Ergonomic handheld OCT angiography probe optimized for pediatric and supine imaging

Large area kidney imaging for pre-transplant evaluation using real-time robotic optical coherence tomography

Optical coherence tomography (OCT) can be used to image microstructures of human kidneys. However, current OCT probes exhibit inadequate field-of-view, leading to potentially biased kidney assessment. Here we present a robotic OCT system where the probe is integrated to a robot manipulator, enabling wider area (covers an area of 106.39 mm by 37.70 mm) spatially-resolved imaging. Our system comprehensively scans the kidney surface at the optimal altitude with preoperative path planning and OCT image-based feedback control scheme. It further parameterizes and visualizes microstructures of large area. We verified the system positioning accuracy on a phantom as 0.0762 ± 0.0727 mm and showed the clinical feasibility by scanning ex vivo kidneys. The parameterization reveals vasculatures beneath the kidney surface. Quantification on the proximal convoluted tubule of a human kidney yields clinical-relevant information. The system promises to assess kidney viability for transplantation after collecting a vast amount of whole-organ parameterization and patient outcomes data.

Optimization of handheld spectrally encoded coherence tomography and reflectometry for point-of-care ophthalmic diagnostic imaging

Significance

Handheld optical coherence tomography (HH-OCT) systems enable point-of-care ophthalmic imaging in bedridden, uncooperative, and pediatric patients. Handheld spectrally encoded coherence tomography and reflectometry (HH-SECTR) combines OCT and spectrally encoded reflectometry (SER) to address critical clinical challenges in HH-OCT imaging with real-time en face retinal aiming for OCT volume alignment and volumetric correction of motion artifacts that occur during HH-OCT imaging.

Aim

We aim to enable robust clinical translation of HH-SECTR and improve clinical ergonomics during point-of-care OCT imaging for ophthalmic diagnostics.

Approach

HH-SECTR is redesigned with (1) optimized SER optical imaging for en face retinal aiming and retinal tracking for motion correction, (2) a modular aluminum form factor for sustained alignment and probe stability for longitudinal clinical studies, and (3) one-handed photographer-ergonomic motorized focus adjustment.

Results

We demonstrate an HH-SECTR imaging probe with micron-scale optical-optomechanical stability and use it for in vivo human retinal imaging and volumetric motion correction.

Conclusions

This research will benefit the clinical translation of HH-SECTR for point-of-care ophthalmic diagnostics.

Repeatability and reproducibility of quantitative OCT angiography measurements from table-top and portable Flex Spectralis devices

PURPOSE

The recent development of a portable investigational handheld OCT-angiography (OCTA) device has allowed for expansion of imaging into the operating room (OR) in addition to standard in-clinic imaging. The aim of this study was to assess intravisit repeatability and intervisit reproducibility of retinal microvasculature measures and central retinal thickness for in-clinic table-top and portable OR compatible OCTA devices.

METHODS

Repeated 10 × 10 OCTA images were acquired in 20 healthy adult participants on two separate visit days using Spectralis spectral-domain OCTA table-top and investigational armature suspended Flex systems. Intravisit and intervisit intraclass correlation coefficients and average absolute percent difference were calculated for quantitative microvasculature measures and CRT.

RESULTS

120 OCTA images were acquired from 20 subjects (n = 20, mean age 26.7 ± 1.61 years, range 24-30 years) with both devices across two separate imaging days. FAZ and CRT measurements had near complete intravisit and intervisit agreement with ICCs between .97 and 1 for both table-top (FAZ ICC .97, .97; CRT ICC .98-1, .98-.99) and Flex (FAZ ICC .97, .95; CRT ICC .99-1, .98-.99) devices. Vessel density measures demonstrated greater variance with only fair to strong agreement (ICC .32-.75) and average absolute percent differences ranging from 2.96 to 6.63%.

CONCLUSION

FAZ and CRT measures for both devices demonstrated high repeatability and reproducibility; retinal vessel density measures demonstrated less. Differences of less than 7% for retinal microvasculature measurements across time and devices are most likely attributable to expectable variance between repeat scans.

Vascular imaging findings in retinopathy of prematurity

Retinopathy of prematurity (ROP) is a vascular disease among preterm infants involving incomplete or abnormal retinal vascularization and is a leading cause of preventable blindness globally. Measurements of ocular blood flow originating from a variety of imaging modalities, including colour Doppler imaging (CDI), fluorescein angiography (FA) and ocular coherence tomography angiography (OCTA), have been associated with changes in ROP patients. Herein, we discuss and summarize the relevant current literature on vascular imaging and ROP reviewed through December 2022. Differences in vascular imaging parameters between ROP patients and healthy controls are reviewed and summarized. The available data identify significantly increased peak systolic velocity (PSV) in the central retinal artery and ophthalmic artery as measured by CDI, increased vascular tortuosity as measured by FA, smaller foveal avascular zone (FAZ) as measured by FA and OCTA, and increased foveal vessel density (VD) and reduced parafoveal VD as measured by OCTA in ROP patients compared with controls. None of the above findings appear to reliably correlate with visual acuity. The studies currently available, however, are inconclusive and lack robust longitudinal data. Vascular imaging demonstrates the potential to aid in the diagnosis, management and monitoring of ROP, alongside retinal examination via indirect ophthalmoscopy and fundus photography.

Implementation of optical coherence tomography in retinopathy of prematurity screening

PURPOSE OF REVIEW

In this review, we explore the investigational applications of optical coherence tomography (OCT) in retinopathy of prematurity (ROP), the insights they have delivered thus far, and key milestones for its integration into the standard of care.

RECENT FINDINGS

While OCT has been widely integrated into clinical management of common retinal diseases, its use in pediatric contexts has been undermined by limitations in ergonomics, image acquisition time, and field of view. Recently, investigational handheld OCT devices have been reported with advancements including ultra-widefield view, noncontact use, and high-speed image capture permitting real-time en face visualization. These developments are compelling for OCT as a more objective alternative with reduced neonatal stress compared to indirect ophthalmoscopy and/or fundus photography as a means of classifying and monitoring ROP.

SUMMARY

OCT may become a viable modality in management of ROP. Ongoing innovation surrounding handheld devices should aim to optimize patient comfort and image resolution in the retinal periphery. Future clinical investigations may seek to objectively characterize features of peripheral stage and explore novel biomarkers of disease activity.

Panretinal handheld OCT angiography for pediatric retinal imaging

Comprehensive visualization of retina morphology is essential in the diagnosis and management of retinal diseases in pediatric populations. Conventional imaging techniques often face challenges in effectively capturing the peripheral retina, primarily due to the limitations in current optical designs, which lack the necessary field of view to characterize the far periphery. To address this gap, our study introduces a novel ultra-widefield optical coherence tomography angiography (OCTA) system. This system, specifically tailored for pediatric applications, incorporates an ultrahigh-speed 800 kHz swept-source laser. The system's innovative design achieves a 140° field of view while maintaining excellent optical performance. Over the last 15 months, we have conducted 379 eye examinations on 96 babies using this system. It demonstrates marked efficacy in the diagnosis of retinopathy of prematurity, providing detailed and comprehensive peripheral retinal angiography. The capabilities of the ultra-widefield handheld OCTA system in enhancing the clarity and thoroughness of retina vascularization assessments have significantly improved the precision of diagnoses and the customization of treatment strategies. Our findings underscore the system's potential to advance pediatric ophthalmology and broaden the scope of retinal imaging.

Handheld contact-type OCT and color fundus system for retinal imaging

We present proof of concept for a handheld contact-type system capable of simultaneous optical coherence tomography (OCT) imaging of the retina and wide-field digital fundus color photography. The study focuses on demonstrating the feasibility of the proposed approach, particularly for eventual use in pediatric patients during examination under anesthesia in the operating room and in the neonatal intensive care unit. Direct contact of the probe with the cornea allows the photographer to maintain a stable position during imaging, reducing motion artifacts in the OCT images. Additionally, it simplifies the alignment process and increases the field of view of the optics. By integrating OCT and fundus imaging into a single device, the proposed compact modular design eliminates the need for separate, space-consuming systems dedicated to each imaging modality.

Five degrees-of-freedom mechanical arm with remote center of motion (RCM) device for volumetric optical coherence tomography (OCT) retinal imaging

Handheld optical coherence tomography (HH-OCT) is gaining popularity for diagnosing retinal diseases in neonates (e.g. retinopathy of prematurity). Diagnosis accuracy is degraded by hand tremor and patient motion when using commercially available handheld retinal OCT probes. This work presents a low-cost arm designed to address ergonomic challenges of holding a commercial OCT probe and alleviating hand tremor. Experiments with a phantom eye show enhanced geometric uniformity and volumetric accuracy when obtaining OCT scans with our device compared to handheld imaging approaches. An in-vivo porcine volumetric image was also obtained with the mechanical arm demonstrating clinical deployability.

A pilot optical coherence tomography angiography classification of retinal neovascularization in retinopathy of prematurity

Extraretinal neovascularization is a hallmark of treatment-requiring retinopathy of prematurity (ROP). Optical coherence tomography angiography (OCTA) offers vascular flow and depth information not available from indirect ophthalmoscopy and structural OCT, but OCTA is only commercially available as a tabletop device. In this study, we used an investigational handheld OCTA device to study the vascular flow in and around retinal neovascularization in seven preterm infants with treatment-requiring ROP and contrasted them to images of vascular flow in six infants of similar age without neovascular ROP. We showed stages of retinal neovascularization visible in preterm infants from 32 to 47 weeks postmenstrual age: Intraretinal neovascularization did not break through the internal limiting membrane; Subclinical neovascular buds arose from retinal vasculature with active flow through the internal limiting membrane; Flat neovascularization in aggressive ROP assumed a low-lying configuration compared to elevated extraretinal neovascular plaques; Regressed neovascularization following treatment exhibited decreased vascular flow within the preretinal tissue, but flow persisted in segments of retinal vessels elevated from their original intraretinal location. These findings enable a pilot classification of retinal neovascularization in eyes with ROP using OCTA, and may be helpful in detailed monitoring of disease progression, treatment response and predicting reactivation.

Identification of novel biomarkers for retinopathy of prematurity in preterm infants by use of innovative technologies and artificial intelligence

Retinopathy of prematurity (ROP) is a leading cause of preventable vision loss in preterm infants. While appropriate screening is crucial for early identification and treatment of ROP, current screening guidelines remain limited by inter-examiner variability in screening modalities, absence of local protocol for ROP screening in some settings, a paucity of resources and an increased survival of younger and smaller infants. This review summarizes the advancements and challenges of current innovative technologies, artificial intelligence (AI), and predictive biomarkers for the diagnosis and management of ROP. We provide a contemporary overview of AI-based models for detection of ROP, its severity, progression, and response to treatment. To address the transition from experimental settings to real-world clinical practice, challenges to the clinical implementation of AI for ROP are reviewed and potential solutions are proposed. The use of optical coherence tomography (OCT) and OCT angiography (OCTA) technology is also explored, providing evaluation of subclinical ROP characteristics that are often imperceptible on fundus examination. Furthermore, we explore several potential biomarkers to reduce the need for invasive procedures, to enhance diagnostic accuracy and treatment efficacy. Finally, we emphasize the need of a symbiotic integration of biologic and imaging biomarkers and AI in ROP screening, where the robustness of biomarkers in early disease detection is complemented by the predictive precision of AI algorithms.

Biphasic change in retinal nerve fibre layer thickness from 30 to 60 weeks postmenstrual age in preterm infants

BACKGROUND/AIMS

The optic nerve development during the critical postnatal weeks of preterm infants is unclear. We aimed to investigate the change of retinal nerve fibre layer (RNFL) in preterm infants.

METHODS

We used an investigational handheld optical coherence tomography (OCT) system to serially image awake preterm infants between 30 and 60 weeks postmenstrual age (PMA) at the bedside. We assessed RNFL thickness in the papillomacular bundle and nasal macular ganglion cell layer+inner plexiform layer (GCL+IPL) thickness. We applied a segmented mixed model to analyse the change in the thickness of RNFL and GCL+IPL as a function of PMA.

RESULTS

From 631 OCT imaging sessions of 101 infants (201 eyes), RNFL thickness followed a biphasic model between 30 and 60 weeks, with an estimated transition at 37.8 weeks PMA (95% CI: 37.0 to 38.6). RNFL thickness increased at 1.8 μm/week (95% CI: 1.6 to 2.1) before 37.8 weeks and decreased at -0.3 μm/week (95% CI: -0.5 to -0.2) afterwards. GCL+IPL thickness followed a similar biphasic model, in which the thickness increased at 2.9 μm/week (95% CI: 2.5 to 3.2) before 39.5 weeks PMA (95% CI: 38.8 to 40.1) and then decreased at -0.8 μm/week (95% CI: -0.9 to -0.6).

CONCLUSION

We demonstrate the feasibility of monitoring RNFL and GCL+IPL thickness from OCT during the postnatal weeks of preterm infants. Thicknesses follow a biphasic model with a transition age at 37.8 and 39.5 weeks PMA, respectively. These findings may shed light on optic nerve development in preterm infants and assist future study designs.

Panretinal Optical Coherence Tomography

We introduce a new concept of panoramic retinal (panretinal) optical coherence tomography (OCT) imaging system with a 140° field of view (FOV). To achieve this unprecedented FOV, a contact imaging approach was used which enabled faster, more efficient, and quantitative retinal imaging with measurement of axial eye length. The utilization of the handheld panretinal OCT imaging system could allow earlier recognition of peripheral retinal disease and prevent permanent vision loss. In addition, adequate visualization of the peripheral retina has a great potential for better understanding disease mechanisms regarding the periphery. To the best of our knowledge, the panretinal OCT imaging system presented in this manuscript has the widest FOV among all the retina OCT imaging systems and offers significant values in both clinical ophthalmology and basic vision science.

Large Area Kidney Imaging for Pre-transplant Evaluation using Real-Time Robotic Optical Coherence Tomography

Optical coherence tomography (OCT) is a high-resolution imaging modality that can be used to image microstructures of human kidneys. These images can be analyzed to evaluate the viability of the organ for transplantation. However, current OCT devices suffer from insufficient field-of-view, leading to biased examination outcomes when only small portions of the kidney can be assessed. Here we present a robotic OCT system where an OCT probe is integrated with a robotic manipulator, enabling wider area spatially-resolved imaging. With the proposed system, it becomes possible to comprehensively scan the kidney surface and provide large area parameterization of the microstructures. We verified the probe tracking accuracy with a phantom as 0.0762±0.0727 mm and demonstrated its clinical feasibility by scanning ex vivo kidneys. The parametric map exhibits fine vasculatures beneath the kidney surface. Quantitative analysis on the proximal convoluted tubule from the ex vivo human kidney yields highly clinical-relevant information.

Preterm infant retinal OCT markers of perinatal health and retinopathy of prematurity

The increasing survival of preterm infants has led to the importance of improving long-term outcomes associated with preterm birth. Antenatal and perinatal insults not only impact mortality, but also long-term disability. While in the intensive care nursery, preterm infants are also exposed to various stressors that lead to long-term cognitive deficits. It is therefore critical to identify early, low-stress, non-invasive biomarkers for preterm infant health. Optical coherence tomography (OCT) is a powerful imaging modality that has recently been adapted to the infant population and provides noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside with low stress relative to conventional examination. In this review we delve into discussing the associations between preterm systemic health factors and OCT-based retinal findings and their potential contribution to the development of non-invasive biomarkers for infant health and for retinopathy of prematurity (ROP).

MACULAR NEUROVASCULAR ABNORMALITIES IN A CHILD WITH INCONTINENTIA PIGMENTI ON HANDHELD OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY

PURPOSE

To report macular neurovascular abnormalities in a child with incontinentia pigmenti using handheld optical coherence tomography (OCT) and OCT angiography (OCT-A).

METHODS

An eye of a child with incontinentia pigmenti enrolled in BabySTEPS was imaged using an investigational noncontact, handheld swept-source OCT device during examination under anesthesia. Custom MATLAB scripts were used to generate depth-resolved vascular slabs, B-scans with flow overlay, and retinal thickness maps.

RESULTS

Depth-resolved OCT and OCT-A imaging demonstrated focal areas of decreased capillary flow that corresponded to areas of both inner retinal and outer retinal thinning on retinal thickness maps. Atypical diving of superficial retinal vessels occurred as they traversed from thin retina to normal-thickness retina.

CONCLUSION

Depth-resolved OCT and OCT-A identified retinal vascular abnormalities that were not evident on fundus photography or fluorescein angiography. This case depicted concurrent, localized abnormalities in retinal thickness and microvasculature in an eye with incontinentia pigmenti.

Automated robot-assisted wide-field optical coherence tomography using structured light camera

Optical coherence tomography (OCT) is a promising real-time and non-invasive imaging technology widely utilized in biomedical and material inspection domains. However, limited field of view (FOV) in conventional OCT systems hampers their broader applicability. Here, we propose an automated system integrating a structured light camera and robotic arm for large-area OCT scanning. The system precisely detects tissue contours, automates scan path generation, and enables accurate scanning of expansive sample areas. The proposed system consists of a robotic arm, a three-dimensional (3D) structured light camera, and a customized portable OCT probe. The 3D structured light camera is employed to generate a precise 3D point cloud of the sample surface, enabling automatic planning of the scanning path for the robotic arm. Meanwhile, the OCT probe is mounted on the robotic arm, facilitating scanning of the sample along the predetermined path. Continuous OCT B-scans are acquired during the scanning process, facilitating the generation of high-resolution and large-area 3D OCT reconstructions of the sample. We conducted position error tests and presented examples of 3D macroscopic imaging of different samples, such as ex vivo kidney, skin and leaf blade. The robotic arm can accurately reach the planned positions with an average absolute error of approximately 0.16 mm. The findings demonstrate that the proposed system enables the acquisition of 3D OCT images covering an area exceeding 20 cm2, indicating wide-ranging potential for utilization in diverse domains such as biomedical, industrial, and agricultural fields.

Ocular Pigmentation Impact on Retinal Versus Choroidal Optical Coherence Tomography Imaging in Preterm Infants

Purpose

To evaluate the association of fundus pigmentation with the visibility of retinal versus choroidal layers on optical coherence tomography (OCT) in preterm infants.

Methods

For infants enrolled in BabySTEPS, ophthalmologists recorded fundus pigmentation (blond, medium, or dark) at the first retinopathy of prematurity (ROP) examination. Bedside OCT imaging was performed at each examination, and a masked grader evaluated all OCT scans from both eyes of each infant for visibility (yes/no) of all retinal layers and of the chorio-scleral junction (CSJ). Multivariable logistic regression was used to assess associations between fundus pigmentation and visibility of all retinal layers and CSJ, controlling for potential confounders (i.e., birth weight, gestational age, sex, OCT system, pupil size, and postmenstrual age at imaging).

Results

Among 114 infants (mean birth weight, 943 grams; mean gestational age, 27.6 weeks), 43 infants (38%) had blond, 56 infants (49%) had medium, and 15 infants (13%) had dark fundus pigmentation. Of 1042 scans, all retinal layers were visible in 977 (94%) and CSJ in 895 (86%). Pigmentation was not associated with retinal layer visibility (P = 0.49), but medium and dark pigmentation were associated with decreased CSJ visibility (medium: odds ratio [OR] = 0.34, P = 0.001; dark: OR = 0.24, P = 0.009). For infants with dark pigmentation, retinal layer visibility increased (OR = 1.87 per week; P ≤ 0.001) and CSJ visibility decreased (OR = 0.78 per week; P = 0.01) with increasing age.

Conclusions

Although fundus pigmentation was not associated with the visibility of all retinal layers on OCT, darker pigmentation decreased CSJ visibility, and this effect increased with age.

Translational Relevance

The ability of bedside OCT to capture retinal layer microanatomy in preterm infants, regardless of fundus pigmentation, may represent an advantage over fundus photography for ROP telemedicine.

Vitreoretinal biomarkers of retinopathy of prematurity using handheld optical coherence tomography: a review

Retinopathy of prematurity (ROP) is caused by abnormal retinal vascularization in premature infants that has the potential for severe long-term vision impairment. Recent advancements in handheld optical coherence tomography (OCT) have enabled noninvasive, high-resolution, cross-sectional imaging of the infant eye at the bedside. The use of handheld OCT devices in the diagnosis of ROP in premature infants has furthered our understanding of disease state and progression. This review discusses the known and novel biomarkers of ROP severity in premature infants identified through handheld OCT and potential for future directions.

Optical Coherence Tomography and Optical Coherence Tomography Angiography in Pediatric Retinal Diseases

Indirect ophthalmoscopy and handheld retinal imaging are the most common and traditional modalities for the evaluation and documentation of the pediatric fundus, especially for pre-verbal children. Optical coherence tomography (OCT) allows for in vivo visualization that resembles histology, and optical coherence tomography angiography (OCTA) allows for non-invasive depth-resolved imaging of the retinal vasculature. Both OCT and OCTA were extensively used and studied in adults, but not in children. The advent of prototype handheld OCT and OCTA have allowed for detailed imaging in younger infants and even neonates in the neonatal care intensive unit with retinopathy of prematurity (ROP). In this review, we discuss the use of OCTA and OCTA in various pediatric retinal diseases, including ROP, familial exudative vitreoretinopathy (FEVR), Coats disease and other less common diseases. For example, handheld portable OCT was shown to detect subclinical macular edema and incomplete foveal development in ROP, as well as subretinal exudation and fibrosis in Coats disease. Some challenges in the pediatric age group include the lack of a normative database and the difficulty in image registration for longitudinal comparison. We believe that technological improvements in the use of OCT and OCTA will improve our understanding and care of pediatric retina patients in the future.

Advances in retinopathy of prematurity imaging

Retinopathy of prematurity (ROP) remains the leading cause of childhood blindness worldwide. Recent advances in ROP imaging have significantly improved our understanding of the pathogenesis and pathophysiological course of ROP including the acute phase, regression, reactivation, and late complications, known as adult ROP. Recent progress includes various contact and noncontact wide-field imaging devices for fundus imaging, smartphone-based fundus photography, wide-field fluorescein angiography, handheld optical coherence tomography (OCT) devices for wide-field en face OCT images, and OCT angiography. Images taken by those devices were incorporated in the recently updated guidelines of ROP, the International Classification of Retinopathy of Prematurity, Third Edition (ICROP3). ROP imaging has also allowed the real-world adoption of telemedicine- and artificial intelligence (AI)-based screening. Recent study demonstrated proof of concept that AI has a high diagnostic performance for the detection of ROP in a real-world screening. Here, we summarize the recent advances in ROP imaging and their application for screening, diagnosis, and management of ROP.

Association of Optical Coherence Tomography-Measured Fibrovascular Ridge Thickness and Clinical Disease Stage in Retinopathy of Prematurity

Importance

Accurate diagnosis of retinopathy of prematurity (ROP) is essential to provide timely treatment and reduce the risk of blindness. However, the components of an ROP examination are subjective and qualitative.

Objective

To evaluate whether optical coherence tomography (OCT)-derived retinal thickness measurements at the vascular-avascular junction are associated with clinical diagnosis of ROP stage.

Design, Setting, and Participants

This cross-sectional longitudinal study compared OCT-based ridge thickness calculated from OCT B-scans by a masked examiner to the clinical diagnosis of 2 masked examiners using both traditional stage classifications and a more granular continuous scale at the neonatal intensive care unit (NICU) of Oregon Health & Science University (OHSU) Hospital. Infants who met ROP screening criteria in the OHSU NICU between June 2021 and April 2022 and had guardian consent were included. One OCT volume and en face image per patient per eye showing at least 1 to 2 clock hours of ridge were included in the final analysis.

Main Outcomes and Measures

Comparison of OCT-derived ridge thickness to the clinical diagnosis of ROP stage using an ordinal and continuous scale. Repeatability was assessed using 20 repeated examinations from the same visit and compared using intraclass correlation coefficient (ICC) and coefficient of variation (CV). Comparison of ridge thickness with ordinal categories was performed using generalized estimating equations and with continuous stage using Spearman correlation.

Results

A total of 128 separate OCT eye examinations from 50 eyes of 25 patients were analyzed. The ICC was 0.87 with a CV of 7.0%. Higher ordinal disease classification was associated with higher axial ridge thickness on OCT, with mean (SD) thickness measurements of 264.2 (11.2) μm (P < .001), 334.2 (11.4) μm (P < .001), and 495.0 (32.2) μm (P < .001) for stages 1, 2, and 3, respectively and with continuous stage labels (ρ = 0.739, P < .001).

Conclusions and Relevance

These results suggest that OCT-based quantification of peripheral stage in ROP may be an objective and quantitative biomarker that may be useful for clinical diagnosis and longitudinal monitoring and may have implications for disease classification in the future.

Insights into the developing fovea revealed by imaging

Early development of the fovea has been documented by histological studies over the past few decades. However, structural distortion due to sample processing and the paucity of high-quality post-mortem tissue has limited the effectiveness of this approach. With the continuous progress in high-resolution non-invasive imaging technology, most notably optical coherence tomography (OCT) and OCT angiography (OCT-A), in vivo visualization of the developing retina has become possible. Combining the information from histologic studies with this novel imaging information has provided a more complete and accurate picture of retinal development, and in particular the developing fovea. Advances in neonatal care have increased the survival rate of extremely premature infants. However, with enhanced survival there has been an attendant increase in retinal developmental complications. Several key abnormalities, including a thickening of the inner retina at the foveal center, a shallower foveal pit, a smaller foveal avascular zone, and delayed development of the photoreceptors have been described in preterm infants when compared to full-term infants. Notably these abnormalities, which are consistent with a partial arrest of foveal development, appear to persist into later childhood and adulthood in these eyes of individuals born prematurely. Understanding normal foveal development is vital to interpreting these pathologic findings associated with prematurity. In this review, we first discuss the various advanced imaging technologies that have been adapted for imaging the infant eye. We then review the key events and steps in the development of the normal structure of the fovea and contrast structural features in normal and preterm retina from infancy to childhood. Finally, we discuss the development of the perifoveal retinal microvasculature and highlight future opportunities to expand our understanding of the developing fovea.

Semi-automated vessel analysis of en face posterior pole vessel maps generated from optical coherence tomography for diagnosis of plus or pre-plus disease

En face retinal vessel maps generated from bedside optical coherence tomography (OCT) can show posterior pole vascular tortuosity and dilation (ie, plus/pre-plus disease). In this proof-of-concept study, we found that ROPtool could trace OCT-generated retinal vessel maps with high reliability and accuracy for detecting plus or pre-plus disease.

Widefield Optical Coherence Tomography in Pediatric Retina: A Case Series of Intraoperative Applications Using a Prototype Handheld Device

Optical coherence tomography (OCT) has changed the standard of care for diagnosis and management of macular diseases in adults. Current commercially available OCT systems, including handheld OCT for pediatric use, have a relatively narrow field of view (FOV), which has limited the potential application of OCT to retinal diseases with primarily peripheral pathology, including many of the most common pediatric retinal conditions. More broadly, diagnosis of all types of retinal detachment (exudative, tractional, and rhegmatogenous) may be improved with OCT-based assessment of retinal breaks, identification of proliferative vitreoretinopathy (PVR) membranes, and the pattern of subretinal fluid. Intraocular tumors both benign and malignant often occur outside of the central macula and may be associated with exudation, subretinal and intraretinal fluid, and vitreoretinal traction. The development of wider field OCT systems thus has the potential to improve the diagnosis and management of myriad diseases in both adult and pediatric retina. In this paper, we present a case series of pediatric patients with complex vitreoretinal pathology undergoing examinations under anesthesia (EUA) using a portable widefield (WF) swept-source (SS)-OCT device.

Association Between Retinal Microanatomy in Preterm Infants and 9-Month Visual Acuity

Importance

Preterm infants are at risk for poor visual acuity (VA) outcomes, even without retinal problems on ophthalmoscopy. Infant retinal microanatomy may provide insight as to potential causes.

Objective

To evaluate the association between preterm infant retinal microanatomy and VA at 9 months' corrected age.

Design, Setting, and Participants

This prospective observational study took place from November 2016 and December 2019 at a single academic medical center and included preterm infants enrolled in Study of Eye Imaging in Preterm Infants (BabySTEPS). Infants were eligible for enrollment in BabySTEPS if they met criteria for retinopathy of prematurity (ROP) screening, were 35 weeks' postmenstrual age or older at the time of first OCT imaging, and a parent or guardian provided written informed consent. Of 118 infants enrolled in BabySTEPS, 61 were included in this analysis. Data were analyzed from March to April 2021.

Exposures

Bedside optical coherence tomography (OCT) imaging at a mean (SD) 39.85 (0.79) weeks' postmenstrual age and monocular grating VA measurement at 9 months' corrected age.

Main Outcomes and Measures

Presence and severity of macular edema and presence of ellipsoid zone at the fovea measured by extracting semiautomated thicknesses of inner nuclear layer, inner retina, and total retina at the foveal center; choroid across foveal 1 mm; and retinal nerve fiber layer (RNFL) across the papillomacular bundle (PMB). Pearson correlation coefficients were calculated and 95% CIs were bootstrapped for the association between retinal layer thicknesses and continuous logMAR VA. Associations were analyzed between retinal microanatomy and normal (3.70 cycles/degree or greater) vs subnormal grating VA at 9 months' corrected age using logistic regression and with logMAR VA using linear regression, adjusting for birth weight, gestational age, and ROP severity at the time of OCT imaging and accounting for intereye correlation using generalized estimating equations.

Results

The mean (SD; range) gestational age of included infants was 27.6 (2.8; 23.0-34.6) weeks, and mean (SD; range) birth weight was 958.2 (293.7; 480-1580) g. In 122 eyes of 61 infants, the correlations between retinal layer thicknesses and logMAR VA were as follows: r, 0.01 (95% CI, -0.07 to -0.27) for inner nuclear layer; r, 0.19 (95% CI, 0.01 to 0.35) for inner retina; r, 0.15 (95% CI, -0.02 to 0.31) for total retina; r, -0.22 (95% CI, -0.38 to -0.03) for choroid; and r, -0.27 (95% CI, -0.45 to 0.10) for RNFL across the PMB. In multivariable analysis, thinner RNFL across the PMB (regression coefficient, -0.05 per 10-μm increase in RNFL thickness; 95% CI, -0.10 to -0.01; P = .046) and prior ROP treatment (regression coefficient, 0.33 for ROP treatment; 95% CI, 0.11 to 0.56; P = .003) were independently associated with poorer 9-month logMAR VA.

Conclusions and Relevance

In preterm infants, RNFL thinning across the PMB was associated with poorer 9-month VA, independent of birth weight, gestational age, need for ROP treatment, and macular microanatomy. Evaluation of RNFL thickness using OCT may help identify preterm infants at risk for poor vision outcomes.

The Development and Clinical Application of Innovative Optical Ophthalmic Imaging Techniques

The field of ophthalmic imaging has grown substantially over the last years. Massive improvements in image processing and computer hardware have allowed the emergence of multiple imaging techniques of the eye that can transform patient care. The purpose of this review is to describe the most recent advances in eye imaging and explain how new technologies and imaging methods can be utilized in a clinical setting. The introduction of optical coherence tomography (OCT) was a revolution in eye imaging and has since become the standard of care for a plethora of conditions. Its most recent iterations, OCT angiography, and visible light OCT, as well as imaging modalities, such as fluorescent lifetime imaging ophthalmoscopy, would allow a more thorough evaluation of patients and provide additional information on disease processes. Toward that goal, the application of adaptive optics (AO) and full-field scanning to a variety of eye imaging techniques has further allowed the histologic study of single cells in the retina and anterior segment. Toward the goal of remote eye care and more accessible eye imaging, methods such as handheld OCT devices and imaging through smartphones, have emerged. Finally, incorporating artificial intelligence (AI) in eye images has the potential to become a new milestone for eye imaging while also contributing in social aspects of eye care.

Portable boom-type ultrahigh-resolution OCT with an integrated imaging probe for supine position retinal imaging

To expand the clinical applications and improve the ease of use of ultrahigh-resolution optical coherence tomography (UHR-OCT), we developed a portable boom-type ophthalmic UHR-OCT operating in supine position that can be used for pediatric subjects, bedridden patients and perioperative conditions. By integrating the OCT sample arm probe with real-time iris display and automatic focusing electric lens for easy alignment, coupling the probe on a self-locking multi-directional manipulator to reduce motion artifacts and operator fatigue, and installing the OCT module on a moveable cart for system mobility, our customized portable boom-type UHR-OCT enables non-contact, high-resolution and high-stability retinal examinations to be performed on subjects in supine position. The spectral-domain UHR-OCT operates at a wavelength of 845 nm with 130 nm FWHM (full width at half maximum) bandwidth, achieving an axial resolution of ≈2.3µm in tissue with an A-line acquisition rate up to 128 kHz. A high-definition two-dimensional (2D) raster protocol was used for high-quality cross-sectional imaging while a cube volume three-dimensional (3D) scan was used for three-dimensional imaging and en-face reconstruction, resolving major layer structures of the retina. The feasibility of the system was demonstrated by performing supine position 2D/3D retinal imaging on healthy human subjects, sedated infants, and non-sedated awake neonates.

Integrated Visualization Highlighting Retinal Changes in Retinopathy of Prematurity From 3-Dimensional Optical Coherence Tomography Data

Importance

Early diagnosis of plus disease is critical in the management of retinopathy of prematurity (ROP). However, there is substantial interexpert disagreement in the diagnosis of plus disease based on vascular changes alone. Information derived from optical coherence tomography (OCT) may help characterize the severity of vascular and structural abnormalities in ROP.

Objective

To describe integrated visualization of 3-dimensional (3-D) data from investigational swept-source OCT optimized to delineate retinal vascular and microanatomical features in eyes with and without ROP.

Design, Setting, and Participants

This cross-sectional, observational report of OCT was captured in the prospective Study of Eye Imaging in Preterm Infants (BabySTEPS) designed in July 2016 at the Duke Health Intensive Care Nursery. Between December 2018 and August 2019, 2 preterm infants born at 24 and 30 weeks' gestation were enrolled, underwent ROP screening, and were imaged at those screening visits. Data at 36 weeks' postmenstrual age were analyzed via this visualization developed between September 2020 and May 2021.

Main Outcomes and Measures

Superimposed en face retinal vascular shadow view (RVSV) montages and thickness maps were used along with OCT B-scans to evaluate retinal vasculature and cross-section in eyes with and without ROP.

Results

In the right eyes of 2 infants, 3-D data were integrated and visualized from investigational bedside OCT imaging at the posterior pole. In the infant who developed type 1 ROP, RVSV-OCT confirmed presence of dilated and tortuous posterior pole vessels, shunting, and incomplete perifoveal vascular development, resulting in a temporal notch of avascular retina in zone 1. The thickness map revealed irregular pockets of thickening and thinning, and integrated visualization outlined the demarcation between thicker vascularized retina and thinner avascular fovea and presence of extraretinal neovascularization overlying elevated vessels in the superior arcades. In the infant without ROP (stage 0), RVSV-OCT revealed no abnormal vascular findings at the posterior pole. The integrated visualization showed a dome-shaped retinal thickening at the fovea, which was confirmed as macular edema.

Conclusions and Relevance

In 2 preterm infants in BabySTEPS, 3-D visualization of OCT findings during the ongoing ROP disease process demonstrated supplemental information about the retinal vasculature and microanatomy that can be useful to clinicians. These additional details provided by OCT could be integrated into future ROP screening methods with artificial intelligence-based analytics.

Optical Coherence Tomography Angiography in Pediatric Retinal Disorders

Purpose:

The rapid and noninvasive nature of optical coherence tomography angiography (OCTA) makes it a potentially valuable tool for imaging the retina in children. With the optimization of tabletop systems and the development of experimental handheld OCTA devices, there is expanded potential for OCTA in the clinic and the operating room. This article reviews the utility of OCTA in some of the most common pediatric retinal disorders.

Methods:

A thorough computerized PubMed search was performed to review relevant published journal articles to contextualize and identify the role of OCTA in common retinal disorders with vascular involvement affecting children. Pertinent results and findings from original investigations and case reports were summarized.

Results:

The ability to quickly collect both qualitative and quantitative information about retinal microvasculature, in both the clinic and operating room settings, with OCTA, has led to the uncovering of microvascular features and morphologic changes in many pediatric retinal disorders such as Coats Disease, familial exudative vitreoretinopathy, incontinentia pigmenti, sickle cell retinopathy, Stargardt Disease, X-linked juvenile retinoschisis, retinopathy of prematurity, diabetic retinopathy in type 1 diabetes, pediatric retinal tumors, and choroidal neovascularization.

Conclusions:

OCTA is a relevant tool to aid early detection, guide intervention, monitor treatment response, and understand pathogenesis in a number of pediatric retinal disorders.

The Impact of Axial Eye Growth on Foveal Avascular Zone Measurements in Children

SIGNIFICANCE

Foveal avascular zone (FAZ) area is a frequently used biomarker in diseases impacting the retinal vasculature in pediatric populations. Variation in axial length between individuals results in differences in lateral image scale, which affect the accuracy of FAZ area measurements. Accordingly, changes in axial length over time within individual children would affect estimates of FAZ area change.

PURPOSE

This study aimed to quantify how changes in axial length over time affect estimates of FAZ area change using optical coherence tomography angiography (OCT-A) images.

METHODS

Twenty pediatric participants (<18 years old) and 40 adult participants were imaged on Optovue's Avanti system (Fremont, CA) and had axial length measurements acquired at two time points. The FAZ was segmented twice using the OCT-A image at each time point. Foveal avascular zone area was estimated at both time points using the assumed/fixed axial length of the OCT-A device (unscaled) and using the participant's axial length (scaled). Changes in FAZ area over time were compared between the pediatric and adult groups using both unscaled and scaled data.

RESULTS

The average ± standard deviation follow-up time was 3.35 ± 1.66 years for the pediatric group and 2.90 ± 1.65 years for the adult group. Using unscaled data, FAZ area seemed to decrease between visits in the pediatric group (P = .004), whereas the FAZ area increased between visits in the adult group (P = .003). When correctly scaled data were used, the FAZ area still increased between visits for the adult group (P < .001), although the FAZ area no longer showed a significant change between visits for the pediatric group (P = .37). When comparing the normalized FAZ area change across visits between unscaled and scaled data, a significant difference was found between the adult and pediatric groups (P < .001).

CONCLUSIONS

Scaled data should be used when measuring FAZ area in pediatric populations, especially in longitudinal studies.

Advantages of Widefield Optical Coherence Tomography in the Diagnosis of Retinopathy of Prematurity

Recent advances in portable optical coherence tomography (OCT) and OCT angiography (OCTA) have resulted in wider fields of view (FOV) and shorter capture times, further expanding the potential clinical role of OCT technology in the diagnosis and management of retinopathy of prematurity (ROP). Using a prototype, handheld OCT device, retinal imaging was obtained in non-sedated infants in the neonatal intensive care unit (NICU) as well as sedated infants in the operating room of Oregon Health & Science University (OHSU) Hospital. In this observational study, we provide an overview of potential advantages of OCT-based disease assessment in ROP. We observed that next-generation OCT imaging (a) may be sufficient for objective diagnosis and zone/stage/plus disease categorization, (b) allows for minimally-invasive longitudinal monitoring of disease progression and post-treatment course, (c) provides three-dimensional mapping of the vitreoretinal interface, and (d) with OCTA, enables dye-free visualization of normal and pathologic vascular development.

Robotically aligned optical coherence tomography with 5 degree of freedom eye tracking for subject motion and gaze compensation

Optical coherence tomography (OCT) has revolutionized diagnostics in ophthalmology. However, OCT requires a trained operator and patient cooperation to carefully align a scanner with the subject's eye and orient it in such a way that it images a desired region of interest at the retina. With the goal of automating this process of orienting and aligning the scanner, we developed a robot-mounted OCT scanner that automatically aligned with the pupil while matching its optical axis with the target region of interest at the retina. The system used two 3D cameras for face tracking and three high-resolution 2D cameras for pupil and gaze tracking. The tracking software identified 5 degrees of freedom for robot alignment and ray aiming through the ocular pupil: 3 degrees of translation (x, y, z) and 2 degrees of orientation (yaw, pitch). We evaluated the accuracy, precision, and range of our tracking system and demonstrated imaging performance on free-standing human subjects. Our results demonstrate that the system stabilized images and that the addition of gaze tracking and aiming allowed for region-of-interest specific alignment at any gaze orientation within a 28° range.

105° field of view non-contact handheld swept-source optical coherence tomography

We demonstrate a handheld swept-source optical coherence tomography (OCT) system with a 400 kHz vertical-cavity surface-emitting laser (VCSEL) light source, a non-contact approach, and an unprecedented single shot 105° field of view (FOV). We also implemented a spiral scanning pattern allowing real-time visualization with improved scanning efficiency. To the best of our knowledge, this is the widest FOV achieved in a portable non-contact OCT retinal imaging system to date. Improvements to the FOV may aid the evaluation of retinal diseases such as retinopathy of prematurity, where important vitreoretinal changes often occur in the peripheral retina.

Enhanced medical diagnosis for dOCTors: a perspective of optical coherence tomography

SIGNIFICANCE

After three decades, more than 75,000 publications, tens of companies being involved in its commercialization, and a global market perspective of about USD 1.5 billion in 2023, optical coherence tomography (OCT) has become one of the fastest successfully translated imaging techniques with substantial clinical and economic impacts and acceptance.

AIM

Our perspective focuses on disruptive forward-looking innovations and key technologies to further boost OCT performance and therefore enable significantly enhanced medical diagnosis.

APPROACH

A comprehensive review of state-of-the-art accomplishments in OCT has been performed.

RESULTS

The most disruptive future OCT innovations include imaging resolution and speed (single-beam raster scanning versus parallelization) improvement, new implementations for dual modality or even multimodality systems, and using endogenous or exogenous contrast in these hybrid OCT systems targeting molecular and metabolic imaging. Aside from OCT angiography, no other functional or contrast enhancing OCT extension has accomplished comparable clinical and commercial impacts. Some more recently developed extensions, e.g., optical coherence elastography, dynamic contrast OCT, optoretinography, and artificial intelligence enhanced OCT are also considered with high potential for the future. In addition, OCT miniaturization for portable, compact, handheld, and/or cost-effective capsule-based OCT applications, home-OCT, and self-OCT systems based on micro-optic assemblies or photonic integrated circuits will revolutionize new applications and availability in the near future. Finally, clinical translation of OCT including medical device regulatory challenges will continue to be absolutely essential.

CONCLUSIONS

With its exquisite non-invasive, micrometer resolution depth sectioning capability, OCT has especially revolutionized ophthalmic diagnosis and hence is the fastest adopted imaging technology in the history of ophthalmology. Nonetheless, OCT has not been completely exploited and has substantial growth potential-in academics as well as in industry. This applies not only to the ophthalmic application field, but also especially to the original motivation of OCT to enable optical biopsy, i.e., the in situ imaging of tissue microstructure with a resolution approaching that of histology but without the need for tissue excision.

OCT Imaging in Infants

Optical coherence tomography (OCT) is widely applied in diagnosis and management of retina diseases particularly macular diseases in adult retina practices. However, it has been under-utilized in pediatric retinal diseases especially in neonates and infants. Utilization of OCT in primary macular diseases in this age group is also uncommon and is less reported. Challenges involved in image acquisition and limitations with available devices technique can explain the limited research and accurate data availability in the literature in this field. Purpose of this review article is to summarize the use of OCT and its importance in various infantile retinal pathologies such as vascular diseases, tumors, retinal dystrophies, and optic nerve pathologies with primary focus on neonates and infants, along with infant choroid. In addition, we also discuss about future directions including OCT angiography for infants.

Depth-Resolved Visualization of Perifoveal Retinal Vasculature in Preterm Infants Using Handheld Optical Coherence Tomography Angiography

Purpose

To establish methods to visualize depth-resolved perifoveal retinal vasculature in preterm infants using handheld optical coherence tomography angiography (OCT-A).

Methods

In this exploratory study, eyes of preterm infants were imaged using an investigational noncontact, handheld swept-source OCT-A device as part of the prospective BabySTEPS infant retinal imaging study. We selected high-quality OCT-A volumes at two developmental stages for analysis. Customized MATLAB scripts were used to segment retinal layers, test offset parameters, and generate depth-resolved OCT-A slabs. The superficial (SCP), intermediate (ICP), and deep (DCP) capillary plexuses were visualized and qualitatively assessed by three image graders.

Results

Six eyes from six preterm infants were included in this analysis. A three-layered perifoveal retinal vasculature was successfully visualized in all three eyes (three infants) in the 40 weeks postmenstrual age (PMA) group (one of three eyes with treated type 1 retinopathy of prematurity [ROP]). No obvious ICP or DCP was found in good-quality scans of the three eyes (three infants) in the 35 weeks PMA group (three of three eyes developed type 1 ROP).

Conclusions

Custom segmentation parameters are useful to visualize perifoveal retinal vasculature in preterm infants. At term age, a three-layered capillary structure is visible in most eyes, while prior to detectable flow within the ICP and DCP, the perifoveal vasculature may be better visualized in two layers.

Translational Relevance

Development of segmentation parameters for depth-resolved OCT-A of perifoveal retinal vasculature in preterm infants facilitates the study of human retinal vascular development and vascular pathologies of ROP.

A review of low-cost and portable optical coherence tomography

Optical coherence tomography (OCT) is a powerful optical imaging technique capable of visualizing the internal structure of biological tissues at near cellular resolution. For years, OCT has been regarded as the standard of care in ophthalmology, acting as an invaluable tool for the assessment of retinal pathology. However, the costly nature of most current commercial OCT systems has limited its general accessibility, especially in low-resource environments. It is therefore timely to review the development of low-cost OCT systems as a route for applying this technology to population-scale disease screening. Low-cost, portable and easy to use OCT systems will be essential to facilitate widespread use at point of care settings while ensuring that they offer the necessary imaging performances needed for clinical detection of retinal pathology. The development of low-cost OCT also offers the potential to enable application in fields outside ophthalmology by lowering the barrier to entry. In this paper, we review the current development and applications of low-cost, portable and handheld OCT in both translational and research settings. Design and cost-reduction techniques are described for general low-cost OCT systems, including considerations regarding spectrometer-based detection, scanning optics, system control, signal processing, and the role of 3D printing technology. Lastly, a review of clinical applications enabled by low-cost OCT is presented, along with a detailed discussion of current limitations and outlook.

Contactless optical coherence tomography of the eyes of freestanding individuals with a robotic scanner

Clinical systems for optical coherence tomography (OCT) are used routinely to diagnose and monitor patients with a range of ocular diseases. They are large tabletop instruments operated by trained staff, and require mechanical stabilization of the head of the patient for positioning and motion reduction. Here we report the development and performance of a robot-mounted OCT scanner for the autonomous contactless imaging, at safe distances, of the eyes of freestanding individuals without the need for operator intervention or head stabilization. The scanner uses robotic positioning to align itself with the eye to be imaged, as well as optical active scanning to locate the pupil and to attenuate physiological eye motion. We show that the scanner enables the acquisition of OCT volumetric datasets, comparable in quality to those of clinical tabletop systems, that resolve key anatomic structures relevant for the management of common eye conditions. Robotic OCT scanners may enable the diagnosis and monitoring of patients with eye conditions in non-specialist clinics.

Differentiating Retinal Detachment and Retinoschisis Using Handheld Optical Coherence Tomography in Stage 4 Retinopathy of Prematurity

Importance

Progression of retinopathy of prematurity (ROP) to stage 4 may require surgical intervention. The partial retinal detachment of stage 4 ROP may involve the fovea (stage 4B ROP) or may not (stage 4A ROP). This determination has heretofore been based on indirect ophthalmoscopy and documented with color fundus photography.

Objective

To investigate optical coherence tomography (OCT) features of eyes with stage 4 ROP and compare them with indirect ophthalmoscopy findings and grading of photographs.

Design, Setting, and Participants

In this study, research and clinical medical records of 15 infants with clinically diagnosed stage 4 ROP were retrospectively reviewed. Infants were treated at an academic center from May 2011 to January 2018.

Main Outcomes and Measures

Review of OCT images for the presence and foveal involvement of retinoschisis, retinal detachment, and/or vitreomacular traction masked to indirect ophthalmoscopy findings.

Results

Of the 15 included infants, 9 (60%) were male, the mean (SD) gestational age at birth was 23.9 (1.1) weeks, and the mean (SD) postmenstrual age at surgery was 42.4 (4.9) weeks. A total of 21 eyes were analyzed, of which 19 had adequate OCT imaging. Optical coherence tomography imaging extended to the retinal midperiphery but did not cover the entire region of possible detachment in each eye. Among these eyes, 7 eyes had peripheral retinoschisis without retinal detachment or foveal involvement, 5 eyes had peripheral retinoschisis and retinal detachment without foveal involvement, 7 eyes had either retinoschisis or retinal detachment involving the fovea, and 2 eyes had poor OCT signal owing to high retinal detachment.

Conclusions and Relevance

Handheld OCT imaging is useful in clinical evaluation of stage 4 ROP to determine foveal involvement and differentiate retinal detachment and retinoschisis. Many infants diagnosed as having stage 4A ROP had retinoschisis without OCT evidence of retinal detachment. This group of infants may represent a substage of stage 4A ROP, ie, stage 4A-schisis by OCT. These findings suggest handheld OCT imaging may be useful in the clinical evaluation of stage 4 ROP. Further investigations are needed to determine if this subgroup portends a different prognosis and if this observation should alter future clinical practice.

High-speed and widefield handheld swept-source OCT angiography with a VCSEL light source

Optical coherence tomography (OCT) and OCT angiography (OCTA) enable noninvasive structural and angiographic imaging of the eye. Portable handheld OCT/OCTA systems are required for imaging patients in the supine position. Examples include infants in the neonatal intensive care unit (NICU) and operating room (OR). The speed of image acquisition plays a pivotal role in acquiring high-quality OCT/OCTA images, particularly with the handheld system, since both the operator hand tremor and subject motion can cause significant motion artifacts. In addition, having a large field of view and the ability of real-time data visualization are critical elements in rapid disease screening, reducing imaging time, and detecting peripheral retinal pathologies. The arrangement of optical components is less flexible in the handheld system due to the limitation of size and weight. In this paper, we introduce a 400-kHz, 55-degree field of view handheld OCT/OCTA system that has overcome many technical challenges as a portable OCT system as well as a high-speed OCTA system. We demonstrate imaging premature infants with retinopathy of prematurity (ROP) in the NICU, a patient with incontinentia pigmenti (IP), and a patient with X-linked retinoschisis (XLRS) in the OR using our handheld OCT system. Our design may have the potential for improving the diagnosis of retinal diseases and help provide a practical guideline for designing a flexible and portable OCT system.

Preterm Infant Stress During Handheld Optical Coherence Tomography vs Binocular Indirect Ophthalmoscopy Examination for Retinopathy of Prematurity

Importance

Binocular indirect ophthalmoscopy (BIO) examination for retinopathy of prematurity (ROP) is a well-known cause of repeated preterm infant stress.

Objective

To compare stress during investigational optical coherence tomography (OCT) imaging to that during BIO for ROP.

Design, Setting, and Participants

This cross-sectional study examined infants at the bedside in the intensive care nursery. Consecutive preterm infants enrolled in Study of Eye Imaging in Preterm Infants (BabySTEPS) who had any research OCT imaging as part of the study. Patients were recruited from June to November 2019, and analysis began April 2020.

Main Outcomes and Measures

Infant stress was measured using modified components of a neonatal pain assessment tool before (baseline) and during OCT imaging and BIO examination of each eye.

Results

For 71 eye examinations of 16 infants (mean [SD] gestational age, 27 [3] weeks; birth weight, 869 [277] g), change from baseline to each eye examination was lower during OCT imaging than during BIO and the difference between OCT imaging and BIO at each eye examination was significant for the following: infant cry score (first eye examination: mean [SD], 0.03 [0.3] vs 1.68 [1.2]; -1.65 [95% CI, -1.91 to -1.39]; second eye examination: mean [SD], 0.1 [0.3] vs 1.97 [1.2]; -1.87 [95% CI, -2.19 to -1.54]), facial expression (first eye: 3 [4%] vs 59 [83%]; -79% [95% CI, -87% to -72%]; second eye: 4 [6%] vs 61 [88%]; -83% [95% CI, -89% to -76%]), and heart rate (first eye: mean [SD], -7 [16] vs 13 [18]; -20 [95% CI, -26 to -14]); second eye: mean [SD], -3 [18] vs 20 [20] beats per minute; -23 [95% CI, -29 to -18]) (P < .001 for all). Change in respiratory rate and oxygen saturation did not differ between OCT imaging and BIO.

Conclusions and Relevance

While the role of OCT alone or in combination with BIO is currently unknown for ROP, these findings suggest that investigational OCT imaging of ROP is less stressful than BIO examination by a trained ophthalmologist.

Advances in multimodal imaging in ophthalmology

Multimodality ophthalmic imaging systems aim to enhance the contrast, resolution, and functionality of existing technologies to improve disease diagnostics and therapeutic guidance. These systems include advanced acquisition and post-processing methods using optical coherence tomography (OCT), combined scanning laser ophthalmoscopy and OCT systems, adaptive optics, surgical guidance, and photoacoustic technologies. Here, we provide an overview of these ophthalmic imaging systems and their clinical and basic science applications.

Birth Weight Is a Significant Predictor of Retinal Nerve Fiber Layer Thickness at 36 Weeks Postmenstrual Age in Preterm Infants

PURPOSE

To assess retinal nerve fiber layer (RNFL) thickness in preterm infants.

DESIGN

Prospective observational study.

METHODS

We imaged 83 awake infants (159 eyes) at 36 ± 1 weeks postmenstrual age (defined as the time elapsed between the first day of the last maternal menstrual period and the time at imaging) using a handheld optical coherence tomography (OCT) system at the bedside. Blinded graders semi-automatically segmented RNFL in the papillomacular bundle (-15 to +15° relative to the fovea-optic nerve axis). We correlated RNFL thickness and 7 characteristics of interest (sex, race, ethnicity, gestational age, birth weight, stage of retinopathy at prematurity, and presence of pre-plus or plus disease) via univariable and multivariable regressions.

RESULTS

RNFL was 3.4 μm thicker in the right eyes than in the left eyes (P < .001). Among 7 characteristics, birth weight was the only independent predictor of RNFL thickness (P < .001). A 250-g increase in birth weight was associated with 5.2 μm (95% confidence interval: 3.3-7.0) increase in RNFL thickness. Compared with very preterm infants, extremely preterm infants had thinner RNFL (58.0 ± 10.7 μm vs 63.4 ± 10.7 μm, P = .03), but the statistical significance disappeared after adjustment for birth weight (P = .25). RNFL thickness was 11.2 μm thinner in extremely low birth weight infants than in very low birth weight infants (55.5 ± 8.3 μm vs. 66.7 ± 10.2 μm; P < .001). The difference remained statistically significant after adjustment for gestational age.

CONCLUSION

Birth weight is a significant independent predictor of RNFL thickness near birth, implying that the retinal ganglion cells reserve is affected by intrauterine processes that affect birth weight.

Foveal Differentiation and Inner Retinal Displacement Are Arrested in Extremely Premature Infants

Purpose

Children with a history of prematurity often have poorly developed foveae but when during development foveal differences arise. We hypothesize that the course of foveal development is altered from the time of preterm birth.

Methods

Eyes of 102 preterm infants undergoing retinopathy of prematurity screening examinations in the STudy of Eye imaging in Premature infantS (BabySTEPS) (NCT02887157) were serially imaged between 30 and 42 weeks postmenstrual age (PMA) using handheld optical coherence tomography systems. Total retinal thickness, inner retinal layer (IRL) thickness, and outer retinal layer (ORL) thickness were measured at the foveal center and parafovea. Foveal put depth, IRL thickness, and ORL thickness were compared between infants born at different gestational ages using mixed effects models.

Results

Foveal pit depth and IRL thickness were inversely related to gestational age; on average, the most premature infants had the thickest IRL and shallowest pits at all PMAs. Differences were evident by 30 weeks PMA and persisted through 42 weeks PMA. The foveal pits of the most premature infants did not progressively deepen, and the IRLs did not continue to thin with increasing chronological age.

Conclusions

Foveation in extremely preterm infants is arrested from the earliest observed ages and fails to progress through term equivalent age. The developmental displacement of the IRL from the foveal center into the parafovea does not occur normally after preterm birth. These observations suggest that foveal hypoplasia seen in children with history of prematurity is due to disturbances in foveal development that manifest within weeks of birth.

Quantitative Handheld Swept-Source Optical Coherence Tomography Angiography in Awake Preterm and Full-Term Infants

Purpose

To compare retinal vascular parameters acquired by handheld swept-source optical coherence tomography angiography (SS-OCTA) between nonsedated preterm and full-term infants.

Methods

Preterm and full-term infants at the University of Washington Medical Center were enrolled. Retinal angiograms (nominal size ∼7 × 7 mm²) were obtained at each routine retinopathy of prematurity (ROP) screening session for preterms and once during the first 72 hours of life for full-terms. Macular vessel area density and nonperfusion area were evaluated on the binarized vasculature map in both small (1.5 × 1.5 mm) and large (3 × 3 mm) quadrants. Average vessel diameter and tortuosity values were obtained from each large vessel branch (length >200 µm). All vascular analyses used previously published algorithms.

Results

Handheld SS-OCTA captured 31 of 55 (56%) high-quality volumes on 8 awake preterm infants (gestational age 28 ± 4 weeks, birth weight 891 ± 314 g, postmenstrual age at first imaging session 37 ± 2 weeks) and 48 of 54 (89%) volumes on 12 awake full-term infants (gestational age 39 ± 1 weeks, birth weight 3405 ± 329 g). Signal-to-noise ratio was 5.08 ± 1.52 dB in preterm and 4.90 ± 1.12 dB in full-term infants. Preterm infants had higher mean large vessel tortuosity compared to full-term infants (P = 0.004). The large nasal quadrant vessel area density of infants with stage 3 and/or pre-plus or worse ROP was higher than other preterm infants (P = 0.007).

Conclusions

Although inadequate image quality limited usable imaging sessions, handheld SS-OCTA achieved adequate signal-to-noise ratio in nonsedated infants for quantitative retinal vascular parameter analysis.

Translational Relevance

Large- and small-vessel parameters were associated with prematurity and ROP severity, respectively.

Slow progressive perifoveal vascular formation in an infant with aggressive posterior retinopathy of prematurity

Aggressive posterior retinopathy of prematurity (AP-ROP) is a severe form of ROP occurring in preterm infants that is characterized by rapid progression and prominent vascularity. We report the use of investigational bedside noninvasive optical coherence tomography angiography to visualize the slow and progressive perifoveal vascular formation in an infant with AP-ROP treated with bevacizumab. We also document extensive vascular shunts and morphological differences between arrested and growing retinal capillaries at the vascular wavefront.

Optical coherence tomography imaging of the pediatric retina

Optical coherence tomography is an increasingly important part of the retinal specialist's and general ophthalmologist's toolkit for diagnosing and managing retinal disease. This review summarizes the unique considerations and available imaging systems with which pediatric ophthalmologists should be familiar when attempting optical coherence tomography in children. Normal developmental changes in foveal and extrafoveal structure and the need for an established pediatric normative database of retinal thicknesses are reviewed. Finally, applications of optical coherence tomography imaging to selected representative pediatric retinal diseases are introduced as examples of how optical coherence tomography in children is furthering the diagnosis and management of vision-threatening retinal diseases.