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

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.

Age-Related Changes in Dynamic Iris Behavior Assessed Using a Programmable Closed-Loop Iris Control System

Purpose

The purpose of this study was to develop and test a programmable closed-loop system for tracking, modulating, and assessing dynamic iris behavior, including in the mid-dilated position.

Methods

A programmable closed-loop iris control system was developed by customizing an ANTERION OCT device (Heidelberg Engineering, Heidelberg, Germany). Custom software was developed to store camera and optical coherence tomography (OCT) images, track pupillary diameter (PD), control a light-emitting diode (LED), and modulate ambient lighting to maintain the iris in a dilated, constricted, or mid-dilated position in real-time. Study participants underwent 3 consecutive 65-second scan sessions. Dynamic iris behavior in the form of peak constriction velocity (PCV) and mid-dilated iris activity (MDIA) were calculated and analyzed offline.

Results

Among 58 participants, 56 (96.6%) were eligible for analysis based on achieving and maintaining mean PD within ±10% of the calculated mid-dilated PD. Mean participant age was 49.8 ± 18.9 years. Mean PCV was 3.92 ± 0.83 mm/s, and mean MDIA was 0.37 ± 0.15 mm. The mean difference between the calculated and achieved mid-dilated PD was 0.166 ± 0.192 mm. There were significant negative correlations between PCV and age (slope = -0.022, P < 0.001) and MDIA and age (slope = -0.004, P < 0.001). Success rates were lower (69.0%) but relationships between dynamic iris behavior and age were similar based on achieving and maintaining mean PD within ±5% of the calculated mid-dilated PD.

Conclusions

A programmable closed-loop iris control system can modulate dynamic iris behavior and maintain the iris in a mid-dilated position. Pupillary constriction velocity and iris activity in the mid-dilated position decrease with age.

Translational Relevance

This system can be applied to study dynamic disease processes involving the iris and establish novel biometric measures that could serve as risk factors for acute and chronic primary angle closure glaucoma (PACG).

The disposable bandage soft contact lenses therapy and anterior segment optical coherence tomography for management of ocular graft-versus-host disease

PURPOSE

To identify the ocular surface changes of ocular graft-versus-host disease (GVHD) using anterior segment optical coherence tomography (AS-OCT) and examine the efficacy of disposable bandage soft contact lens (BSCL) treatment in ocular GVHD patients.

METHODS

This study is a prospective, Phase II clinical trial. Nineteen patients diagnosed with chronic GVHD based on the NIH criteria and ocular symptoms of NIH eye score 2 or greater were enrolled. Disposable BSCL was applied to the GVHD-affected eyes with topical antibiotic coverage. Ocular exams, eye symptom surveys, and AS-OCT were performed with signed informed consent. Patients were followed for one to three months.

RESULTS

Thirty-eight eyes of 19 patients with ocular GVHD underwent BSCL treatment in this study. AS-OCT scans were done in 14 out of 19 patients. The mean best-corrected visual acuity at enrollment, 2-week, and 4-week visits was 0.180, 0.128, and 0.163 logMAR, respectively. Twenty-four out of 25 eyes (96 %) that initially presented with conjunctival inflammation, twenty-three out of 30 eyes (76.7 %) that initially presented with punctate epithelial erosion, and 8 out of 15 (53.3 %) eyes that initially presented with filamentous keratopathy showed improvement after wearing BSCL for 2 to 4 weeks. AS-OCT revealed corneal epithelial irregularity, abnormal meibomian gland orifice, and conjunctival hyperemia, in patients with ocular GVHD.

CONCLUSIONS

BSCL treatment provided significant subjective and objective improvements in ocular GVHD patients. Meanwhile, we found that AS-OCT can be a promising diagnostic tool to characterize the ocular surface changes associated with ocular GVHD.

Comparing the Effect of Lens Extraction With Endocycloplasty to Lens Extraction Alone in Eyes With Plateau Iris Configuration: Pilot Study

PRECIS

Lens extraction with endocycloplasty (LE/ECPL) results in greater angle deepening than LE alone in plateau iris eyes. This study directly compares an LE/ECPL treatment group with a control group.

PURPOSE

Quantitatively determine the effect of LE/ECPL versus LE alone for eyes with plateau iris configuration/plateau iris syndrome (PIC/PIS) on angle parameters.

METHODS

Patients with PIC/PIS who underwent LE/ECPL or LE alone were reviewed. Eyes with ultrasound biomicroscopy-documented PIC that underwent anterior segment optical coherence tomography examination before and after treatment were included. Angle parameters, angle opening distance (AOD), trabecular-iris space area (TISA), and trabecular-iris circumference volume (TICV) were calculated. Angle parameters were compared between treatments using a 2-sample t test. P-values were adjusted by the false discovery rate method (P*). A paired t test was used to compare treated (nasal) and untreated (temporal) angles in LE/ECPL-treated eyes.

RESULTS

Twenty-three eyes of 14 participants were included. Ten eyes (43%) eyes of 7 participants were treated with LE/ECPL, and 13 eyes (57%) of 7 participants were treated with LE alone. Angles were deepened in both groups (P<0.001). Changes in AOD, TISA, and TICV showed that the magnitude of deepening in treated (nasal) quadrants was greater in LE/ECPL eyes than in LE alone eyes (P<0.05). ECPL-treated angles deepened more than the untreated angles by AOD, TISA, and TICV (P<0.002).

CONCLUSION

Our study suggests that LE/ECPL is more effective than LE alone in opening the anterior chamber angle and that ECPL deepens treated angles more than untreated angles. This study directly compares an LE/ECPL treatment group with a control group, LE alone, allowing for separation of the effect of ECPL from LE.

The Use of Anterior-Segment Optical-Coherence Tomography for the Assessment of the Iridocorneal Angle and Its Alterations: Update and Current Evidence

The introduction of anterior-segment optical-coherence tomography (AS-OCT) has led to improved assessments of the anatomy of the iridocorneal-angle and diagnoses of several mechanisms of angle closure which often result in raised intraocular pressure (IOP). Continuous advancements in AS-OCT technology and software, along with an extensive research in the field, have resulted in a wide range of possible parameters that may be used to diagnose and follow up on patients with this spectrum of diseases. However, the clinical relevance of such variables needs to be explored thoroughly. The aim of the present review is to summarize the current evidence supporting the use of AS-OCT for the diagnosis and follow-up of several iridocorneal-angle and anterior-chamber alterations, focusing on the advantages and downsides of this technology.