Preprocessing of Iris Images for BSIF-Based Biometric Systems: Binary Detected Edges and Iris Unwrapping.

This work presents a novel approach to enhancing iris recognition systems through a two-module approach focusing on low-level image preprocessing techniques and advanced feature extraction. The primary contributions of this paper include: (i) the development of a robust preprocessing module utilizing the Canny algorithm for edge detection and the circle-based Hough transform for precise iris extraction, and (ii) the implementation of Binary Statistical Image Features (BSIF) with domain-specific filters trained on iris-specific data for improved biometric identification. By combining these advanced image preprocessing techniques, the proposed method addresses key challenges in iris recognition, such as occlusions, varying pigmentation, and textural diversity. Experimental results on the Human-inspired Domain-specific Binarized Image Features (HDBIF) Dataset, consisting of 1892 iris images, confirm the significant enhancements achieved. Moreover, this paper offers a comprehensive and reproducible research framework by providing source codes and access to the testing database through the Notre Dame University dataset website, thereby facilitating further application and study. Future research will focus on exploring adaptive algorithms and integrating machine learning techniques to improve performance across diverse and unpredictable real-world scenarios.

Fractional-order Sprott K chaotic system and its application to biometric iris image encryption.

Fractional-order (FO) chaotic systems exhibit random sequences of significantly greater complexity when compared to integer-order systems. This feature makes FO chaotic systems more secure against various attacks in image cryptosystems. In this study, the dynamical characteristics of the FO Sprott K chaotic system are thoroughly investigated by phase planes, bifurcation diagrams, and Lyapunov exponential spectrums to be utilized in biometric iris image encryption. It is proven with the numerical studies the Sprott K system demonstrates chaotic behaviour when the order of the system is selected as 0.9. Afterward, the introduced FO Sprott K chaotic system-based biometric iris image encryption design is carried out in the study. According to the results of the statistical and attack analyses of the encryption design, the secure transmission of biometric iris images is successful using the proposed encryption design. Thus, the FO Sprott K chaotic system can be employed effectively in chaos-based encryption applications.

Prediction of footplate position after implantable collamer lens implantation based on iris and ciliary body morphologies.

PURPOSE: To investigate the factors affecting footplate position and its influence on vault characteristics after implantable collamer lens (ICL) implantation. SETTING: Hunan Provincial People's Hospital, Changsha, China. DESIGN: Retrospective case series. METHODS: This study included 124 patients (124 eyes). Ultrasound biomicroscopy (UBM) was performed to assess the iris and ciliary body morphologies and observe the footplate position. Using multiple linear regression, the relationship between various ocular and ICL parameters and the vault as well as the factors affecting the footplate distance (FD) were analyzed. Based on the FD, 3 groups were formed: group 1 (<500 µm), group 2 (500 to 1000 µm), and group 3 (>1000 µm). The distribution of the vault range postoperatively was observed for the 3 groups. RESULTS: Ciliary sulcus angle and FD significantly affected the vault (adjusted R2 = 0.190, F = 6.763, P < .001), with FD being the most important factor influencing the vault (ß = -0.383, P < .001). Postoperative UBM revealed that the footplate was located at different positions in the posterior chamber, with the majority (52%) being located on the ciliary body. The mean size of the 4 footplate orientations was 0.88 ± 0.24 mm. Multiple linear regression analysis revealed that ciliary body thickness (CBT), iris curvature (IC), and ICL iris contact length (IRCL) significantly influenced the FD (adjusted R2 = 0.373, F = 11.432, P < .001). The vault range differed significantly among the 3 groups (X 2 = 32.33, P < .001). CONCLUSIONS: Different postoperative ICL footplate positions significantly affect the vault. CBT, IC, and IRCL can alter the position of the footplate from the expected position. This study provides reference for ICL size selection and vault prediction.

A method for extracting corneal reflection images from multiple eye images.

The incident light reflected from the cornea is rich in information about the human surroundings, and these reflected rays are imaged by the camera, which can be used for research on human consciousness and gaze analysis, and produce certain help in the fields of psychology, human computer interaction and disease diagnosis. However, limited by the low corneal reflection ability, when a high-definition camera captures corneal reflecting rays, a large amount of color and texture interference from the iris can seriously contaminate the corneal reflection images, resulting in low usability and ubiquity of corneal reflection images. In this paper, we propose a corneal reflection image extraction method with multiple eye images as input. We align the iris regions of multiple eye images with the help of iris localization method, and by comparing multiple iris regions, we obtain the complementary iris regions, so that the iris interference in the corneal reflection region can be stripped completely. A large number of experiments have demonstrated that our work can effectively mitigate iris interference and effectively improve the quality of corneal reflection images.

Anterior segment swept-source optical coherence tomography and ultrasound biomicroscopy in iris and ciliary body lesions.

OBJECTIVES: Differentiation of iris and ciliary body lesions as benign or malignant and cystic or solid is important. The aim of this study was to compare anterior segment swept-source optical coherence tomography (AS SS-OCT) and ultrasound biomicroscopy (UBM) findings in iris and ciliary body tumors. RESEARCH DESIGN AND METHODS: Forty-two eyes of 38 cases with iris and ciliary body tumors imaged with UBM and AS SS-OCT between September 2018 and September 2023 were evaluated retrospectively. RESULTS: Of 42 eyes, 14 had melanoma, 14 iris pigment epithelial (IPE) cysts, 7 nevi, 3 Lisch nodules, 2 iris stromal cysts, 1 pars plana cysts, and 1 iris mammillations. An equivalent (100%) visualization of the anterior tumor margin was obtained with both techniques. Compared to AS SS-OCT, UBM was superior for posterior margin visualization in melanocytic tumors and IPE cysts. Bland-Altman plots demonstrated good agreement between UBM and AS SS-OCT for melanocytic tumors < 2.5 mm in base diameter and < 2 mm in thickness. CONCLUSIONS: Although, UBM is the gold standard for ciliary body and iridociliary tumors. AS SS-OCT should be considered as an excellent alternative to UBM, especially in minimally elevated iris lesions.

Reverse pupillary block, in contemporary scleral intraocular lens procedures.

BACKGROUND: To evaluate the frequency and anterior segment optical coherence tomography parameters of patients with scleral fixated intraocular lenses (IOL) and reverse pupillary block (RPB). METHODS: Retrospective analysis at a tertiary care centre (Department for Ophthalmology and Optometry, Medical University of Vienna, Austria). We researched our records for patients who underwent scleral fixated IOL implantation from January 2018 till February 2023. Patients were included only if there was at least one adequate post-operative scan of anterior segment optical coherence tomography (AS-OCT) available. Initially, AS-OCT scans were assessed for IOL tilt and decentration employing a 3D scan and then later for anterior chamber angle (ACA), aqueous anterior chamber depth (AQD), pupil diameter and iris-IOL distance using the 2D scan at a 0° angle. Both an iris-IOL distance of 0 or less and an ACA of more than 70° were required to define an RPB. RESULTS: A total of 110 patients met the inclusion criteria, 41 were treated using the Carlevale, 33 the four flanged, 24 the Yamane and 12 the Scharioth technique, respectively. RPB was found in 32 patients (29%). Twenty patients with RPB were treated using YAG peripheral iridotomy, mean ACA decreased from 91.91° ± 13.77 to 61.02° ± 8.52, (p < 0.001), mean AQD decreased from 4.67 mm ± 0.47 to 4.31 ± 0.36 mm (p < 0.001) and mean iris-IOL distance increased from -0.09 ± 0.04 to 0.33 ± 0.30 (p < 0.001). CONCLUSIONS: RPB is found in a third of eyes who have undergone scleral fixated IOL implantation without iridectomy. YAG peripheral iridotomy is a potent option to treat RPB, and subsequently reduce the risk of iris chafing and secondary inflammation or glaucoma.

Iris neovascularization and neurotrophic keratopathy following ultrasound cycloplasty in refractory glaucoma: case series.

BACKGROUND: Ultrasound cycloplasty is a noninvasive surgery used to reduce intraocular pressure in patients with glaucoma, with fewer severe complications. This report presents several cases of iris neovascularization and neurotrophic keratopathy following ultrasound cycloplasty. CASE PRESENTATION: Six patients diagnosed with refractory glaucoma underwent ultrasound cycloplasty at our clinic. Three cases developed iris neovascularization at postoperative day 3, week 2 and week 4 respectively, with intraocular pressure ranging from 12 to 24 mmHg. The other three cases developed neurotrophic keratopathy at postoperative week 3, week 6 and week 8 which completely healed within 60 days. CONCLUSIONS: Iris neovascularization and neurotrophic keratopathy can be triggered after ultrasound cycloplasty, which are uncommon and self-limited but potentially vision-threatening. Preoperative risk assessment and regular postoperative follow-up are recommended to manage complications effectively.

Diagnostic criteria of anterior segment swept-source optical coherence tomography to detect gonioscopic angle closure.

AIMS: To compare the diagnostic performance of 360° anterior segment optical coherence tomography assessment by applying normative percentile cut-offs versus iris trabecular contact (ITC) for detecting gonioscopic angle closure. METHODS: In this multicentre study, 394 healthy individuals were included in the normative dataset to derive the age-specific and angle location-specific normative percentiles of angle open distance (AOD500) and trabecular iris space area (TISA500) which were measured every 10° for 360°. 119 healthy participants and 170 patients with angle closure by gonioscopy were included in the test dataset to investigate the diagnostic performance of three sets of criteria for detection of gonioscopic angle closure: (1) the 10th and (2) the 5th percentiles of AOD500/TISA500, and (3) ITC (ie, AOD500/TISA500=0 mm/mm2). The number of angle locations with angle closure defined by each set of the criteria for each eye was used to generate the receiver operating characteristic (ROC) curve for the discrimination between gonioscopic angle closure and open angle. RESULTS: Of the three sets of diagnostic criteria examined, the area under the ROC curve was greatest for the 10th percentile of AOD500 (0.933), whereas the ITC criterion AOD500=0 mm showed the smallest area under the ROC (0.852) and the difference was statistically significant with or without adjusting for age and axial length (p<0.001). The criterion ≥90° of AOD500 below the 10th percentile attained the best sensitivity 87.6% and specificity 84.9% combination for detecting gonioscopic angle closure. CONCLUSIONS: Applying the normative percentiles of angle measurements yielded a higher diagnostic performance than ITC for detecting angle closure on gonioscopy.

Cysts and tumours of the iris: Diagnostic tools and key management considerations-A review.

The iris is a unique structure, with exquisite variations in colour and form. Pathological changes, specifically including iris cysts and tumours are relatively uncommon, difficult to diagnose, and yet potentially blinding or life-threatening. Based on a comprehensive literature review, with highly illustrated key case examples, this report aims to guide the clinician in filtering the differential diagnoses of iris cysts and tumours. Evaluation is in the context of key diagnostic clinical tools and management considerations. Diagnostic imaging techniques include serial anterior segment photography, ultrasound, anterior segment optical coherence tomography, and iris fluorescein angiography, however, the roles of computerised topography and magnetic resonance imaging are also considered in this review. Management includes categorisation in terms of solid iris tumours (melanocytic vs. non-melanocytic), or iris cysts (primary vs. secondary) that may be usefully differentiated by clinical assessment, avoiding more invasive interventions. Cystic lesions are generally benign, although implantation cysts in particular cause significant complications and surgical challenges. Most solid tumours are melanocytic and also typically benign. However, in larger lesions, rapid growth, symptoms and complications more likely indicate malignancy, requiring further investigation.

Correlation of fitzpatrick skin type and iris color with tumor size in 823 patients with uveal melanoma.

PURPOSE: To determine the correlation of Fitzpatrick Skin Type (FST) and iris color with tumor size (tumor thickness and basal diameter) in patients with uveal melanoma. DESIGN: Retrospective Cohort METHODS: Retrospective cohort from a single ocular oncology center of 823 patients with uveal melanoma and documented FST, iris color, and tumor size. Patients were classified by FST (type I, II, and III-V) and iris color (blue, green, and brown) on the basis of external facial photography. There were no FST type VI patients. Tumor thickness was classified into small [< 3 millimeter (mm)], medium (3.1-8.0 mm), or large (> 8.0 mm), and basal diameter into small (< 10 mm), medium (10.1-15 mm) or large (> 15 mm). The correlation of FST and iris color with tumor thickness and basal diameter was evaluated using the Kruskal-Wallis H test. RESULTS: The FST classification was type I (n = 92, 11%), type II (n = 643, 78%), or III-V (n = 88, 11%), and iris color was blue (n = 472, 57%), green (n = 102, 12%), or brown (n = 249, 30%). A comparison of FST revealed differences in mean tumor thickness (P = 0.04) and basal diameter (P = 0.006). Iris color showed no difference for mean tumor thickness (P = 0.41) or basal diameter (P = 0.48). There was a statistically significant difference with brown iris color relative to FST III-V for mean tumor thickness (P = 0.003) and basal diameter (P = 0.001) but no difference with blue or green iris color (P > 0.05). CONCLUSIONS: Iris color alone showed no difference in tumor size, but those with brown iris color and FST type III-V demonstrated larger tumor thickness and basal diameter.

Quantitative analysis of dynamic iris changes in primary angle-closure disease with long axial lengths: the Handan Eye Study.

OBJECTIVE: To investigate dynamic iris changes in patients with primary angle-closure disease (PACD) with long axial length (AL) compared to those with short and medium AL. METHODS: This observational cross-sectional study enrolled participants aged 35 years or older from the Handan Eye Study follow-up examination who were diagnosed with PACD and underwent Visante anterior segment optical coherence tomography (ASOCT) imaging under light and dark conditions. The right eye of each participant was included in the analysis. AL was categorized as short (<22.0 mm), medium (≥22.0 to ≤23.5 mm), or long (>23.5 mm). Anterior segment parameters, including iris dynamic changes, were compared among the three groups with different ALs. RESULTS: Data from 448 patients with PACD were analyzed. We found that 10.9% of included eyes had a long AL with a flatter cornea; larger central anterior chamber depth, angle opening distance, anterior chamber width, anterior chamber area, and volume; and smaller lens thickness and lens vault (LV) (P < 0.05) than those with short AL. No significant difference existed between the three groups in iris thickness, iris cross-sectional area (IA), iris curvature, or pupil diameter (PD) change between light and dark (P > 0.05). The significant associated factors for IA changes were area recess area (ARA) in the dark, LV in the dark, and PD change from light to dark (P < 0.05). CONCLUSIONS: Dynamic and static iris parameters were consistent across patients with PACD with short, medium, or long AL and may contribute to the pathogenesis of angle closure in atypical PACD.

Simultaneous evaluation of iris area and subfoveal choroidal thickness in Fuchs uveitis syndrome.

BACKGROUND/AIMS: To simultaneously evaluate iris area (IA) and subfoveal choroidal thickness (SFCT) in eyes with Fuchs Uveitis Syndrome (FUS). METHODS: We prospectively recruited a case series of patients with FUS at our institution, simultaneously measuring IA with anterior segment spectral domain optical coherence tomography (SD-OCT) and SFCT with enhanced depth imaging optical coherence tomography (EDI-OCT). Iris images were analyzed by ImageJ software. We tested the differences in intereye IA and SFCT with the healthy eye (HE) using the Wilcoxon test, and clinical interpretation was controlled by intraclass correlation coefficient (ICC) between two masked specialists. RESULTS: Sixteen patients with unilateral FUS were included. Six were female, and the age range was 37 to 67 (median age 48 years, IQR 41-60). ICC of 98.9%, with a lower confidence interval of 97%. Eyes with FUS had a significant thinning of the total iris median area (p < 0.002), restricted to the temporal and nasal areas compared to the HE (p < 0.01 and < 0.001, respectively). SFCT was also significantly thinner compared to the HE (p < 0.0001). A low correlation was found between iris and choroidal thinning in FUS eyes (rs = 0.21; p = 0.4). CONCLUSIONS: This study found reduced iris area and subfoveal choroidal thickness in eyes with FUS compared to the normal fellow eye.

Atypical presentation of bilateral iridoschisis with abnormal visibility of iris vessels: Role of anterior segment optical coherence tomography.

PURPOSE: To describe clinical and anterior segment optical coherence tomography (AS-OCT) findings in a patient with bilateral iridoschisis and unilateral angle closure glaucoma (ACG) associated with abnormal visibility of iris vessels. CASE PRESENTATION: A 67-year-old male patient with a history of red and painful left eye (LE) one year earlier, presented to our ophthalmology department for a routine examination.Ophthalmic examination of the right eye revealed narrow anterior chamber with sectorial iris atrophy associated to abnormal visibility of an iris vessel. Intraocular pressure (IOP) was 12 mmHg with normal optic disc appearance. LE anterior chamber was narrow with diffuse iris atrophy and abnormal vessels visibility. IOP was 28 mmHg with an important optic disc excavation. On gonioscopy, angle was narrow without neovessels nor synechiae. AS-OCT of both eyes revealed shallow angles, iris splitting with material release in the anterior chamber, while pigmented epithelium was preservedAnti-glaucoma eye drops were prescribed and peripheral laser iridotomy was performed in both eyes with decreased IOP at 14 mmHg in the LE. CONCLUSION: Iridoschisis is a rare ocular condition characterized by a separation between the anterior and posterior layers of iris stroma with several clinical presentations, and may be associated with abnormal visibility of iris vessels in some cases. The diagnosis of iridoschisis may be challenging and AS-OCT can be a very useful tool to confirm the diagnosis in atypical presentations and to detect associated angle closure.

The correlation of anterior segment structures in primary congenital glaucoma by ultrasound biomicroscopy with disease severity and surgical outcomes.

PURPOSE: To evaluate the anterior segment structures using ultrasound biomicroscopy (UBM) in primary congenital glaucoma (PCG) and explore their correlation with disease severity and surgical outcomes. METHODS: Clinical information of PCG patients who underwent UBM prior to their first glaucoma surgeries from September 2014 to March 2021 were reviewed. The study included 214 UBM images of 154 PCG eyes and 60 fellow unaffected eyes. Anterior segment characteristics were analyzed. UBM parameters, including the iris thickness (IT) at variant distances from the pupil edge and iris root, anterior chamber depth (ACD), and pupil diameter (PD), were compared between two groups and their relationship with clinical factors and surgical outcomes were analyzed in PCG eyes. RESULTS: PCG eyes had unclear scleral spur, thin iris, wide anterior chamber angle, deep anterior chamber, rarefied ciliary body, elongated ciliary processes, and abnormal anterior iris insertion. ITs were thinner, ACD was deeper, and PD was larger in PCG eyes than fellow unaffected eyes (all P < 0.001). In PCG eyes, thinner ITs correlated with bilateral involvement and earlier age at presentation, and larger PD correlated with earlier age at presentation (P = 0.030) and higher intraocular pressure (P < 0.001). Thinner IT2 (P = 0.046) and larger PD (P = 0.049) were identified as risk factors for surgical failure. CONCLUSION: UBM is a powerful technique to exam anterior segment structures in PCG. The anatomical features are associated with disease severity and surgical outcomes, providing essential clinical insights.

Progressive Changes in the Anterior Segment and Their Impact on the Anterior Chamber Angle in Primary Angle Closure Disease.

PURPOSE: To investigate longitudinal changes in the anterior segment (AS) using serial optical coherence tomography (OCT) images and determine the impact of these changes on the anterior chamber angle (ACA) in eyes with primary angle closure disease (PACD) treated with laser peripheral iridotomy (LPI). DESIGN: Retrospective clinical cohort study. METHODS: This study included 103 patients with PACD who underwent LPI and were followed up by a mean 6.7 ± 1.7 AS-OCT examinations for a mean 6.5 ± 2.9 years. Temporal changes in AS-OCT parameters, including anterior chamber depth (ACD), angle opening distance (AOD750), angle recess area (ARA750), iris thickness (IT750), lens vault (LV), and pupil diameter (PD), were analyzed by multivariate linear mixed effects models (LMEMs). RESULTS: Multivariate LMEMs showed that decrease in AOD750 was not significant (-1.59 µm/y, P = .222); however, ARA750 decreased over time (-2.3 × 103 µm2/y, P = .033) and SSA showed marginal significance (-0.20°/y, P = .098), and LV increased significantly (11.6 µm/y, P < .001) after LPI. Mean LV change was negatively associated with AOD750, ARA750, and SSA, whereas PD was negatively associated with ARA750 (P < .001 each). PD decreased with aging (-13.7 µm/y, P = .036), accompanied by thinning of IT750 (-1.7 µm/y, P = .063). CONCLUSIONS: LV tends to increase with aging, which contributes to the shallowing of the anterior chamber and narrowing of ACA in PACD eyes treated with LPI. In the meantime, pupillary constriction and subsequent peripheral iris thinning associated with aging could possibly offset the effect of ACA narrowing.

The use of optical coherence tomography angiography to measure changes in iris vasculature after strabismus surgery.

INTRODUCTION: Anterior segment ischemia (ASI) is a rare but potentially sight-threatening complication of strabismus surgery. Preoperative imaging of the iris vasculature may be appropriate in patients at high risk of ASI. In clinical practice, this is currently done through invasive fluoresceine or indocyanine green (ICG) angiography and in study context through laser speckle contrast imaging. The purpose of this study is to investigate the use of noninvasive optical coherence tomography angiography (OCTA) as a screening tool for ASI in strabismus surgery. METHODS: A prospective interventional trial was conducted from September until November 2021 at the Leuven University Hospitals. Patients scheduled for strabismus surgery to one or more rectus muscles underwent OCTA preoperatively and at day two postoperatively. The vascular density was calculated for all images with sufficient quality. Information on risk factors for ASI was collected. A two-sided t-test was used for pairwise comparison pre- and postoperatively. Filling defects were qualitatively assessed. RESULTS: Eighteen patients were included. In only seven muscles of five patients, images of sufficient quality on both image acquisition moments were suitable for statistical analysis. The mean age of these patients was 45.2 years and 40% were women. A mean vascular density of 53,099% preoperatively and a mean density of 50,782% postoperatively with a mean decrease of 2.316% (p = .318, 95% confidence interval [-2.886; 7.516]) was found. No filling defects were identified. DISCUSSION: The small final number of images contributing to statistical analysis shows that current application of the OCTA technique is hampered by poor image quality and poor repeatability. We identified difficulties in the image acquisition process and variable pupil size due to iris muscle contractions as the two main reasons. We believe that adjustments in the OCTA software such as pupil tracking and tracking of iris vasculature can largely overcome these limitations. Furthermore, there is a need for a normative database to allow good quantitative comparison and risk stratification. We conclude that OCTA could be suitable for screening in prevention of ASI with both qualitative and quantitative analysis if adjustments are made.

Imaging analysis of the biological parameters of the lens in patients with cortical age-related cataracts using ultrasound biomicroscopy.

BACKGROUND: The spatial position of the lens in patients with cortical age-related cataract (CARC) is unclear. We investigated a basis for the assessment of visual quality after cataract surgery by analysing the ultrasound biomicroscopic characteristics of the biological parameters of the lens in patients with CARC. METHODS: In this retrospective study, 119 patients (50 males and 69 females, totalling 238 eyes) with CARC who underwent simple cataract surgery were selected. The lens thickness (LT), axial length (AL), anterior chamber depth (ACD), lens vault (LV), trabecular-iris angle (TIA), iris-lens angle (ILA), iris-lens contact distance (ILCD) were measured by A-scan ultrasound and ultrasound biomicroscopy. The corresponding lens position (LP) and relative lens position (RLP) were calculated. RESULTS: LP was greater in men than in women (P < 0.05), LV was smaller in men than in women (P = 0.002), ILA and ILCD were not statistically significant (P = 0.072 and P = 0.854, respectively). There were significant differences in TIA, ILA, and ILCD in the four quadrants (all P < 0.05), with a trend in the distribution of TIA: superior < inferior < nasal < temporal, ILA: nasal < inferior < temporal < superior, and ILCD: superior < temporal < inferior < nasal. CONCLUSIONS: The lens protrudes more obviously in females than in males and the lens tilts to a certain extent with the increase of age and tends to be more upward and temporal in the supine position. Therefore, trends in lens-related parameters in patients with CARC should be taken seriously.

The ocular anterior segment examination of perinatal newborns by wide-field digital imaging system: a cross-sectional study.

PURPOSE: The aim of this study was to evaluate and summarize the developmental rules of the ocular anterior segment of neonates by means of wild-field digital imaging system. METHODS: We used the wide-field digital imaging system to sequentially capture images of the neonates' eyes within 42 days after delivery, including the ocular surface, anterior segment, and fundus. At the same time, basic information at the time of birth and examination was collected. RESULTS: Among 248 newborns, 51.21% were male. Abnormalities of the anterior segment such as visualization of anterior chamber angle vessels (79.03%) and iris vessels (51.21%), iris process (42.34%), persistent pupillary membranes (19.35%), albinism, congenital cataracts, corneal leucoma, and subconjunctival hemorrhage were observed in this study. There were significant differences in the appearance of iris vessels among different sex, gestational age and birth weight, postmenstrual age and weight at the time of examination and iris color groups. The iris vessels were more visualized in males relative to females (OR = 6.313, 95% CI 2.529-15.759). The greater the postmenstrual age at the time of examination, the lower the visualization of iris vessels (OR = 0.377, 95% CI 0.247-0.575). In addition, although visualization of anterior chamber angle vessels differed within the birth gestation age and weight at examination groups, there was no significant correlation by regression analysis. CONCLUSIONS: The anterior segment of perinatal neonates can be visualized by the wide-field digital imaging system. The neonatal iris and anterior chamber angle are immature, and the visible vessels at the anterior chamber angle that vanish later than the surface of the iris are characteristic structures.

Comparative study of the effects of laser peripheral iridotomy and cataract surgery on anterior chamber angle parameters in primary angle closure suspect patients.

INTRODUCTION: Prophylactic laser peripheral iridotomy (LPI) and cataract surgery are considered the primary treatments for primary angle closure suspect (PACS) as they have proven effectiveness in widening the iridocorneal angle and addressing the underlying anatomical issues associated with this condition. The objective of this study is to compare the impact of LPI and cataract surgery on anterior chamber angle parameters, aiming to fill the existing research gap. METHODOLOGY: A prospective comparative study was conducted, involving 76 eyes of 61 patients. The study focused on patients diagnosed with PACSs and early cataract. The patients received treatment either through LPI or cataract surgery. Comprehensive eye examination was performed, including gonioscopy and anterior segment parameters were measured using anterior segment ocular coherence tomography (ASOCT). Follow-up examinations were conducted at 1 week and 1 month after the procedures, which included ASOCT and gonioscopy performed during the 1-month follow-up. RESULTS: All anterior chamber angle parameters increased significantly after treatment in both groups, including trabecular iris angle (TIA), angle opening distance at 250, 500 and 750 µm (AOD 250, AOD500, AOD750), trabecular iris surface area at 500 and 750 µm (TISA500, TISA750) and angle recess area at 500 and 750 µm from scleral spur (ARA500, ARA750) (p<0.05 for all). Moreover, all these parameters were greater after cataract surgery than after LPI (p<0.05 for all). CONCLUSION: Compared with LPI, cataract extraction resulted in a wider anterior chamber angle. Moreover, no residual angle closure was observed after cataract extraction, which could morphologically prevent the progress of angle closure. Thus, cataract extraction is superior to LPI in PACSs with early cataract in widening the anterior chamber angle.