ATA and STS diameters more accurately depicted anatomic relationships for phakic IOL sizing than WTW.

Agreement of anterior segment measurements between LenStar LS 900 optical biometer and OPD Scan III wavefront aberrometer devices in eyes with cataract.

PURPOSE: To compare the inter-device agreement of anterior eye segment measurements between LenStar LS 900 optical biometer and OPD Scan III wavefront aberrometer. METHODS: This is a retrospective study involving 59 patients (78 eyes) with cataract. Their angle Alpha, angle Kappa, pupil size and white-to-white (WTW) distance were measured by LenStar LS 900 optical biometer and OPD Scan III wavefront aberrometer, respectively, and pairwise agreement comparisons were performed between them. RESULTS: The most agreement of various parameters was occurred, with intraclass correlation coefficient (ICC) of WTW = 0.930; angle Alpha = 0.853; angle Kappa = 0.898; and pupil size = 0,976 in bright environment. Furthermore, in dark environment, the ICC of WTW, angle Alpha, angle Kappa, and pupil size were 0.927, 0.791, 0.915, and 0.990, respectively. Bland-Altman plot showed similar excellent agreement in the outcomes of the two devices for these measurements testing. CONCLUSIONS: There was an excellent agreement between the LenStar LS 900 optical biometer and OPD Scan III wavefront aberrometer for WTW, angle Alpha, angle Kappa, and pupil size measurements. In clinical practice, these measurements obtained by LenStar LS 900 optical biometer and OPD Scan III wavefront aberrometer can be used interchangeably.

The relationships between lens diameter and ocular biometric parameters: an ultrasound biomicroscopy-based study.

Purpose: This study aims to explore the relationships between lens diameter (LD) measured with ultrasound biomicroscopy (UBM) and ocular biometric parameters. Methods: Ocular biometric parameters including axial length (AL), white-to-white distance (WTW), anterior chamber depth (ACD), lens thickness (LT) and anterior segment length (ASL) were measured with IOL-Master 700, and the direct measurement of LD was conducted through UBM (ArcScan Insight 100). Relationships between LD and ocular biometric parameters were then investigated. Eyes with AL ≥ 28 mm were defined as eyes with extreme myopia, and eyes with AL < 28 mm were defined as eyes without extreme myopia. Results: A total of 194 eyes from 194 subjects were included. The mean LD was 9.58 ± 0.49 mm, ranging from 8.60 to 10.96 mm. According to univariate analysis, larger LD was associated with elder age, male gender, larger WTW, ACD and ASL (all p < 0.05). Meanwhile, the LD was positively correlated with AL in eyes without extreme myopia (p < 0.05), but not in eyes with extreme myopia (p > 0.05). Backward stepwise regressions revealed that a larger LD was associated with larger WTW, ASL and AL in eyes without extreme myopia (all p < 0.05), while ASL was the only significant variable in eyes with extreme myopia (p < 0.05). Conclusion: Larger WTW, ASL and AL in eyes without extreme myopia, as well as longer ASL in eyes with extreme myopia indicated a larger LD, which provides guidance in personalized surgical choice and promises ideal visual outcomes.

The influencing factors of surgically induced astigmatism in phacoemulsification / 西安交通大学学报(医学版)

【Objective】 To investigate the influencing factors of surgically induced astigmatism (SIA) in phacoemulsification. 【Methods】 Cataract phacoemulsification was performed in 69 patients with regular corneal astigmatism from December 2021 to March 2022. SIA of the anterior corneal surface, posterior corneal surface and simulated keratometry (SimK) in the diameter range of 3 mm, 5 mm and 7 mm centered at the apex of the cornea was observed. Pearson correlation analysis was used to analyze SIA with age, axial length (AL), anterior chamber depth (ACD), white-to-white (WTW), and central corneal thickness (CCT). Multiple linear regression was used to analyze the influencing factors of SIA. 【Results】 The mean age of the 69 patients was (63.25±14.74) years old, and 28 (40.58%) were male. The analysis found that the |SIA| of SimK was negatively correlated with WTW (r=-0.265, P=0.028), the |SIA| of 3 mm, 5 mm, 7 mm anterior surface was negatively correlated with WTW (r=-0.320, P=0.007; r=-0.337, P=0.005; r=-0.287, P=0.017), and the |SIA| of 3 mm, 5 mm, 7 mm posterior surface was negatively correlated with AL (r=-0.390, P=0.001; r=-0.352, P=0.003; r=-0.317, P=0.008). Multiple regression analysis showed that WTW was negatively correlated with |SIA| of SimK, 3 mm, 5 mm, 7 mm anterior surface and 3 mm posterior surface (B=-0.261, P=0.047; B=-0.387, P=0.016; B=-0.323, P=0.009; B=-0.297, P=0.041; B=-0.085, P=0.049). WTW was positively correlated with XSIA of 3 mm anterior surface, YSIA of 5 mm, and 7 mm anterior surface (B=0.347, P=0.040; B=0.318, P=0.034; B=0.403, P=0.010). AL was negatively correlated with |SIA| on the posterior surface of 3 mm and 5 mm (B=-0.023, P=0.021; B=-0.034, P=0.030). 【Conclusion】 During cataract surgery, the effect of ocular biological parameters such as axial length and corneal diameter on SIA should be considered.

Prediction of vault after implantable collamer lens implantation and its research progress / 国际眼科杂志(Guoji Yanke Zazhi)

Myopia is considered to be a disease occurred under the influence of genetic and environmental factors, and it can only be restored by corrective surgeries. The current surgical methods include laser surgeries and phakic intraocular lens(PIOL)implantation, and PIOL has the advantages of wide range of correction, repeatable procession and small damage to corneal tissue. Furthermore, good visual acuity can be achieved after implantation of intraocular lens. Implantable collamer lens(ICL)is the most common surgical method in this group. The vertical distance between the highest point of the posterior central surface of the implanted lens and the anterior surface of the crystalline lens is called vault. It will cause serious complications if the vault turns out to be abnormal. Up to now, there is no optimal prediction method. This research focuses on vault, discusses the ideal range of postoperative vault, the safety and effectiveness of this surgery, and analyzes the existing prediction methods to provide directions for future clinical research.

Daily Variations of Corneal White-to-White Diameter Measured with Different Methods.

Purpose: A precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter. Patients and Methods: Horizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit). Results: The two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times. Conclusion: The manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied.

Safety and anterior chamber structure of evolution implantable Collamer lens implantation with short white-to-white corneal diameters.

Introduction: To evaluate the safety and anterior chamber structure of implantation of the Evolution (EVO) implantable Collamer lens (EVO-ICL) in patients with short white-to-white (WTW) corneal diameters. Materials and methods: The study population was divided into two groups: the experimental group (34 eyes of 34 patients) with WTW corneal diameters of ≤10.6 mm and the control group (59 eyes of 59 patients) with WTW corneal diameters of >10.6 mm. The outcome measures included uncorrected distance visual acuity, corrected distance visual acuity, refractive power, intraocular pressure (IOP), anterior chamber angle, depth, volume, and vault. Results: The safety indices of the experimental and control groups were 1.17 ± 0.30 and 1.12 ± 0.14, respectively (P > 0.05); the effectiveness indices were 1.16 ± 0.31 and 1.07 ± 0.17, respectively (P > 0.05). The simulation curves of the expected and actual corrections in the experimental and control groups were y = 0.9876x - 0.0927 and y = 0.9799x + 0.0343, respectively. There were no significant differences between the IOPs and anterior chamber structures of the two groups (P > 0.05). The average vaults of the experimental and control groups were 395.76 ± 155.32 and 389.49 ± 135.01 µm, respectively (P > 0.05). Conclusion: EVO-ICL implantation in patients with short WTW corneal diameters (≤ 10.6 mm) was determined to be a safe, effective, and predictable method for correcting myopia. The changes in the anterior chamber structure were still within normal limits after the surgery, the IOP remained stable, and the ideal vault was achieved after the surgery.

Agreement between the biometric measurements used to calculate the size of the implantable collamer lenses measured with four different technologies.

Purpose: To evaluate the agreement between the biometric measurements used to calculate the size of the implantable collamer lenses (ICL) with different technologies: swept-source optical coherence tomography, spectral domain optical coherence tomography, and Scheimpflug tomography. Methods: This retrospective observational study included subjects undergoing refractive surgery with posterior chamber phakic IOL implantation to correct their myopia. The anterior chamber depth (ACD) and the horizontal white to white (WTW) or the angle to angle (ATA) distance were measured with the following four devices: the IOLMaster 700 biometer (Carl Zeiss Meditec, Jena, Germany), based on swept-source optical coherence tomography; the Cirrus and Visante optical coherence tomographs (Carl Zeiss Meditec) based on low-coherence interferometry; and the Pentacam rotating Scheimpflug camera (Oculus, Wetzlar, Germany). Results: In the horizontal corneal diameter measurements, there were statistically significant differences between Pentacam-IOLMaster 700 pair (P < 0.001) and Pentacam-Visante pair (P < 0.001). WTW from CIRRUS showed the lowest correlation when paired with Pentacam and IOLMaster 700 (R2 = 0.452 and 0.385 for Visante and R2 = 0.494 and 0.426 for Cirrus). Regarding the linear correlation of the ACD measurements, all pairs of devices were statistically significant and all of them showed a very good correlation index. Conclusion: There is a good agreement between the different devices under evaluation for ACD measurements. As for WTW, the values measured with the different devices showed large discrepancies with low correlation levels, especially when comparing the tomographs with the other devices under evaluation.

Lens-vault analysis and its correlation with other biometric parameters using swept-source OCT

Purpose: To measure lens vault (LV) and to assess its correlation with various ocular parameters in healthy eyes, using for all measurements the same high-resolution swept-source optical coherence tomographer (SS-OCT).Methods: We prospectively recruited 67 Caucasian healthy patients whose mean age was 41.9 ± 12.4 years; only their right eye was included in the study. Data were all recorded with the ANTERION SS-OCT and comprised, for each patient, 5 consecutive measurements of LV, anterior chamber depth (ACD), lens thickness (LT), axial length (AL), white-to-white (WTW) distance, central corneal thickness (CCT), anterior chamber volume (ACV) and spur-to-spur (STS) distance.Results: Mean LV was 0.26 ± 0.23 mm (ranging from -0.24 to 0.78 mm). Data analysis revealed a statistically significant negative correlation between LV and ACD (R=-0.80, p < 0.001), AL (R = -0.36, p = 0.002), and ACV (R = -0.68, p < 0.001), and a positive correlation between LV and LT (R = 0.67, p < 0.001), and age (R = 0.53, p < 0.001). In contrast, no statistically significant correlation was found between LV and WTW (R=-0.17, p = 0.15), CCT (R = 0.11, p = 0.36) or STS (R=-0.10, p = 0.41).Conclusions: Taking into account our findings about intra-parameter correlation levels, we believe that LV should be measured and analyzed together with other ocular parameters in clinical routine practice both for diagnosis and for some refractive surgeries. (AU)

Lens-vault analysis and its correlation with other biometric parameters using swept-source OCT.

PURPOSE: To measure lens vault (LV) and to assess its correlation with various ocular parameters in healthy eyes, using for all measurements the same high-resolution swept-source optical coherence tomographer (SS-OCT). METHODS: We prospectively recruited 67 Caucasian healthy patients whose mean age was 41.9 ±â€¯12.4 years; only their right eye was included in the study. Data were all recorded with the ANTERION SS-OCT and comprised, for each patient, 5 consecutive measurements of LV, anterior chamber depth (ACD), lens thickness (LT), axial length (AL), white-to-white (WTW) distance, central corneal thickness (CCT), anterior chamber volume (ACV) and spur-to-spur (STS) distance. RESULTS: Mean LV was 0.26 ± 0.23 mm (ranging from -0.24 to 0.78 mm). Data analysis revealed a statistically significant negative correlation between LV and ACD (R=-0.80, p < 0.001), AL (R = -0.36, p = 0.002), and ACV (R = -0.68, p < 0.001), and a positive correlation between LV and LT (R = 0.67, p < 0.001), and age (R = 0.53, p < 0.001). In contrast, no statistically significant correlation was found between LV and WTW (R=-0.17, p = 0.15), CCT (R = 0.11, p = 0.36) or STS (R=-0.10, p = 0.41). CONCLUSIONS: Taking into account our findings about intra-parameter correlation levels, we believe that LV should be measured and analyzed together with other ocular parameters in clinical routine practice both for diagnosis and for some refractive surgeries.