Optical coherence tomography (OCT) systems utilize 2D scanning methods to acquire reflectance-based volumetric images of samples, such as the human retina, with micrometer-scale depth resolution. A common method for performing this scanning at high speeds is to use a pair of sequential, single-axis galvanometer scanners. An undesired effect of using separated scanners is the variation in the beam position at the pupil plane, a phenomenon known as beam wander or pupil wobble. This can lead to loss of signal and vignetting artifacts in the resulting images. To overcome these limitations, we propose a method to deterministically analyze the pupil wobble in a given retinal OCT system and to correct for the displacement using pupil tracking OCT with a 2D scanning mirror placed anti-conjugate to the pupil plane. We demonstrate that we can model the pattern of pupil wobble present in any OCT system both theoretically and empirically and then use a pupil tracking system to correct for the displacement of the beam to acquire OCT images without the imposed artifacts.

Optical coherence tomography (OCT) is an interferometric technique for micron-level imaging in biological and non-biological contexts. As a non-invasive, non-ionizing, and video-rate imaging modality, OCT is widely used in biomedical and clinical applications, especially ophthalmology, where it functions in many roles, including tissue mapping, disease diagnosis, and intrasurgical visualization. In recent years, the rapid growth of medical robotics has led to new applications for OCT, primarily for 3D free-space scanning, volumetric perception, and novel optical designs for specialized medical applications. This review paper surveys these recent developments at the intersection of OCT and robotics and organizes them by degree of integration and application, with a focus on biomedical and clinical topics. We conclude with perspectives on how these recent innovations may lead to further advances in imaging and medical technology.

Optical coherence tomography (OCT) is an indispensable imaging modality for the diagnosis and management of many common eye diseases. We previously presented a fixedbase robotic OCT system to enable automated imaging and alleviate the necessity for restricted patient posture required by traditional clinical OCT. To adapt our system to diverse clinic environments, we introduce a mobile robotic OCT system designed for imaging patients in diverse clinical configurations. Our system includes a robot arm, a vertical motorized lift, and a wheeled cart housing essential components for the entire system, and is equipped with real-time motion planning algorithms for head movement tracking and obstacle avoidance during imaging sessions. We validate the system's workspace through robot kinematics and clinical simulation, evaluate dynamic tracking accuracy in real world experiments, and demonstrate obstacle avoidance capability in both simulation and real world. These features will allow us to perform OCT imaging in real clinical settings in the near future.

Optical coherence tomography (OCT) has revolutionized diagnostics in retinal ophthalmology. Traditional OCT requires minimal relative motion between the subject and scanner, which is difficult to achieve with handheld devices and/or non-stabilized subjects. We recently introduced robotically-aligned OCT (RAOCT) as an alternative that promises to alleviate these minimal-movement requirements by tracking the subject and compensating for their motion with dynamic hardware components in real-time. However, hardware and image processing delays lead to residual motion artifacts even after automatic alignment and motion compensation. Here, we introduce a novel sensor-driven digital motion correction approach that overcomes these shortcomings. Our method leverages synchronized sensing of both the subject's eye and the scanner hardware to continuously estimate the imaging system state during acquisition. The A-scans are then remapped using a ray-tracing model of the system at the precise moment of acquisition. We demonstrate that, in addition to motion compensation from RAOCT, our method further reduces residual artifacts by 88.3 %, 80.4%, and 62.6 % across axial, lateral, and rotational motions, respectively. We also show our correction in human retinal OCT images where residual errors from acquisition were reduced down to 12.4 mu m, 0.11 degrees, and 0.39 degrees for axial, lateral, and rotational motion, respectively. (c) 2025 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

The introduction of optical coherence tomography (OCT) in the 1990s revolutionized diagnostic ophthalmic imaging. Initially, OCT's role was primarily in the adult ambulatory ophthalmic clinics. Subsequent advances in handheld form factors, integration into surgical microscopes, and robotic assistance have expanded OCT's utility and impact outside of its initial environment in the adult outpatient ophthalmic clinic. In this review, we cover the use of OCT in the neonatal intensive care unit (NICU) environment with a handheld OCT, recent developments in intraoperative OCT for data visualization and measurements, and recent work and demonstration of robotically aligned OCT systems outside of eye clinics. Of note, advances in these areas are a legacy of our colleague, the late Joseph Izatt. OCT has been an important innovation for ocular diagnostics, and these advances have helped it continue to extend in new directions.

PURPOSE:To review the evidence on the safety and effectiveness of epithelium-off corneal collagen cross-linking (CXL) for the treatment of progressive corneal ectasia. METHODS:A literature search of the PubMed database was most recently conducted in March 2024 with no date restrictions and limited to studies published in English. The search identified 359 citations that were reviewed in abstract form, and 43 of these were reviewed in full text. High-quality randomized clinical trials comparing epithelium-off CXL with conservative treatment in patients who have keratoconus (KCN) and post-refractive surgery ectasia were included. The panel deemed 6 articles to be of sufficient relevance for inclusion, and these were assessed for quality by the panel methodologist; 5 were rated level I, and 1 was rated level II. There were no level III studies. RESULTS:This analysis includes 6 prospective, randomized controlled trials that evaluated the use of epithelium-off CXL to treat progressive KCN (5 studies) and post-laser refractive surgery ectasia (1 study), with a mean postoperative follow-up of 2.4 years (range, 1-5 years). All studies showed a decreased progression rate in treated patients compared with controls. Improvement in the maximum keratometry (Kmax) value, corrected distance visual acuity (CDVA), and uncorrected distance visual acuity (UDVA) was observed in the treatment groups compared with control groups. A decrease in corneal thickness was observed in both groups but was greater in the CXL group. Complications were rare. CONCLUSIONS:Epithelium-off CXL is effective in reducing the progression of KCN and post-laser refractive surgery ectasia in most treated patients with an acceptable safety profile. FINANCIAL DISCLOSURE(S):Proprietary or commercial disclosure may be found after the references.

Significance:Imaging deep structures with optical coherence tomography (OCT) is difficult in highly scattering biological tissue, such as the sclera. There is a need to visualize the suprachoroidal space and choroid through the sclera to study suprachoroidal drug delivery. Aim:We aim to develop optical methods to image through the highly scattering sclera with a custom-built OCT system to visualize the suprachoroidal space and drug delivery within. Approach:We developed a custom handheld OCT scanner to image the anterior segment and suprachoroidal space in ex vivo eye models. Tartrazine (Yellow 5) solution, which has been shown to optically clear biological tissue in the visible regime, was tested as a clearing agent to optimize near infrared OCT imaging through the sclera. Results:Tartrazine dramatically increased OCT signal return from the deeper sclera and choroid and thus enabled visualization of the suprachoroidal drug delivery after transscleral injection. Conclusions:We demonstrated successful optical clearing of the thick, porcine sclera with a compact handheld OCT system to image the suprachoroidal space. We believe there is broader potential to use optical clearing with handheld OCT for a variety of previously inaccessible, highly scattering tissue samples.

Objective We developed a novel slit lamp photography (SLP) generative adversarial network (GAN) model using limited data to supplement and improve the performance of an Artificial Intelligence (AI) based microbial keratitis (MK) screening model. Design Cross-sectional study. Subjects SLPs of 57 healthy and 27 MK eyes were prospectively and retrospectively collected at a tertiary care ophthalmology clinic at a large, academic institution. Methods We trained the GAN model StyleGAN2-ADA on healthy and MK SLPs to generate synthetic images. To assess synthetic image quality, we performed a visual Turing test. Three cornea fellows tested their ability to identify 20 images each of 1) real healthy, 2) real diseased, 3) synthetic healthy, and 4) synthetic diseased. We also used Kernel Inception Distance (KID) to quantitatively measure realism and variation of synthetic images. Using the same dataset used to train the GAN model, we trained two DenseNet121 AI models to grade SLP images as healthy or MK with 1) only real images and 2) real supplemented with GAN-generated images. Main Outcome Measures Classification performance of microbial keratitis screening models trained with only real images compared to a model trained with both limited real and supplemented synthetic GAN images. Results For the visual Turing test, the fellows on average rated synthetic images as good quality (83.3% ± 12.0% of images), and synthetic and real images were found to depict pertinent anatomy and pathology for accurate classification (96.3% ± 2.19% of images). These experts could distinguish between real and synthetic images (accuracy: 92.5% ± 9.01%). Analysis of KID score for synthetic images indicated realism and variation. The MK screening model trained on both limited real and supplemented synthetic data (AUROC: 0.93, bootstrapping 95% CI: 0.77-1.0) outperformed the model trained with only real data (AUROC: 0.76, 95% CI: 0.50-1.0), an improvement of 0.17 (95% CI 0-0.4; two-tailed t-test p=0.076). Conclusion AI-based MK classification may be improved by supplementation of limited real training data with synthetic data generated by GANs.

[This corrects the article DOI: 10.1117/1.JBO.29.12.120501.].

PURPOSE. To develop a quantitative tool for assessing the posterior ocular shape using widefield, volumetric optical coherence tomography (OCT) in eyes with myopia. METHODS. This observational, cross-sectional study included 178 eyes from 113 participants. Participants underwent a standardized eye examination, including ocular biometry and a custom ultrawide OCT. True ocular shape was reconstructed by tracing the beam propagation from the system to the posterior eye. Gaussian curvature quantified the localized ocular shape, which was further categorized into five distinct categories. An ocular shape irregularity (OSI) was calculated using principal component analysis. Linear regression with breakpoints analyzed the relationship between ocular shape parameters and axial length (AL). RESULTS. Increased curvature mean and variance were associated with more severe myopia (P < 0.001). Curvature categories (convex, normal, concave, and highly concave) differed significantly between the groups (all P < 0.001). Their correlations with AL revealed significant breakpoints between 27.1 and 27.2 mm. OSI, as a single metric for quantifying ocular shape distortion, was associated with more severe myopia (P < 0.001), and its correlation with AL revealed a breakpoint at 27.2 mm with a fourfold increase in slope steepness beyond this pivot. Determination of OSI was highly reproducible and could also be obtained with fewer scans. CONCLUSIONS. Eyes exceeding 27.2 mm in length exhibit pronounced shape changes. Our framework can be seamlessly integrated into commercial OCTs for ocular shape deformation detection, which could aid in identifying eyes with pathologic myopia.