Influence of anterior chamber depth and vault on anterior chamber angle morphology after phakic posterior chamber intraocular lens implantation.

PURPOSE: This study aims to investigate the influence of anterior chamber depth (ACD) and vault on the anterior chamber angle (ACA) morphology in myopic individuals implanted with posterior chamber phakic intraocular lenses. METHODS: This retrospective case series involved 231 eyes receiving a 13.2-mm implantable collamer lens (ICL). Preoperative anterior chamber anatomy was assessed using anterior segment optical coherence tomography (AS-OCT) and optical tomography, while postoperative evaluation employed AS-OCT. ACA morphology was characterized pre- and postoperatively through trabecular iris angle (TIA750), ACA distance opening (AOD750) and trabecular iris space area (TISA750). The influence of ACD and vault was examined by categorizing the sample into ACD (shallow, average and deep) and vault (low, optimal and high) groups. RESULTS: Preoperative ACA morphology varied based on ACD, with shallower ACDs exhibiting narrower TIA750, smaller AOD750 and TISA750. ICL implantation induced greater ACA narrowing more in the deep ACD group (TIA750 = 20.1 degrees; AOD750 = 0.82 mm and TISA750 = 0.44 mm2) compared to the shallow ACD group (TIA750 = 15.2 degrees; AOD750 = 0.44 mm and TISA750 = 0.21 mm2). Postoperatively, deeper ACDs showed larger ACAs. Increasing vault magnitude led to increased ACA narrowing, with the low vault group exhibiting smaller closure (TIA750 = 14.3 degrees; AOD750 = 0.56 mm and TISA750 = 0.29 mm2) compared to the high vault group (TIA750 = 20.8 degrees; AOD750 = 0.73 mm and TISA750 = 0.36 mm2). The magnitude of ACA narrowing associated with the vault had a consistent effect across different ACD groups. CONCLUSIONS: Posterior chamber intraocular lens implantation results in ACA narrowing, the extent of which is contingent upon preoperative anterior chamber and ACA morphology, with additional influence from vault magnitude.

Investigation into the usefulness of cynomolgus monkeys with spontaneously elevated intraocular pressure as a model for glaucoma treatment research.

Many glaucoma treatments focus on lowering intraocular pressure (IOP), with novel drugs continuing to be developed. One widely used model involves raising IOP by applying a laser to the trabecular iris angle (TIA) of cynomolgus monkeys to damage the trabecular meshwork. This model, however, presents challenges such as varying IOP values, potential trabecular meshwork damage, and risk of animal distress. This study investigated whether animals with naturally high IOP (>25 mmHg) could be used to effectively evaluate IOP-lowering drugs, thereby possibly replacing laser-induced models. Relationships between TIA size, IOP, and pupil diameter were also examined. Three representative IOP-lowering drugs (latanoprost, timolol, ripasudil) were administered, followed by multiple IOP measurements and assessment of corneal thickness, TIA, and pupil diameter via anterior segment optical coherence tomography (AS-OCT). There was a positive correlation was noted between IOP and corneal thickness before instillation, and a negative correlation between IOP and TIA before instillation. Our findings suggest animals with naturally high IOP could be beneficial for glaucoma research and development as a viable replacement for the laser-induced model and that measuring TIA using AS-OCT along with IOP yields a more detailed evaluation.

Anterior segment parameters on optical coherence tomography in healthy South Asian children.

PURPOSE: High resolution spectral domain optical coherence tomography (SD-OCT) was used to assess the anterior segment structure parameters in healthy South Asian children. METHODS: 108 eyes of 54 healthy children ≤ 16 years were recruited after a thorough eye exam. The anterior segment analysis was be done by Optopol Revo 80 high resolution SD-OCT. Central corneal thickness (CCT), Angle opening distance (AOD), Anterior chamber (AC) angle, Trabecular iris space area (TISA), Trabecular iris angle (TIA), iris thickness at 2 mm, internal AC diameter and lens vault were evaluated. RESULTS: Mean age was 11.38 years. Mean IOP was 13.63 mmHg, mean axial length, 22.82 mm, mean spherical equivalent, -0.14 D, mean CCT, 532.6 µm and mean CDR was 0.31. The mean internal AC diameter was 11609.15 µm. The nasal and temporal AC angles was 53.54° and 50.37°, respectively [P = .033]. The nasal and temporal AOD500 were 0.9 mm and 0.85 mm, respectively [P = .629]. The nasal and temporal AOD750 were 1.21 mm and 1.06 mm, respectively [P = .583]. The nasal TIA was 41.75°; the temporal TIA; 40.24° [P = .325]. The nasal TISA500 was 0.33 mm2; the temporal TISA500, 0.31 mm2 [P = .012]. The nasal TISA750 was 0. 59 mm2; the temporal TISA750, 0.56 mm2 [P = .746]. The nasal iris thickness at 2 mm was 483.54 µm; the temporal iris thickness, 505.8 µm [P = .273]. The mean lens vault was -519.58 µm. CONCLUSIONS: Our study data depicts the normal anterior segment parameters in healthy Pakistani children.

Distribution of anterior chamber angle measurements in South African young adults: an optical coherence tomography study.

PURPOSE: Assessment of anterior chamber angle (ACA) variables is important to screen, diagnose and monitor ocular anomalies. Even though data on ACA variables, such as angle-opening distance taken at 500 µm (AOD500) and trabecular-iris angle (TIA), are available in the literature, limited information is available about these variables in African sub-populations. The purpose of this study is to describe the distribution of ACA measurements (AOD500 and TIA) in a South African young adult population. METHODS: In this cross-sectional study, 700 young adults were recruited from a university student population using two-stage random sampling. The Optovue iVue 100 optical coherence tomographer was used to measure the ACA variables. The distribution of the AOD500 and TIA measurements was analysed using descriptive and inferential statistics. Data from only the right eyes were analysed because the ACA measurements in the two eyes showed high levels of interocular symmetry. RESULTS: The measurements for the nasal and temporal ACAs were asymmetrically distributed (p < 0.001). The median AOD500 measurements in the nasal and temporal angles were 539 µm and 542 µm, respectively. The median TIA measurements were similar (~ 36°) in the two horizontal angles. The temporal ACA measurements were slightly higher than the nasal ACA measurements. Females had higher median ACA measurements than males (p ≥ 0.029). CONCLUSION: The ACA measurements in South African young adults resemble non-Gaussian curves. The ACA measurements are different from that reported in other sub-populations worldwide and most participants had ACA measurements associated with non-occludable ACAs.

Association Between Anterior Chamber Angle and Corneal Endothelial Cell Density in Chronic Angle Closure.

PURPOSE: To study the association between corneal endothelial cell density (ECD) and degree of anterior chamber angle (ACA) opening in eyes with chronic angle closure glaucoma. METHODS: The study was conducted at JEC Eye Hospitals in Indonesia. Treatment-naïve patients aged ≥40 years with IOP >21 mmHg and peripheral anterior chamber depth (ACD) grade 2 or less by Van Herick's technique were recruited. Trabecular iris angle (TIA; degree) was measured using anterior segment optical coherence tomography (AS-OCT) and classified as: grade 1 ≤10°, grade 2 11-20°, and grade 3 >20°. Noncontact specular microscopy was performed, and the following corneal parameters were obtained:ECD (cells/mm2), coefficient of variation (CV; µm2/cell), percentage of hexagonal cells, and central corneal thickness (CCT; µm). RESULTS: A total of 52 eyes from 52 subjects were recruited (16 grade 1 TIA, 24 grade 2 TIA, and 12 grade 3 TIA). Presenting IOP was not significantly different between groups. The median central corneal ECD was 2684.5 (1433-2934), 2587.0 (1902-3103), and 2441.0 (1659-3005) cells/mm2 in grade 1, 2, and 3 TIA, respectively, with no significant differences across the groups (P = 0.67). The CV was lowest in grade 3 TIA (36.4 ± 7.2 µm2/cell), and highest in grade 1 TIA (38.3 ± 9.6 µm2/cell), but the differences were not significant (P = 0.74). Likewise, the percentage of hexagonality and CCT was not significantly different. TIA was not correlated with IOP but was modestly correlated with age. CONCLUSION: The corneal ECD and morphological characteristics such as CV and hexagonality were not significantly different across various TIA grading in chronic angle closure. This may reflect the lack of chronic and gradual IOP insult on corneal endothelial parameters as TIA did not show direct effect towards IOP.

A Study Validating the Estimation of Anterior Chamber Depth and Iridocorneal Angle with Portable and Non-Portable Slit-Lamp Microscopy.

This study assessed the anterior chamber depth (ACD) and iridocorneal angle using a portable smart eye camera (SEC) compared to the conventional slit-lamp microscope and anterior-segment optical coherence tomography (AS-OCT). This retrospective case-control study included 170 eyes from 85 Japanese patients. The correlation between the ACD evaluations conducted with the SEC and conventional slit-lamp was high (r = 0.814). The correlation between the Van-Herick Plus grade obtained using two devices was also high (r = 0.919). A high kappa value was observed for the Van-Herick Plus grading (Kappa = 0.757). A moderate correlation was observed between the ACD measured using AS-OCT and the slit-lamp image acquired with the conventional slit-lamp microscope and SEC (r = 0.609 and 0.641). A strong correlation was observed between the trabecular-iris angle (TIA) measured using AS-OCT and Van-Herick Plus grade obtained with the conventional slit-lamp microscope and SEC (r = 0.702 and 0.764). Strong correlations of ACD evaluation and high kappa value of the Van-Herick Plus grading indicated the adequate subjective assessment function of the SEC. Moderate correlations between the ACD objective measurement and evaluation and strong correlation between the TIA and Van-Herick Plus grade suggested the good objective assessment function of the SEC. The SEC demonstrated adequate performance for ACD evaluation and angle estimation.

Analysis and Modeling of Anatomical Changes of the Anterior Segment of the Eye After Cataract Surgery with Consideration of Different Phenotypes of Eye Structure.

PURPOSE: To study the relationship between phacoemulsification-related changes and the baseline parameters of the anterior chamber. SETTING: Military Institute of Medicine, Warsaw, Medical University of Lublin, Medical University of Bialystok. MATERIAL AND METHODS: The study included 228 patients. Anterior chamber depth (ACD), trabecular-iris angle (TIA), central lens thickness (CLT) and axial length of the eye (AXL) were determined prior to and 6 months after surgery. These measurements were used to calculate the ACD(index) describing the degree of postoperative changes in the anterior chamber. K-means clustering, multiple regression and neural networks were used for the analysis. RESULTS: Cataract surgery was reflected by changes in ACD and TIA. The character of changes was described by ACD(index) (p < 0.05). Mean ACD0 was 2.51 ± 0.45 mm and increased to 3.84 ± 0.35 mm (p < 0.05), whereas mean TIA0 was 22.84 ± 7.43° and increased to 30.97 ± 7.99° (p < 0.05). ΔACD and ΔTIA were determined on the basis of baseline parameters defined by ACD(index), characterizing the structural type of the eye. The variability of ACD(index) explained 42.65% of variance in ΔACD and ΔTIA. The quality of network for validation and test samples was from 0.72 to 0.83. CONCLUSIONS: Cataract surgery-related changes in ACD and TIA are determined by the type of the eye. Although the linear model of the relationship between baseline parameters of the eye and their postoperative changes is correct, it does not explain the degree of the latter phenomenon. Preoperative consideration of other parameters characterizing anatomical relationships of the eye would enable the prediction of phacoemulsification-related changes in the anterior segment.

Association between baseline angle width and induced angle opening following prophylactic laser peripheral iridotomy.

PURPOSE: To evaluate the association between baseline angle width and laser peripheral iridotomy (LPI)-induced opening of the anterior chamber angle. METHODS: Anterior segment optical coherence tomography images captured before and after LPI were analyzed to determine the angle opening distance at 250 µm (AOD250), 500 µm (AOD500), and 750 µm (AOD750) from the scleral spur; trabecular-iris space area at 500 µm (TISA500) and 750 µm (TISA750) from the scleral spur; angle recess area at 750 µm (ARA750) from the scleral spur; and trabecular-iris angle (TIA). Differences in preoperative and postoperative measurements for the anterior chamber angle width parameters were compared by paired Student's t-tests. Univariate and linear mixed-effects regression models were used to examine the association between baseline and LPI-induced opening of anterior chamber angle width parameters. RESULTS: Eighty-four eyes of 52 primary angle closure suspects were included in the analysis. AOD250, AOD500, AOD750, TISA500, TISA750, ARA750, and TIA significantly increased following LPI by paired Student's t-tests (all P < 0.0001). Lower baseline measurements were significantly associated with greater postoperative opening in all anterior chamber angle width parameters in both univariate and linear mixed-effects regression analyses (all P < 0.05). CONCLUSIONS: Our results showed significant opening of the anterior chamber angle width after LPI and demonstrated an inverse association between baseline and LPI-induced opening of the anterior chamber angle width, such that eyes with a more crowded anterior chamber angle undergoing LPI had a greater magnitude of increase in anterior chamber angle width after the procedure.

Changes of Anterior Chamber Depth and Angle After Cataract Surgery Measured by Anterior Segment OCT

PURPOSE: To report the change of anterior chamber parameters according to cataract severity after cataract surgery and to determine its relationship to the severity of cataract by using anterior segment optical coherence tomography. METHODS: We measured the anterior chamber parameters in 19 eyes of 14 patients before, 1 week after, and 1 month after cataract surgery by slit lamp-adapted optical coherence tomography (SL-OCT). The measured parameters were as follows : the anterior chamber depth (ACD), the angle-opening distance 250 micrometer from the scleral spur (AOD250), the angle-opening distance 500 micrometer from the scleral spur (AOD500), and the trabecular-iris angle (TIA). We analyzed the relationship between the severity of cataract and the change of the anterior chamber parameters. RESULTS: The ACD, AOD250, AOD500, and TIA increased significantly at postoperative 1 week (P=0.000, 0.002, 0.005, 0.022) and 1 month (P=0.000, 0.004, 0.001, 0.002). The preoperative parameters were negatively correlated with the differences between the postoperative 1 week and preoperative parameters (gamma=-0.834, -0.591, -0.421, -0.826) and between postoperative 1 month and preoperative parameters (gamma=-0.659, -0.700, -0.770, -0.821). The change of parameters at postoperative 1 week (by N P=0.959, 0.916, 0.824, 1.000, by C P=0.454, 0.665, 0.578, 0.578) and 1 month (by N P=0.858, 0.973, 0.959, 0.959, by C P=0.999, 0.207, 0.950, 0.981) were not significantly different according to the severity of cataract (N, C). CONCLUSIONS: Our results showed that cataract surgery significantly deepened the anterior chamber and widened its angle. The shallower and narrower the preoperative anterior chamber depth and angle were, respectively, the greater the postoperative changes of anterior chamber depth and angle were.