Optical Coherence Tomography Imaging System Research Articles

Ultrasound-induced reorientation for multi-angle optical coherence tomography

Organoid and spheroid technology provide valuable insights into developmental biology and oncology. Optical coherence tomography (OCT) is a label-free technique that has emerged as an excellent tool for monitoring the structure and function of these samples. However, mature organoids are often too opaque for OCT. Access to multi-angle views is highly desirable to overcome this limitation, preferably with non-contact sample handling. To fulfil these requirements, we present an ultrasound-induced reorientation method for multi-angle-OCT, which employs a 3D-printed acoustic trap inserted into an OCT imaging system, to levitate and reorient zebrafish larvae and tumor spheroids in a controlled and reproducible manner. A model-based algorithm was developed for the physically consistent fusion of multi-angle data from a priori unknown angles. We demonstrate enhanced penetration depth in the joint 3D-recovery of reflectivity, attenuation, refractive index, and position registration for zebrafish larvae, creating an enabling tool for future applications in volumetric imaging.

Evaluating the diagnostic performance with neurovascular segregation of the retinal nerve fibre layer in glaucoma

Aims/Purpose: To evaluate the diagnostic performance in detecting eyes with glaucoma by segregating the neuronal and vascular components in circumpapillary optical coherence tomography (OCT) and OCT angiography (OCTA) scans.Methods: In this study, 93 participants with glaucoma were age‐ and gender‐matched with normal controls with no ocular diseases. OCT and OCTA volumetric images of one eye from each participant were acquired using a prototype high resolution swept source OCT imaging system (Zeiss PlexElite) using a 6 mm x 6 mm imaging protocol centered at the optic nerve head. Circumpapillary OCT and OCTA images with a diameter of 3.46 mm were subsequently generated. Information from the circumpapillary and enface OCTA images were used to isolate and segregate the vascular components from the circumpapillary retinal nerve fibre layer (RNFL), which was obtained using a deep learning segmentation approach. Thicknesses of the RNFL with and without the vascular components were measured and diagnostic performance was evaluated using area under the receiving operating characteristic curve (AUC) analysis. Both global and quadrant (superior, inferior, nasal and temporal) measurements around the optic nerve head were considered.Results: Imaging data of one eye from 154 healthy and 143 glaucoma participants were acquired. Using only the global RNFL thickness, the detection of glaucoma achieved an AUC of 0.877 ± 0.021. With the vascular components excluded from the global RNFL thickness, an AUC of 0.890 ± 0.020 was obtained. When the vascular and non‐vascular components of the RNFL in the different quadrants were modelled separately, AUC improved to 0.927 ± 0.015, and was found to be significantly higher than the detection of glaucoma using global measures (p < 0.001).Conclusions: Segregation of vascular and non‐vascular components in the retinal nerve fibre layer led to an improvement in glaucoma detection. Further improvements were observed when the contributions of the components in the RNFL quadrants were modelled separately.

RMAP-ResNet: Segmentation of brain tumor OCT images using residual multicore attention pooling networks for intelligent minimally invasive theranostics

Background and objectiveThe occurrence of brain tumors seriously affects patients both mentally and physically, reducing their quality of life. Automatic recognition and segmentation of tumor boundaries are essential for computer-aided diagnosis and treatment. While optical coherence tomography (OCT) has been widely employed in the detection and analysis fundus lesions and vascular segmentation due to its high resolution and real-time imaging advantages, the segmentation of brain tumor OCT images based on deep neural network has not been studied. However, despite the encoding and decoding structure based on deep learning has achieved good results in medical image segmentation, these models still face limitations in accurately segmenting tumor OCT images due to variations in tumor shapes, sizes, and numbers, and the low contrast of OCT images. Accurate segmentation of tumor tissue contours is crucial as the absence of this mechanism hampers the effective application of OCT imaging methods for brain tumor diagnosis and treatment in clinical practice. Therefore, we propose a novel neural network that can accurately segment brain tumors and their residual tissues in OCT images. MethodsIn this study, we propose a novel residual multi-core attention pooling network (RMAP ResNet) for the segmentation of tumorous and its residual tissue. The RMAP module primarily relies on multiple associative effective receptive fields. These fields enable the detection of targets of various sizes. The module also incorporates an attention structure to adjust connection weights, suppressing irrelevant information and emphasizing the characteristics of tumor OCT images. This process restores the contextual dependencies. ResultsWe validated our proposed RMAP ResNet method on the dataset of mouse tumor OCT imaging obtained using the sweep source OCT imaging system. The experimental results demonstrate that RMAP ResNet achieves superior performance in tumor tissue segmentation. The proposed method improves the quality of tumor segmentation for various shapes and sizes, leading to superior results. RMAP ResNet achieved Dice and IoU values of 94.78% and 90.58%, respectively, confirming the effectiveness and advancement of our proposed technology. ConclusionsOur proposed method addresses the crucial issue of the limited use of the OCT imaging modality in tumor resection surgery. It overcomes the challenge of visually identifying the tumor boundary in OCT modality imaging, where physicians using the naked eye may encounter difficulties. This study has potential applications in the fields of surgical navigation and intelligent minimally invasive treatment of brain tumors.

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.

Iridocorneal angle imaging of a human donor eye by spectral-domain optical coherence tomography

Iridocorneal angle (ICA) details particularly the trabecular meshwork (TM), Schlemm’s canal (SC), and collector channels (CCs) play crucial roles in the regulation of the aqueous outflow in the eyes and are closely associated with glaucoma. Current clinical gonioscopy imaging provides no depth information, and studies of 3D high-resolution optical coherence tomography (OCT) imaging of these structures are limited. We developed a custom-built spectral-domain (SD-) OCT imaging system to fully characterize the angle details. Imaging of a human cadaver eye reveals the visibility of details in the TM/SC/CC region via a ’crossline’ scanning and a series of image processing. This shows that ICA imaging can be used for preoperative glaucoma inspections in the clinical setting with the proposed prototype.

Automatic 3D reconstruction of an anatomically correct upper airway from endoscopic long range OCT images.

Endoscopic airway optical coherence tomography (OCT) is a non-invasive and high resolution imaging modality for the diagnosis and analysis of airway-related diseases. During OCT imaging of the upper airway, in order to reliably characterize its 3D structure, there is a need to automatically detect the airway lumen contour, correct rotational distortion and perform 3D airway reconstruction. Based on a long-range endoscopic OCT imaging system equipped with a magnetic tracker, we present a fully automatic framework to reconstruct the 3D upper airway model with correct bending anatomy. Our method includes an automatic segmentation method for the upper airway based on dynamic programming algorithm, an automatic initial rotation angle error correction method for the detected 2D airway lumen contour, and an anatomic bending method combined with the centerline detected from the magnetically tracked imaging probe. The proposed automatic reconstruction framework is validated on experimental datasets acquired from two healthy adults. The result shows that the proposed framework allows the full automation of 3D airway reconstruction from OCT images and thus reveals its potential to improve analysis efficiency of endoscopic OCT images.

Mapping optical scattering properties to physical particle information in singly and multiply scattering samples.

Optical coherence tomography (OCT) leverages light scattering by biological tissues as endogenous contrast to form structural images. Light scattering behavior is dictated by the optical properties of the tissue, which depend on microstructural details at the cellular or sub-cellular level. Methods to measure these properties from OCT intensity data have been explored in the context of a number of biomedical applications seeking to access this sub-resolution tissue microstructure and thereby increase the diagnostic impact of OCT. Most commonly, the optical attenuation coefficient, an analogue of the scattering coefficient, has been used as a surrogate metric linking OCT intensity to subcellular particle characteristics. To record attenuation coefficient data that is accurately representative of the underlying physical properties of a given sample, it is necessary to account for the impact of the OCT imaging system itself on the distribution of light intensity in the sample, including the numerical aperture (NA) of the system and the location of the focal plane with respect to the sample surface, as well as the potential contribution of multiple scattering to the reconstructed intensity signal. Although these considerations complicate attenuation coefficient measurement and interpretation, a suitably calibrated system may potentiate a powerful strategy for gaining additional information about the scattering behavior and microstructure of samples. In this work, we experimentally show that altering the OCT system geometry minimally impacts measured attenuation coefficients in samples presumed to be singly scattering, but changes these measurements in more highly scattering samples. Using both depth-resolved attenuation coefficient data and layer-resolved backscattering coefficients, we demonstrate the retrieval of scattering particle diameter and concentration in tissue-mimicking phantoms, and the impact of presumed multiple scattering on these calculations. We further extend our approach to characterize a murine brain tissue sample and highlight a tumor-bearing region based on increased scattering particle density. Through these methods, we not only enhance conventional OCT attenuation coefficient analysis by decoupling the independent effects of particle size and concentration, but also discriminate areas of strong multiple scattering through minor changes to system topology to provide a framework for assessing the accuracy of these measurements.

MURIN: Multimodal Retinal Imaging and Navigated-laser-delivery for dynamic and longitudinal tracking of photodamage in murine models.

Laser-induced photodamage is a robust method for investigating retinal pathologies in small animals. However, aiming of the photocoagulation laser is often limited by manual alignment and lacks real-time feedback on lesion location and severity. Here, we demonstrate a multimodality OCT and SLO ophthalmic imaging system with an image-guided scanning laser lesioning module optimized for the murine retina. The proposed system enables targeting of focal and extended area lesions under OCT guidance to benefit visualization of photodamage response and the precision and repeatability of laser lesion models of retinal injury.

Improved in vivo optical coherence tomography imaging of animal peripheral nerves using a prism nerve holder.

Modern optical volumetric imaging modalities, such as optical coherence tomography (OCT), provide enormous information about the structure, function, and physiology of living tissue. Although optical imaging achieves lateral resolution on the order of the wavelength of light used, and OCT achieves axial resolution on a similar micron scale, tissue optical properties, particularly high scattering and absorption, limit light penetration to only a few millimeters. In addition, in vivo imaging modalities are susceptible to significant motion artifacts due to cardiac and respiratory function. These effects limit access to artifact-free optical measurements during peripheral neurosurgery to only a portion of the exposed nerve without further modification to the procedure. We aim to improve in vivo OCT imaging during peripheral neurosurgery in small and large animals by increasing the amount of visualized nerve volume as well as suppressing motion of the imaged area. We designed a nerve holder with embedded mirror prisms for peripheral nerve volumetric imaging as well as a specific beam steering strategy to acquire prism and direct view volumes in one session with minimal motion artifacts. The axially imaged volumes from mirror prisms increased the OCT signal intensity by over a 1.25-mm imaging depth in tissue-mimicking phantoms. We then demonstrated the new imaging capabilities in visualizing peripheral nerves from direct and side views in living rats and minipigs using a polarization-sensitive OCT system. Prism views have shown nerve fascicles and vasculature from the bottom half of the imaged nerve which was not visible in direct view. We demonstrated improved OCT imaging during neurosurgery in small and large animals by combining the use of a prism nerve holder with a specifically designed beam scanning protocol. Our strategy can be applied to existing OCT imaging systems with minimal hardware modification, increasing the nerve tissue volume visualized. Enhanced imaging depth techniques may lead to a greater adoption of structural and functional optical biomarkers in preclinical and clinical medicine.

Multiscale joint segmentation method for retinal optical coherence tomography images using a bidirectional wave algorithm and improved graph theory.

Morphology and functional metrics of retinal layers are important biomarkers for many human ophthalmic diseases. Automatic and accurate segmentation of retinal layers is crucial for disease diagnosis and research. To improve the performance of retinal layer segmentation, a multiscale joint segmentation framework for retinal optical coherence tomography (OCT) images based on bidirectional wave algorithm and improved graph theory is proposed. In this framework, the bidirectional wave algorithm was used to segment edge information in multiscale images, and the improved graph theory was used to modify edge information globally, to realize automatic and accurate segmentation of eight retinal layer boundaries. This framework was tested on two public datasets and two OCT imaging systems. The test results show that, compared with other state-of-the-art methods, this framework does not need data pre-training and parameter pre-adjustment on different datasets, and can achieve sub-pixel retinal layer segmentation on a low-configuration computer.

Efficacy of a new generation intracoronary optical coherence tomography imaging system with fast pullback.

We sought to investigate whether a novel, fast-pullback, high-frequency optical coherence tomography (HF-OCT) imaging system enables data acquisition with a reduced amount of contrast agents while retaining the same qualitative and quantitative lesion assessment to conventional OCT. The increased amount of administered contrast agents is a major concern when performing intracoronary OCT. The present study is a single-center, prospective, observational study including 10 patients with stable coronary artery disease. A total of 28 individual coronary arteries were assessed by both fast-pullback HF-OCT and by conventional OCT. The contrast volume used in each OCT run for the HF-OCT system was significantly lower than for the conventional OCT system (5.0 ± 0.0 mL vs. 7.8 ± 0.7 mL, respectively, with a mean difference of -2.84 [95% confidence interval [CI]: -3.10 to -2.58]). No significant difference was found in the median value of the clear image length between the two OCT systems (74 mm [interquartile range[IQR]; 63, 81], 74 mm [IQR; 71, 75], p = 0.89). Fast-pullback HF-OCT showed comparable measurements to conventional OCT, including minimum lumen area (3.27 ± 1.53 mm2 vs. 3.21 ± 1.53 mm2 , p = 0.27), proximal reference area (7.03 ± 2.28 mm2 vs. 7.03 ± 2.34 mm2 , p = 0.96), and distal reference area (5.93 ± 1.96 mm2 vs. 6.03 ± 2.02 mm2 , p = 0.23). Qualitative OCT findings were comparable between the fast-pullback HF-OCT runs and conventional OCT with respect to identifying lipid-rich plaques, calcifications, layered plaques, macrophages, and cholesterol crystals. With the fast pullback function of a novel HF-OCT imaging system, we acquired OCT images using a significantly lower amount of contrast volume while retaining a comparable qualitative and quantitative lesion assessment to conventional OCT.

Triple-clad W-type fiber mitigates multipath artifacts in multimodal optical coherence tomography.

Multimodal endoscopic optical coherence tomography (OCT) can be implemented with double-clad fiber by using the presumed single-mode core for OCT and the higher numerical aperture cladding for a secondary modality. However, the quality of OCT in double-clad fiber (DCF) based systems is compromised by the introduction of multipath artifacts that are nt present in single-mode fiber OCT systems. Herein, the mechanisms for multipath artifacts in DCF are linked to its modal contents using a commercial software package and experimental measurement. A triple-clad W-type fiber is proposed as a method for achieving multimodal imaging with single-mode quality OCT in an endoscopic system. Simulations of the modal contents of a W-type fiber are compared to DCF and single-mode fiber. Finally, a W-Type fiber rotary catheter is used in a DCF-based endoscopic OCT and autofluorescence imaging (AFI) system to demonstrate multipath artifact free OCT and AFI of a human fingertip.

Developing Drosophila melanogaster Models for Imaging and Optogenetic Control of Cardiac Function.

Using Drosophila melanogaster (fruit fly) as a model organism has ensured significant progress in many areas of biological science, from cellular organization and genomic investigations to behavioral studies. Due to the accumulated scientific knowledge, in recent years, Drosophila was brought to the field of modeling human diseases, including heart disorders. The presented work describes the experimental system for monitoring and manipulating the heart function in the context of a whole live organism using red light (617 nm) and without invasive procedures. Control over the heart was achieved using optogenetic tools. Optogenetics combines the expression of light-sensitive transgenic opsins and their optical activation to regulate the biological tissue of interest. In this work, a custom integrated optical coherence tomography (OCT) imaging and optogenetic stimulation system was used to visualize and modulate the functioning D. melanogaster heart at the 3rd instar larval and early pupal developmental stages. The UAS/GAL4 dual genetic system was employed to express halorhodopsin (eNpHR2.0) and red-shifted channelrhodopsin (ReaChR), specifically in the fly heart. Details on preparing D. melanogaster for live OCT imaging and optogenetic pacing are provided. A lab-developed integration software processed the imaging data to create visual presentations and quantitative characteristics of Drosophila heart function. The results demonstrate the feasibility of initiating cardiac arrest and bradycardia caused by eNpHR2.0 activation and performing heart pacing upon ReaChR activation.

External-cavity laser diode using acousto-optic deflector as tunable grating.

In this study, a novel, to the best of our knowledge, external-cavity laser diode (ECLD) without a diffraction grating is proposed and demonstrated. In the proposed configuration, an acousto-optic deflector (AOD) acts not only as a deflector but also as a diffraction grating. Thus, the AOD functions as a wavelength-selective device, which helps improve the overall performance of the ECLD. In fact, the proposed configuration realizes a wide range of wavelength scanning with a simple configuration, highly efficient optical feedback, and a steady optical resonator with a constant cavity length. We confirm that the wavelengths scanned with the proposed ECLD agree well with theoretical calculations. The scanning range and maximum frequency response reached approximately 60 nm and 50 kHz, respectively. Moreover, reproducible measurements of the three-dimensional thickness distribution of a thin glass plate indicates that the proposed ECLD can be used for optical coherence tomography imaging systems.

Retinal fundus image superresolution generated by optical coherence tomography based on a realistic mixed attention GAN.

Optical coherence tomography (OCT) is widely used to diagnose retinal diseases. However, due to the limited resolution of OCT imaging systems, the quality of fundus images displayed is not satisfactory, which hinders the diagnosis of patients by ophthalmologists. This is an inevitable problem of OCT imaging systems, but few people have given attention to it. We attempt to solve this problem through deep learning methods. In this paper, we propose a single-image superresolution (SISR) model that is based on a generative adversarial network (GAN) for restoring low-resolution (LR) OCT fundus images to high-resolution (HR) counterparts. To obtain more realistic images, we craft the training data set by obtaining the real blur kernels of the LR images instead of using the bicubic interpolation kernel. The baseline of our generator is similar to that of an enhanced superresolution generative adversarial network (ESRGAN), but we creatively propose a mixed attention block (MAB). In contrast to other superresolution (SR) tasks, to adapt to the characteristics of OCT imaging systems, our network can reconstruct LR images with different upscaling factors in the height and widthdirections. The results of qualitative and quantitative experiments prove that our model is capable of reconstructing retinal fundus images clearly andaccurately. We propose a new GAN model for enhancing the quality of displayed OCT retinal fundus images and achieve state-of-the-artresults.

Longitudinal morphological and functional characterization of human heart organoids using optical coherence tomography

Organoids play an increasingly important role as in vitro models for studying organ development, disease mechanisms, and drug discovery. Organoids are self-organizing, organ-like three-dimensional (3D) cell cultures developing organ-specific cell types and functions. Recently, three groups independently developed self-assembling human heart organoids (hHOs) from human pluripotent stem cells (hPSCs). In this study, we utilized a customized spectral-domain optical coherence tomography (SD-OCT) system to characterize the growth of hHOs. Development of chamber structures and beating patterns of the hHOs were observed via OCT and calcium imaging. We demonstrated the capability of OCT to produce 3D images in a fast, label-free, and non-destructive manner. The hHOs formed cavities of various sizes, and complex interconnections were observed as early as on day 4 of differentiation. The hHOs models and the OCT imaging system showed promising insights as an in vitro platform for investigating heart development and disease mechanisms.

Mechanistic Insights into the Pathogenesis of Proliferative and Nonproliferative Vitreomacular Traction

To describe the vitreoretinal interface in vitreomacular traction (VMT) by using novel optical coherence tomography (OCT) methods; wide-angle montage, and pseudomotion OCT imaging systems. Observational case series. Wide-angle montage OCT images of horizontal and vertical scans through the fovea were acquired in 50 eyes of 46 consecutive patients with VMT. Baseline fundus scans were obtained. These were followed by scans acquired with an eye-tracking system performed immediately after vertical and horizontal eye movements. Three scans were then superimposed to compare changes in the contour and position of the posterior vitreous. The subjects were classified as VMT with ("proliferative"; 48.0%) and without ("nonproliferative"; 52.0%) thickened posterior vitreous. Epiretinal membrane was observed in 26.9% of nonproliferative and 95.8% of proliferative VMT eyes (P=3.6×10-7). No eye of proliferative and 57.7% of nonproliferative VMT eyes had wavy contoured posterior vitreous (P=4.0×10-6). None with proliferative VMT, but 91.7% of nonproliferative VMT eyes, showed motion induced changes of posterior vitreous following eye movement (P=2.0×10-8). The posterior vitreous detachment extended beyond the scanned area in 34.6% of nonproliferative and 8.3% of proliferative VMT eyes (P=.040). By dynamically evaluating the vitreoretinal interface of patients with VMT, the static contraction forces of a thickened posterior vitreous at the macula are implicated in proliferative VMT. This contractile force is not strongly implicated in the majority of VMT eyes with nontaut and more mobile vitreous (nonproliferative VMT). VMT and its associated complications are determined by at least 2 different pathophysiological mechanisms.

Long-Term, Noninvasive In Vivo Tracking of Progenitor Cells Using Multimodality Photoacoustic, Optical Coherence Tomography, and Fluorescence Imaging.

Stem cell regenerative medicine therapies have emerged as promising treatments for currently incurable diseases. A remaining challenge for cell therapies is the ability to track the migration and distribution of the transplanted cells in a long-term, noninvasive manner in vivo to assess their efficacy. This study develops a noninvasive, and high spatial resolution photoacoustic microscopy (PAM) and optical coherence tomography (OCT) imaging system for in vivo tracking of subretinally injected progenitor human retinal pigment epithelium cells (ARPE-19) labeled with chainlike gold nanoparticle (CGNP) clusters in RPE damage. CGNP provided significant PAM, OCT, and fluorescence signals to selectively track the migration of ARPE-19 cells in living rabbit eyes for 3 months. PAM and OCT imaging allow accurate anatomical information to determine the exact retinal layer in which the transplanted ARPE-19 cells are located which was confirmed by histology. This presents an efficient and advanced technology to visualize fundamental biological processes of cell therapies in complex in vivo environments in real time.

Synthetic polarization-sensitive optical coherence tomography by deep learning

Polarization-sensitive optical coherence tomography (PS-OCT) is a high-resolution label-free optical biomedical imaging modality that is sensitive to the microstructural architecture in tissue that gives rise to form birefringence, such as collagen or muscle fibers. To enable polarization sensitivity in an OCT system, however, requires additional hardware and complexity. We developed a deep-learning method to synthesize PS-OCT images by training a generative adversarial network (GAN) on OCT intensity and PS-OCT images. The synthesis accuracy was first evaluated by the structural similarity index (SSIM) between the synthetic and real PS-OCT images. Furthermore, the effectiveness of the computational PS-OCT images was validated by separately training two image classifiers using the real and synthetic PS-OCT images for cancer/normal classification. The similar classification results of the two trained classifiers demonstrate that the predicted PS-OCT images can be potentially used interchangeably in cancer diagnosis applications. In addition, we applied the trained GAN models on OCT images collected from a separate OCT imaging system, and the synthetic PS-OCT images correlate well with the real PS-OCT image collected from the same sample sites using the PS-OCT imaging system. This computational PS-OCT imaging method has the potential to reduce the cost, complexity, and need for hardware-based PS-OCT imaging systems.

Prevalence of Ocular Diseases in Human Donor Eyes in New Zealand: A Study Based on Clinical and Histological Imaging.

Fundus pathology in donor eyes was correlated with cross-sectional Optical Coherence Tomography (OCT) images and histological assessment was performed to determine the prevalence of retinal diseases without the constraints imposed during in vivo clinical imaging. A fundus camera and OCT imaging system was adapted to enable posterior segment imaging of the entire post-mortem human eye. Retinas from 59 donors (57 retina pairs and two single globes) were imaged in a seven-field imaging format and cross-sectional analysis was done using OCT. To confirm that the signs observed represented true disease incidence analysis of disease markers including gliosis (Glial Fibrillary Acidic Protein), hemichannel expression (Connexin43), Müller cell activation (vimentin) and choroidal endothelial cells (CD-31) and macrophages (CD-68 marker) was performed. Pathological signs were correlated with clinical diagnoses in eyes from 25 donors (donor ages 45-87 years) but lesions were also found in 23 eyes (donor ages 39- 83 years) with no previously reported clinical diagnosis. Retinas from six donors aged 21-89 years of age were unremarkable. Of all donors, five donors had signs of age related macular degeneration (AMD) and 14 had signs of diabetic retinopathy (DR). Their lesions correlated with OCT and histopathology showed signs of activated microglia, Müller cell hyper-reactivity, increased Cx43 expression and choroidal inflammation. These data indicate that with over 8% of donors showing signs of AMD and 24% of donors showing signs of DR the incidence of AMD may be 1.7 times higher and DR up to 1.6 times higher than clinically reported. The detection of pathological signs characteristic of AMD and DR in donors suggests a higher prevalence of posterior segment abnormalities amongst New Zealanders donors than previously reported. A more detailed evaluation protocol of the posterior segment in patients will aid detection of lesions that are none the less pathological signs.