Comparison of anterior segment and lens biometric measurements in patients with cataract

Assessing the Impact of Tropicamide on Anterior Segment Parameters in Diabetic Patients: A Randomized Clinical Trial

INTRODUCTION

Evaluation of anterior segment parameters is crucial in ophthalmic procedures such as intraocular surgeries and contact lens fitting. However, the use of tropicamide in diabetic patients presents challenges due to its potential impact on biometric measurements. This study aims to investigate and compare the effects of 0.5% and 1% tropicamide on anterior segment parameters in diabetic patients.

METHODS

This double-masked randomized clinical trial enrolled 98 patients with diabetes mellitus. Participants were randomly assigned to receive either 0.5% or 1% tropicamide. Anterior segment parameters were measured using Pentacam HR (Oculus Optikgeräte GmbH, Wetzlar, Germany) before and 30 minutes after tropicamide administration. Parameters included anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), keratometry, central corneal thickness (CCT), white-to-white distance (WTW), and pupillary diameter (PD).

RESULTS

Both concentrations of 0.5% and 1% tropicamide induced significant changes in anterior segment parameters. There was a notable increase in PD (2.99 ± 0.62, 3.11 ± 0.55, respectively, both P-values < 0.001), ACD (both 0.10 ± 0.05, both P-values < 0.001), ACV (16.69 ± 9.56, 17.51 ± 9.26, respectively, both P-values < 0.001), and WTW (0.06 ± 0.14, 0.03 ± 0.30, respectively, both P-values < 0.001), along with a decrease in ACA (-3.50 ± 10.65, -3.30 ± 6.87, P-value < 0.001 and P-value=0.001, respectively), and CCT (-6.10 ± 8.06, -6.39 ± 9.97, respectively, both P-values < 0.001) post-dilation. However, no significant changes were observed in keratometry (front Km (-0.03 ± 0.19, -0.04 ± 0.21, respectively), back Km (0.01 ± 0.05, 0.004 ± 0.05, respectively), P-values> 0.05).

CONCLUSION

Both concentrations of tropicamide exhibited comparable effects on anterior segment parameters in diabetic patients. These post-dilation changes should be considered for accurate intraocular lens power calculation and decision-making for cataract, phakic intraocular lens, and refractive surgeries.

The rate of vault changes after ICL V4c implantation and its correlation with anterior segment parameters

Purpose

To investigate the rate of vault changes after implantation of ICL V4c and the correlation with anterior segment parameters.

Methods

A total of 64 eyes were studied from the 37 myopic subjects recruited. CASIA2 was used to record the vault at 1 week, 1 month, 3 months and 6 months after the operation as well as the preoperative anterior segment parameters including pupil diameter, lens vault, anterior chamber depth, anterior chamber width, iris area (IA), iris thickness, angle opening distance, angle recess area, trabecular iris space area, and trabecular iris angle. The rates of vault change in different time intervals were compared and the correlations between the rates and anterior segment parameters were analyzed. P < 0.05 was considered statistically significant.

Results

The rate of vault decrease was -19.53 ± 111.28 μm/month between 1 week and 1 month, -19.90 ± 29.71 μm/month between 1 month and 3 months and -4.25 ± 18.10 μm/month between 3 months and 6 months; hence the rate was shown to slow down significantly from 3 months post-operation (P = 0.024). The average rate of vault changes showed a significant positive correlation with IA (R2 = 0.140, F = 4.980, P = 0.01). No significant correlation was found with other anterior segment parameters (all P > 0.05).

Conclusion

The rate of decreasing vault significantly slowed down from 3 months post-operation. A larger IA may imply a lower decreasing rate of vault change.

Comparison of a New Scheimpflug Camera and Swept-Source Optical Coherence Tomographer for Measurements of Anterior Segment Parameters

INTRODUCTION

This study evaluated the differences and agreement between a new Scheimpflug camera (Scansys) and a swept-source anterior segment optical coherence tomographer (CASIA 2) for measurements of the anterior segment of the eye in normal subjects.

METHODS

This prospective study included 84 eyes from 84 normal adult subjects who underwent three consecutive measurements with the Scansys and the CASIA 2 in random order. The mean keratometry (Km), astigmatism magnitude (AST), J0, and J45 vectors for both anterior and posterior corneal surfaces, central corneal thickness (CCT), thinnest corneal thickness (TCT), and anterior chamber depth (ACD) were obtained by both devices. The difference between these two devices was assessed using paired t test and violin plots. Bland-Altman plots and 95% limits of agreement (LoAs) were used to evaluate agreement.

RESULTS

No statistically significant differences between the two devices were found for the anterior AST, anterior J45, and posterior J45 (P > 0.05). The remaining parameters were statistically significant (P ≤ 0.05), but the differences not clinically significant. The violin plots showed that the distribution and probability density of the measured parameters were similar for both devices. Bland-Altman plots revealed high agreement for the measured parameters between the Scansys and CASIA 2, with narrow 95% LoAs.

CONCLUSIONS

In terms of assessing parameters for the anterior segment, our study indicated that Scansys and CASIA 2 generally showed significant agreement. The two devices used in this study's assessment of all the parameters can be used interchangeably in refractive analysis.

Analysis of temporal changes in thickness from conjunctiva to sclera after plication of the medial rectus muscle measured by anterior segment optical coherence tomography

PURPOSE

We evaluated long-term changes in conjunctival bulge after medial rectus muscle (MR) tightening using the plication method.

STUDY DESIGN

Retrospective and observational.

METHODS

Patients who underwent MR plication for exotropia from December 2016-March 2020 at Okayama University Hospital were included. Thirty two eyes of 27 patients were enrolled. The thickness from the conjunctiva to sclera (TCS) at the limbus and insertion sites were measured using anterior segment optical coherence tomography preoperatively and 1 month, 4 months, and 12 months postoperatively. Correlations between the 1- and 12 month postoperative TCS and amount of MR tightening were analyzed.

RESULTS

Preoperative and 4 month postoperative TCS at the limbus site were not significantly different (P=0.07). The 12 month postoperative TCS at the insertion site was significantly thinner than at 1 month postoperative (P<0.01), although significantly thicker than the preoperative TCS (P<0.01). No significant correlations were found between the amount of MR tightening (in mm) and 1- or 12 month postoperative TCS at the limbus (P=0.62 and P=0.98, respectively) and insertion (P=0.50 and P=0.24, respectively) sites.

CONCLUSION

The TCS at the insertion site peaked at 1 month postoperatively, continued to decrease for longer than 4 months postoperatively, continuing until 12 months postoperatively. The TCS at the insertion site 12 months postoperatively is thicker than preoperatively. The TCS at both the limbus and insertion sites was not related to the amount of medial rectus muscle tightening.

A Comparison Between Ultrasound Pachymetry and CASIA2 (Anterior-Segment Optical Coherence Tomography) in the Measurement of Central Corneal Thickness

Background and objective Due in part to its effect on intraocular pressure (IOP) measurements, the assessment of central corneal thickness (CCT) is recognized as an essential part of the initial glaucoma assessment. The most widely utilized clinical technique to measure CCT is ultrasound pachymetry (USP). In recent years, many dedicated anterior-segment optical coherence tomography scanners (AS-OCTs) have been developed. Previous studies have compared CCT measurements between USP and various AS-OCTs. This study aimed to assess the degree of agreement between USP and CASIA2 (Tomey Corporation, Nagoya, Japan), a second-generation swept-source AS-OCT developed in Japan. Methodology The data on CCT screening measurements of 156 eyes (88 patients) performed over a period of three months, from January to March 2020, on glaucoma patients attending the Royal Hallamshire Hospital (RHH) in Sheffield, UK were collected retrospectively and statistically analyzed. Results The average age of the 88 patients included in the study was 66 years (range: 20-86 years). Our findings show that when compared to CASIA2 measurements, USP measurement of the CCT resulted in significantly thicker values (paired t-test: t=23.15,p<2.2 x 10^-16). The average difference between the two methods was 19.98 ± 10.78 μm. It is hypothesized that this difference may be due in part to inaccurate probe placement during ultrasound probe measurement, resulting in thicker CCT values. Conclusion The observed difference may be clinically significant as it could induce clinical discrepancy in terms of perceived glaucoma risk in patients. Therefore, USP and CASIA2 should not be used interchangeably, and clinicians should take into account the significant difference between these methods.

Swept-source optical coherence tomography and ultrasound biomicroscopy study of anterior segment parameters in primary angle-closure glaucoma

PURPOSE

To evaluate the agreement between swept-source OCT (CASIA2) and UBM in primary angle-closure glaucoma.

METHODS

Eighty eyes of 40 participants diagnosed with primary angle-closure glaucoma were examined. Parameters measured included angle opening distance (AOD), angle recess area (ARA), trabecular iris space area (TISA), trabecular iris angle (TIA), lens vault (LV), anterior chamber depth (ACD), and anterior chamber width (ACW). Angle images of nasal, temporal, superior, and inferior were acquired by the anterior segment mode of CASIA2 and UBM. One-way analysis of variance and paired t-test were used for statistical analysis, and the agreement was analyzed by internal correlation coefficient (ICC) and Bland-Altman method.

RESULTS

One-way ANOVA pairwise comparison showed that CASIA2 or UBM had the narrowest superior chamber angle and the widest temporal chamber angle in patients with primary angle-closure glaucoma. The paired t-test showed that inter-device AOD, TIA, ARA, and TISA of superior chamber angle had significant differences (p < 0.001). There was no significant difference in the measured values of LV, ACD, and ACW (p > 0.05). The agreement of all parameters is good through the Bland-Altman method comparison. ICC result showed moderate agreement in other angle parameters except for superior ARA500 (0.739).

CONCLUSION

In the anterior chamber angle measurement process, we should pay more attention to the superior chamber angle covered by eyelids. Although the agreement is acceptable between CASIA2 and UBM, the measurements could not be considered interchangeable due to the tremendous statistical difference between the two devices.

The Influence of 0.5% Tropicamide on Anterior Segment Parameters With CASIA2 in Emmetropic, Myopic, and Hyperopic Eyes

Aim: To evaluate the effects of 0.5% tropicamide on anterior segment parameters with the CASIA2 imaging device in emmetropic, myopic, and hyperopic eyes.

Methods: In this prospective study, a total of 125 subjects (34 emmetropic subjects, 57 myopic subjects, and 34 hyperopic subjects) at the Shanghai Eye and ENT Hospital of Fudan University were recruited from June 2021 to September 2021. The 0.5% tropicamide solution was used once every 5 min a total of 5 times for cycloplegia. The anterior segment parameters were recorded by CASIA2 before and after cycloplegia. Changes in anterior segment parameters were compared among the three refractive groups.

Results: Crystalline lens rise (CLR) and crystalline lens thickness (CLT) significantly decreased in all three refractive groups after cycloplegia (all p < 0.01). The anterior radius of lens (ARL) and anterior chamber depth (ACD) significantly increased in all three refractive groups after cycloplegia (all p < 0.01). Posterior radius of lens (PRL) significantly increased in hyperopic eyes after cycloplegia (p < 0.01) while it remained unchanged in emmetropic eyes and myopic eyes. Central corneal thickness (CCT), anterior chamber width (ACW), lens decentration (LD), and lens tilt (LT) remained unchanged after cycloplegia in all three refractive groups (all p > 0.05). Changes in CLR, CLT, ARL, PRL, and ACD in hyperopic eyes were greater than those in emmetropic eyes and myopic eyes (all p < 0.05).

Conclusion: Apart from various changes in anterior segment parameters after application by 0.5% tropicamide in all three refractive groups, significant changes in CLR, CLT, ARL, PRL, and ACD in hyperopic eyes should be noted for proper clinical interpretation.

Refractive error characteristics and influence on ocular parameters in patients with unilateral congenital ptosis

Background

The study aimed to investigate the difference in refractive status and ocular parameters between ptotic and fellow eyes in patients with unilateral congenital ptosis.

Methods

Thirty patients (53% males, age 22.00 ± 11.41 years) with unilateral congenital ptosis diagnosed and treated at the First Affiliated Hospital of Sun-yat Sen University were enrolled and underwent detailed refractive examinations from March 2019 to February 2022. Ocular biometric measurements were performed by an IOL Master 700 biometer. The differences in refractive error characteristics, best-corrected visual acuity (BCVA), and ocular parameters including axial length (AL), central corneal thickness (CCT), aqueous depth (AQD), anterior chamber depth (ACD), lens thickness (LT), and keratometry values between ptotic and fellow eyes were analysed.

Results

A lower BCVA (logMAR, median (IQR), 0.00 (− 0.13,0.00), P = 0.009) and a higher incidence of amblyopia (n (%), 7(23%), P = 0.016) were observed in ptotic eyes. The CCT of ptotic eyes was greater than that of fellow eyes (mean ± SD, 539.83 ± 26.73 μm, P < 0.001). The keratometry values at the flat axis (K1) and mean corneal power (Km) were smaller in ptotic eyes (mean ± SD, 42.11 ± 1.49 D, 42.68 ± 1.52 D, respectively, both P = 0.001). There was no significant difference in AL between ptotic and fellow eyes.

Conclusions

Congenital ptosis influences ocular parameters, mainly causing a thicker and flatter cornea. Patients with unilateral congenital ptosis might have lower BCVA in the ptotic eyes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02511-x.

Detection of Anterior Hyaloid Membrane Detachment Using Deep-Range Anterior Segment Optical Coherence Tomography

The visibility of anterior hyaloid membrane (AHM) and Berger’s space in phakic eyes was investigated. In 624 eyes of 624 patients, the retrolental space was scanned with the deep-range anterior segment optical coherence tomography (AS-OCT, CASIA2, Tomey). Subgroup analysis was conducted in 223 eyes undergoing cataract surgery. The logistic regression analysis using the backward-elimination method was performed to evaluate the influence of various factors on the visibility of AHM (dependent variable). Explanatory variables included age, gender, axial length, corneal power, corneal cylinder, and the Co III gradings. Intrarater repeatability for AHM visibility was excellent with the prevalence-adjusted bias-adjusted kappa (κ coefficient) of 0.90. AHM was observed in 43 eyes (6.9%). The patients with visible AHM (68.1 ± 8.8 years) were significantly older than those without visible AHM (52.6 ± 25.6 years) (p < 0.001). The logistic regression analysis in the cataract surgery subgroup revealed that axial length (p = 0.030) and corneal power (p = 0.043) were significantly associated with AHM visibility. The mean absolute refractive error from target was significantly larger in eyes with visible AHM (0.670 ± 0.384 D) than with invisible AHM (0.494 ± 0.412 D) (p = 0.037). The postoperative refractive prediction was less accurate in eyes with visible AHM, but no significant tendency existed in terms of myopic or hyperopic shifts.

Correlation Between Degree of Lens Opacity and the Phacoemulsification Energy Parameters Using Different Imaging Methods in Age-Related Cataract

Purpose

To compare the correlation between degree of lens opacity and the phacoemulsification energy parameter in patients with age-related cataract as determined by slit lamp, 25-MHz ultrasound biomicroscopy (UBM), and Scheimpflug imaging (Pentacam) and to evaluate the application of these three methods to measuring lens opacification.

Methods

This observational study was conducted in 319 patients (381 eyes) with different types of age-related cataract. The average age of patients was 67.3 ± 11.4 years. The degree of lens opacity acquired by slit lamp, 25-MHz UBM, and Pentacam was determined by the Lens Opacity Classification System III (LOCSIII), pixel units calculated by ImageJ, and lens density, respectively. We primarily analyzed and compared the correlation between lens opacity and the cumulative dissipated energy (CDE) values of phacoemulsification.

Results

Cortical, nuclear, and posterior subcapsular (PSC) cataracts were evaluated as follows: LOCSIII grades 3.31 ± 1.42, 3.29 ± 1.49, and 0.91 ± 0.83; pixel units 120.91 ± 22.8, 93.2 ± 15.9, and 99.7 ± 13.0; and lens density 51.8 ± 31.2, 21.2 ± 6.10, and 53.3 ± 35.3, respectively. The CDE values were 12.1 ± 12.4, 13.5 ± 9.11, and 3.93 ± 1.96. In cortical cataract, there was a linear correlation among LOCSIII, pixel units, and CDE value (r = 0.560, r = 0.832, and r = 0.582, respectively; both P < 0.05), but lens density had no correlation with other parameters. In nuclear cataract, there was a linear correlation among LOCSIII, lens density, and CDE value (r = 0.747, r = 0.865, and r = 0.906, respectively; both P < 0.05), but pixel units had no correlation with other parameters. In PSC, only pixel units and LOCSIII showed a correlation.

Conclusions

The various imaging methods offered different advantages in terms of determining lens opacity, a feature related to types of age-related cataracts. Choosing the most suitable imaging method to evaluate lens opacification based on the type of age-related cataract is important for accurately predicting the phacoemulsification parameters for cataract surgery.

Translational Relevance

Determining the appropriate phacoemulsification strategy depends on quantitative analysis of the degree of lens opacity to reduce intraoperative and postoperative complications and to obtain the optimal postoperative visual outcome.

In-vivo Lens Biometry Using the Novel Ultrasound Biomicroscopy

Background and Aim

To assess the reproducibility of the novel ultrasound biomicroscopy, Insight 100 and its agreement with a swept-source optical coherence tomography, CASIA2.

Methods

A total of 96 volunteers (96 eyes) were enrolled. The radius of anterior lens curvature (RAL), the radius of posterior lens curvature (RPL), lens thickness (LT), and lens diameter (LD) were measured with Insight 100 and CASIA2. A semiautomated software was used to adjust the measurement of LT (LT_S) and LD (LD_S) by Insight 100. Intraobserver and interobserver reproducibility of Insight 100 measurements, and the agreement of results from Insight 100 and CASIA2 were assessed with 95% limit of agreement (LoA), intraclass correlation coefficient (ICC), Pearson correlation, and linear regression.

Results

For Insight 100 measurements, the intraobserver ICCs of RAL, RPL, LT_S, and LD_S measurement were 0.996, 0.973, 0.936, and 0.889, and the interobserver ICCs were 0.987, 0.890, 0.974, and 0.816, respectively. There was an excellent correlation in LT measurements (R = 0.961, P < 0.001) but poor agreements in other parameters between the two devices. The LD measurements tended to be larger (95% CI: 0.768–0.928) in CASIA2 when compared with Insight 100.

Conclusion

Insight 100 could obtain highly repeatable lens biometry in vivo. With better signal penetration, it shows promising potential in future clinical applications.

Agreement of Anterior Segment Parameter Measurements With CASIA 2 and IOLMaster 700

Purpose

To compare the difference and agreement in central corneal thickness (CCT), keratometry (K), anterior chamber depth (ACD), aqueous depth (AQD), and lens thickness (LT) measured with CASIA 2 and IOLMaster 700 in patients with cataract.

Methods

A total of 81 patients with cataract (81 eyes) scheduled for phacoemulsification were prospectively collected from March to May, 2020 in the cataract department of Zhongshan Ophthalmic Center, Sun Yat-sen University, including 43 males and 38 females with age of 61.5 ± 10.6 years. CCT, anterior Kf, anterior Ks, real Kf, real Ks, ACD, AQD, and LT were measured with CASIA 2 and IOLMaster 700. Paired t-test, intraclass correlation coefficients (ICCs), 95% limit of agreement (95% LoA), and Bland-Altman plots were performed and used to analyze the difference and agreement between the two devices.

Results

There was no statistically significant difference in anterior K measurement with the CASIA 2 (44.3 ± 1.66 mm) and IOLMaster 700 (44.31 ± 1.67 mm, P = 0.483). Differences among the CCT, anterior Kf, real Kf, real Ks, ACD, AQD, and LT measured by the two instruments were statistically significant (P &lt; 0.001). The ICCs of CCT, anterior Kf, anterior Ks, real Kf, real Ks, ACD, AQD, and LT measurements between the two devices were 0.892, 0.991, 0.991, 0.827, 0.817, 0.937, 0.926, and 0.997, respectively. The 95% LoA between CASIA 2 and IOLMaster 700 was −30.06 to 0.43 μm for CCT, −0.3 to 0.48 D for anterior Kf, −0.46 to −0.43 D for anterior Ks, −1.49 to −0.49 D for real Kf, −1.62 to −0.49 D for Real Ks, −0.03 to 0.24 mm for ACD, 0.04 to 0.25 mm for AQD, and −0.06 to 0.09 mm for LT.

Conclusion

Anterior Kf, anterior Ks, ACD, AQD, and LT have excellent agreement between the two devices. CCT, real Kf, and real Ks have moderate agreement between the two devices. It is recommended to use anterior Kf, anterior Ks, ACD, AQD, and LT interchangeably between CASIA 2 and IOLMaster 700.

Analysis of Lens Thickness Distribution Based on Swept-Source Optical Coherence Tomography (SS-OCT)

Objective

This study aimed to analyze the distribution of lens thickness (LT) and its associations in age-related cataract patients based on swept-source optical coherence tomography (SS-OCT).

Methods

This cross-sectional study included 59,726 Chinese age-related cataract patients. Only right-eye data were included in the study. Repeated measures of ocular parameters were performed using an IOL Master 700 device. The distributions of ocular biometric data including anterior chamber depth (ACD), LT, axial length (AL), central corneal thickness (CCT), white-to-white (WTW), and mean keratometry (MK) and their associations with age were assessed. The anterior segment (AS) was measured as the sum of CCT, ACD, and LT, while the vitreous chamber depth (VCD) was calculated as the difference between AL and AS. The values of LT : AL, AS : AL, and VCD : AL in different AL groups and their changes are the main outcome measures used to observe the proportion of the anterior and posterior segments of the eye.

Results

Biometric data were available for 59,726 individuals. The mean age was 68.81 years (range = 40–100); 40.62% were male and 59.38% were female. Mean anterior chamber depth (ACD) was 3.02 ± 0.44 mm, mean LT was 4.51 ± 0.44 mm, mean axial length (AL) was 23.89 ± 1.92 mm, mean central corneal thickness (CCT) was 0.53 ± 0.03 mm, mean white-to-white (WTW) was 11.64 ± 0.44 mm, and mean keratometry (MK) was 44.27 ± 1.65 diopter. Female patients had shorter AL, shallower ACD, smaller CCT and WTW, decreased LT, and steeper corneas (p < 0.005). ACD revealed the strongest negative correlation (p ≤ 0.001, r = –0.682) with LT. Age (p ≤ 0.001, r = 0.348) showed a moderate positive correlation, whereas MK (p ＜ 0.05, r = 0.011), CCT (p ≤ 0.001, r = 0.041) had a weak positive correlation and WTW (p ≤ 0.001, r = –0.034) had a weak negative correlation with LT. A nonlinear correlation was found between LT and AL. LT increased with age in both males and females. LT changed variably in eyes with AL less than 27 mm, LT decreased as AL increased, then LT gradually increased as AL increased in extremely long and extra-long eyes (p ≤ 0.001). LT : AL and AS : AL decreased as AL increased, VCD : AL gradually increased as AL increased in highly myopic eyes, and VCD : AL increased by about 0.01 for every 1 mm increase in AL.

Conclusions

Among Chinese age-related cataract patients, we found LT to have the strongest relation with ACD. The lens was thicker in elderly patients and women. The correlation between LT and AL is not a simple negative correlation; with the increase of age, LT decreases first and then increases. The proportion of VCD is constantly rising with the elongation of AL.

Effect of age and cycloplegia on the morphology of the human crystalline lens: swept-source OCT study

PURPOSE

To evaluate the effect of age and cycloplegia on the morphology of the crystalline lens using a swept-source optical coherence tomography (SS-OCT) system.

SETTING

Hospital.

DESIGN

Prospective cross-sectional study.

METHODS

The parameters including anterior chamber depth (ACD), the radii of curvature of the anterior and posterior surface of the crystalline lens (ALR and PLR), lens thickness (LT), lens equatorial diameter (LED), and lens vault (LV) were quantified by the SS-OCT before and after cycloplegia. The paired t test was used to compare the parameters before and after cycloplegia. A multivariate linear regression model was built to analyze the association between the parameters/cycloplegia-induced changes and age, while adjusting for the effect of axial length, refractive status, and sex.

RESULTS

76 individuals (age range, 18 to 86 years) were recruited. The ALR and ACD were negatively correlated with age (P ≤ .002), and the LT, LV, and LED were positively correlated with age (P ≤ .004). In participants younger than 60 years, the ALR and ACD significantly increased, whereas the LV and LT significantly decreased after cycloplegia (all P < .001). With aging, cycloplegia-induced differences of ALR (P = .001) and ACD (P = .014) significantly decreased, and of LT (P < .001), LT (P < .001), and LV (P = .001) significantly increased.

CONCLUSIONS

The crystalline lens morphology measured by the SS-OCT revealed steepening anterior surface and increasing equatorial diameter with age. Cycloplegia caused a significant change of anterior surface morphology in participants younger than 60 years, and this effect diminished with age.

Lens Biometry in Congenital Lens Deformities: A Swept-Source Anterior Segment OCT Analysis

Aims: To investigate the lens biometric parameters in congenital lens deformities, using a novel technique of swept-source anterior segment optical coherence tomography (SS-ASOCT).

Methods: This prospective study included patients with microspherophakia (MSP), coloboma lentis (CL), and posterior lenticonus (PL). For this cohort, 360-degree high-resolution lens images were obtained using the latest SS-ASOCT (CASIA2, Tomey Corp, Nagoya, Japan). The lens biometric parameters were calculated by the CASIA2 built-in software for anterior lens radius (ALR), posterior lens radius (PLR), anteroposterior distance (APD), anterior chamber depth (ACD), equatorial diameter (Eq Dia), rear projection length (RPL), and maximum diameter of the lesion (MDL).

Results: This study included two eyes each with MSP and CL and one eye with PL. The lens of MSP was spherical and posteriorly dislocated, with decreased ALR and PLR, Eq Dia, but increased APD. In patients with CL, the coloboma was isolated, bilateral, inferior, and located toward the maldeveloped ciliary body. High astigmatism was mainly lenticular, and this was calculated by the ALR and PLR. Regarding the site of coloboma, a significant decrease in ALR was observed, while the PLR and APD were not affected. The PL eyes had a cone-shaped protrusion of the posterior lens surface with a subtle cataractous region around the apex. An extremely high posterior surface curvature was observed with a mean PLR of 1.67 mm. The RPL and MDL were about 1.80 and 0.4 mm, respectively, which were homogenous at different sections.

Conclusions: The CASIA2 is a valuable option for in vivo crystalline lens measurement for congenital lens deformities, enabling the accurate diagnosis and providing illuminating insights into the pathogenesis of MSP, CL, and PL

Stability of Intraocular Lens With Different Haptic Design: A Swept-Source Optical Coherence Tomography Study

Purpose: To investigate the stability of intraocular lens (IOLs) with different haptics by swept-source anterior-segment optical coherence tomography (AS-OCT).

Methods: Sixty-eight eyes from 55 patients received the implantation of Rayner 920H (Closed C-loop Group), Zeiss 509M (Plate Group) or Lenstec SOFTEC HD (C-loop Group) IOLs. The tilt and decentration of IOLs were evaluated using AS-OCT at least 1 month postoperatively.

Results: Mean decentration and tilt of IOLs were 0.18 ± 0.12 mm (range 0.02 to 0.59 mm) and 5.63 ± 1.65° (range 2.2 to 9.6°) respectively. Decentration was significantly smaller in the plate haptic group (0.12 ± 0.06 mm) as compared to the C-loop group (0.22 ± 0.13 mm, P = 0.02). The tilt of IOL was also significantly smaller in the plate haptic group (4.96 ± 0.89°) as compared to the C-loop group (6.28 ± 1.83°, P = 0.01). There was marginal difference between the Closed C-loop group (5.52 ± 1.74°) and C-loop group (6.28 ± 1.83°, P = 0.07).

Conclusions: The Plate-haptic IOLs should have better stability for the decentration and tilt than the C-loop design IOLs.

Inspection of the lens thickness with preoperative biometric measurements prevents an erroneous interpretation of posterior capsule during FLACS

Optical opacity reduces quality of biometry images, making it potentially difficult to find the correct location for irradiation during femtosecond laser-assisted cataract surgery (FLACS). After experiencing a case of posterior capsule (PC) rupture because of optical opacity, we started lens thickness (LT) inspection, which indicates comparison of between intra- and pre-operatively measured LT. We retrospectively investigated the effectiveness of the LT inspection. One observer reviewed all FLACS treatment summaries for 3 years by CATALYS in the Jikei University Hospital, Tokyo. Based on the lines defining the PC on intraoperative OCT images, all cases were classified into three groups: undescribed, appropriate and inappropriate PC. Among the 1070 cases, 1047 cases had appropriate PC. In 19 cases, the PC line was undescribed because of dense cataract. Among 474 cases with no inspection, 4 cases had an inappropriate PC. Whereas, in 596 cases with the LT inspection, there was no case of an inappropriate PC. LT inspection significantly reduced the cases with inappropriate PC. The safety margins normally work to prevent severe complications. However, rare outlier cases had a high risk of severe complications. We propose LT inspection could be the most practical and convenient way for safety surgery.

Three-dimensional measurement for spherical and nonspherical shapes of contact lenses

In recent years, with the development of precise lathe-cutting equipment, special shaped contact lenses (CL) have been crafted. However, while it is possible to manufacture such a lens, its shape evaluation has not been well-established. We conducted a basic optical experiment using special lenses to measure a spherical lens and nonspherical mold. As the measurement sample, a metal ball, special CL, and a toric-shaped mold were adopted. In order to accurately measure those real shapes, we proposed an algorithm in which the probe light is vertically incident to the sample surface within a numerical aperture of the optical probe. For this algorithm, we developed the specialized time-domain optical coherence tomography (TD-OCT), which was designed to conduct circular scanning while maintaining vertical incidence by driving a two-axis (vertical and horizontal) micro-electromechanical system mirror with a phase difference of 90°. The shape, thickness distribution, and curvature radii of both front and back surfaces of a CL were estimated with this OCT signal analysis and sphere fitting. The shape and curvature radius were evaluated by using the simulated data under the same experimental conditions. They were sufficiently accurate based on the resolution of this OCT. Also, a toric-shaped mold was evaluated by comparing the relationship between each coordinate and intensity of the interference signal. As a result, it is confirmed that the experimental result and the simulated matched well.

Subtle changes of the crystalline lens after cycloplegia: a retrospective study

BACKGROUND

The purpose of this study was to evaluate the shape of the crystalline lens in terms of biometry and diopters before and after cycloplegia using the CASIA2 swept-source (SS) optical coherence tomography (OCT) system on the anterior segment.

METHODS

This was a retrospective study. Children and adolescents (26 males and 29 females, aged 4-21 years) with simple ametropia were selected for optometry and CASIA2 imaging at 2 separate visits before and after cycloplegia. Diopter values were derived from the spherical power (S) obtained by optometry. Biometric parameters of the crystalline lens, including the anterior chamber depth (ACD), anterior and posterior curvature of the lens (ACL and PCL), lens thickness (LTH), lens decentration (LD), lens tilt (LT), and equivalent diameter of the lens (LED), were measured by the CASIA2 system. The differences in these parameters after compared with before cycloplegia were determined, and their relationships were analyzed.

RESULTS

Fifty-five participants (106 eyes) were initially enrolled. There was a significant difference (P < 0.05) in the S (t=-7.026, P < 0.001), ACD (t=-8.796, P < 0.001), ACL (t=-13.263, P < 0.001) and LTH (t = 7.363, P < 0.001) after compared with before cycloplegia. The change in the PCL (t = 1.557, P = 0.122), LD (t = 0.876, P = 0.383), LT (t = 0.440, P = 0.661) and LED (t=-0.351, P = 0.726) was not statistically significant (P > 0.05). There was a significant (P < 0.05) correlation of the change in the S with that in the ACL (r = 0.466, P < 0.001), LTH (r=-0.592, P < 0.001), and LED (r = 0.223, P = 0.021) but not the PCL (r = 0.19, P = 0.051), LD (r=-0.048, P = 0.0628) or LT (r=-0.022, P = 0.822). Furthermore, the change in the ACD was closely related to the change in crystalline morphology. However, in children and adolescents, we found that the change in crystalline morphology was unrelated to age.

CONCLUSIONS

Changes in lens morphology after compared with before cycloplegia are mainly related to the ACL and LTH, but there is no difference in the PCL, LD, LT, or LED. In the adolescent population, change in the S is related to change in the ACL, LED and LTH. However, age is unrelated to the shape and tendency of the crystalline lens. Further research is required to determine whether the same conclusion applies to different age groups and different refractive states (myopia, hyperopia, emmetropia) .

Age-related Changes in Crystalline Lens Tilt and Decentration: A Swept-source Optical Coherence Tomography Study

Purpose

To investigate the age-related tilt and decentration of crystalline lenses using a swept-source optical coherence tomography biometer (Casia 2, TOMEY, Japan).

Setting

Eye Hospital, Wenzhou Medical University, Wenzhou, Zhejiang, China.

Design

Cross-sectional study.

Methods

The direction and magnitude of the crystalline lens were evaluated in 230 participants with ages ranging from 7 to 90 years using swept-source optical coherence tomography. The participants were divided into four age groups, and the differences among the groups were analyzed. Multiple linear regression was used to investigate the main factors influencing crystalline lens tilt and decentration.

Results

The natural crystalline lens tilted towards the inferotemporal direction with a mean magnitude of 4.3+/-1.5[degrees] (range 0.7-8.95[degrees]). The average decentration toward the superotemporal direction was 0.17+/-0.12 mm (range 0.03-1.15 mm). There was mirror symmetry between the right and left eyes. There were significant differences in the crystalline lens tilt and decentration among the age groups. Multiple linear regression showed that changes in crystalline lens tilt depended on angle [alpha] (p<.01) and anterior chamber depth (ACD; P=.008), while crystalline lens decentration depended on angle [kappa] (P=.003), age (P<.01), and angle [alpha] (P=.002).

Conclusions

Although there was a significant difference in crystalline lens tilt and decentration among age groups, the variation in the crystalline lens position was partially affected by age. The crystalline lens tilt was greater in eyes with wider angle [alpha] and shallower ACD, while crystalline lens decentration was greater in younger eyes with wider angles [kappa] and [alpha].

Comparison of ocular biometric measurements in patients with cataract using three swept-source optical coherence tomography devices

BACKGROUND

Precise measurement of ocular biometry is critical for determining intraocular lens power. Newly developed swept-source optical coherence tomography (SS-OCT) - based ocular biometric devices, ANTERION and CASIA2 provide ocular biometric measurements as IOLMaster 700. This study aimed to assess agreement between three devices.

METHODS

This retrospective comparative study includes patients with cataract who underwent ocular biometric measurements with three devices, ANTERION, CASIA2, and IOLMaster 700, at Seoul National University Hospital, in April 2020. Anterior keratometry, total keratometry, central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), and axial length (AL) were the main parameters for the comparison. To assess the agreement between the devices, intraclass coefficient (ICC) and Bland-Altman analysis with 95% limits of agreement (LoA) were used.

RESULTS

A total of 47 eyes of 29 patients were measured with three devices. Average anterior keratometry showed excellent agreement (ICC ≥ 0.989), and the mean difference was less than 0.1 D. However, the ICC of the total average keratometry ranged from 0.808 to 0.952, and the difference was more than 0.43 D. The AL measured by ANTERION and IOLMaster 700 showed excellent agreement (ICC = 0.999), and the mean difference was 0.005 mm. The ANTERION and IOLMaster 700 did not obtain AL in six (12.8%) and three (6.4%) cases, respectively (P = 0.001 by Fisher's exact test). The CCT, ACD, and LT also showed excellent agreement (ICC > 0.9).

CONCLUSIONS

The new SS-OCT-based devices, ANTERION, and CASIA2 showed a good agreement with IOLMaster 700 in measuring ocular biometry except for the total keratometry. The AL of ANTERION and IOLMaster 700 showed excellent agreement.

Repeatability of automated measurements by a new anterior segment optical coherence tomographer and biometer and agreement with standard devices

We assess repeatability of automatic measurements of a new anterior segment optical coherence tomographer and biometer (ANTERION) and their agreement with those provided by an anterior segment-optical coherence tomography device combined with Placido-disk corneal topography (MS-39) and a validated optical biometer (IOLMaster 500). A consecutive series of patients underwent three measurements with ANTERION and one with MS-39. A subgroup of patients underwent biometry also with IOLMaster 500. Repeatability was assessed by means of within-subject standard deviation, coefficient of variation (COV), and intraclass correlation coefficient (ICC). Agreement was investigated with the 95% limits of agreement. Paired t-test and Wilcoxon matched-pairs test were performed to compare the measurements of the different devices. Repeatability of ANTERION measurements was high, with ICC > 0.98 for all parameters except astigmatism (0.963); all parameters apart from those related to astigmatism revealed a COV < 1%. Repeatability of astigmatism improved when only eyes whose keratometric astigmatism was higher than 1.0 D were investigated. Most measurements by ANTERION and MS-39 showed good agreement. No significant differences were found between measurements by ANTERION and IOLMaster, but for corneal diameter. ANTERION revealed high repeatability of automatic measurements and good agreement with both MS-39 and IOLMaster for most parameters.

Agreement between anterior segment parameters obtained by a new ultrasound biomicroscopy and a swept-source fourier-domain anterior segment optical coherence tomography

Purpose: To evaluate the agreement between anew UBM and an SS-OCT. Methods: The scans of the right eye of each volunteer were obtained using the two devices. Data were fitted and recorded including: central corneal thickness (CCT), aqueous depth (AQD) (the distance from endothelium to lens), angle-to-angle distance (ATA), lens thickness (LT), diameter of the lens in the horizontal direction (LDia^angle: distance between the sharp angles on both sides of the lens, LDia^arc: distance between the vertex of the circular arcs on both sides of the lens), anterior and posterior corneal radius (Rf and Rb). Results: 25 eyes were included in this study. It could be seen that the differences in CCT, LDia^angle, Rf measured by the two instruments were not statistically significant. Bland-Altman analysis plots of CCT, LDia^angle and Rf showed mean differences of 0.2 µm, 0.01mm and 0.0mm for the 2 devices, respectively. Conclusion: The values of CCT, LDia^angle and Rf obtained via two instruments were not clinically interchangeable and the AQD, ATA, LT, and Rb have poor agreement affected by accommodation. We can estimate the real lens diameter by subtracting 0.61 ± 0.43mm when the lens diameter can only be simulated with SS-OCT.

Comparison of postoperative anterior segment changes associated with pars plana vitrectomy with and without vitreous base shaving

AIM

To compare changes in anterior segment topography and axial length (AL) evaluated with Pentacam and IOL Master after pars plana vitrectomy (PPV) performed with and without vitreous base shaving.

METHODS

This prospective study included patients who underwent PPV or phacoemulsification+PPV (Phaco+PPV) for various indications. Patients who underwent total posterior hyaloid detachment and excessive vitreous base shaving with scleral indentation were referred to as complete PPV (c-PPV). The patients whom posterior hyaloid was separated as far as the posterior arcades and vitreous base shaving with scleral depression was not performed were classified as the partial PPV (p-PPV) group. All patients underwent detailed ophthalmologic examinations preoperatively and 1wk, 1, and 3mo postoperatively. Changes in the anterior chamber depth (ACD), anterior chamber volume (ACV), iridocorneal angle (ICA), central corneal thickness (CCT), and keratometric measurements (K₁ and K₂) were evaluated with Pentacam HR. Changes in the AL measurements were analyzed with IOL Master.

RESULTS

A significant increase in ACD was observed in c-PPV cases (P=0.02), but this increase was not significant in the p-PPV group (P=0.053). In contrast, ICA increased significantly in the c-PPV group (P=0.02) but decreased in the p-PPV group (P=0.09). BCVA was significantly improved in the c-PPV group from week 1 (P<0.001) while the increase in the p-PPV group reached significance at 3mo (P=0.035). CCT increased in the first week and later returned to baseline in both groups. No significant differences in the other parameters were observed between the groups, and there were no significant changes in intraocular pressure, ACV, AL, K₁ or K₂ values (P>0.05 for all).

CONCLUSION

Incomplete posterior hyaloid excision and not removing the vitreous base in PPV surgeries may create a more stable anterior chamber, thus preventing the downward movement of the lens-iris diaphragm, and may cause ciliary body retraction, thereby reducing ICA. Awareness of these effects can provide some amount of guidance to physicians in selecting the appropriate PPV procedure and preempting surgical complications.

Measurement algorithm for real front and back curved surfaces of contact lenses

The optical measurement algorithm for the real front and back surfaces of contact lenses from their center to periphery accurately and simultaneously is proposed. It is an algorithm that makes light incident vertically along the curved surfaces of contact lenses under the condition that the difference of curvature radii between the front and back surfaces is small enough within the NA of the optical probe. For this purpose, we adopted time-domain optical coherence tomography (OCT) with translation and rotation mechanisms. The shape, thickness distribution, and curvature radii of both surfaces were estimated with OCT signal analysis and circular approximation. The measured results were compared with the designed values and the measured data from a conventional shape measurement device. The curved shape of both surfaces and thickness were well matched with the designed values from lens center to periphery. In a curvature radius of the front surface, there was a proportional bias with a limit of agreement of -0.77% to -2.09%, and the correlation coefficient was 0.57. On the back surface, there was no systematic bias, and minimal detectable change was 0.178 mm, in a range of 95% confidential interval. The proposed algorithm well visualized the real shape and optical characteristics of the contact lens with enough accuracy to the design.

Comparison of Anterior Ocular Biometric Measurements Using Swept-Source and Time-Domain Optical Coherence Tomography

Purpose

To compare central corneal thickness (CCT), aqueous depth (AQD), and anterior chamber depth (ACD) measurements using the swept-source (CASIA SS-1000, Tomey, Japan) and time-domain (Visante, Carl Zeiss Meditec, USA) anterior segment optical coherence tomographers (OCT) in normal eyes.

Methods

Sixty-eight eyes of 68 subjects were included. Three consecutive scans of each subject were obtained using both devices in a random order by one experienced operator. Standard deviation (S _w), coefficient of repeatability (CoR), coefficients of variation (CoV), and intraclass correlation coefficients (ICC) were used to evaluate the intraoperator repeatability. Agreement was assessed using the Bland-Altman plots and 95% limits of agreement (LoA).

Results

All measurements of the swept-source OCT (SS-OCT) and time-domain OCT (TD-OCT) showed high repeatability with low CoR (CCT: 2.34 μm and 6.16 μm; AQD: 0.05 mm and 0.09 mm; ACD: 0.06 mm and 0.09 mm), low CoV (CCT: 0.16% and 0.42%; AQD: 0.61% and 0.97%; ACD: 0.53% and 0.83%), and high ICC (>0.98). The mean CCT with SS-OCT was slightly thicker than the results with TD-OCT (difference = 4.55 ± 2.62 μm, P < 0.001). There was no statistically significant difference in AQD or ACD measurements between the two devices (0.01 ± 0.05 mm, P=0.111; 0.02 ± 0.05 mm, P=0.022, respectively). The 95% LoA between the SS-OCT and TD-OCT were -0.59 to 9.69 μm for CCT, -0.10 to 0.12 mm for AQD, and -0.09 to 0.12 mm for ACD.

Conclusions

High levels of repeatability and agreement were found between the two devices for all three parameters, suggesting interchangeability. SS-OCT demonstrated superior repeatability compared with TD-OCT.

Comparison of a new anterior segment optical coherence tomography and Oculus Pentacam for measurement of anterior chamber depth and corneal thickness

Background

Accurate measurements of anterior chamber depth (ACD) and regional corneal thickness are especially important for the diagnosis and treatment of many ocular disease. This study aimed to evaluate the repeatability and reliability of a new swept source anterior segment optical coherence tomography (AS-OCT) and its agreement with Oculus Pentacam for measurements of ACD and corneal thickness (CT).

Methods

The central corneal thickness (CCT), superior corneal thickness (SCT), inferior corneal thickness (ICT), nasal corneal thickness (NCT), temporal corneal thickness (TCT) and ACD of the right eye from forty-nine adults aged 18 to 36 years (24.78±4.36 years old) were measured with Pentacam and AS-OCT (CASIA2). All subjects were measured twice with each device. The repeatability was determined using the coefficient of repeatability (COR), the relative COR and the limits of agreement (LOA). Bland-Altman plot was also used for evaluating the agreement between parameters from the two devices.

Results

For the repeatability of CASIA2, the COR of the two measurements of ACD, CCT, SCT, ICT, NCT and TCT was 0.31 mm, 18.58, 25.83, 28.32, 26.71 and 22.09 µm respectively. There were no statistically significant differences between the CT and ACD measurements by CASIA2 (P>0.05). For measurements with Pentacam and CASIA2, the COR of ACD, CCT, SCT, NCT, ICT and TCT was 0.294 mm, 13.10, 51.57, 48.06, 56.21 and 47.69 µm respectively. No significant differences were found between the values measured by CAISA2 and Pentacam for CT and ACD (P>0.05). The Bland-Altman analysis also suggested high consistency between measurements obtained by Pentacam and CASIA2.

Conclusions

Our results suggest that Pentacam and CASIA2 have good agreement in CT and ACD measurements. The two devices can be considered interchangeable for these parameters' measurements in healthy subjects when monitoring corneal conditions or planning ocular surgery. However, subtle differences between CASIA2 and Pentacam should also be kept in mind for certain specific clinical or research purposes.

Development of a new intraocular lens power calculation method based on lens position estimated with optical coherence tomography

A new method is developed and validated for intraocular lens (IOL) power calculation based on paraxial ray tracing of the postoperative IOL positions, which are obtained with the use of anterior segment optical coherence tomography. Of the 474 eyes studied, 137 and 337 were grouped into training and validation sets, respectively. The positions of the implanted IOLs of the training datasets were characterized with multiple linear regression analyses one month after the operations. A new regression formula was developed to predict the postoperative anterior chamber depth with the use of the stepwise analysis results. In the validation dataset, postoperative refractive values were calculated according to the paraxial ray tracing of the cornea and lens based on the assumption of finite structural thicknesses with separate surface curvatures. The predicted refraction error was calculated as the difference of the expected postoperative refraction from the spherical-equivalent objective refraction values. The percentage error (within ±0.50 diopters) of the new formula was 84.3%. This was not significantly correlated to the axial length or keratometry. The developed formula yielded excellent postoperative refraction predictions and could be applicable to eyes with abnormal proportions, such as steep or flat corneal curvatures and short and long axial lengths.

Comparison of radius of anterior lens surface curvature measurements in vivo using the anterior segment optical coherence tomography and Scheimpflug imaging

Background

To assess the radius of anterior lens surface curvature (RAL) measurements with anterior segment optical coherence tomography (AS-OCT) in comparison with Scheimpflug imaging.

Methods

This prospective, cross-sectional study was carried out at Zhongshan Ophthalmic Center, Guangzhou, China. We enrolled 59 eyes, including 30 eyes from 30 cataractous volunteers (59 to 87 years) and 29 eyes from 29 young participants (19 to 49 years). After mydriasis, the RAL was measured automatically by the built-in software in the AS-OCT (CASIA 2). The Scheimpflug images were measured with the build-in caliper tool of the Scheimpflug camera (Pentacam), and RAL were further calculated with the principle of best-fitted circle. Intraobserver and interobserver reproducibility of RAL measurement using Scheimpflug camera were evaluated with limit of agreement (LoA) and intraclass correlation coefficient (ICC). Consistency between RAL measurement of Scheimpflug camera and AS-OCT were assessed with LoA, correlation analysis and linear regression.

Results

For all subjects, intraobserver (LoA: −0.25 to 0.23 mm, ICC: 0.996) and interobserver reproducibility (LoA: −0.85 to 0.92 mm, ICC: 0.947) of RAL were good using Scheimpflug imaging. Both AS-OCT and Scheimpflug imaging found that the age-related cataract participants had smaller RAL (P=0.010, P=0.001 respectively). LoA of RAL measurement between AS-OCT and Scheimpflug imaging was −3.83 to −0.79 mm, and the Pearson correlation efficient was 0.909 (P<0.001). The RAL values measured by AS-OCT were significantly greater than that by Scheimpflug camera with a mean difference of 2.31 mm for all participants (P<0.001). The RAL measurement could be converted using the equation: Y_{CASIA 2} =1.155 × X_Pentacam + 1.060.

Conclusions

Both Scheimpflug camera system with internal caliper tool and the AS-OCT are fast and non-contact tools that could measure RAL successfully. The two measurement results are highly correlated and interchangeable through linear regression equation.