Disease-related and age-related changes of anterior chamber angle structures in patients with primary congenital glaucoma: An in vivo high-frequency ultrasound biomicroscopy-based study

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.

Primary congenital glaucoma: An iridotrabeculodysgenesis?

PURPOSE

To analyze primary congenital glaucoma (PCG) anterior chamber and angle anomalies over 360° as possible biomarkers of severity and prognosis.

METHODS

A cross-sectional observational study was conducted analyzing anterior segment anomalies of PCG patients over 4 years of age who underwent trabeculectomy combined with trabeculotomy and age-matched controls using anterior segment optical coherence tomography (ASOCT), CASIA-2. Anterior iridotrabecular adhesions or anterior iris insertion was identified and quantified from the scleral spur using the iridotrabecular contact (ITC) index parameter as a surrogate.

RESULTS

There was a variable but significantly increased anterior iridotrabecular adhesion on ITC index, ITC area, corneal volume, anterior chamber volume, iris volume, anterior chamber depth, and small/absent trabecular meshwork in PCG eyes compared to control eyes. In PCG eyes, anterior iridotrabecular adhesion had a positive correlation with pre-operative central corneal thickness (CCT) (r = 0.53, P = 0.02), review iris thickness (r = 0.4, P = 0.04), and ITC area (r = 0.85, P < 0.001). Review iris thickness had a negative correlation with pre-operative vertical cup-disc ratio (r = -0.51, P = 0.008). Iris hypoplasia with fewer or absent folds, collarette, pupillary ruff, and pupillary ruff to collarette distance was significantly different from controls.

CONCLUSION

ASOCT in PCG eyes has shown that they have variable anterior iridotrabecular tissue adhesions, anomalous tissue/membranes in the angle, and iris hypoplasia correlating with pre-operative cup-disc ratio. These features could be used as gonioscopic and clinical biomarkers to assess the severity and prognosis of the disease. The presence of abnormal iris morphology and iridotrabecular tissue anomalies in PCG suggests that it is more than just isolated trabeculodysgenesis and is probably best considered as part of the anterior segment dysgenesis spectrum.

Genetic Aspects of Glaucoma: An Updated Review

Glaucoma is a group of diverse diseases characterized by cupping of the optic nerve head due to the loss of retinal ganglion cells. It is the most common cause of irreversible blindness throughout the world; therefore, its timely diagnosis and early detection through an ophthalmological examination are very important. We, herein, present the information on the epidemiology, pathophysiology, clinical diagnosis, and treatment of glaucoma. We also emphasize the investigations of the last decades that have allowed identifying numerous genes and susceptibility genetic factors. We have also described in detail the genes whose mutations cause or contribute to the development of the disease.

Evaluation of the Anterior Chamber Angle Structures in Perinatal Infants Using a Wide-Field Digital Fundus Camera

OBJECTIVE

This study aimed to evaluate the ability of a digital fundus camera to observe the development of the anterior chamber angle (ACA) in premature infants.

METHODS

Forty-eight eyes of preterm infants (n=48) were examined by a digital fundus camera to observe the development of the ACA. ACA grading was performed based on the visualization of the anterior chamber structures according to the Scheie Angle Depth Evaluating System.

RESULTS

ACA images from all 48 infants were successfully acquired using RetCam3. The corrected gestational age ranged from 30 weeks to 49 weeks, which covered the period from 2 months preterm to >2 months post-term. As the corrected gestational age increased, the corrected gestational age grading was significantly decreased. The mean corrected gestational ages of the infants corresponding to the ACA classification from grade IV to grade 0 were 32.75±1.89, 37.20±1.30, 39.75±2.38, 40.56±2.24, and 44.23±2.14 weeks, respectively, which were all significantly different (P<0.05). The regression analysis showed a linear correlation between the grading of the ACA and the corrected gestational age (R²=0.724, P=0.0001).

CONCLUSION

The ACA of a full-term newborn can be fully detected and evaluated by a digital fundus camera. For premature infants, part of the ACA is not visible physiologically; however, it should not be misdiagnosed as angle closure or a narrow angle.

Deep Learning Segmentation, Visualization, and Automated 3D Assessment of Ciliary Body in 3D Ultrasound Biomicroscopy Images

Purpose

This study aimed to develop a fully automated deep learning ciliary body segmentation and assessment approach in three-dimensional ultrasound biomicroscopy (3D-UBM) images.

Methods

Each 3D-UBM eye volume was aligned to the optic axis via multiplanar reformatting. Ciliary muscle and processes were manually annotated, and Deeplab-v3+ models with different loss functions were trained to segment the ciliary body (ciliary muscle and processes) in both en face and radial images.

Results

We trained and tested the models on 4320 radial and 3864 en face images from 12 cadaver eye volumes. Deep learning models trained on radial images with Dice loss achieved the highest mean F1-score (0.89) for ciliary body segmentation. For three-class segmentation (ciliary muscle, processes, and background), radial images with Dice loss achieved the highest mean F1-score (0.75 for the ciliary process and 0.82 for the ciliary muscle). Part of the ciliary muscle (10.9%) was misclassified as the ciliary process and vice versa, which occurred owing to the difficulty in differentiating the ciliary muscle–processes border, even by experts. Deep learning segmentation made further editing by experts at least seven times faster than a fully manual approach. In eight cadaver eyes, the average ciliary muscle, process, and body volumes were 56 ± 9, 43 ± 13, and 99 ± 18 mm³, respectively. The average surface area of the ciliary muscle, process, and body were 346 ± 45, 363 ± 83, and 709 ± 80 mm², respectively. We performed transscleral cyclophotocoagulation in cadaver eyes to shrink the ciliary processes. Both manual and automated measurements from deep learning segmentation show a decrease in volume, surface area, and 360° cross-sectional area measurements.

Conclusions

The proposed deep learning segmentation of the ciliary body and 3D measurements showed transscleral cyclophotocoagulation-related changes in the ciliary body.

Translational Relevance

Automated ciliary body assessment using 3D-UBM has the translational potential for ophthalmic treatment planning and monitoring.

Weill-Marchesani syndrome 4 caused by compound heterozygosity of a maternal submicroscopic deletion and a paternal nonsense variant in the ADAMTS17 gene: A case report

Purpose

To retrospectively report a case of Weill-Marchesani syndrome 4 (WMS4) with compound heterozygous variants of ADAMTS17 gene.

Observations

The patient was a 7-year-old boy with progressively worsening eyesight and intermittent elevated intraocular pressure (IOP) for two years. His IOPs were temporarily controlled using anti-glaucoma drugs. At presentation he had a shallow anterior chamber, lens subluxation, spherophakia and extensive synechial angle closure with high myopia in both eyes. Ultrasound biomicroscopy (UBM) identified thickened zonule fibers and anteriorly rotated, flat and slender ciliary processes, both of which worsened and were accompanied by obvious iris bombe after miosis. Gene testing showed compound heterozygosity of a maternal submicroscopic deletion on chromosome 15q26.3 (0.774 Mb) affecting the sequences of ADAMTS17, LYSMD4 and CERS3 as well as a paternal nonsense variant (c.1051_1053delAAGinsTAA, P.K351X) in the ADAMTS17 gene in the proband. The diagnosis of WMS4 was confirmed by genetic testing. Phacoemulsification (Phaco), intraocular lens (IOL) implantation, and irido-zonulo-hyaloid-vitrectomy (IZHV) combined with Ahmed Glaucoma Valve (AGV) implantation as a staged or one-stage surgery effectively lowered IOP, deepened ACD, improved visual acuity, and resolved the configuration of the ciliary processes in both eyes.

Conclusion and Importance

Recessive ADAMTS17 variants are associated with WMS4. We report here compound heterozygous variants in ADAMTS17 causing WMS4, and anatomically highlighted the possible pathophysiology for its clinical phenotype. A modified surgical approach with Phaco, IOL implantation, and IZHV combined with AGV implantation could be used to treat these complicated cases.

Ultrasound biomicroscopy of the anterior segment in patients with primary congenital glaucoma: a review of the literature

PURPOSE

Primary congenital glaucoma (PCG) is a form of childhood glaucoma caused by maldevelopment of the anterior chamber. Disease severity differs greatly amongst patients. Ultrasound biomicroscopy (UBM) is a non-invasive technique that can visualize the anterior segment in infants in vivo. The purpose of this narrative review is to make an overview of the UBM data in PCG and study the applicability of UBM in characterizing the disease.

METHODS

An online search was performed on PubMed in December 2020. After a critical appraisal of the included articles, study and patient characteristics were summarized. The UBM measurements of the anterior segment in PCG of the different studies were analysed.

RESULTS

Six studies were included in this review. All were cross-sectional prospective studies. A total of 221 PCG eyes were examined. PCG eyes showed a larger trabecular iris angle, decreased iris thickness, narrower or absent Schlemm's canal and an increased zonular length compared to controls. Abnormal tissue membrane covering the trabecular meshwork and abnormal insertion of the iris and ciliary process were frequently found. The success rate of glaucoma surgery depended on the severity of anterior segment malformations found with UBM.

CONCLUSION

Malformations of the anterior segment in PCG can be demonstrated by UBM in vivo. This imaging can help to characterize disease severity and might support surgical treatment decisions.

Repeatability and Reliability of Quantified Ultrasound Biomicroscopy Image Analysis of the Ciliary Body at the Pars Plicata

Most of the ciliary body and ciliary processes of the eye cannot be directly visualized in vivo because of the posterior location of the pars plicata to the posterior chamber and iris. However, ciliary anatomy can be effectively imaged using ultrasound biomicroscopy (UBM) by placing the probe close to the limbus, perpendicular to this structure. Previous studies measuring ciliary body parameters in meridian UBM images found that these parameters were measured with poor reliability and repeatability. This study evaluates the intra-observer reliability and inter-observer agreement of a standardized protocol for measuring six ciliary parameters in transverse or quadrant UBM images that capture an entire row of ciliary processes. All six ciliary parameters have high intra-observer reliability, with ciliary body thickness, ciliary process length and ciliary process density measurements being the most consistent for each observer. The coefficient of variation for each observer ranged from 1.4%-15%. Inter-observer agreement was also high for all six parameters, with an intra-class correlation coefficient >0.8. Utilizing transverse UBM images of the pars plicata allows for consistent quantitative analysis in control subjects.

A systematic review of ultrasound biomicroscopy use in pediatric ophthalmology

Ultrasound biomicroscopy (UBM) is the only available option for noninvasive, high-resolution imaging of the intricate iridociliary complex, and for anterior segment imaging with corneal haze or opacity. While these unique features render UBM essential for specific types of trauma, congenital anomalies, and anterior segment tumors, UBM imaging has found clinical utility in a broad spectrum of diseases for structural assessments not limited to the anterior intraocular anatomy, but also for eyelid and orbit anatomy. This imaging tool has a very specific niche in the pediatric population where anterior segment disease can be accompanied by corneal opacity or clouding, and anomalies posterior to the iris may be present. Pediatric patients present additional diagnostic challenges. They are often unable to offer detailed histories or fully cooperate with examination, thus amplifying the need for high-resolution imaging. This purpose of this systematic review is to identify and synthesize the body of literature involving use of UBM to describe, evaluate, diagnose, or optimize treatment of pediatric ocular disease. The collated peer-reviewed research details the utility of this imaging modality, clarifies the structures and diseases most relevant for this tool, and describes quantitative and qualitative features of UBM imaging among pediatric subjects. This summary will include information about the specific applications available to enhance clinical care for pediatric eye disease.

Deep Learning Model for Accurate Automatic Determination of Phakic Status in Pediatric and Adult Ultrasound Biomicroscopy Images

Purpose

Ultrasound biomicroscopy (UBM) is a noninvasive method for assessing anterior segment anatomy. Previous studies were prone to intergrader variability, lacked assessment of the lens-iris diaphragm, and excluded pediatric subjects. Lens status classification is an objective task applicable in pediatric and adult populations. We developed and validated a neural network to classify lens status from UBM images.

Methods

Two hundred eighty-five UBM images were collected in the Pediatric Anterior Segment Imaging Innovation Study (PASIIS) from 80 eyes of 51 pediatric and adult subjects (median age = 4.6 years, range = 3 weeks to 90 years) with lens status phakic, aphakic, or pseudophakic (n = 33, 7, and 21 subjects, respectively). Following transfer learning, a pretrained Densenet-121 model was fine-tuned on these images. Metrics were calculated for testing dataset results aggregated from fivefold cross-validation. For each fold, 20% of total subjects were partitioned for testing and the remaining subjects were used for training and validation (80:20 split).

Results

Our neural network trained across 60 epochs achieved recall 96.15%, precision 96.14%, F1-score 96.14%, false positive rate 3.74%, and area under the curve (AUC) 0.992. Feature saliency heatmaps consistently involved the lens. Algorithm performance was compared using 2 image sets, 1 from subjects of all ages, and the second from only subjects under age 10 years, with similar performance under both circumstances.

Conclusions

A neural network trained on a relatively small UBM image set classified lens status with satisfactory recall and precision. Adult and pediatric image sets offered roughly equivalent performance. Future studies will explore automated UBM image classification for complex anterior segment pathology.

Translational Relevance

Deep learning models can evaluate lens status from UBM images in adult and pediatric subjects using a limited image set.