This PDF file contains the front matter associated with SPIE Proceedings Volume 12824, including the Title Page, Copyright information, Table of Contents, and Conference Committee information.

Adaptive optics (AO) ophthalmoscopes enable retinal imaging at cellular resolution. The small field of view (FOV) and high magnification of these instruments make inclusion of a fixation channel critical for controlling the patch of retina that is stimulated with light and imaged. Here, we develop a more powerful fixation channel that is integrated with an improved stimulus channel in the Indiana AO optical coherence tomography (AO-OCT) system. It uses all stock components except one 3D printed optical mount and some machined adaptor plates. We balanced the trade-offs between subject working distance, steering field of view, dioptric correction range, and stimulus light efficiency and achieved better performance in all areas compared to our previous channel. We report on the overarching objectives of the integrated fixation and stimulus channel, its design and its validation as illustrated by several AO-OCT imaging examples. While intended for our AO-OCT system, the design, components, and performance trade-offs are general enough to be applicable to many other AO ophthalmoscopes in the field.

Simultaneous dual-channel offset imaging provides isotropic images of retinal microstructures that enable phase imaging in the living eye with enhanced visualization contrast. Phase imaging is widely used in microscopy and biomedical imaging to reveal structures not visible in standard imaging due to their low scattering properties. We implement the technique in a line-scanning approach using a high-speed 2D camera to visualize microstructures in the living eye with enhanced contrast, that were only visible with other modalities, such as flying-spot scanning laser ophthalmoscopy (SLO). A simplified phase imaging system has the potential to be quantitative, with diagnostic value for retinal diseases, and may enable monitoring treatment. Methods for super-resolution reconstruction were explored to break the diffraction limit. SLO phase imaging exploits forward-scatter through phase objects in the retina and subsequent reflection (rescatter) of intensity-encoded diffuse reflections for detection; line-scan ophthalmoscopy (LSO) phase imaging works in the opposite way, in which the offset line-beam produces oblique back-illumination enabling the diffractive/refractive effects of phase objects in the inner retina to be imaged in transmission. The former scrambles optical phase information, the latter preserves it. This design has several advantages over conventional SLOs: 1) the LSO has a reduced number of optical elements, which results in a short optical path and compact design, 2) only one moving part, thus hardware and electronics are simplified, and 3) the LSO is inherently safer because the beam is focused in only one dimension on the retina.

Adaptive optics imaging techniques are invaluable for cellular-level retina visualization. While AO Flood illumination ophthalmoscopes provide distortion-free, high-speed images, they lack contrast. On the other hand, AO scanning laser ophthalmoscopes offer highly contrasted images due to point by point illumination and spatial filtering but suffer from low pixel throughput and distortion artifacts. Our recent advancements, using a DMD integrated AO-FIO, show that we can illuminate and capture multiple spatially separated zones, achieving contrast close to the one of a confocal microscope. Our theoretical framework emphasizes that each zone must be smaller than 100μm in both directions or smaller than 10μm in only one direction to minimize the diffuse light component. Building upon these results, we developed a cutting-edge confocal rolling slit ophthalmoscope, able to achieve brightfield contrast similar to a confocal ophthalmoscope, along with phase contrast images. We utilize a classical sCMOS camera with a rolling shutter synchronized with the line source scanning of the field of view. The system makes use of all the incident photons that can be collected, whether singly, multiply scattered or absorbed. Easy digital switching between the darkfield and brightfield, as well as modification of the size and offset of the detection aperture, enhances the adaptability and versatility of this multimodal imaging system, allowing for fine-tuning of imaging modalities and comprehensive exploration of the retina.

Small animals, such as rodents, are attractive options for investigating the intrinsic process of retinal degeneration. In this study, we used phase-sensitive optical coherence tomography to explore the comprehensive dynamics of rats’ outer retinas in response to visual stimuli. By calculating the temporal phase difference between different outer retinal bands, we revealed highly reproducible retinal dynamics, on the order of tens of nanometers, related to different parts of the outer retina. Our approach may pave the way for preclinical optoretinography study in small animals, facilitating clinical translations for the early detection of neurodegenerative diseases.

Assessment of the functional response of photoreceptors plays an important role in assessing and treating vision loss. Optoretinography (ORG) is an emerging non-invasive technique that measures the photoreceptors’ functional response to external light stimuli using optical coherence tomography (OCT) or other phase-sensitive imaging modalities. Recently a novel velocity-based ORG method was demonstrated, illustrating the feasibility of measuring photoreceptor function with clinical-grade OCT systems. Here we test this technique on diseaseaffected retinae of human subjects. The disease-affected retinae exhibited altered responses when compared to a healthy volunteer. The findings indicate promise for this novel tool to find applications in the clinic and clinical research.

Cone photoreceptors are central to vision and die in many retinal degenerative diseases. High-resolution retinal imaging methods–notably adaptive optics optical coherence tomography (AO-OCT)–use these cells’ reflectance profiles to characterize their morphologic and functional properties in the living human eye to assess their health. While some cone cells reveal reflections that correspond to identifiable features such as the inner segment/outer segment junction (IS/OS) and cone outer segment tip (COST), other cells can generate additional unexplained reflections that complicate our ability to characterize their reflectance profile. Here, we present a new quantitative method to properly identify cone reflections in AO-OCT images that correspond to their features. We use this method to estimate the prevalence of any additional cone reflections in healthy eyes and eyes with retinitis pigmentosa (RP) and to identify the true COST reflection. Using our method as a ground truth, we find that the conventional method (which identifies COST as the brightest reflection between IS/OS and retinal pigment epithelium) misidentified COST in 6.1±1.5% of cones in healthy controls. In the transition zones of RP, this rate can increase to 18.8%. In these cones, our method’s estimate of cone outer segment length and optoretinogram response differed by 36.8 ± 12.8% and 20.7 ± 17.6%, respectively, in healthy controls, and by 79.5 ± 21.2% and 34.9 ± 24.8% in the transition zone of RP.

Proliferative diabetic retinopathy (PDR) and retinal vein occlusion (RVO) are severe ocular diseases that can cause retinal vascular damage and are the leading source of vision loss. Hyalocytes are macrophage-like cells residing in the retina that play critical roles in inflammation and immunity. For this study, we acquired multiple optical coherence tomography (OCT) volumes at two timepoints (30-min interval) from patients with PDR, central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) using commercialized OCT devices and evaluated the hyalocyte progression with dynamic changes in vasculature. We observed the abnormal spatial distribution of hyalocytes under different conditions, and will further study the correlation of changes in hyalocyte distribution and vessel perfusion.

The accommodation of the crystalline lens allows for sharp vision in the close and distant range. Conditions such as cataracts can make it necessary to replace the natural tissue with an artificial intraocular lens (IOL), which lacks the ability to accommodate. The alternatives that are currently under investigation include accommodating IOLs or refilling the lens bag with hydrogels. Here, we investigate the possibility to remove and refill only the central part (nucleus) of a cataract lens, thereby preserving its ability to accommodate. This approach avoids damage to the lens cortex to prevent stiffening of the capsular bag—a significant drawback of complete lens refilling. The nucleus of the lenses of porcine eyes was fragmented via fs-laser treatment and removed by phacoemulsification. The lens’s mechanical properties, ray tracing properties and curvature were investigated with an in-house developed measurement setup, including a lens stretching device for simulation of accommodation. This yielded quantifiable data on the transparency, accommodation capabilities and focus shift of treated versus untreated lenses. While native transparency could not yet be achieved, refilled eyes exhibited the same focal shift as non-refilled, indicating functional accommodation. Measurements of the curvature revealed stronger flattening of refilled eyes. Apart from the study of partial lens refill, the stretcher device and respective protocols presented here possess great potential in IOL development, presbyopia research or characterization of model lenses.

In this conference proceeding we illustrate an early concept of a new anterior eye imaging method—optical transmission tomography (OTT). Thanks to the 20× larger viewing area, OTT can enhance the precision of corneal cell/nerve density biomarkers compared to clinical specular and confocal microscopies. This holds promise for improving the selection of candidates for refractive surgery and for reducing the incidence rates of post-surgical dry eye, endothelial decompensation as well as other common complications.

Accurate differentiation of uveal melanoma and choroidal nevi is critical for optimal patient care, preventing unnecessary procedures for benign lesions while ensuring timely intervention for potentially malignant cases. This study aimed to validate deep learning classification of these lesions and to evaluate the impact of different color fusion options on classification performance. To evaluate the effect of color fusion options on the classification performance, we tested early fusion, intermediate fusion, and late fusion using ultra-widefield retinal images. Specificity, sensitivity, F1-score, accuracy, and the area under the curve (AUC) of a receiver operating characteristic (ROC) were used to assess the performance of the deep learning model. The results show that the color fusion options significantly impacted the deep learning classification performance, with intermediate fusion emerging as the best strategy, outperforming both single-color learning and the other fusion strategies. The intermediate fusion strategy had an accuracy of 89.72%, sensitivity of 85.05%, specificity of 91.64, F1 score of 0.8492 and an AUC of 0.9335. These compelling results emphasize the vast potential of deep learning to enhance the accuracy of diagnosis and classification of UM and choroidal nevi, leading to improved patient outcomes and optimized treatment strategies. By harnessing the power of deep learning and color fusion strategies, this study not only provides valuable insights into the application of these approaches in the field of ophthalmology but also highlights their critical significance in automating the classification of UM and choroidal nevi.

While the a-wave of mouse electroretinogram (ERG) occurs within 50 milliseconds after exposure to light, the optoretinogram (ORG) slower than a 20Hz sampling rate could face limitations in observing immediate morphological changes from the retina. In this study, we develop a compact custom-built mouse ORG system based on spectral domain optical coherence tomography (SD-OCT) for 100Hz~1KHz B-scan rates comprised of 100 kHz A-scans. All the optics of the developed ORG system are designed on a 24 x 24 inches optical breadboard to move easily as well as to combine with the ERG system in a dark room. Without using a fundus camera, the OCT system provides en-face images from high-pass filtering and square of the OCT spectral signal for mouse retinal positioning in-vivo before acquiring ORG data. The 490nm LED for light stimulus is generated to make uniform illumination at the mouse retina using the Maxwellian view method. The common path of the OCT scanning light and the visible LED is built with achromatic doublet lens combinations based on optical simulation with Opticstudio^® . The developed compact ORG system can not only observe light-evoked responses with 1~10 milliseconds but also be used for the studies of correlations between ORG and ERG in the mouse retina.

Meibomian gland dysfunction (MGD) is a significant cause of evaporative dry eye disease, occurring when the meibomian glands (MGs) in the eyelids produce abnormal lipid amounts. MG morphological features are crucial indicators of MG function and dry eye symptoms. However, the relationship between MG morphological irregularities and MGD remains unclear. To address this, we develop an integrated deep-learning-enabled monitoring system within a portable meibography device, enabling early identification and quantification of irregularly-shaped MGs. Our approach comprises two key technical components. First, a customized model is fine-tuned to classify MG irregularities into four types: overlapping, shortening, thickening, and tortuosity. We then quantitatively analyze MG irregularity ratios among four meiboscore groups of varying MG atrophy degrees and examine their connection to Ocular Surface Disease Index (OSDI) indexes from a subjective symptom perspective. From meiboscore 0 to 3, the overlapping MG ratio decreases by 17 %, and the shortening MG ratio increases by 12 %. Furthermore, we’ve built a handheld device equipped with infrared (IR) LED arrays and a USB camera to facilitate long-term and dynamic assessment. This meibography technology is compatible with common operating systems and can be integrated into a smartphone. The high-resolution images captured by this device can be used to assess various types of irregularities. This intelligent portable system offers an automatic and efficient quantitative evaluation of MG morphological irregularities, enabling home inspection and reducing costs. It has the potential to be applied in diagnosing and monitoring MG conditions, facilitating the management of MGD.

We introduced an improved iteration of a panoramic retinal (panretinal) handheld swept-source OCT angiography (OCTA) imaging system with an 800kHz VCSEL light source. The advanced system successfully achieved a remarkable 140° field of view (FOV, visual angle measured from the pupil plane), enabling comprehensive imaging coverage from the posterior pole to the peripheral retina in a single capture.

After wrapping on the eye, a soft contact lens can improve a patient's retinal image quality by correcting the patient's wavefront aberrations, including defocus, astigmatism, etc., and its optical zone size or diameter is a critical factor that affects the lens performance. With lens decentration, the lens optical zone edge could only partially cover the patient's pupil area, leading to significant wavefront correction errors. If there is a considerable lens thickness variation at the edge of the lens optical zone, the optical zone edge could also generate a substantial amount of scattering, which will also degrade the retinal image contrast. Thus, it is essential to characterize the optical zone diameter precisely. An interferometer-based imaging system can typically be used for the characterization. However, at specific soft contact lens power ranges (-3D, for example), it is impossible to identify the optical zone boundary even with an interference fringe-based imaging system. In this experiment, we used a Shack-Hartmann-based wavefront sensor to directly measure the soft contact lens optical zone in a power range of -12 to +6D. A software package is also developed to analyze the captured images and generate the optical zone diameter. The results are compared with interferometer imaging-based results and the original lens design. Our results indicated the developed method (including both the Shack-Hartmann imaging system and the software package) was able to precisely characterize the soft contact lens optical zone within the whole lens power range.

Optoretinography (ORG) involves imaging the intrinsic optical signal (IOS) of the retina and when used with optical coherence tomography (OCT) offers a noninvasive, objective evaluation of retinal function. The recently proposed Knox–Thompson (KT) method, a phase-based ORG, induces fluctuations and noise in the ORG signal based on the selected path, referred to as the KT path. However, the strategy for selecting this path has not been firmly established. Therefore, we implemented Dijkstra’s algorithm, a renowned shortest path algorithm, to select the KT path to minimize noise in phase-based ORG data. Our study used a healthy pigmented rabbit as the test subject. IOS images were captured using point-scan swept-source OCT with a white light–emitting diode with a 400–800nm wavelength range used as a light stimulus for approximately 6s during the ORG. The light intensity was adjusted to ensure a photopigment bleaching level of 63%. In the KT method, the reference time is constantly updated to construct the KT path. Changes in thickness were calculated by correlating the phase difference with varying reference times. The KT path was optimized with Dijkstra’s algorithm. Thus, the ORG signal from the optimized KT path exhibited less phase dispersion than that from the KT path with a fixed time interval and produced smoother changes over time in the thickness between the ellipsoid zone and the retinal pigment epithelium. We believe that this improved method will contribute to the practical implementation of OCT–ORG in clinical settings.

Glaucoma is characterized by the irreversible retinal ganglion cells (RGCs) loss and has received great research and clinical attention due to its complex mechanism and loss of effective treatment. Longitudinal in vivo study on glaucoma in mouse model can be a promising approach to unveil the mechanism of glaucoma. In this paper, we use a silicon oil (SO) induced glaucoma model on mouse and the adaptive optics two photon microscope system to evaluate whether the aberration from both mouse eye and SO can be corrected and then longitudinal imaging with subcellular resolution on the mouse retina can be achieved.

The wall-to-lumen ratio (WLR) of retinal blood vessels promises a sensitive marker for functional assessment of eye conditions. However, in vivo measurement of vessel wall thickness and lumen diameter is still technically challenging, hindering the wide application of WLR in research and clinical settings. In this study, we demonstrate the feasibility of using optical coherence tomography (OCT) as one practical method for in vivo quantification of WLR in the retina. Based on three-dimensional vessel tracing, lateral en face and axial B-scan profiles of individual vessels were constructed. By employing adaptive depth segmentation that traces each blood vessel for en face OCT projection, the vessel wall thickness and lumen diameter could be reliably quantified. A comparative study of control and 5xFAD mice confirmed WLR as a sensitive marker of the eye condition.

The purpose of this study is to investigate the effect of light delivery location on spectral efficiency in trans-palpebral illumination. In comparison to transpupillary illumination, trans-palpebral illumination offers a pupil dilation-free alternative for widefield fundus photography. However, the spectral efficiency is influenced by the spatial variance of light properties across the palpebra and sclera. To assess the spatial dependency of spectral illumination efficiency, four narrow-band light sources spanning visible and near-infrared (NIR) wavelengths were employed. Comparative analysis revealed a notable reliance of visible light efficiency on spatial location, whereas NIR light efficiency exhibited minimal sensitivity to the illumination location.

We use optical modelling to reconstruct the pseudophakic eye for 4 different accommodative intra-ocular lens (AIOL) design concepts and map their respective stray light retinal intensity images over a wide range of field of view. The results provide a comparison of stray light performance, both quantitative and qualitative, between the competing AIOL designs. In addition, a deeper analysis of the ray trace offers insights on the various sources of AIOL stray light and leads to operative conclusions on how to minimize AIOL-induced stray light artifacts.

A line-field optical coherence tomography (LFOCT) application is implemented for real-time in vivo corneal and retinal imaging. In contrast to other described systems of LFOCT that use single-shot high-speed cameras, we describe the first results utilizing a camera with continuous high-speed data transfer and display. The system is based on a previously published design using a center wavelength of 840nm and a bandwidth of 50nm. The system’s B-frame and en-face display speed reaches up to 5000 frames per second corresponding to 2,500,000 A-lines. A visible light camera is used to detect the interferometric signal to reduce costs and improve optomechanical integration. Balancing the sensitivity vs. acquisition speed allows continuous high data transfer and processing rates and simplifies the implementation as a bedside system. Higher frame rates are important for scan positioning on non-compliant subjects such as infants and children.

This study addresses the debated topic of the anatomic origins of the second and third outer retinal bands in optical coherence tomography (OCT). Given the complexity of biological tissue composition and cellular arrangement, pinpointing the precise source of outer retinal OCT signals is challenging. We explored this issue using a polarization-controlled full-field OCT (FF-OCT) system, capitalizing on the fact that light polarization can be modified by the birefringence and scattering properties of biological tissues. Quantitative comparison of cross-polarized and parallel-polarized OCT images supports that the second outer retinal band encompasses contributions from both the ellipsoid zone (EZ) and the inner segment/outer segment (IS/OS) junction, while the third band appears to reflect contributions from both the interdigitation zone (IZ) and photoreceptor OS tips. The comparative analysis of cross-polarized and parallel-polarized OCT images not only aids in understanding the anatomic correlates of OCT signals but also holds promise for offering new biomarkers of ocular conditions.

This study investigates the efficacy of the red, green, and blue channels in color fundus photography on the deep learning classification of retinopathy of prematurity (ROP). We used a total of 200 color fundus images from four ROP stages and applied the transfer learning for deep learning classification. To enhance visibility, contrast limiting adaptive histogram equalization (CLAHE) was utilized. Multi-color-channel fusion approach was tested to determine its effect on ROP classification. For individual channel classification, the green channel demonstrated the best results, with an accuracy of 80.5%, sensitivity of 61%, and specificity of 87%. Multi-color-channel fusion provided slightly better performance than green channel with an accuracy of 81%, sensitivity of 62%, and specificity of 87.33%. After CLAHE, the red-only, green-only, and RGB-fusion showed comparable performance, with accuracies of 83.5%, 84%, and 84.25, sensitivities of 67%, 68% and 68.5%, and specificities of 89%, 89.33% and 89.50%, respectively. This observation suggests that the red channel after contrast enhancement can provide sufficient information for ROP stage classification.

The phoropter is a device commonly used by eye doctors to facilitate the prescribing of corrective lenses by trying different lens combinations and receiving feedback from the patient about the effects of the combination on their vision. We present here an early stage phoropter design that enables the patent to adjust their prescription while minimizing clinician involvement. We further describe designs for a low-cost deformable mirror that will enable commercial adoption of this novel phoropter design.

Cataracts is an ocular condition that blurs images at the retina due to intraocular scattering, where surgery is currently the only solution. Recently a non-invasive correction of cataracts was suggested using wavefront shaping techniques. This approach was also helped by the measurement of the Optical Memory Effect to study the maximal size of the optimized image. In this work we optimize the wavefront after passing through ex-vivo cataractous crystalline lenses for the first time. We also study the Optical Memory Effect of the crystalline lenses before and after the wavefront optimization, where we find important differences that will help us being more rigorous when determining the optimized-image’s isoplanatic patch.

The tessellation of the retina is of clinical importance, especially in the study of myopia. This paper presents an automated grading algorithm for tessellation based on the calculation of three Tessellated Fundus Indices (TFIs). Our new algorithm utilizes the red (R), green (G), and blue (B) color components of the region of interest (ROI) surrounding the fovea in fundus images to determine the degree of tessellation, categorized into grades 0, 1, and 2. Excessive brightness in fundus images can result in overexposure, which in turn can introduce inaccuracies when calculating TFI values in the region of interest (ROI) using the red, green, and blue (R, G, B) components. Prior to calculating the TFIs, the method applies luminosity and contrast variation correction to the fundus images automatically. This correction process is achieved through a series of steps: first, applying row-wise and column-wise 1-dimensional low-pass filtering (1DLF); then, computing the luminosity surface by subtracting the smoothed image from the original grayscale image. To maintain luminosity consistency, the original image channels are equalized using the luminosity surface, followed by histogram stretching for enhanced contrast. Finally, the algorithm computes B/R (Blue/Red) and G/R (Green/Red) ratios for each pixel in the original image and multiplies them by the red channel of the contrast-stretched image. The proposed algorithm was evaluated on a dataset of 60 fundus images from varying degrees of myopia, demonstrating its effectiveness in grading tessellation accurately. The automated approach streamlines the grading process, offering potential benefits in clinical settings and facilitating large-scale screenings for myopic eyes.

A binocular visual adaptive optics simulator with automatic convergence control and real time aberration measurement and correction for both eyes simultaneously is presented.

Retinal ganglion cells (RGCs) are the layer of neurons in the retina that output directly to the brain. In primates, there are approximately 20 distinct types which each transmit an independent encoding of the external visual world in parallel to the brain.¹ The wide variety of RGC types suggests that the retina undertakes a sophisticated set of computations that our used by higher brain areas to decode the visual world. Yet, little is known about the majority of the different types of RGCs present in the primate retina largely due to the rarity of many of them. Current understanding of RGCs largely derives from ex vivo electrophysiology experiments which are acute and require severing the optic nerve.² This preparation removes the opportunity to study vision as an intact system and puts a time limit on how long a sample is viable for study before the tissue dies. Traditional electrophysiology also struggles to study the RGCs that serve the fragile fovea, the central high-resolution region of the retina. Adaptive optics (AO) ophthalmoscopy coupled with functional imaging and optogenetics provides a unique set of tools which allows the study of individual RGCs in situ.^3,4 Here we describe a plan for a novel split field of view AO ophthalmoscope that will deliver visual stimuli precisely controlled in space, time, and color to the receptive fields of specific RGCs, while also simultaneously optically recording functional calcium responses from the same RGCs. The device also enables psychophysical experiments to study the perceptual impact of RGC types via optogenetics.