Establishing Age-Adjusted Reference Ranges for Iris-Related Parameters in Open Angle Eyes with Anterior Segment Optical Coherence Tomography

Changes in Anterior Segment Morphology and Intraocular Pressure after Cataract Surgery in Non-glaucomatous Eyes

BACKGROUND

It is known that cataract extraction is associated with a significant reduction in intraocular pressure, especially in narrow angled eyes; however, the modifications of anterior segment parameters associated with this phenomenon have still not been completely defined. The purpose of this study was to evaluate changes in anterior segment anatomy and intraocular pressure after cataract surgery in non-glaucomatous eyes.

METHODS AND MATERIAL

This retrospective case series study included 64 eyes of 64 consecutive patients who underwent phacoemulsification with intraocular lens implantation. Anterior segment parameters and intraocular pressure were assessed and compared before and 6 months after surgery. Anterior segment imaging was performed using Casia SS-1000 anterior segment optical coherence tomography (Tomey, Nagoya, Japan). Anterior segment measurements included anterior chamber depth, anterior chamber width, anterior chamber volume, angle opening distance at 500 µm anterior to the scleral spur, angle recess area 750 µm from the scleral spur, lens vault, trabecular iris space area at 500 µm from the scleral spur, and trabecular iris angle at 500 µm from the scleral spur. Intraocular pressure was measured using the Goldmann applanation tonometer (Model AT 900 C/M, Haag-Streit, Bern, Switzerland). Anterior segment parameters and the relationship of changes in intraocular pressure were also evaluated.

RESULTS

All anterior segment parameters increased significantly after surgery (p < 0.05). Both angle opening distance at 500 µm anterior to the scleral spur and anterior chamber depth changes were positively correlated with the preoperative lens vault. The mean intraocular pressure significantly decreased from 14.91 mmHg (± 2.8 SD) to 12.91 mmHg (± 3.13 SD) (p < 0.001). Changes in intraocular pressure correlated negatively with values for the width of the preoperative anterior chamber (r = - 0.533; p = 0.001).

CONCLUSION

Cataract surgery led to significant widening of the anterior chamber angle and lowering of intraocular pressure. Further investigations are needed to better understand whether anterior chamber width may be a new independent predictive factor for reduction in postoperative intraocular pressure.

Clinical applications of anterior segment swept-source optical coherence tomography: A systematic review

Optical coherence tomography (OCT) is a non-invasive method that provides the opportunity to examine tissues by taking cross-sectional images. OCT is increasingly being used to evaluate anterior segment (AS) pathologies. Swept-source (SS) OCT allows greater penetration and achieves better visualization of the internal configuration of AS tissues due to the longer wavelength employed and high scan speeds. We reviewed the utilization of AS SS-OCT in various conditions including glaucoma, ocular surface pathologies, iris tumors, refractive surgery, cataract surgery, and scleral diseases. A systematic literature search was carried out on PubMed, Scopus, and Web of Science databases between January 1, 2008, and September 1, 2022 using the following keywords: AS SS-OCT; dry eye and SS-OCT; ocular surface and SS-OCT; cornea and SS-OCT; dystrophy and SS-OCT; glaucoma and SS-OCT; ocular surface tumors and SS-OCT; conjunctival tumors and SS-OCT; refractive surgery and SS-OCT; cataract and SS-OCT; biometry and SS-OCT; sclera and SS-OCT; iris and SS-OCT; ciliary body and SS-OCT; artificial intelligence and SS-OCT. A total of 221 studies were included in this review. Review of the existing literature shows that SS-OCT offers several advantages in the diagnosis of AS diseases. Exclusive features of SS-OCT including rapid scanning, deeper tissue penetration, and better image quality help improve our understanding of various AS pathologies.

Predicting demographic characteristics from anterior segment OCT images with deep learning: A study protocol

Introduction

Anterior segment optical coherence tomography (AS-OCT) is a non-contact, rapid, and high-resolution in vivo modality for imaging of the eyeball’s anterior segment structures. Because progressive anterior segment deformation is a hallmark of certain eye diseases such as angle-closure glaucoma, identification of AS-OCT structural changes over time is fundamental to their diagnosis and monitoring. Detection of pathologic damage, however, relies on the ability to differentiate it from normal, age-related structural changes.

Methods and analysis

This proposed large-scale, retrospective cross-sectional study will determine whether demographic characteristics including age can be predicted from deep learning analysis of AS-OCT images; it will also assess the importance of specific anterior segment areas of the eyeball to the prediction. We plan to extract, from SUPREME^®, a clinical data warehouse (CDW) of Seoul National University Hospital (SNUH; Seoul, South Korea), a list of patients (at least 2,000) who underwent AS-OCT imaging between 2008 and 2020. AS-OCT images as well as demographic characteristics including age, gender, height, weight and body mass index (BMI) will be collected from electronic medical records (EMRs). The dataset of horizontal AS-OCT images will be split into training (80%), validation (10%), and test (10%) datasets, and a Vision Transformer (ViT) model will be built to predict demographics. Gradient-weighted Class Activation Mapping (Grad-CAM) will be used to visualize the regions of AS-OCT images that contributed to the model’s decisions. The accuracy, sensitivity, specificity, and area under the receiver operating characteristic (ROC) curve (AUC) will be applied to evaluate the model performance.

Conclusion

This paper presents a study protocol for prediction of demographic characteristics from AS-OCT images of the eyeball using a deep learning model. The results of this study will aid clinicians in understanding and identifying age-related structural changes and other demographics-based structural differences.

Trial registration

Registration ID with open science framework:10.17605/OSF.IO/FQ46X.

Using Anterior Segment Optical Coherence Tomography (ASOCT) Parameters to Determine Pupillary Block Versus Plateau Iris Configuration

PRéCIS:: The potential parameters for differentiating pupillary block (PB) from plateau iris configuration (PIC) on anterior segment optical coherence tomography (ASOCT) are lens/pupil size parameters and angles. Further study is needed to determine a landmark peripheral to the centroid of the iris.

PURPOSE

Investigate anterior segment parameters to distinguish between 2 mechanisms of angle closure, PB and PIC, using swept-source Fourier domain ASOCT.

PATIENTS AND METHODS

Retrospective ASOCT images from narrow angle eyes were reviewed. PIC was defined either by ultrasound biomicroscopy and/or clinically when an iridoplasty was performed. Images were read by a masked reader using Anterior Chamber Analysis and Interpretation software to identify scleral spur landmarks and calculate anterior chamber, peripheral angle, iris size, iris shape, and lens/pupil size parameters. ASOCT parameters were summarized and compared using the 2-sample t test. Thresholds and area under receiver operating characteristic curve were calculated using logistic regression analysis.

RESULTS

One hundred eyes (66 PB and 34 PIC) of 100 participants were reviewed. Of all ASOCT parameters, iris length in each quadrant, pupil arc, lens/pupil parameters (pupil arc, lens vault, and pupil diameter), all pupillary margin-center point-scleral spur landmark (PM-C-SSL) parameters, and all except superior central iris vault parameters were significantly different between PB and PIC. On threshold evaluation, lens/pupil parameters had the greatest area under receiver operating characteristic curve values (0.77 to 0.80), followed by PM-C-SSL angles (0.71 to 0.75).

CONCLUSIONS

We propose that the pupil size parameters and PM-C-SSL angle are the most reliable novel ASOCT parameters to distinguish between PB and PIC eyes. These parameters do not rely on the visibility of the posterior iris surface, which is difficult to identify with ASOCT, but may be ambient lighting dependent.