Distribution and Determinants of Anterior Chamber Angle and Anterior Chamber Volume in Young Chinese Adults.

PURPOSE: Current study aimed to understand the distribution and determinants of anterior chamber angle (ACA) and anterior chamber volume (ACV) in Chinese young adults, which can help fill current data gaps and aid in early detection and intervention for high-risk population of primary angle closure glaucoma. METHODS: This cross-sectional study utilized data from 2014 participants who completed questionnaire and eye examination in September 2021. ACV and ACA were measured using a Pentacam tomographer. Spherical equivalent (SE) was evaluated by autorefractor without cycloplegia. Central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were evaluated using Corvis-ST. Axial length (AL), corneal radius (CR), anterior chamber depth (ACD), and white to white were assessed using the IOL Master. RESULTS: A total of 1635 students were included in the analysis. The mean ACV and AVA were 194.74 ± 32.30 µL and 38.81 ± 4.84°, respectively. Males have a larger ACV and wider ACA than females. ACV was positively correlated with ACA (r = 0.24, p < 0.001), and the correlation was stronger for non-myopic students than for myopic students. Multivariable linear regression model showed that AL (ß = 2.41), CR (ß = -4.12), CCT (ß = -0.11), ACD (ß = 97.93), and bIOP (ß = 0.40) were associated with ACV, and CCT (ß = -0.01), CR (ß = 0.38), and ACD (ß = 7.41) were associated with ACA (all p < 0.05). Random forest model indicated that ACD was the most critical predictor of both ACV and ACA. CONCLUSIONS: This study reported the distribution and determinants of ACA and ACV. Deeper ACD was associated with larger ACV and wider ACA.

Anterior segment parameters after trabeculectomy in pseudoexfoliation glaucoma versus primary open-angle glaucoma.

Background: The effects of trabeculectomy on anterior segment parameters have been widely investigated. However, the stabilization time for various glaucoma types after trabeculectomy remains debatable. We investigated the effect of mitomycin C-augmented trabeculectomy on ocular anterior segment parameters in primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) during short-term follow-up using the Pentacam HR. Methods: In this retrospective observational study, consecutive patients diagnosed with medically uncontrolled POAG or PXG who underwent MMC-augmented trabeculectomy were recruited. All individuals underwent detailed ocular examinations. All trabeculectomies were performed by a single surgeon using the same technique. Anterior segment parameters, including anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and central corneal thickness (CCT) were measured using the Pentacam HR, along with intraocular pressure (IOP) using a Goldmann applanation tonometer, pre-operatively and at 1-week, 1-month, and 3-month post-operative visits. Results: We included 80 patients with a median (range) age of 58.0 (41.0-86.0) years having a nearly similar sex ratio. The study groups were matched according to sex and age (both P > 0.05). The group-by-time interaction was significant for CCT and ACV (both P < 0.05) but not for IOP, ACD, and ACA (all P > 0.05). The mean (standard deviation [SD]) IOP, ACD, and ACA were comparable between groups (all P > 0.05) during the 3-month period; however, they changed significantly over time in both groups (all P < 0.001). The mean CCT and ACV were comparable between groups at each time point (all P > 0.05), except at the 1-month post-operative visit, at which the mean (SD) ACV was significantly lower in the PXG group (P < 0.05). We found a comparable mean (SD) CCT between paired visits in each group (all P > 0.05), except for the mean (SD) CCT at 3 months, which was significantly lower than that at the 1-month post-operative visit in the PXG group (P < 0.05). We found a comparable mean (SD) ACV between paired visits in each group (all P > 0.05); however, it was significantly lower at the 1-month post-operative versus the baseline visit in both groups and resumed a significantly higher value at the 1-month versus the 1-week visit and at the 3-month versus the 1-month visit in the PXG group (all P < 0.05). Conclusions: We observed significant changes in IOP, ACD, and ACA over 3 months after post-augmented trabeculectomy in eyes with POAG and PXG; however, the majority of anterior segment parameters were comparable between the two groups. Further large-scale studies with longer follow-up periods should be conducted to verify the post-operative fluctuations in these parameters in POAG and PXG.

The effect of systemic sclerosis and its subtypes on ocular anterior and posterior segment parameters.

PURPOSE: To evaluate anterior and posterior segment parameters in the eyes of patients with systemic sclerosis (SSc) and examine the effect of disease and disease subtypes on these parameters. METHODS: This cross-sectional study included 54 eyes of 27 SSc patients and 54 eyes of 27 age- and sex-matched healthy controls. In addition to a complete ophthalmologic examination, all patients were examined using a Scheimpflug camera, specular microscopy, and spectral domain optical coherence tomography. RESULTS: The mean age of the patients was 52.5 ± 11.4 years and 19 patients were female. Anterior chamber volume, central corneal thickness, and central macular thickness (CMT) were significantly lower in the eyes of SSc patients compared to healthy controls (p = 0.01, p = 0.03, and p = 0.006, respectively). When evaluated according to SSc subtype, CMT was lower in diffuse SSc patients (p = 0.001), while mean retinal nerve fiber layer (RNFL) and inferior quadrant RNFL values were lower in limited SSc (p = 0.003 and p = 0.005, respectively). CONCLUSION: In the eyes of patients with SSc, some ocular parameters may show decreases compared to healthy individuals, presumably secondary to disease-related vasculopathy and fibrosis. CMT and RNFL parameters may be affected differently according to disease subtype.

SeqCorr-EUNet: A sequence correction dual-flow network for segmentation and quantification of anterior segment OCT image.

The accurate segmentation of AS-OCT images is a prerequisite for the morphological details analysis of anterior segment structure and the extraction of clinical biological parameters, which play an essential role in the diagnosis, evaluation, and preoperative prognosis management of many ophthalmic diseases. Manually marking the boundaries of the anterior segment tissue is time-consuming and error-prone, with inherent speckle noise, various artifacts, and some low-quality scanned images further increasing the difficulty of the segmentation task. In this work, we propose a novel model called SeqCorr-EUNet with a dual-flow architecture based on convolutional gated recursive sequence correction for semantic segmentation and quantification of AS-OCT images. An EfficientNet encoder is employed to enhance the intra-slice features extraction ability of semantic segmentation flow. The sequence correction flow based on ConvGRU is introduced to extract inter-slice features from consecutive adjacent slices. Spatio-temporal information is fused to correct the morphological details of pre-segmentation results. And the channel attention gate is inserted into the skip-connection between encoder and decoder to enrich the contextual information and suppress the noise of irrelevant regions. Based on the segmentation results of the anterior segment structures, we achieved automatic extraction of essential clinical parameters, 3D reconstruction of the anterior chamber structure, and measurement of anterior chamber volume. The proposed SeqCorr-EUNet has been evaluated on the public AS-OCT dataset. The experimental results show that our method is competitive compared with the existing methods and significantly improves the segmentation and quantification performance of low-quality imaging structures in AS-OCT images.

Short-term changes detected by corneal topography and optical coherence tomography after prophylactic laser iridotomy in primary angle closure suspect.

PURPOSE: To evaluate early changes in anterior segment parameters by Scheimpflug-Placido disc topography system and changes in retinal layers by optical coherence tomography in primary angle-closure suspects after laser peripheral iridotomy. METHODS: One eye of 26 patients with primary angle closure suspect and of 20 healthy subjects were included in this retrospective cross-sectional study. Anterior chamber depth/volume, iridocorneal angle and central corneal thickness were obtained by Scheimpflug-Placido disc topography system. Retinal thickness, retinal nerve fiber layer thickness and ganglion cell-inner plexiform layer thickness were acquired by optical coherence tomography. All the tests were repeated 1 week and 1 month after laser peripheral iridotomy. RESULTS: The mean ages of the patients and healthy controls were 64.8 ± 10.7 years and 64.5 ± 3.9 years, respectively (p = 0.990). Anterior chamber depth/volume and iridocorneal angle value were lower in the PACS group (p < 0.001, for all). Anterior chamber volume and iridocorneal angle increased significantly after laser peripheral iridotomy (p = 0.004, for both). While foveal thickness decreased significantly after laser peripheral iridotomy (p = 0.027), retinal nerve fiber layer thickness increased in superior and temporal quadrants (p = 0.038 and p = 0.016, respectively). CONCLUSION: Our results suggest that LPI in patients with PACS provides improved retinal thickness and RNFL thickness, as well as anterior chamber parameters.

Evaluation of changes in anterior segment morphology using Sirius Scheimpflug-Placido disk topographer following laser peripheral iridotomy in primary angle-closure disease.

Purpose: To assess the morphological changes in the anterior segment following laser peripheral iridotomy (LPI) in primary angle-closure disease (PACD) using Sirius Scheimpflug-Placido disk corneal topographer. Methods: This was a prospective observational study. A total of 52 eyes of 27 patients with PACD who underwent LPI were analyzed for iridocorneal angle (ICA), anterior chamber depth (ACD), anterior chamber volume (ACV), horizontal visible iris diameter (HVID), corneal volume (CV), central corneal thickness (CCT), and horizontal anterior chamber diameter (HACD) 1 week following LPI, using Sirius Scheimpflug-Placido disk corneal topographer. Data analysis was done using Statistical Package for the Social Sciences (SPSS) software version 19.0, and paired t-test was used to assess the statistical significance. Results: Laser peripheral iridotomy was performed in 43 eyes with primary angle-closure suspect (PACS), six eyes with primary angle closure (PAC), and three eyes with primary angle-closure glaucoma (PACG). The analysis of the data showed statistically significant changes in anterior segment parameters of ICA, ACD, and ACV. Post-laser increase in ICA from 34.13° ± 2.64° to 34.75° ± 2.84° (P < 0.041), mean ACD increase from 2.21 ± 0.25 to 2.35 ± 0.27 mm (P = 0.01), and mean ACV increase from 98.19 ± 12.13 to 104.15 ± 11.16 mm3 (P = 0.001) were noted. Conclusion: Significantly quantifiable short-term changes in the anterior chamber parameters of ICA, ACD, and AC volume were seen after LPI in patients with PACD on Sirius Scheimpflug-Placido disc corneal topographer.

Correlations of Corneal Curvature with Corneal Spherical Aberration and Anterior Chamber Parameters in Eyes with Shallow Anterior Chambers.

INTRODUCTION: This study aimed to investigate the distribution of corneal spherical aberration (CSA) and the relationship between corneal curvature with CSA and anterior chamber parameters in age-related cataract patients with normal axial lengths and shallow anterior chambers. METHODS: Preoperative data of age-related cataract patients were collected in this retrospective comparative study. According to the average corneal curvature, the eyes were divided into groups of Km < 42 diopters (D), 42 D ≤ Km < 45 D, and Km ≥ 45 D. The axial length (AL) and corneal curvature were obtained using IOLMaster. CSA, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), and corneal diameter (CD) were acquired according to Pentacam. The above parameters were compared among the three groups. Correlation analysis was applied to these parameters. RESULTS: The average CSA value of 753 eyes was 0.41 ± 0.27 µm, with no significant difference among the three groups. Overall, CSA was significantly correlated with corneal curvature and ACD. The comparison of ACD among the three groups showed significant differences between the Km ≥ 45 D group, Km < 42 D group, and 42 D ≤ Km < 45 D group. Corneal curvature was positively correlated with ACD, and further analysis confirmed that the relationship was significant only in the Km ≥ 45 D group. There were statistically significant differences in CD between the three groups. A significant correlation was found in corneal curvature and CD in all eyes, which was also found in the 42 D ≤ Km < 45 D group and the Km ≥ 45 D group. Concerning ACV and ACA, no correlation with corneal curvature was found. In addition, the mean ACV and ACA of the three groups did not show any significant difference. CONCLUSIONS: CSA was higher in this population and had individual variance. Compared with ACD, ACV and ACA were more stable in different corneal curvatures and more objective in representing the anterior chamber space.

The iridocorneal angle and related anterior segment structures in pediatric anisohyperopic amblyopic eyes.

Objectives: We aimed at investigating the iridocorneal angle, anterior segment structural differences, and their relationship in pediatric anisohyperopic amblyopic eyes. Methods: This study was designed as an observational case-control study. We prospectively evaluated the pediatric patients who were newly diagnosed with hyperopic anisometropic amblyopia. Iridocorrneal angle in four sectors, axial length, and anterior segment structures were compared to emmetropic fellow and control eyes using Pentacam and IOLMaster 700 devices. The anisohyperopia and iridocorneal angle related factors were determined in hyperopic anisometropic amblyopic eyes. Results: Forty-three hyperopic anisometropic amblyopic eyes, 43 fellow eyes, and 44 control eyes were included. The mean axial length, anterior chamber volume, and anterior chamber depth were significantly reduced in the study eyes compared to the fellow (p < 0.001, p = 0.021, and p = 0.045, respectively) and control eyes (p < 0.001, p = 0.001, and p = 0.009, respectively). The average iridocorneal angle was significantly lower in the study eyes than in the fellow and control eyes (p < 0.001 and p = 0.018, respectively). The iridocorneal angle correlated with anterior chamber depth (r = 0.49, p = 0.013), anterior chamber volume (r = 0.42, p = 0.038), the anterior radius of curvature (r =-0.54, p = 0.005), the posterior radius of curvature (r =-0.58, p = 0.002), and lens thickness (Rho =-0.41, p = 0.033) in the study eyes. Anisohyperopia was related to the interocular difference in axial length (Rho = 0.53, p = 0.005), anterior chamber depth (Rho = 0.53, p = 0.005), and anterior chamber volume (Rho = 0.42, p = 0.031). Conclusion: Pentacam and IOLMaster 700 are suitable for non-contact imaging of iridocorneal angle and anterior segment structures in the pediatric age. These biometric differences and their relationship should be kept in mind whenever anterior or posterior segment surgery is planned for pediatric anisohyperopic amblyopic eyes.

Short-term effects of two types of goggles on intraocular pressure and anterior eye segment biometrics.

BACKGROUND: To evaluate and compare the changes in intraocular pressure and anterior eye segment biometrics during and after wearing two types of commonly used swimming goggles. METHODS: In a cross-sectional study, a total of 40 healthy adults aged between 18 and 60 years old were selected to wear two kinds of common swimming goggles (ocular socket and orbital goggles). Intraocular pressure and anterior segment biometry were evaluated before wearing, at 2 and 5 min of wearing, and at 5 min after removing the goggles. Intraocular pressure (IOP), corneal front keratometry values (K1, K2, Km), central corneal thickness (CCT), central anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) were measured. RESULTS: The IOP at 2 min (21.0 ± 2.2 mmHg) and 5 min (21.2 ± 2.3 mmHg) was significantly higher than before wearing goggles (17.7 ± 2.1 mmHg). The IOP after the goggles were removed and at 5 min after the goggles were removed was 18.4 ± 2.3 mmHg and 17.7 ± 2.1 mmHg, respectively. ACV, ACD, and ACA values all decreased while the googles were worn. After the goggles were removed, these changes gradually returned to baseline values, with no significant difference in the values before and after. CONCLUSION: This study proves that wearing orbital goggles can lead to an acute increase in IOP and a slight decrease in ACV, ACD, and ACA. However, once the goggles are removed, these indicators return to baseline levels, showing that wearing orbital goggles has no significant lasting effect on IOP and anterior segment parameters.

Anterior chamber morphology changes in eyes with narrow angles by Scheimpflug imaging: Pilocarpine versus laser peripheral iridotomy.

PURPOSE: To evaluate morphometric variables, like anterior chamber angle (ACA), anterior chamber volume (ACV) and central anterior chamber depth (CACD) after pilocarpine administration and after prophylactic laser peripheral iridotomy (LPI) in eyes with primary angle-closure disease (PACD). DESIGN: Prospective cohort study METHODS: Ninety-one eyes of 91 patients with narrow angles were consecutively enrolled in this prospective interventional study. All patients were classified into primary angle-closure suspect (PACS), primary angle-closure (PAC) and primary angle-closure glaucoma (PACG). If both eyes were eligible, one eye was randomly selected for study inclusion. ACV, ACD and ACA were evaluated using Scheimpflug imaging technology at three time points: at baseline (T0), 45 min after application of pilocarpine before LPI (T1) and at one-month post-LPI (T2). RESULTS: PACS, PAC and PACG groups included 25 (27.4%), 24 (26.3%) and 42 (46.1%) eyes, respectively. At both time points T1 and T2, mean pupil diameter, ACV and ACA changed significantly (P = 0.00). In all subgroups, ACD decreased significantly at T1 and then increased significantly at T2. ACA was widened by 6 degrees in angles < 26 degrees as compared to 3 degrees in > 26 degrees eyes. In PACG group, mean ACV increased significantly between T0 and T2 (P = 0.0). Other parameters like mean cornea volume (P = 0.27), central corneal thickness (P = 0.29) showed no significant change between time points (T0, T1 and T2). Pilocarpine instillation caused a significant increase in ACA, ACV and ACD CONCLUSION: Scheimpflug imaging detected significant changes in ACD post-LPI and post-pilocarpine in all groups. However, ACV changed significantly only in PACS and PACG. CLINICAL TRIALS REGISTRATION: Gels and blots/image manipulation: Author declares that the final image submitted represent the original data. All unprocessed images are with corresponding author and will make available if required.

Effects of Cyclopentolate Hydrochloride Dosage on Anterior Segment Parameters in Young Adults (Measured with Pentacam).

PURPOSE: To assess the effects of 0.5% and 1% cyclopentolate on the main parameters of the anterior segment (central corneal thickness (CCT), anterior chamber angle (ACA), depth (ACD) and volume (ACV)) in low/moderate myopia and hyperopia along with the effect on IOP. PATIENTS AND METHODS: Both eyes of 30 subjects (15 myopic and 15 hyperopic) with mean age±standard deviation of 21.4±3.6 years were enrolled. Each participant was administered two drops of cyclopentolate 1% in the right eye and two drops of cyclopentolate 0.5% in the left eye, 15 minutes apart. All participants underwent intraocular pressure (IOP) measurement using noncontact tonometry, and anterior chamber parameter measurement using Pentacam. RESULTS: Following the use of 0.5% and 1% cyclopentolate among the hyperopic group, there was a statistically significant increase in ACD for 1% (pre 2.762±0.28 mm and post 2.89±0.25 mm) and 0.5% (pre 2.71±0.28 and post 2.86±0.27 mm) and ACV for 1% (pre 141.40±20.59 mm3 and post 154.35±19.69 mm3) and 0.5% (pre 137.40±20.48 mm3 and post 152.93±20.50 mm3). In contrast, ACA decreased with both doses 1% and 0.5%, but was not statistically significant (p for both >0.05%). With 0.5% and 1% cyclopentolate among the myopia group, there was a significant increase in ACD following cyclopentolate 1% (pre 3.18±0.22 mm and post 3.25±0.21 mm) and 0.5% (pre 3.200±0.22 mm and post 3.26±0.05 mm), p˂0.05. The ACV was significantly increased following 1% cyclopentolate, p˂0.001. The ACA showed a statistically significant decrease following cyclopentolate 1%, P=0.01, but not a significant decrease after cyclopentolate 0.5%, P=0.170. There was a significant increase in the IOP after 1%, p˂0.001, while a decrease with 0.5%, p=0.008. CONCLUSION: A topical dosage of cyclopentolate 1% showed significant changes in ACA and ACV among the hyperopia and myopic groups compared to 0.5%. Therefore, it is important to consider the use of a 0.5% cyclopentolate dosage to minimize changes to anterior chamber parameters.

Corneal and lens densitometry in patients with vernal keratoconjunctivitis.

AIM: To evaluate corneal and crystalline lens densitometry in patients with vernal keratoconjunctivitis (VKC). METHODS: This is a case-control study. Patients with VKC and age-gender-matched healthy controls underwent a complete ophthalmologic examination with corneal and crystalline lens densitometry measurements. Additionally, the anterior chamber parameters comprise anterior and posterior Kmean and astigmatism, anterior chamber depth (ACD), anterior chamber volume (ACV), anterior chamber angle (ACA), pachymeter, and corneal volume (CV). Patients who had clinically grade 0 or grade 1 VKC and with only tarsal conjunctiva involvement during the conductance of the study were included. The variables were compared statistically. RESULTS: One hundred and nine eyes were included in the study, in which fifty-one were in the VKC group. There were 25 males in the VKC group (26 female) and 22 males in the control group (36 female). A statistically significant difference was found between the groups in terms of posterior corneal astigmatism (p = 0.02). The mean corneal pachymeter, CV, ACD, ACA, and ACV were similar in both groups (p = 0.63, p = 0.26, p = 0.60, p = 0.41, and p = 0.32, respectively). The total mean corneal densitometry in the zones extending from 6 to 10 mm and 10 to 12 mm was increased in the VKC group compared to the control group (p = 0.04 and p = 0.012, respectively). The mean crystalline lens was found to be denser in the VKC group compared to the control group (8.96 ± 1.6 vs. 8.5 ± 0.57, respectively, p = 0.04). CONCLUSION: Posterior corneal astigmatism is increased in VKC cases in comparison with age- and gender-matched controls. The peripheral anterior 6-12 mm annular corneal zone showed increased corneal densitometry in VKC cases compared to the healthy subjects. Additionally, the lens clarity is found to be decreased subclinically in VKC cases compared to control cases.

Segmentation Errors in the Measurement of Volumetric Parameters by Swept-Source Anterior Segment Optical Coherence Tomography.

Purpose: To investigate the error rate of segmentation in the automatic measurement of anterior chamber volume (ACV) and iris volume (IV) by swept-source anterior segment optical coherence tomography (SS-ASOCT) in narrow-angle and wide-angle eyes. Methods: In this study, fifty eyes from 25 narrow-angle subjects and fifty eyes from 25 wide-angle subjects were enrolled. SS-ASOCT examinations were performed and each SS-ASOCT scan was reviewed, and segmentation errors in the automatic measurement of ACV and IV were classified and manually corrected. Error rates were compared between the narrow-angle and the wide-angle groups, and ACV and IV before and after manual correction were compared. Results: A total of 12,800 SS-ASOCT scans were reviewed. Segmentation error rates of angle recess, iris root, posterior surface of the iris, pupil margin, and anterior surface of the lens were 84.06, 93.30, 13.15, 59.21, and 25.27%, respectively. Segmentation errors of angle recess, iris root, posterior surface of the iris, and pupil margin occurred more frequently in narrow-angle eyes, while more segmentation errors of the anterior surface of the lens were found in wide-angle eyes (all P < 0.001). ACV decreased and IV increased significantly after manual correction of segmentation errors in both groups (all P < 0.01). Conclusion: Segmentation errors were prevalent in the volumetric measurement by SS-ASOCT, particularly in narrow-angle eyes, leading to mismeasurement of ACV and IV.

Chronological changes of the anterior chamber structure, axial length, and refraction in patients with Vogt-Koyanagi-Harada disease.

PURPOSE: To clarify the chronological changes in the anterior chamber structure and identify the spherical equivalent and axial length to assess the effects of steroid pulse treatment in patients with Vogt-Koyanagi-Harada disease with active uveitis. METHODS: The anterior chamber condition, including anterior chamber volume, central anterior chamber depth, peripheral anterior chamber depth, anterior chamber angle, and pupil diameter, was measured using Pentacam, and axial length was measured using IOLMaster in patients with Vogt-Koyanagi-Harada disease between June 2015 and February 2018. Furthermore, the best-corrected visual acuity, spherical equivalent, and retinal foveola thickness were also analyzed. All patients were treated with steroid pulse. All these factors were compared before and at 1 and 6 months of treatment. RESULTS: Significant changes were observed in the anterior chamber volume, central anterior chamber depth, peripheral anterior chamber depth, anterior chamber angle, axial length, best-corrected visual acuity, spherical equivalent, and retinal foveal thickness before and at 1 and 6 months of steroid pulse treatment (P < 0.001, P < 0.001, P < 0.001, P = 0.0015, P = 0.027, P < 0.001, P = 0.0043, and P < 0.001, respectively). No significant difference was observed in the pupil diameter before and at 1 month and 6 months of steroid pulse treatment (P = 0.11). CONCLUSION: The anterior chamber structure, axial length, best-corrected visual acuity, spherical equivalent, and retinal foveal thickness were dramatically changed by steroid pulse treatment in patients with Vogt-Koyanagi-Harada disease who develop active uveitis. These changes were completed within 1 month.

Anterior chamber dimensions, angles and pupil diameter in patients with Down syndrome: A comparative population-based study.

Purpose: To study the anterior chamber (AC) dimensions, angles and pupil diameter (PD) in patients with Down syndrome compared to normal controls. Methods: Prospective study is comparing the AC parameters in patients with Down syndrome aged 10-30 years and age-matched controls. Extracted indices included average anterior chamber depth on the 2-mm ring (ACD-2 mm), 4-mm ring (ACD-4 mm), at the corneal apex from the endothelium (endo-ACD), at the corneal apex from the epithelium (epi-ACD), anterior chamber volume (ACV), mean anterior chamber angle (ACA), and PD measured by Pentacam. Results: Data from 202 patients with Down syndrome (age 17.2 ± 4.8 years) were compared with 190 normal controls (age 17.2 ± 4.5 years). In Down and normal groups, mean ± SD were 2.51 ± 0.31 and 2.83 ± 0.34 mm for ACD-2 mm, 1.65 ± 0.30 and 1.93 ± 0.31 mm for ACD-4 mm, and 3.03 ± 0.29 and 3.24 ± 0.26 mm for endo-ACD, 3.54 ± 0.29 and 3.80 ± 0.26 mm for epi-ACD, mean 169.31 ± 30.38 and 200.17 ± 33.20 mm3 for ACV, 40.69 ± 4.50 and 39.97 ± 4.12° for ACA, and 2.79 ± 0.62 and 3.59 ± 0.80 mm for PD, respectively (all P < 0.001). None of the studied indices significantly correlated with age, except for ACA (P = 0.011). All parameters, except for PD, were significantly higher in males compared to females (all P < 0.001). Temporal ACA was significantly wider in male subjects (44.61 ± 6.52 vs. 42.24 ± 6.52°; P < 0.001). Conclusion: The AC in patients with Down syndrome is smaller than normal individuals. AC in females with Down syndrome is smaller than males, and the narrower ACA is attributable to the difference in the temporal angle and not the ACA in other meridians.

Observation of anterior chamber volume after cataract surgery with swept-source optical coherence tomography.

PURPOSE: To investigate the changes in the anterior chamber volume (ACV) with swept-source optical coherence tomography (SS-OCT) after cataract surgery and the factors that influence these ACV changes. METHODS: This was a prospective cohort study. Fifty-one patients who underwent cataract surgery were enrolled. Their ACV, anterior chamber depth, and angle widths were measured with SS-OCT before and 1 day, 1 week, and 1 month after surgery. The associations between the changes in ACV and posterior vitreous detachment (PVD) and axial length (AXL) were determined. RESULTS: Compared with the preoperative volume, ACV increased significantly at all three time points after surgery (all p < 0.001). ACV was greater at 1 week after surgery than at 1 day after surgery (p < 0.001). Both AXL and the presence of PVD were significantly associated with the change in ACV at 1 day after surgery (p = 0.005). However, neither PVD nor AXL affected the change in ACV between 1 day and 1 week after surgery. CONCLUSIONS: ACV stabilized in the first week after cataract surgery. The absorption of irrigation fluid and balanced salt solution in the vitreous cavity contributed to the change in ACV 1 week after surgery. Eyes with longer AXL and PVD tended to show less change in ACV at 1 day after surgery.

Anterior segment Scheimpflug imaging for detecting primary angle closure disease.

PURPOSE: To evaluate the capability of anterior segment Scheimpflug imaging for detecting primary angle closure disease (PACD): primary angle closure suspect, primary angle closure, and primary angle closure glaucoma, using cutoff points derived from reference databases of healthy subjects. METHODS: Eighty-seven patients with PACD and 49 age-matched control subjects were included. We evaluated the sensitivity and specificity of anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) to differentiate patients with PACD from controls. Additionally, the study's raw data was analyzed via receiver operating characteristic curves for comparison. RESULTS: One standard deviation from the normative data's mean values was used as the cutoff point and yielded a sensitivity and specificity of 96.2% and 92.6% for ACD, 97.1% and 75.9% for ACV, and 93.3% and 72.2% for ACA, respectively. Receiver operating characteristic analysis of the raw data showed the area under the curve to be 0.984, 0.975, and 0.931 for ACD, ACV, and ACA, respectively. CONCLUSIONS: Our study demonstrated that the parameters of anterior segment Scheimpflug imaging, particularly ACD, accurately discriminate PACD. This was the first study to validate the device's normative data in a separate population. With its high reproducibility, ease of use, non-invasiveness, and speed, anterior segment Scheimpflug imaging is a potentially powerful screening tool for PACD.

Anterior chamber indices in a population-based study using the Pentacam.

PURPOSE: To determine the distribution of anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) values in a rural population over 5 years of age using the Pentacam. METHODS: In this cross-sectional study, samples were selected from over 1-year-old inhabitants of two villages in Iran using a multistage cluster sampling approach. All participants underwent the measurement of uncorrected and corrected visual acuity and auto-refraction, retinoscopy, subjective refraction, and slit lamp examination. Finally, corneal imaging was done for all subjects over 5 years of age using the Pentacam. RESULTS: Of 3851 selected individuals, 3314 participated in the study, of whom 2681 met the inclusion criteria. The mean age of the sample was 36.03 ± 18.5 years (range 6-90 years). The mean ACD, ACA, and ACV values were 3.37 mm (95% CI: 3.37-3.39), 34.82° (95% CI: 34.45-35.2), and 159.17 µL (95% CI: 156-161.36), respectively. The results of multiple linear regression models showed that ACD, ACA, and ACV values reduced with age, and ACD and ACV values were significantly higher in males. ACA and ACV values correlated inversely with central corneal thickness, while the ACA value correlated directly with keratometry and inversely with the ACV value. CONCLUSION: This study is one of the few studies in the world showing changes in ACD values in different age groups using the Pentacam. According to the results, aging was associated with a decline in the mean ACD, ACA, and ACV values. These parameters were the largest in patients with emmetropia and smallest in hyperopic subjects.

Low iris and anterior chamber volume is associated with deepening after laser peripheral iridotomy in primary angle closure suspects.

PURPOSE: To evaluate the association between baseline ocular variables and the widening of the anterior chamber angle by laser peripheral iridotomy (LPI) in primary angle closure suspects (PACS) using a new Fourier-domain swept-source anterior segment optical coherence tomography (FD-ASOCT). METHOD: Sixty-six PACS eyes of 41 individuals were enrolled in this prospective interventional case series. An FD-ASOCT (Casia SS-1000 OCT; Tomey, Nagoya, Japan) was used to measure biometric baseline variables and at 1 month after the LPI. Paired t test was used to compare the difference between pre-and post-LPI measurements. Multivariate regression analysis was used to test for an association between baseline iris thickness and volume, anterior chamber depth and volume, and lens vault with a widening of the angle after an LPI. Changes in trabecular iris space area and angle opening distance after the LPI were main outcome measures. RESULTS: The mean age of participants was 58.6 ± 8.7 years, 68.2% of whom were female. The angle opening distance, recess area, and trabecular iris surface area at 500 µm increased by 48 to 73% (all P < 0.001). Lens vault and iris volume did not change. A low anterior chamber volume and low iris volume were associated with angle greater deepening by LPI. CONCLUSION: Eyes with a shallow anterior chamber and thinner irises are more likely to experience angle opening from an LPI.

Changes in anterior chamber volume after implantation of posterior chamber phakic intraocular lens in high myopia.

BACKGROUND: The present study aimed to assess changes in, and the factors that influence, anterior chamber volume (ACV) after implantable contact lens (ICL) implantation in high myopia eyes using a Pentacam. METHODS: The study sampled 26 high myopia patients (45 eyes) who were treated with ICL implantation. These patients were followed for an average of 4.28 months postoperatively. ACV was measured with a Pentacam preoperatively and at 3 months postoperatively. The data were analyzed by paired samples Wilcoxon signed-rank test. Generalized estimating equation (GEE) model adjusting within-patient intereye correlations in addition to Pearson's and Spearman's correlation tests were performed to determine associations. RESULTS: The mean ACV was 198.33 ± 33.08 mm3 before surgery and 118.65 ± 17.70 mm3 after surgery. A significant decrease of 79.68 mm3 (40.18%) (Z = 5.841, P <  0.001) was detected. Positive correlations were found between ACV changes and ICL central vault (r = 0.528, P <  0.001) and preoperative anterior chamber depth (ACD) (r = 0.665, P <  0.001). There were positive correlations between postoperative ACV and postoperative anterior chamber angle (ACA) at 3:00 o'clock (r = 0.448, P = 0.002) and at 9:00 o'clock (r = 0.405, P = 0.006). GEE regression model showed that postoperative ACV significantly positively correlated with preoperative ACV (P = 0.002), ACD (P = 0.002) and horizontal ACA (P = 0.005) and negatively correlated with ICL central vault (P <  0.001). CONCLUSION: Complementary to vault and ACD, ACV is a sensitive parameter with certain value of preoperative assessment and postoperative monitoring in ICL implantation.