scholarly journals Optical Coherence Tomography Reveals Sigmoidal Crystalline Lens Changes during Accommodation

Vision ◽  
2018 ◽  
Vol 2 (3) ◽  
pp. 33
Author(s):  
George Gibson ◽  
Fiona Cruickshank ◽  
James Wolffsohn ◽  
Leon Davies
Keyword(s):  
Optical Coherence Tomography ◽  
Refractive Index ◽  
Contact Lenses ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Crystalline Lens ◽  
Optical Coherence ◽  
Accommodative Response ◽  
Schematic Eye ◽  
Lens Surface

This study aimed to quantify biometric modifications of the anterior segment (AS) during accommodation and to compare them against changes in both accommodative demand and response. Thirty adults, aged 18–25 years were rendered functionally emmetropic with contact lenses. AS optical coherence tomography (AS-OCT) images were captured along the 180° meridian (Visante, Zeiss Meditec, Jena, Germany) under stimulated accommodative demands (0–4 D). Images were analysed and lens thickness (LT) was measured, applying a refractive index correction of 1.00. Accommodative responses were also measured sequentially through a Badal optical system fitted to an autorefractor (Shin Nippon NVision-K 5001, Rexxam, Japan). Data were compared with Dubbelman schematic eye calculations. Significant changes occurred in LT, anterior chamber depth (ACD), lens centroid (i.e., ACD + LT/2), and AS length (ASL = ACD + LT) with accommodation (all p < 0.01). There was no significant change in CT with accommodation (p = 0.81). Measured CT, ACD, and lens centroid values were similar to Dubbelman modelled parameters, however AS-OCT overestimated LT and ASL. As expected, the accommodative response was less than the demand. Interestingly, up until approximately 1.5 D of response (2.0 D demand), the anterior crystalline lens surface appears to be the primary correlate. Beyond this point, the posterior lens surface moves posteriorly resulting in an over-all sigmoidal trajectory. he posterior crystalline lens surface demonstrates a sigmoidal response with increasing accommodative effort.

scholarly journals Anterior Segment Biometry with Phenylephrine and Tropicamide during Accommodation Imaged with Ultralong Scan Depth Optical Coherence Tomography

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Junna Zhang ◽  
Yang Ni ◽  
Peng Li ◽  
Wen Sun ◽  
Mengyun Liu ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Crystalline Lens ◽  
Repeated Measurements ◽  
Optical Coherence ◽  
Posterior Surface ◽  
Optical Zone

Purpose. To investigate the influence of phenylephrine and tropicamide on anterior segment biometry with ultralong scan depth optical coherence tomography (UL-OCT) during accommodation. Methods. In this study, 20 left eyes of healthy volunteers with a mean ± standard deviation age of 31.05 ± 5.84 years and a mean refraction of −1.16 ± 1.11 diopters (range 0∼−3.0 D) were imaged using UL-OCT after instillation of artificial tears, phenylephrine, and tropicamide in three follow-up trials, respectively. At each follow-up trial, two repeated measurements were performed at states of relax and 5D accommodative stimulation. The dimensional parameters included central corneal thickness (CCT), anterior chamber depth (ACD), pupil diameter (PD), lens thickness (LT), and horizontal radii of the lens anterior and posterior surface curvatures (LAC and LPC). Results. Tropicamide led to larger pupil, deeper ACD, thinner LT, and flatter crystalline lens surface (P<0.05). Phenylephrine induced an increase in PD (P<0.05), while no significant changes were seen in ACD, LT, LAC, and LPC (P>0.05). CCT did not change after both phenylephrine and tropicamide instillation in this study (P>0.05). Tropicamide induced the loss of accommodation and phenylephrine achieved pupil dilation without affecting the accommodation. PD, ACD decreased, LT increased significantly and the anterior and posterior surface of the lens in a 6.294 mm of diameter optical zone became steeper during accommodation after administration of phenylephrine (P<0.05). Conclusion. The anterior segment physiology changed after tropicamide instillation. Besides, tropicamide induced the loss of accommodation and phenylephrine preserved the accommodation with a larger pupil. And, the anterior and posterior surface of lens in a 6.294 mm of diameter optical zone became steeper during the accommodation.

scholarly journals Changes in anterior segment optical coherence tomography following pars plana vitrectomy without tamponade

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Alireza Khodabande ◽  
Massood Mohammadi ◽  
Hamid Riazi-Esfahani ◽  
Shahab Karami ◽  
Massood Mirghorbani ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Chamber ◽  
Pars Plana Vitrectomy ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Optical Coherence ◽  
Mean Values ◽  
Iop Measurement ◽  
Pars Plana ◽  
The Mean

Abstract Background To evaluate changes in anterior segment morphology on anterior segment optical coherence tomography (AS-OCT) following pars plana vitrectomy (PPV) without tamponade. Methods Patients who underwent PPV without tamponade for epiretinal membrane were evaluated. Eligible patients underwent intraocular pressure (IOP) measurement and AS-OCT preoperatively as well as 1 month and 6 months post-operatively. Anterior chamber width (ACW), anterior chamber depth (ACD), trabecular iris angle (TIA), angle opening distance at 500 and 750 µm (AOD), and trabecular iris space area at 500 and 750 µm (TISA) at four quadrants were recorded and analyzed. Additionally, the mean values of TIA (MTIA), AOD (MAOD), and TISA (MTISA) for each eye (mean of four quadrants) were analyzed. Results 23 patients completed the study. The mean age of participants was 56.4 ± 3.6 years of age and 13/23 (56%) were female. Mean IOP of patients was 18.1 ± 1.1, 18.3 ± 1.1, and 18.1 ± 1.2 preoperatively,1 month post-operatively, and 6 months post-operatively, respectively. (p = 0.83). No difference was detected post-operatively in measurements of ACW, ACD, MTIA, MAOD500, MAOD750, MTISA500, and MTISA750. Conclusion Pars plana vitrectomy without tamponade was not associated with changes in anterior chamber morphology.

scholarly journals Refractive index measurement of the isolated crystalline lens using optical coherence tomography

2008 ◽  
Vol 48 (27) ◽  
pp. 2732-2738 ◽  
Author(s):  
Stephen R. Uhlhorn ◽  
David Borja ◽  
Fabrice Manns ◽  
Jean-Marie Parel
Keyword(s):  
Optical Coherence Tomography ◽  
Refractive Index ◽  
Crystalline Lens ◽  
Optical Coherence ◽  
Refractive Index Measurement ◽  
Index Measurement

scholarly journals Assessment of anterior chamber configuration changes after phacoemulsification with swept-source optical coherence tomography

2019 ◽  
Author(s):  
Man Hu ◽  
Qian Zheng ◽  
Zhangliang Li ◽  
Pingjun Chang ◽  
Yun-e Zhao
Keyword(s):  
Optical Coherence Tomography ◽  
Cataract Surgery ◽  
Anterior Chamber ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Optical Coherence ◽  
Swept Source ◽  
Narrow Angle ◽  
Age Related ◽  
Shallow Anterior Chamber

Abstract Background To assess the changes of anterior chamber angle in patients with shallow anterior chamber and normal anterior chamber after phacoemulsification and intraocular lens implantation (IOL) using anterior segment swept-source optical coherence tomography (AS-SS-OCT). Methods This was a prospective case control study; 60 eyes of 60 patients who underwent cataract surgery. Based on anterior chamber depth (ACD) and gonioscopy findings, the eyes were classified into two groups, shallow anterior chamber group (30 eyes) and normal anterior chamber group (30 eyes). AS-SS-OCT was used to measure ACD and angle parameters angle opening distance (AOD), angle recess area (ARA), trabecular iris space area(TISA), and trabecular iris angle (TIA). Serial changes in each group were measured before and 3 months after phacoemulsification and IOL, and the differences between the two groups were compared. Results All angle parameters including ACD, AOD, ARA, TISA, and TIA in both groups at 3 months after cataract surgery were significantly different from the preoperative values (p<0.01). In addition, we found significant differences of all angle parameters between groups of shallow anterior chamber (SAC) and normal anterior chamber (NAC) (All P< 0.05). Besides, the TISA750 in superior quadrant and anterior chamber volume (ACV) were significantly smaller in the group of SAC than those in the group of NAC (P = 0.041 and 0.002, respectively). Conclusions The parameters of anterior chamber increased significantly in both two groups but not increase to the same extent 3 months after phacoemulsification. Iris thickening may also be one of the narrow angle factors,not just age-related lens thickening.

scholarly journals Prediction of effective Lens position using anterior segment optical coherence tomography in Chinese subjects with angle closure

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yuzhou Wu ◽  
Shunhua Zhang ◽  
Yong Zhong ◽  
Ailing Bian ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Partial Coherence ◽  
Angle Closure ◽  
Optical Coherence ◽  
Training Set ◽  
Lens Position ◽  
Regression Formula ◽  
Validation Set

Abstract Purpose To assess the accuracy of biometric parameters measured by anterior segment optical coherence tomography (AS-OCT) and partial coherence interferometry (PCI) in prediction of effective lens position (ELP) compared with previous formulas in PACG patients. Methods 121 PACG eyes were randomly divided into training set (85 eyes) and validation set (36 eyes) with same procedure including AS-OCT, PCI, phacoemulsification and IOL implantation surgery. Preoperative anterior chamber depth (pre-ACD), scleral spur depth (SSD), scleral spur width (SSW), lens vault (LV) and cornea thickness (CT) were measured from AS-OCT image. Axial length (AL) and corneal power (K) were measured by PCI. All the 7 parameters were analyzed by multiple linear regression in training set and a statistic regression formula was developed. In validation set, one-way ANOVA was applied to compare the new regression formula with Sanders-Retzlaff-Kraff theoretic (SRK/T), Holladay 1, Haigis, and a regression formula developed in previous study. Results The coefficient of determination (R2) of different parameter combinations are 0.19 (pre-ACD, AL), 0.25 (AL, K) and 0.49 (SSD, AL, SSW) in training set. In validation set, the correlation between predicted and measured ELP are: new formula (R2 = 0.50, P = 0.9947) Holladay 1 (R2 = 0.12, P < 0.0001), SRK/T (R2 = 0.11, P < 0.0001) and Haigis (R2 = 0.06, P < 0.0001). Conclusion Among 7 tested parameters, pre-ACD contribute little in ELP prediction. Formula consist of SSD, AL and SSW showed better accuracy than other formulas tested.

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

2021 ◽  
Vol 8 ◽  
Author(s):  
Ze-xu Chen ◽  
Wan-Nan Jia ◽  
Yong-Xiang Jiang
Keyword(s):  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Crystalline Lens ◽  
Maximum Diameter ◽  
Swept Source ◽  
Biometric Parameters ◽  
Projection Length ◽  
Lens Surface ◽  
Lens Radius

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

scholarly journals Risk factors and evaluation of keratoconus progression after penetrating keratoplasty with anterior segment optical coherence tomography

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Junko Yoshida ◽  
Tetsuya Toyono ◽  
Rika Shirakawa ◽  
Takashi Miyai ◽  
Tomohiko Usui
Keyword(s):  
Risk Factors ◽  
Optical Coherence Tomography ◽  
Penetrating Keratoplasty ◽  
Corneal Thickness ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Optical Coherence ◽  
Graft Size ◽  
Corneal Power ◽  
Corneal Thinning

Abstract To determine the risk factors and unique characteristics of keratoconus (KC) progression after penetrating keratoplasty (PK), anterior segment optical coherence tomography parameters were statistically analyzed in comparison with eyes undergoing PK for other diseases as a control. Ninety-one eyes maintaining clear PK grafts for over 10 years were divided into 2 groups according to the primary indication for PK (KC vs Others groups). Corneal thinning indicators (inferior host thinnest corneal thickness/central corneal thickness [IHT/CCT], inferior graft thinnest corneal thickness/CCT [IGT/CCT]), were smaller whereas anterior chamber depth, and steepest corneal power (Ks), and maximum corneal power (Kmax) were larger in the KC group with statistical significance. Graft size, Kmax and Ks correlated with IHT/CCT and IGT/CCT in the KC group. These correlations were not detected in controls. Graft size and postoperative period were selected by multivariate regression analysis as factors for corneal ectatic changes in the KC group. In conclusion, KC eyes long after PK show inferior graft and host corneal thinning, and corneal protrusion. Corneal power parameters such as Kmax or Ks can be used to monitor KC progression after PK. A small graft might lead to KC progression after PK.

scholarly journals Anterior chamber angle imaging with swept-source optical coherence tomography: comparison between CASIAII and ANTERION

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Poemen Pui-man Chan ◽  
Gilda Lai ◽  
Vivian Chiu ◽  
Anita Chong ◽  
Marco Yu ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Anterior Chamber ◽  
Anterior Segment ◽  
Anterior Chamber Depth ◽  
Angle Closure ◽  
Optical Coherence ◽  
Anterior Chamber Angle ◽  
Swept Source ◽  
Scan Pattern ◽  
Chamber Angle

Abstract This study compared the test–retest variabilities and measurement agreement of anterior chamber angle (ACA) dimensions measured by two anterior segment swept-source optical coherence tomography (SS-OCT)—the ANTERION (Heidelberg Engineering, Heidelberg, Germany) and CASIAII (Tomey, Nagoya, Japan). Thirty-eight subjects, 18 patients with primary angle closure and 20 healthy participants with open angles, were included. The mean age was 54.7 ± 15.8 years (range: 26–75 years). One eye of each subject was randomly selected for anterior segment imaging by ANTERION and CASIAII, using the same scan pattern (6 evenly spaced radial scans across the anterior segment for three times) in the same visit. The between- and within-instrument agreement and repeatability coefficients of angle open distance (AOD500), trabecular-iris space area (TISA500), lens vault (LV), scleral spur-scleral spur distance (SSD), anterior chamber depth (ACD), and pupil diameter (PD) were measured. The anterior and posterior boundaries of the cornea, iris, and lens were automatically segmented by the SS-OCT instruments; the scleral spur was manually located by a single masked observer. There were significant differences between ANTERION and CASIAII measurements; the SSD, PD, and ACD were smaller whereas AOD500 and TISA500 were greater in ANTERION compared with CASIAII (P < 0.001). Anterior segment measurements obtained from the two SS-OCT instruments showed strong associations (R2 ranged between 0.866 and 0.998) although the between-instrument agreement was poor; the spans of 95% limits of between-instrument agreement were ≥ 1.5-folds than the within-instrument agreement for either instrument. Whereas both SS-OCT instruments showed low test–retest measurement variabilities, the repeatability coefficients of AOD500, TISA500, ACD, and PD were slightly smaller for CASIAII than ANTERION (P ≤ 0.012).

scholarly journals Correlation between vaulting intraoperative and postoperative of EVO implantable Collamer lens: a retrospective study of real-time observations of vaulting using the RESCAN 700 system

2020 ◽  
Author(s):  
Nian Guan ◽  
Xiao-Nong Zhang ◽  
Wan-Jun Zhang
Keyword(s):  
Optical Coherence Tomography ◽  
Intraocular Pressure ◽  
Retrospective Study ◽  
Multivariable Analysis ◽  
Anterior Chamber Depth ◽  
Crystalline Lens ◽  
Optical Coherence ◽  
Implantable Collamer Lens ◽  
Corrected Visual Acuity ◽  
Intraoperative Optical Coherence Tomography

Abstract Background: The prediction of implantable Collamer lens (ICL) vaulting is one of the most important parameters for ICL implantation for safety, aqueous humor circulation, and lens transparency.Methods: This was a retrospective study. A RESCAN 700 was used for intraoperative observation of vaulting. Spectral-domain optical coherence tomography was used for imaging. Results: Finally, 51 patients (102 eyes) were included in the study. Compared with the eyes with normal vaulting, those with high vaulting had higher preoperative diopter values (P=0.039), lower preoperative corrected visual acuity (P=0.006), lower preoperative intraocular pressure (P=0.029), higher preoperative anterior chamber depth (P=0.004), lower preoperative crystalline lens rise (P=0.046), higher ICL spherical equivalent (P=0.030), higher intraoperative vaulting (P<0.001), and lower intraocular pressure at 1 month (P=0.045). The multivariable analysis showed that the only factors independently associated with high vaulting at 1 month after surgery was the intraoperative vaulting value (odds ratio=1.005, 95% confidence interval: 1.002-1.007, P<0.001). The intraoperative and 1-month postoperative vaulting values were correlated (R2=0.562).Conclusions: The RESCAN700 system can be used to perform intraoperative optical coherence tomography to predict the vaulting value at 1 month.

Sign in / Sign up

Export Citation Format

Share Document