Retinal Imaging System Research Articles

Non-mydriatic ultra-widefield diffraction-limited retinal imaging.

We demonstrate a new non-mydriatic ultra-widefield optical coherence tomography retinal imaging system, designed with custom optics to improve the imaging field of view, lateral resolution, and patient comfort. The key motivation is to address the challenge with conventional systems that require pupillary dilation, adding time, expense, discomfort, and medical risk to the examination of the retina. Our system provides an ultrawide 100° field of view (beam scanning angle at the scanning pivot point) and maintains a lateral resolution of 20 µm on the center. It also allows a generous working distance of 16 mm, 2-3 times longer than existing ultra-widefield OCT imaging systems. This advanced system was able to avoid iris vignetting artifacts without pharmacological dilation and ensure diffraction-limited ultra-widefield imaging under a generalized eye model. This enables a comprehensive evaluation of retina diseases, especially those affecting the peripheral regions.

Safety and therapeutic efficacy of 577 nm yellow solid krypton laser for retinopathy of prematurity; A prospective pilot study.

To evaluate the outcome of 577 nm yellow solid krypton laser as an independent treatment modality for Retinopathy of Prematurity. Prospective, non-comparative, non-randomized, interventional. A prospective pilot study was conducted on 30 treatment eyes with retinopathy of prematurity (ROP) who underwent treatment with a 577 nm yellow solid state krypton laser. 3nethraNEO pediatric retinal imaging system was used to screen these infants born between March to August 2022. Pre procedure data such as gestational age (weeks), birth weight (g), and exposure to risk factors were recorded. Power (mW), exposure duration (msec), and number of laser spots administered were noted. Pain was assessed using the Neonatal Pain/Agitation and Sedation Scale (N-PASS). Post procedure data such as regression, persistence or reactivation of disease, and adverse effects were looked for. All eyes were followed up for a period of 3 months. Chi-square test, Fisher's exact test. Out of 30 eyes, 09 (30%) had type I and 21 (70%) had non-type I ROP. In type I disease, the mean power used was 88+/-10 mW with exposure duration of 130+/-27 msec and an average number of 890+/-260 burns were administered. In non-type I disease, the mean power used was 87+/-10 mW with an exposure duration of 150 ms and an average number of 900+/-290 burns were administered. The mean pain score calculated was 5 in type I and 6 in non-type I ROP. All eyes showed regression of disease after treatment. 577 nm yellow solid krypton laser was safe and effective in treating retinopathy of prematurity disease.

A retinal imaging system for combined measurement of optic nerve head vascular pulsation and stimulated vasodilation in humans

Vascular pulsation at the optic nerve head (ONH) reflects vessel properties. Reduction in the stimulated retinal vasodilatory capacity has been reported in diabetes, but its relation with vascular pulsation is unknown. Here we report a new retinal imaging system for correlative assessment of ONH vascular pulsation and stimulated retinal vasodilation. Retinal reflectance images were acquired before and during light flicker stimulation to quantify arterial and venous vasodilation (DAR, DVR) in subjects with and without diabetic retinopathy (N = 25). ONH vascular pulsation amplitude and frequency (PA, PF), were quantified by curve fitting of periodic intensity waveforms acquired in retinal vasculature (RV) and ONH tissue (ONHT) regions. The relationships between pulsation metrics, heart rate (HR), intraocular pressure (IOP), and vasodilatory responses were evaluated. Pulsation metrics were not significantly different between regions (p ≥ 0.70). In RV, inter-image variabilities of PA and PF were 10% and 6%, whereas inter-observer variabilities were 7% and 2% respectively. In both regions, PF was correlated with HR (p ≤ 0.001). PA was associated with DAR in both regions (p ≤ 0.03), but only with DVR in RV (p ≤ 0.05). Overall, ONH vascular pulsation was associated with stimulated retinal vasodilation, suggesting diabetes may have concomitant effects on retinal vasculature compliance and neurovascular coupling.

An innovative multi-modal retinal imaging system for in vivo retinal detection in small animals.

This paper presents an innovative retinal imaging system tailored for in vivo fundus detection in small animals. This system integrates Scanning Laser Ophthalmoscopy (SLO) and optical Coherence Tomography (OCT) techniques, enabling the simultaneous generation of images from various modalities, including SLO reflectance, SLO fluorescein angiogram, OCT, and OCT angiogram. The existing multi-modal retinal imaging systems generally encounter limitations such as the inability to detect peripheral lesion areas attributed to small Field of View (FOV) design and susceptibility to sample motion due to slow data acquisition speed. To address these challenges, it's essential to underscore that this proposed system offers a range of notable advantages, including its compact design, the capacity for widefield imaging with a FOV of up to 100°, and a rapid OCT A-scan rate of 250 kHz, notably exceeding the capabilities of pre-existing multi-modal retinal imaging systems. Validation of the system involved imaging the eyes of normal wild-type mice and diseased mice afflicted with retinal detachment and choroidal neovascularization (CNV). The favorable imaging results demonstrate the system's reliability in identifying retinal lesions in small animals.

Research on improving the universality of adaptive optical retinal imaging system

Research on improving the universality of adaptive optical retinal imaging system

Colocating Teleophthalmology Within Primary Care Settings to Improve Access to Diabetic Retinopathy Screening: Retrospective Descriptive Evaluation.

Annual retinal exams for patients with diabetes are critical as diabetic retinopathy is the number one cause of preventable blindness in working-age adults in the United States. Currently, most patients with diabetes in the United States receive a referral from their primary care provider to see an ophthalmologist for their annual dilated eye exam, which can be an added inconvenience and expense. As such, there is a need for alternative screening strategies within an outpatient network. The use of a telemedicine platform in a primary care setting serves as a novel strategy to increase diabetic retinopathy screening rates. In order to provide better access to diabetic retinopathy screening for our patients, cameras were placed in 3 primary care practices in October 2017 as part of an 8-month pilot program. Specialized cameras from Intelligent Retinal Imaging Systems (IRIS) were used to acquire images that could be interpreted remotely by ophthalmologists within the LifeBridge Health network for the diagnosis of diabetic retinopathy and the detection of other types of pathology (eg, macular edema). The aim of this retrospective descriptive study was to examine whether a telemedicine platform can be used as a cost-effective way to increase diabetic retinopathy screening rates in the primary care setting. Aggregate screening volume and diagnostic data were collected for each of the 3 practice locations for the 8-month pilot period (October 30, 2017, through June 30, 2018). Additionally, payor reimbursement data and equipment cost data were used to determine the payback period for each of the 3 practice locations. The pilot program proved the business case that implementation of the IRIS camera in 3 practice locations could result in enough patients being screened to pay for the cost of the camera within a maximum of 2 years. The 3 practices showed increased diabetic retinopathy screening rates of 1%, 6%, and 24%, respectively, and were all able to screen enough patients to be on track to pay off the cost of the camera within 2 years of implementation. Aggregate data from the pilot period showed that of the 1213 patients who were screened, approximately 17.1% (n=207) were diagnosed with diabetic retinopathy and an additional 17.7% (n=215) were suspected of having some other form of pathology. Of note, 10.1% (n=123) were also identified as being "IRIS saves," defined as having pathology identified that was severe enough to be considered an imminent threat to their vision. This retrospective descriptive study suggests that a telemedicine platform can be used to improve diabetic retinopathy screening rates in the primary care setting within a large health care system in a cost-effective way that allows for the cost of the equipment to be recouped through billing within a maximum of 2 years.

Use of a Smartphone-Based Device for Fundus Examination in Birds: A Pilot Study.

Simple SummaryEye examination is crucial for therapeutic plans and rehabilitation of birds in wildlife rehabilitation centers. However, fundus examination using classical direct or indirect ophthalmoscopy techniques can be challenging in those species. The aim of the study was to assess the use of a smartphone-based retinal imaging system in birds. Fundus examination was feasible in most bird species examined in this study. The difficulties of carrying out the examination seem to be related to the form of the globe, the color of the iris, and the quality of pupil dilation. Further investigations are necessary to confirm these findings.Ophthalmic examination is essential in the avian triage process in order to apply prompt therapeutic plans and evaluate rehabilitation potential. Fundoscopy is traditionally performed by direct or indirect ophthalmoscopy. Recent technological developments have enabled the design of a small-sized and affordable retinal imaging system to examine the fundus. We investigate the use of a smartphone-based device to realize fundus examination through a prospective cross-sectional observational study. Seventy-seven eyes of 39 birds of 15 different species were evaluated using the smartphone-based device in a rescue wildlife center. Pupil dilation was achieved prior to examination via rocuronium topical application. Assessment of fundus by the smartphone was classified as satisfactory, moderately satisfactory, and unsatisfactory. Fundus examination was also performed with a 20D, 30D, or 78D lens for comparison. Pupillary dilation was satisfactory, moderately satisfactory, or absent in 17, 32, and 28 eyes, respectively. Fundus examination with the smartphone-based device was satisfactory, moderately satisfactory, or unsatisfactory in 44, 15, and 18 eyes, respectively. The feasibility of the fundus examination was affected by the form of the globe; by the quality of pupil dilation; by the color of the iris (images could not be obtained from species with an orange, bright iris); and by the species, with owls (Strigiformes) being the easiest to observe. Based on these findings, fundus examination was feasible in most bird species examined in this study.

Multi-modal and multi-scale clinical retinal imaging system with pupil and retinal tracking

We present a compact multi-modal and multi-scale retinal imaging instrument with an angiographic functional extension for clinical use. The system integrates scanning laser ophthalmoscopy (SLO), optical coherence tomography (OCT) and OCT angiography (OCTA) imaging modalities and provides multi-scale fields of view. For high resolution, and high lateral resolution in particular, cellular imaging correction of aberrations by adaptive optics (AO) is employed. The entire instrument has a compact design and the scanning head is mounted on motorized translation stages that enable 3D self-alignment with respect to the subject’s eye by tracking the pupil position. Retinal tracking, based on the information provided by SLO, is incorporated in the instrument to compensate for retinal motion during OCT imaging. The imaging capabilities of the multi-modal and multi-scale instrument were tested by imaging healthy volunteers and patients.

RETRACTED ARTICLE: Google’s new AI technology detects cardiac issues using retinal scan

The retina enables for direct evaluation of retinal vessel calibre in order to estimate cardiovascular risk. Images, on the other hand, are acquired at random points in the cardiac cycle, making it impossible to make accurate measurements of retinal vessel calibre and restricting their application in clinical settings. This has already been demonstrated in healthy individuals. Worse resolution images and longer delay durations between mechanical start and image collection were also linked to lower retinal vascular calibre measuring accuracy in these studies. Ophthalmologists have widely used retinal fundus imaging systems to examine the health of the optic nerve, vitreous, macula, retina and their blood vessels. This research aims at studying novel and accurate algorithms for the automated extraction of the retinal vascular network and its abnormalities from colour retinal images for disease prediction and to determine whether ECG-gating retinal photographs refine retinal vessel calibre measurements, and to explore the validity, reliability and acceptability of this novel approach relative to common peripheral risk markers of cardiovascular disease.

Application of Optical Coherence Tomography to a Mouse Model of Retinopathy.

Optical coherence tomography (OCT) offers a noninvasive method for the diagnosis of retinopathy. The OCT machine can capture retinal crosssectional images from which the retinal thickness can be calculated. Although OCT is widely used in clinical practice, its application in basic research is not as prevalent, especially in small animals such as mice. Because of the small size of their eyeballs, it is challenging to conduct fundus imaging examinations in mice. Therefore, a specialized retinal imaging system is required to accommodate OCT imaging on small animals. This article demonstrates a small-animal-specific system for OCT examination procedures and a detailed method for image analysis. The results of retinal OCT examination of very-low-density lipoprotein receptor (Vldlr) knockout mice and C57BL/6J mice are presented. The OCT images of C57BL/6J mice showed retinal layers, while those of Vldlr knockout mice showed subretinal neovascularization and retinal thinning. In summary, OCT examination could facilitate the noninvasive detection and measurement of retinopathy in mouse models.

A multi-regression approach to improve optical coherence tomography diagnostic accuracy in multiple sclerosis patients without previous optic neuritis

BackgroundOptical coherence tomography (OCT) is a retinal imaging system that may improve the diagnosis of multiple sclerosis (MS) persons, but the evidence is currently equivocal. To assess whether compensating the peripapillary retinal nerve fiber layer (pRNFL) thickness for ocular anatomical features as well as the combination with macular layers can improve the capability of OCT in differentiating non-optic neuritis eyes of relapsing-remitting MS patients from healthy controls. Methods74 MS participants (n = 129 eyes) and 84 age- and sex-matched healthy controls (n = 149 eyes) were enrolled. Macular ganglion cell complex (mGCC) thickness was extracted and pRNFL measurement was compensated for ocular anatomical factors. Thickness measurements and their corresponding areas under the receiver operating characteristic curves (AUCs) were compared between groups. ResultsParticipants with MS showed significantly thinner mGCC, measured and compensated pRNFL (p ≤ 0.026). Compensated pRNFL achieved better performance than measured pRNFL for MS differentiation (AUC, 0.75 vs 0.80; p = 0.020). Combining macular and compensated pRNFL parameters provided the best discrimination of MS (AUC = 0.85 vs 0.75; p < 0.001), translating to an average improvement in sensitivity of 24 percent for differentiation of MS individuals. ConclusionThe capability of OCT in MS differentiation is made more robust by accounting OCT scans for individual anatomical differences and incorporating information from both optic disc and macular regions, representing markers of axonal damage and neuronal injury, respectively.

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.

Development of 3D Printed Smartphone-Based Multi-Purpose Fundus Camera (MultiScope) for Retinopathy of Prematurity

Retinopathy of Prematurity (ROP) is a prominent source of low vision and blindness in preterm babies. Wide-Field Digital Retinal Imaging (WFDRI) systems acquire accurate digital images which are very useful for identification, documentation and transmitting the various retinal diseases. This telemedicine technique has potential for an alternative tool for Binocular Indirect Ophthalmoscopy(BIO) in ROP screening, but it is very expensive and accessibility for poor communities is limited. Capabilities of good illumination, high resolution camera and processing speed of the modern smartphones are being identified as a substitute. Potential applications of 3D printing is that it provides a severe impact in medical field, especially in ophthalmology sector. Competences of 3D printing are very useful for the development of retinal camera from any smartphone with the help of 3D printable devices. The primary aim of this study is to develop a handheld 3D printed smartphone-based multi-purpose fundus camera for ROP screening. The secondary aim is to check the feasibility and compare the digital fundus images obtained from the developed fundus camera against the commercial RetCam imaging. The proposed cost effective and remote reading device is an alternative to WFDRI for ROP screening and can improve the potential of ROP care for low resource communities.

Design and Simulation of an Ultra-Wide Field Optical Coherence Tomography Retinal Imaging System

Peripheral retinal imaging is a unique approach for assessing and monitoring ocular diseases. In this paper, we proposed a design for an optical coherence tomography system to accomplish ultrawide field (&gt;120°) retinal imaging without montages. Scanning of the sample arm was achieved via two ellipsoidal mirrors. The optical design software Zemax and an eye model were used to estimate the inherent aberrations in the system and the optical performance of retinal imaging. Simulation results of the aberrations in the designed system indicated that the designed system can achieve an unprecedented imaging field of view (FOV) while maintaining acceptable resolution without sacrificing the working distance. This work suggests that ultrawide field optical coherence tomography retinal imaging is achievable, which is highly important for the diagnosis and treatment of ocular—especially peripheral—retinopathy.

Analysis of fundus examination results in 8 808 pediatric patients in Northwest China

Objective: To explore the incidence and age distribution of fundus abnormalities in pediatric patients aged 0-3 years in northwest China. Methods: A retrospective study of the clinical data of 8808 pediatric patients aged 0-3 years who underwent fundus examination with a wide-filed digital retinal imaging system and an indirect ophthalmoscope in our hospital from January 2008 to December 2019 were performed. There were 5092 males and 3716 females, with a median age of 1 month (range, 3 days to 3 years), a mean gestational age of 34.32 (SD 2.92) weeks (range, 24 to 42 weeks) and a mean birth weight of 2006.92 (SD 709.23) g (range, 490 to 5500 g), from Shaanxi Province (7415 cases, 84.18%), Gansu Province (770 cases, 8.74%), Ningxia Hui Autonomous Region (94 cases, 1.07%), Qinghai Province (53 cases, 0.60%), Xinjiang Uygur Autonomous Region (14 cases, 0.16%) and other neighboring areas (462 cases, 5.25%). The fundus condition of the enrolled pediatric patients was documented to calculate the annual detection rate. The joinpoint regression model was drawn to estimate the annual percent change and average annual percent change. The constituent ratios and age distribution of different types of fundus abnormalities were finally analyzed. Results: Fundus abnormalities were detected in 2 531 cases (28.74%). During the 12 years, the number of pediatric patients undergoing fundus examination each year in our center increased rapidly in the first 7 years, and then kept almost stable, while the number of fundus abnormality cases increased year by year. The positive detection rate showed an overall upward trend with an average annual percent change of +7.2%, and it was +30.09% from 2016 to 2019. Among all the pediatric patients with fundus abnormalities, there were 1 678 cases with developmental diseases (66.30%), 232 cases with hereditary diseases (9.16%), 140 cases with ocular tumor (5.53%), 64 cases with ophthalmic manifestations of systemic diseases (2.53%), 31 cases with ocular trauma (1.23%), 12 cases with infectious diseases or inflammation (0.48%) and 438 cases with other ocular abnormalities (17.31%). The top 5 abnormalities were retinopathy of prematurity (ROP; 1477 cases, 58.36%), gray patchy retinopathy (225 cases, 8.89%), retinal hemorrhage (157 cases, 6.20%), retinoblastoma (137 cases, 5.41%) and familial exudative vitreoretinopathy (77 cases, 3.04%). Fundus abnormalities varied with age. ROP, developmental diseases other than ROP, hereditary diseases, ocular trauma and infectious diseases were mostly detected in pediatric patients at 0-6 months old, while tumors were mostly detected after 1 year old. Conclusions: The detection rate of fundus abnormalities in the Department of Ophthalmology of Xijing Hospital of Air Force Medical University, a tertiary referral center in northwest China, increased notably year by year. The abnormalities were mainly developmental and hereditary lesions as well as of certain age distribution. They occurred with the highest frequency between birth and 6 months of age, in which ROP was in the ascendancy. Meanwhile, the detection rate of other developmental, hereditary and neoplastic disorders increased with age. Therefore, a comprehensive and objective understanding of the fundus disease in infants is essential. (Chin J Ophthalmol, 2021, 57: 777-783).

Automated Detection and Counting of Hard Exudates for Diabetic Retinopathy by using Watershed and Double Top-Bottom Hat Filtering Algorithm

Diabetic Retinopathy (DR) is one of diabetes complications that affects our eyes. Hard Exudate (HE) are known to be the early signs of DR that potentially lead to blindness. Detection of DR automatically is a complicated job since the size of HE is very small. Besides, our community nowadays lack awareness on diabetic where they do not know that diabetes can affect eyes and lead to blindness if regular check-up is not performed. Hence, automated detection of HE known as Eye Retinal Imaging System (EyRis) was created to focus on detecting the HE based on fundus image. The purpose of this system development is for early detection of the symptoms based on retina images captured using fundus camera. Through the captured retina image, we can clearly detect the symptoms that lead to DR. In this study, proposed Watershed segmentation method for detecting HE in fundus images. Top-Hat and Bottom-Hat were use as enhancement technique to improve the quality of the image. This method was tested on 15 retinal images from the Universiti Sains Malaysia Hospital (HUSM) at three different stages: Normal, NPDR, and PDR. Ten of these images have abnormalities, while the rest are normal retinal images. The evaluation of the segmentation images would be compared by Sensitivity, F-score and accuracy based on medical expert's hand drawn ground truth. The results achieve accuracy 0.96 percent with 0.99 percent sensitivity for retinal images.

Identification of treatment-warranted retinopathy of prematurity by neonatal nurse specialist

ObjectiveTo determine the accuracy in the identification of infants with treatment-warranted retinopathy of prematurity (ROP) by a trained and experienced ROP neonatal nurse specialist compared with skilled ophthalmologists.MethodsA single-centre, prospective,...

Emulated retinal image capture (ERICA) to test, train and validate processing of retinal images

High resolution retinal imaging systems, such as adaptive optics scanning laser ophthalmoscopes (AOSLO), are increasingly being used for clinical research and fundamental studies in neuroscience. These systems offer unprecedented spatial and temporal resolution of retinal structures in vivo. However, a major challenge is the development of robust and automated methods for processing and analysing these images. We present ERICA (Emulated Retinal Image CApture), a simulation tool that generates realistic synthetic images of the human cone mosaic, mimicking images that would be captured by an AOSLO, with specified image quality and with corresponding ground-truth data. The simulation includes a self-organising mosaic of photoreceptors, the eye movements an observer might make during image capture, and data capture through a real system incorporating diffraction, residual optical aberrations and noise. The retinal photoreceptor mosaics generated by ERICA have a similar packing geometry to human retina, as determined by expert labelling of AOSLO images of real eyes. In the current implementation ERICA outputs convincingly realistic en face images of the cone photoreceptor mosaic but extensions to other imaging modalities and structures are also discussed. These images and associated ground-truth data can be used to develop, test and validate image processing and analysis algorithms or to train and validate machine learning approaches. The use of synthetic images has the advantage that neither access to an imaging system, nor to human participants is necessary for development.

Imaging the pediatric retina: An overview.

Recent decade has seen a shift in the causes of childhood blinding diseases from anterior segment to retinal disease in both developed and developing countries. The common retinal disorders are retinopathy of prematurity and vitreoretinal infections in neonates, congenital anomalies in infants, and vascular retinopathies including type 1 diabetes, tumors, and inherited retinal diseases in children (up to 12 years). Retinal imaging helps in diagnosis, management, follow up and prognostication in all these disorders. These imaging modalities include fundus photography, fluorescein angiography, ultrasonography, retinal vascular and structural studies, and electrodiagnosis. Over the decades there has been tremendous advances both in design (compact, multifunctional, tele-consult capable) and technology (wide- and ultra-wide field and noninvasive retinal angiography). These new advances have application in most of the pediatric retinal diseases though at most times the designs of new devices have remained confined to use in adults. Poor patient cooperation and insufficient attention span in children demand careful crafting of the devices. The newer attempts of hand-held retinal diagnostic devices are welcome additions in this direction. While much has been done, there is still much to do in the coming years. One of the compelling and immediate needs is the pediatric version of optical coherence tomography angiography. These needs and demands would increase many folds in future. A sound policy could be the simultaneous development of adult and pediatric version of all ophthalmic diagnostic devices, coupled with capacity building of trained medical personnel.

Neonatal eye screening for 203 healthy term new-borns using a wide-field digital retinal imaging system

BackgroundThe current practice for new-born eye examination by an Ophthalmologist in Malaysian hospitals is limited to only preterm new-borns, syndromic or ill infants. Healthy term new-borns are usually discharged without a thorough eye examination. This study is aimed at determining the proportion and types of ocular abnormalities detected in purportedly healthy term new-borns.MethodThis cross-sectional study is comprised of 203 participants, all purportedly healthy term new-born infants from the Obstetrics and Gynaecology ward at Hospital Kuala Lumpur over a 6 months period. The examination list includes external eye examination, red reflex test, and fundus imaging using a wide-field digital retinal imaging system (Phoenix Clinical ICON Paediatric Retinal Camera) by a trained Investigator. The pathologies detected were documented. The results were compared and correlated with similar studies published in the literature previously.ResultsTotal ocular abnormalities were detected in 34% of the infants. The most common finding was retinal haemorrhage in 29.6% of the infants, of which 53.3% occurred bilaterally. Spontaneous vaginal delivery (SVD) remained the greatest risk factor which has nearly 3.5 times higher risk of new-borns developing retinal haemorrhage compared to Lower Segment Caesarean Section (LSCS). There was a 6% increased likelihood of developing retinal haemorrhage for every 1-min increment in the duration of 2nd stage of labour.ConclusionUniversal eye screening for all new-borns using a wide-field digital imaging system is realistically possible, safe, and useful in detecting posterior segment disorders. The most common abnormality detected is retinal haemorrhage.