Artificial intelligence-enabled ophthalmoscopy for papilledema: a systematic review protocol

Papilledema is a pathology delineated by the swelling of the optic disc secondary to raised intracranial pressure (ICP). Diagnosis by ophthalmoscopy can be useful in the timely stratification of further investigations, such as magnetic resonance imaging or computed tomography to rule out pathologies associated with raised ICP. In resource-limited settings, in particular, access to trained specialists or radiological imaging may not always be readily available, and accurate fundoscopy-based identification of papilledema could be a useful tool for triage and escalation to tertiary care centres. Artificial intelligence (AI) has seen a rise in neuro-ophthalmology research in recent years, but there are many barriers to the translation of AI to clinical practice. The objective of this systematic review is to garner and present a comprehensive overview of the existing evidence on the application of AI in ophthalmoscopy for papilledema, and to provide a valuable perspective on this emerging field that sits at the intersection of clinical medicine and computer science, highlighting possible avenues for future research in this domain.

ZEISS PLEX Elite 9000 Widefield Optical Coherence Tomography Angiography as Screening Method for Early Detection of Retinal Hemangioblastomas in von Hippel-Lindau Disease

Purpose

To evaluate early detection of retinal hemangioblastomas (RHs) in von Hippel-Lindau disease (VHLD) with widefield optical coherence tomography angiography (wOCTA) compared to the standard of care in ophthalmologic VHLD screening in a routine clinical setting.

Methods

We conducted prospective comparisons of three screening methods: wOCTA, standard ophthalmoscopy, and fluorescein angiography (FA), which was performed only in uncertain cases. The numbers of detected RHs were compared among the three screening methods. The underlying causes for the lack of detection were investigated.

Results

In 91 eyes (48 patients), 67 RHs were observed (mean, 0.74 ± 1.59 RH per eye). FA was performed in eight eyes. Ophthalmoscopy overlooked 25 of the 35 RHs detected by wOCTA (71.4%) due to the background color of the choroid (n = 5), small tumor size (n = 13), masking by a bright fundus reflex (n = 2), and masking by surrounding retinal scars (n = 5). However, wOCTA missed 29 RHs due to peripheral location (43.3%). The overall detection rates were up to 37% on the basis of ophthalmoscopy alone, up to 52% for wOCTA, and 89% for FA. Within the retinal area covered by wOCTA, the detection rates were up to 46.7% for ophthalmoscopy alone, up to 92.1% for wOCTA, and 73.3% for FA.

Conclusions

The overall low detection rate of RHs using wOCTA is almost exclusively caused by its inability to visualize the entire peripheral retina. Therefore, in unclear cases, FA is necessary after ophthalmoscopy.

Translational Relevance

Within the imageable retinal area, wOCTA shows a high detection rate of RHs and therefore may be suitable to improve screening for RHs in VHLD.

Retinal Changes in Patients With Covid-19 and Different Expressiveness of Metabolic Changes

AIMS

 To study the relationship between the severity of COVID-induced metabolic changes and the structure and frequency of retinal changes, according to funduscopy data in patients with different clinical courses of COVID-19.

MATERIALS AND METHODS

 117 patients with COVID-19 were examined. While examining patients, severity of the course of COVID-19, the expressiveness of changes in the metabolic status were determined; fundus image registration was performed with portable fundus cameras Pictor Plus Fundus Camera and VistaView (Volk Optical).

RESULTS

 As a result of the research, retinal changes were found in 49 (41.9 %) patients with COVID-19. In 8 (16.3 %) cases, clinically significant (vitreous hemorrhage, prethrombosis of the central retinal vein or branches of the central retinal vein, thrombosis of the central retinal vein or branches of the central retinal vein) COVID-induced retinal and ophthalmological changes were observed, which caused a decrease in visual acuity. In 41 (83.7 %) cases, clinically insignificant changes (cotton wool spots, narrowed retinal vessels, intraretinal and petechial hemorrhages, tortuosity and dilatation of retinal venules) COVID-induced retinal changes were observed. Clinically significant retinal changes occur in patients with a statistically significantly higher level of D-dimer and a greater percentage of lung parenchyma lesion than in the group of patients with clinically insignificant retinal changes (p < 0.05).

CONCLUSIONS

 The structure of retinal changes in patients with COVID-19 correlates with the severity of the clinical course of the disease and changes in the metabolic status of patients. Metabolic changes are correlated with retinal changes and can be predictive for preventing general vascular complications in COVID-19.

Smartphone ophthalmoscope as a tool in teaching direct ophthalmoscopy: a crossover randomized controlled trial

To evaluate the effectiveness of smartphone ophthalmoscope (SO) in teaching ophthalmoscopy, compared with direct ophthalmoscope (DO). In this cross-over study, 45 final-year medical students attending sessions at a single institution were randomly allocated to two groups (A and B). Both groups attended two training sessions. In the first session, Group A students were taught ophthalmoscopy using DO and Group B students using SO. In the second session, the training sessions were crossed over. A series of eye models with 10 letters placed on the inner surface were designed to assess the students' skill on ophthalmoscopy. Students performed ophthalmoscopy on the eye models, recorded their findings, and completed a questionnaire of feedback on DO and SO. The main outcome measure was the score of ophthalmoscopy, assessed by the student correctly recording each letter (score 1 for each letter). For Group A, the mean score of ophthalmoscopy on the eye model using DO and SO was 3.9±2.4 and 8.2±2.2, respectively. For Group B, the mean score of ophthalmoscopy on the eye model using SO and DO 8.7±1.8 and 5.7±3.5 . Students scored significantly higher in ophthalmoscopy when using SO than DO (P<0.001). They expressed better visualization of the fundus using SO than DO (4.49±0.65 vs 4.13±0.81, P=0.004). Students' performance of ophthalmoscopy was better when SO was used compared with DO. The use of SO as an adjunctive tool is recommended to improve the effectiveness of teaching ophthalmoscopy.

Worm in the Eye: A Case Report of Ocular Neurocysticercosis With Adherent Retinal Cyst

Neurocysticercosis is caused by cysticercus cellulosae, the larval stage of Taenia solium, commonly referred to as the pork tapeworm. These larvae form cysts in several organs, including the brain, spinal cord, and eye. Neurocysticercosis is recognized by the World Health Organization as a public health issue and stands as the foremost preventable cause of epilepsy worldwide. Ocular neurocysticercosis refers to the concurrent involvement of the eyes and brain with cysticercus lesions. Neurological symptoms include focal deficits, intracranial hypertension, or cognitive decline. In the eye, the orbital type commonly presents with periocular swelling, ptosis, diplopia, restriction of ocular motility, or decreased vision. The ocular type shows signs of retinal detachment, a macular hole, and inflammation. A 45-year-old female presented with pain in his right eye with blurred vision for 15 days. On USG and MRI of the eye, a thin-walled lesion was noted. The brain showed a few calcified granulomas in the right parietal lobe on MRI. The left eye was normal. If left untreated, the cysts can lead to a severe inflammatory reaction in the eye, which may eventually lead to blindness. This blindness caused by cysticercus is preventable, and hence, early diagnosis and prompt medical or surgical treatment are essential.

New Insights into the Diagnosis and Age Determination of Retinal Hemorrhages from Abusive Head Trauma: A Systematic Review

(1) Background: Head trauma represents the first cause of death in abused children, but diagnostic knowledge is still limited. The characteristic findings of abusive head trauma (AHT) are retinal hemorrhages (RH) and additional ocular findings, including optic nerve hemorrhages (ONH). However, etiological diagnosis must be cautious. (2) Methods: The Preferred Reporting Items for Systematic Review (PRISMA) standards were employed, and the research focus was the current gold standard in the diagnosis and timing of abusive RH. (3) Results: Sixteen articles were included for qualitative synthesis. The importance of an early instrumental ophthalmological assessment emerged in subjects with a high suspicion of AHT, with attention to the localization, laterality, and morphology of the findings. Sometimes it is possible to observe the fundus even in deceased subjects, but the current techniques of choice consist of Magnetic Resonance Imaging and Computed Tomography, also useful for the timing of the lesion, the autopsy, and the histological investigation, especially if performed with the use of immunohistochemical reactants against erythrocytes, leukocytes, and ischemic nerve cells. (4) Conclusions: The present review has made it possible to build an operational framework for the diagnosis and timing of cases of abusive retinal damage, but further research in the field is needed.

Revisiting the oil droplet sign in keratoconus: Utility for early keratoconus diagnosis and screening

PURPOSE

An annular dark shadow (ADS) reflex has been observed while performing direct ophthalmoscopy on subjects with keratoconus. This study describes a method that may serve as a diagnostic technique for early keratoconus and may be used as a quantitative measure of severity.

METHODS

Healthy keratoconic subjects and keratoconus suspects underwent corneal tomography and a full ocular examination. Keratoconus severity was graded based on Belin ABCD criteria. An iPhone camera was connected to a direct ophthalmoscope to take a picture of the eye. The height of the ASD was measured using the AutoCAD software. Differences between subject groups were evaluated by chi-squared and Mann-Whitney tests. Spearman correlation compared ocular parameters and the height of the ADS. A multiple stepwise linear regression was used to predict the height of the ADS based on clinical parameters.

RESULTS

Fifty-eight subjects participated in this study: 37 healthy controls (37 eyes) and 21 keratoconics or keratoconus suspects (37 eyes). The ADS was present in all keratoconic and keratoconus-suspect eyes but in none of the controls. The height of the ADS was significantly correlated with keratoconus severity. Front corneal surface root mean square of higher order aberrations, sphere and anterior radius of curvature from the front apex curve are significant predictors of the height of the ADS.

CONCLUSIONS AND RELEVANCE

The ADS may be a useful method to diagnose keratoconus and keratoconus-suspect cases and serve as a grading and follow-up method for tracking disease severity.

Building Clinical Skills Teaching Materials: A Study of Cognitive Task Analysis Versus Free Recall Instruction to Teach Canine Indirect Ophthalmoscopy

Ophthalmoscopy is a core component of a complete ophthalmic examination. Due to its complex technical aspects and patients becoming uncooperative if the procedure is prolonged, it can be a difficult skill for a novice to learn and develop proficiency in. Skills instruction is typically provided by subject matter experts (SMEs) through free recall without an agreed-upon instructional framework. This can lead to unintentional omission of essential steps and knowledge required to perform skills correctly. Cognitive task analysis (CTA) allows for construction of standardized instructional protocols that encompass the knowledge and skills experts apply when performing tasks. The objectives of this study were to (a) develop a CTA-based teaching protocol for canine indirect ophthalmoscopy and (b) compare the steps verbalized or demonstrated by SMEs during free recall instruction versus those ultimately identified by CTA. Four SMEs participated in free recall instructional sessions and interviews used for the development of a CTA-based teaching protocol for novice learners. The CTA-based protocol identified 66 steps and sub-steps considered essential for successfully performing canine indirect ophthalmoscopy. During instructional sessions, SMEs on average failed to verbalize 57.1% of clinical knowledge steps, did not verbalize or demonstrate 68.3% and 9.5% of action steps, and did not verbalize or demonstrate 73.2% and 40.4% of decision steps, respectively. This study demonstrates that SMEs teaching indirect ophthalmoscopy by free recall may unintentionally omit important steps, suggesting that compared with free recall, CTA may generate more comprehensive and thus potentially more effective instructional materials for teaching technical skills in veterinary medicine.

A New Approach to Non-mydriatic Portable Fundus Imaging

INTRODUCTION

The present study proposes a new hand-held non-mydriatic fundus camera for retinal imaging. The goal is to design a fundus camera which is equally effective in both clinical and telemedicine scenarios.

AREAS COVERED

A new retinal illumination approach is proposed to address the main dilemma of the optical design, i.e., balancing efficacy with structural simplicity. This is achieved by symmetrical and co-axial placement of multiple illumination sources along the optical pathway. Each illumination source includes a white and a Near Infra-Red (NIR) LED, which are placed adjacent to each other. Hence, the camera can produce a view-finder with NIR illumination without the need for additional beam-splitters and filters.

EXPERT OPINION

The proposed design blends the structural simplicity of the 'off-axis illumination with the wide field of view and uniform illumination of the 'ring' illumination. Moreover, the camera is designed to work with Android-based smartphones, which can easily be mounted and interfaced. The efficacy of the proposed camera is determined by ocular safety analysis and comparative evaluation with a table-top fundus camera. The results convincingly demonstrate the ability of the proposed camera as a primary driver of a wide-scale screening program in both clinical and remote resource constraint environments.

Uncorrected refractive error in a university community

Aims and Background

To determine the prevalence and pattern of uncorrected refractive error among staff of a Nigerian university.

Patient and Methods

A cross-sectional study of consecutive staff of the University of Nigeria, Nsukka, Nigeria who presented for a 10-day free eye screening program. Demographic data and data on eye care awareness and knowledge were obtained with a combination of self-administered and interviewer-administered questionnaires in the English language. Clinical examinations included visual acuity taken at 6 m with Snellen's chart; noncontact tonometry; pen-torch eye examination; and direct ophthalmoscopy; autorefraction and subjective refraction.

Results

One thousand and eighty-three subjects aged 18-82 years (mean = 44.1 ± 12.15 years) comprising 568 females (52.4%) and 515 males (47.6%) were screened. Eighty-nine subjects (8.3%) were visually impaired and five subjects (0.5%) were blind. Three hundred and fifty-six subjects were diagnosed with refractive error (356/1083; 32.9%), out of which 149 subjects (41.9%) were uncorrected. The prevalence of uncorrected refractive error in this study population was 13.8%. Astigmatism was the commonest refractive error, whereas hypermetropia and hypermetropic astigmatism were the commonest spherical and astigmatic errors, respectively.

Conclusion

A significant proportion of the staff of this Nigerian university still lives with uncorrected refractive error with its attendant consequences. Regular eye checks should be done by the staff of our universities and effort should be intensified in eye care awareness creation among the populace, including the apparently enlightened communities.

The Role of Funduscopy in Severe Thrombocytopenia: A Prospective Study

PURPOSE

Platelet transfusions for patients suffering from severe thrombocytopenia are regulated by clinical bleedings and platelet counts. The aim of this study was to assess the prevalence of retinal hemorrhage in patients with hematologic and oncologic malignancies and severe thrombocytopenia, and to determine the benefit of systematic funduscopic examination in this setting.

MATERIALS AND METHODS

Hospitalized patients with hematologic and oncologic malignancies having a platelet count less than 25,000 per µL underwent indirect ophthalmoscopy. The prevalence of retinal hemorrhage and its correlation with different patients' characteristics were determined. The decision to transfuse platelets or not following bedside indirect ophthalmoscopy was left at the discretion of the treating physician.

RESULTS

A total of 34 severe thrombocytopenic patients were included in the study. The prevalence of retinal hemorrhage was detected in 10 patients (29.4%). No significant correlation was found between the occurrence of retinal hemorrhage and age, platelet count or thrombocytopenia etiology (P >0.05). No significant difference was found concerning the rate of transfusion between those with and without retinal hemorrhage.

CONCLUSION

According to our statistical results, retinal hemorrhage is a frequent finding in severely thrombocytopenic patients. Early detection may lead to an increase in the platelet transfusion threshold from to 30,000 per µL offering additional protection against spontaneous bleedings. Funduscopy is a safe and easy exam to perform systematically in patients with severe thrombocytopenia.

Adrien van Trigt, and the first published ophthalmoscopic images (De Speculo Oculi, 1853)

A. C. van Trigt's 1853 doctoral thesis, De Speculo Oculi or De Oogspiegel, is generally recognized to contain the first ever published images of the interior of living human eyes. One of its 12 images is recognized and often reproduced as the first published. Others, showing physiological processes such as retinal venous pulsations and arteriolar light reflexes, and pathological processes such as retinal detachment and retinitis pigmentosa, are scarcely ever noted in the literature. Although van Trigt is widely recognized for this accomplishment, virtually nothing has been written about him or his thesis. This article describes his life, his artistic talent and diverse interests, and his thesis with its rarely credited original ophthalmoscopic observations and illustrations.

Imaging the Retinal Vasculature

Advances in retinal imaging are enabling researchers and clinicians to make precise noninvasive measurements of the retinal vasculature in vivo. This includes measurements of capillary blood flow, the regulation of blood flow, and the delivery of oxygen, as well as mapping of perfused blood vessels. These advances promise to revolutionize our understanding of vascular regulation, as well as the management of retinal vascular diseases. This review provides an overview of imaging and optical measurements of the function and structure of the ocular vasculature. We include general characteristics of vascular systems with an emphasis on the eye and its unique status. The functions of vascular systems are discussed, along with physical principles governing flow and its regulation. Vascular measurement techniques based on reflectance and absorption are briefly introduced, emphasizing ways of generating contrast. One of the prime ways to enhance contrast within vessels is to use techniques sensitive to the motion of cells, allowing precise measurements of perfusion and blood velocity. Finally, we provide a brief introduction to retinal vascular diseases.

Retinal changes in febrile seizures in children: a retrospective analysis in Tuzla Canton, Bosnia and Herzegovina

Aim To evaluate the possibility of retinal haemorrhages or any other retinal pathology caused by febrile seizures alone in children aged between 2 months and 15 years. Methods Children aged between 2 months and 15 years admitted to the hospital following seizures were examined within 48 hours of admission. The seizures were classified by a paediatric neurologist and a detailed ocular examination, including indirect ophthalmoscopy, was performed by an ophthalmologist. Results In the period between May 2019 and May 2020 a total number of 106 children were examined. There were 66 (62.3%) male and 40 (37.7%) female children. The youngest patient was 2 months old and the oldest patient was 15 years old. None of the children was found to have retinal haemorrhages or any other retinal pathology. Conclusion Retinal haemorrhages or any other acute retinal findings in children with febrile seizures are very rare, but we cannot rule out its occurrence. The finding of retinal haemorrhages in a child admitted with a history of seizure should trigger a detailed search for other causes of those haemorrhages, especially shaken baby syndrome. Due to the lack of any manifestations on the retina after febrile seizure, maybe it is time that the current protocol and guidelines, considering obligatory fundus examination, should be re-examined.

Impact on patient management of non-mydriatic fundus photography compared to direct ophthalmoscopy in a regional Australian emergency department

OBJECTIVE

To investigate the management impact of non-mydriatic fundus photography (NMFP) implementation for appropriate ED patients; compare the diagnostic accuracy of direct ophthalmoscopy (DO) and NMFP, and determine the prevalence of fundus pathology in a regional Australian ED.

METHODS

This before/after crossover study prospectively enrolled patients presenting with headache, neurological deficit, visual disturbance and/or hypertensive urgency. Patients received DO examination, then separate NMFP examination. Emergency clinicians (ECs) were surveyed on their patient management plans following both DO examination and NMFP imaging. Telemedicine review of NMFP images was performed by an ophthalmologist within 48 h, and any additional management changes were documented.

RESULTS

The use of NMFP influenced changes in management in 52 (39%) of 133 enrolled patients (95% confidence interval 31-48%). Of these, 65% were escalations of management due to acute fundus pathology, while 35% were de-escalating changes following normal fundus findings. ECs diagnostic accuracy for acute fundus pathology improved from 0% to 29% sensitivity, and 59% to 84% specificity using DO and NMFP respectively, and telemedicine registrar review increased this to 50% sensitivity and 86% specificity. The period prevalence of acute fundus pathology was 10.5% (95% confidence interval 6-17%).

CONCLUSION

The addition of NMFP images can significantly impact the management of ED patients requiring fundus examination, facilitating expedited and optimised patient care. NMFP improves ECs diagnostic acumen for fundus pathology over DO examination and telehealth specialist review is important for diagnostic accuracy. There is a clinically important prevalence of fundus pathology in this regional ED setting.

Cone photoreceptor reflectance variation in the northern tree shrew and thirteen-lined ground squirrel

In vivo images of human cone photoreceptors have been shown to vary in their reflectance both spatially and temporally. While it is generally accepted that the unique anatomy and physiology of the photoreceptors themselves drives this behavior, the exact mechanisms have not been fully elucidated as most studies on these phenomena have been limited to the human retina. Unlike humans, animal models offer the ability to experimentally manipulate the retina and perform direct in vivo and ex vivo comparisons. The thirteen-lined ground squirrel and northern tree shrew are two emerging animal models being used in vision research. Both models feature cone-dominant retinas, overcoming a key limitation of traditional rodent models. Additionally, each possesses unique but well-documented anatomical differences in cone structure compared to human cones, which can be leveraged to further constrain theoretical models of light propagation within photoreceptors. Here we sought to characterize the spatial and temporal reflectance behavior of cones in these species. Adaptive optics scanning light ophthalmoscopy (AOSLO) was used to non-invasively image the photoreceptors of both species at 5 to 10 min intervals over the span of 18 to 25 min. The reflectance of individual cone photoreceptors was measured over time, and images at individual time points were used to assess the variability of cone reflectance across the cone mosaic. Variability in spatial and temporal photoreceptor reflectance was observed in both species, with similar behavior to that seen in human AOSLO images. Despite the unique cone structure in these animals, these data suggest a common origin of photoreceptor reflectance behavior across species. Such data may help constrain models of the cellular origins of photoreceptor reflectance signals. These animal models provide an experimental platform to further explore the morphological origins of light capture and propagation.

eFOCUS 2: A randomised crossover trial of smartphone fundoscopy and direct ophthalmoscopy aiming to improve optic disc interpretation by medical students with e-learning support

BACKGROUND

Ophthalmoscopy and its interpretation are complex. We aimed to compare the diagnostic accuracy of smartphone fundoscopy with traditional direct ophthalmoscopy for optic disc interpretation, with e-learning support.

METHODS

We conducted a randomised, crossover study of 102 medical students. Students were offered e-learning for optic disc interpretation. A fundoscopy objective structured clinical examination was conducted after an introductory lecture and 10-min practical training session on smartphone fundoscopy and traditional ophthalmoscopy. Participants examined patients and simulator slides with a randomised crossover between smartphone [D-eye (Padova, Italy) or iExaminer (Welch Allyn, Macquarie Park, Australia)] and traditional ophthalmoscopy (Welch Allyn). Optic discs were graded independently by three masked ophthalmologists. The primary outcome was the ability to interpret an optic disc as normal or abnormal. Secondary outcomes included other optic disc aspects; student preferences; and e-learning performance.

RESULTS

Students' agreement with the gold standard for an abnormal or normal disc was significantly greater using a smartphone (74.4%) than with direct ophthalmoscopy (68.1%, p = 0.032). More students preferred smartphone (74%) over direct ophthalmoscopy (26%, p < 0.001). E-learning led to an improvement in optic disc interpretation scores (mean improvement = 4.5%, 95% CI = 3.7-5.2, p < 0.001).

CONCLUSIONS

Medical students are more accurate at recognising an abnormal optic disc using smartphone fundoscopy than traditional direct ophthalmoscopy, and have a strong preference for smartphone fundoscopy. E-learning may improve the interpretation of optic disc abnormalities. Smartphone fundoscopy may mitigate some technical challenges of fundoscopy and reinvigorate use of this valuable clinical examination.

Digital ophthalmoscopy: through a non-specialist lens

The ophthalmoscope has been a mainstay for non-specialist physicians to review a range of disorders affecting patient fundi. Its design has remained unchanged since its inception and while relatively easy to operate, gaining mastery of it can prove challenging. Training is limited by its single-user interface with the lack of attachments to augment its design and therefore facilitate skill acquisition. Documentation is variable depending on the competence of the individual to satisfactorily see enough of the fundi, and the accuracy with which they can describe their findings. Several groups have looked to find adaptions to smartphones in order to develop user-friendly and affordable alternative to the traditional ophthalmoscope. A digital solution has the potential to provide greater versatility by enhancing documentation, improved training pathways and facilitating more efficient care, with options for geographically disparate healthcare settings to access teleophthalmology input.

European confederation of medical mycology quality of clinical candidaemia management score: A review of the points based best practice recommendations

Candidaemia is associated with high mortality. In the last few years, several guidelines have been published on the management of Candida bloodstream infection. However, adherence to the practice guidelines has been suboptimal. In order to facilitate and objectively measure the adherence to good practice recommendations, a scoring criterion was published by the European Confederation of Medical Mycology (ECMM). The ECMM Quality (EQUAL) of Clinical Candidaemia Management is an audit tool that comprises of 10 quality indicators. Each quality indicator is allotted between 1 and 3 points. The maximum achievable score is 22 or 19 in patients with or without a central venous catheter, respectively. This paper reviews each of the 10 quality indicators and provides the context for improving quality within the individual domains. The review also suggests areas that are in need of further clarity or areas which merit attention in the future updates of the EQUAL scoring system so that clinicians are able to derive maximum benefit from the audit tool. The EQUAL scoring tool is an important milestone in the quality improvement aspect of the management of candidaemia and contributes to the various components of clinical governance in the management of Candida infection of the bloodstream.

Cellular-Scale Imaging of Transparent Retinal Structures and Processes Using Adaptive Optics Optical Coherence Tomography

High-resolution retinal imaging is revolutionizing how scientists and clinicians study the retina on the cellular scale. Its exquisite sensitivity enables time-lapse optical biopsies that capture minute changes in the structure and physiological processes of cells in the living eye. This information is increasingly used to detect disease onset and monitor disease progression during early stages, raising the possibility of personalized eye care. Powerful high-resolution imaging tools have been in development for more than two decades; one that has garnered considerable interest in recent years is optical coherence tomography enhanced with adaptive optics. State-of-the-art adaptive optics optical coherence tomography (AO-OCT) makes it possible to visualize even highly transparent cells and measure some of their internal processes at all depths within the retina, permitting reconstruction of a 3D view of the living microscopic retina. In this review, we report current AO-OCT performance and its success in visualizing and quantifying these once-invisible cells in human eyes.

Non-Mydriatic Ultra-Wide Field Imaging Versus Dilated Fundus Exam and Intraoperative Findings for Assessment of Rhegmatogenous Retinal Detachment

Background: to compare the extent of the detached retina and retinal tears location in rhegmatogenous retinal detachment (RRD) among non-mydriatic ultra-wide field (UWF) imaging, dilated fundus exam (DFE), and intraoperative evaluation. Methods: this retrospective chart review comprised 123 patients undergoing surgery for RRD. A masked retina specialist analyzed the UWF fundus images for RRD area, status of the macula, and presence and location of retinal breaks. The same variables were collected from a database including DFE and intraoperative recordings. Evaluation methods were compared. Results: mean age was 59.8 ± 14.9 years. Best-corrected visual acuity improved from 0.25 ± 0.3 (Snellen) to 0.67 ± 0.3 at 12 months (p = 0.009). The RRD description and assessment of macula status (34.5% macula-on) did not differ between UWF, DFE, and intraoperative examination. The inferior quadrant was involved most frequently (41.5%), followed by the superior (38.9%), temporal (27.8%) and nasal quadrant (14.8%). Intraoperative exam detected 96.7% of retinal tears compared with DFE (73.2%, p = 0.008) and UWF imaging (65%, p=0.003). UWF imaging and DFE did not differ significantly. Conclusion: RRD extent on DFE and UWF images was consistent with intraoperative findings. UWF and DFE detection of peripheral retinal tears was similar, but 25% of retinal breaks were missed until intraoperative evaluation.

Axonal Transport as an In Vivo Biomarker for Retinal Neuropathy

We illuminate a possible explanatory pathophysiologic mechanism for retinal cellular neuropathy by means of a novel diagnostic method using ophthalmoscopic imaging and a molecular imaging agent targeted to fast axonal transport. The retinal neuropathies are a group of diseases with damage to retinal neural elements. Retinopathies lead to blindness but are typically diagnosed late, when substantial neuronal loss and vision loss have already occurred. We devised a fluorescent imaging agent based on the non-toxic C fragment of tetanus toxin (TTc), which is taken up and transported in neurons using the highly conserved fast axonal transport mechanism. TTc serves as an imaging biomarker for normal axonal transport and demonstrates impairment of axonal transport early in the course of an N-methyl-D-aspartic acid (NMDA)-induced excitotoxic retinopathy model in rats. Transport-related imaging findings were dramatically different between normal and retinopathic eyes prior to presumed neuronal cell death. This proof-of-concept study provides justification for future clinical translation.

Use of Smartphones to Detect Diabetic Retinopathy: Scoping Review and Meta-Analysis of Diagnostic Test Accuracy Studies

BACKGROUND

Diabetic retinopathy (DR), a common complication of diabetes mellitus, is the leading cause of impaired vision in adults worldwide. Smartphone ophthalmoscopy involves using a smartphone camera for digital retinal imaging. Utilizing smartphones to detect DR is potentially more affordable, accessible, and easier to use than conventional methods.

OBJECTIVE

This study aimed to determine the diagnostic accuracy of various smartphone ophthalmoscopy approaches for detecting DR in diabetic patients.

METHODS

We performed an electronic search on the Medical Literature Analysis and Retrieval System Online (MEDLINE), EMBASE, and Cochrane Library for literature published from January 2000 to November 2018. We included studies involving diabetic patients, which compared the diagnostic accuracy of smartphone ophthalmoscopy for detecting DR to an accurate or commonly employed reference standard, such as indirect ophthalmoscopy, slit-lamp biomicroscopy, and tabletop fundus photography. Two reviewers independently screened studies against the inclusion criteria, extracted data, and assessed the quality of included studies using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, with disagreements resolved via consensus. Sensitivity and specificity were pooled using the random effects model. A summary receiver operating characteristic (SROC) curve was constructed. This review is reported in line with the Preferred Reporting Items for a Systematic Review and Meta-analysis of Diagnostic Test Accuracy Studies guidelines.

RESULTS

In all, nine studies involving 1430 participants were included. Most studies were of high quality, except one study with limited applicability because of its reference standard. The pooled sensitivity and specificity for detecting any DR was 87% (95% CI 74%-94%) and 94% (95% CI 81%-98%); mild nonproliferative DR (NPDR) was 39% (95% CI 10%-79%) and 95% (95% CI 91%-98%); moderate NPDR was 71% (95% CI 57%-81%) and 95% (95% CI 88%-98%); severe NPDR was 80% (95% CI 49%-94%) and 97% (95% CI 88%-99%); proliferative DR (PDR) was 92% (95% CI 79%-97%) and 99% (95% CI 96%-99%); diabetic macular edema was 79% (95% CI 63%-89%) and 93% (95% CI 82%-97%); and referral-warranted DR was 91% (95% CI 86%-94%) and 89% (95% CI 56%-98%). The area under SROC curve ranged from 0.879 to 0.979. The diagnostic odds ratio ranged from 11.3 to 1225.

CONCLUSIONS

We found heterogeneous evidence showing that smartphone ophthalmoscopy performs well in detecting DR. The diagnostic accuracy for PDR was highest. Future studies should standardize reference criteria and classification criteria and evaluate other available forms of smartphone ophthalmoscopy in primary care settings.

Retinoprotective Effect of 2-Ethyl-3-hydroxy-6-methylpyridine Nicotinate

An important task of pharmacology is to find effective agents to improve retinal microcirculation and resistance to ischemia. The purpose of the study is to pharmacologically evaluate the retinoprotective effect of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate in a rat model of retinal ischemia–reperfusion. A retinal ischemia–reperfusion model was used, in which an increase in intraocular pressure (IOP) to 110 mmHg was carried out within 30 min. The retinoprotective effect of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate at a dose of 3.8 mg/kg, in comparison with nicotinic acid at a dose of 2 mg/kg and emoxipine at a dose of 2 mg/kg, was estimated by the changes in the eye fundus during ophthalmoscopy, the retinal microcirculation level with laser Doppler flowmetry (LDF), and electroretinography (ERG) after 72 h of reperfusion. The use of 2-ethyl-3-hydroxy-6-methylpyridine nicotinate prevented the development of ischemic injuries in the fundus and led to an increase in the retinal microcirculation level to 747 (median) (lower and upper quartiles: 693;760) perfusion units (p = 0.0002) in comparison with the group that underwent no treatment. In the group with the studied substance, the b-wave amplitude increased significantly (p = 0.0022), and the b/a coefficient increased reliably (p = 0.0002) in comparison with the group with no treatment. Thus, 2-ethyl-3-hydroxy-6-methylpyridine nicotinate has established itself as a potential retinoprotector.

Deep Phenotyping of PDE6C-Associated Achromatopsia

Purpose

To perform deep phenotyping of subjects with PDE6C achromatopsia and examine disease natural history.

Methods

Eight subjects with disease-causing variants in PDE6C were assessed in detail, including clinical phenotype, best-corrected visual acuity, fundus autofluorescence, and optical coherence tomography. Six subjects also had confocal and nonconfocal adaptive optics scanning light ophthalmoscopy, axial length, international standard pattern and full-field electroretinography (ERG), short-wavelength flash (S-cone) ERGs, and color vision testing.

Results

All subjects presented with early-onset nystagmus, decreased best-corrected visual acuity, light sensitivity, and severe color vision loss, and five of them had high myopia. We identified three novel disease-causing variants and provide phenotype data associated with nine variants for the first time. No subjects had foveal hypoplasia or residual ellipsoid zone (EZ) at the foveal center; one had an absent EZ, three had a hyporeflective zone, and four had outer retinal atrophy. The mean width of the central EZ lesion on optical coherence tomography at baseline was 1923 μm. The mean annual increase in EZ lesion size was 48.3 μm. Fundus autofluorescence revealed a central hypoautofluorescence with a surrounding ring of increased signal (n = 5). The mean hypoautofluorescent area at baseline was 3.33 mm2 and increased in size by a mean of 0.13 mm2/year. Nonconfocal adaptive optics scanning light ophthalmoscopy revealed residual foveal cones in only one of two cases. Full-field ERGs were consistent with severe generalized cone system dysfunction but with relative preservation of S-cone sensitivity.

Conclusions

PDE6C retinopathy is a severe cone dysfunction syndrome often presenting as typical achromatopsia but without foveal hypoplasia. Myopia and slowly progressive maculopathy are common features. There are few (if any) residual foveal cones for intervention in older adults.

Comparison of optic disc evaluation methods in neurology emergency patients

BACKGROUND

The optic disc examination is critical for the diagnostics of several acute neurological disorders. However, dilation of the pupil is not recommended for neurological patients, which complicates ophthalmoscopy.

AIMS OF THE STUDY

Present pilot study compared a portable fundus camera to an ophthalmoscope in fundus examinations of neurological emergency patients. To our knowledge, this is the first comparative study of the subject. The fundus photographs were later reviewed with an ophthalmologist.

METHODS

The study included 60 adults, volunteer neurological emergency patients with either headache, cerebrovascular disorder, or acute confusional state (delirium). Patients' non-mydriatic fundus examination was conducted with an ophthalmoscope and a Smartscope Pro fundus camera.

RESULTS

Fundus photography succeeded in 56 (93%), partially succeeded in 2 (3%), and failed in 2 (3%) cases compared with ophthalmoscopy that succeeded in 35 (58%), partially succeeded in 14 (23%), and failed in 11 (18%) cases (P < .0005). The researcher and the ophthalmologist agreed in the findings in 54 out of 58 cases (93%). In six cases (7%), the researcher had failed to detect a non-critical ophthalmic finding.

CONCLUSIONS

The neurological fundus examination by fundus camera seems to be superior to regular ophthalmoscopy in defining the critical optic disc findings in emergency patients.

Estimation Dynamic Distance Direct Ophthalmoscopy (eDDDO): A novel, objective method for the quantitative assessment of accommodation in young children

Purpose

To describe estimation dynamic distance direct ophthalmoscopy (eDDDO) and compare it with the monocular estimation method of dynamic retinoscopy (eDR) for the assessment of accommodation in children.

Methods

In this prospective observational cohort study, an ophthalmologist performed eDDDO followed by eDR in children with normal eyes, and then under the partial effects of cyclopentolate and tropicamide to assess performance of eDDDO with eDR under the condition of pharmacologically induced accommodation failure. Only one eye of each child was recruited in the study. To study the inter-observer variation, two masked pediatric ophthalmology fellows performed eDDDO in the similar manner.

Results

For the comparison of eDDDO with eDR, 60 eyes of 60 patients were recruited. The mean age of the patients was 10.4 years. The mean accommodation on eDDDO was 3.0D, 5.1D, 9.8D, and 11.3D at 40 cm, 25 cm, 10 cm, and 8 cm, respectively and 3.0D, 5.0D, 9.5D, and 11.0D on eDR. The eDDDO overestimated accommodation by a mean 0.17D (95% CL 0-0.48D, P = 0.5). The correlation of eDDDO with eDR was excellent (Pearson r 0.98, T value 76.0). The inter-observer difference with eDDDO was not significant (mean 1D, 95% CL 0-2.6D, P = 0.9) and the correlation between two observers was excellent (Pearson r 0.9, T value 12.7). The eDDDO and eDR were also performed on 12 eyes of 6 children with a mean age of 8.5 years (range 8-12 years) under the partial effect of cyclopentolate and tropicamide, where eDDDO overestimated the accommodation by a mean 0.3D (95% CL 0- 1.2D, P = 0.7) and the correlation was excellent (Pearson r 1.0, T value 45).

Conclusion

eDDDO is a simple, reliable, quantitative, and objective technique of accommodation assessment for children. Further studies with larger sample are required to assess its performance in disorders of accommodation affecting younger children and in children with ocular comorbidities.

Comparison of the clinical estimation of cup-to-disk ratio by direct ophthalmoscopy and optical coherence tomography

Objective:

To compare the clinical estimation of cup-to-disk ratio determined by direct ophthalmoscopy and optical coherence tomography in glaucoma diagnosis and monitoring.

Methods:

A retrospective, cross-sectional study involving a review of 71 optical coherence tomography scans dating from June 2011 to January 2012 at a private imaging lab in Ghana. At the respective referring facilities, only 31 out of the 71 corresponding patient records were successfully reviewed.

Results:

Majority (54.84%) of the 31 patient records successfully reviewed were women. The mean age was 44.54 ± 16.15 years. Cup-to-disk ratio was grouped into ⩽0.4, >0.4–0.6, >0.6–0.8, and >0.8–1.0 based on direct ophthalmoscopy values. The overall mean cup-to-disk ratio estimated by the optical coherence tomography and direct ophthalmoscopy were 0.72 ± 0.21 and 0.60 ± 0.26, respectively. Overall, there was no statistically significant difference in the mean cup-to-disk ratio estimation by direct ophthalmoscopy and optical coherence tomography [right eye (p = 0.0629); left eye (p = 0.0766)]. There was a statistically significant difference between direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for values ⩽0.4 [right eye (p = 0.0061); left eye (p = 0.0063)] and values >0.4–0.6 [right eye (p = 0.0243); left eye (p = 0.0498)]. There was no statistically significant difference between conventional direct ophthalmoscopy and optical coherence tomography cup-to-disk ratio estimation for cup-to-disk ratio >0.6.

Conclusion:

We recommend clinicians document which method they use in evaluating optic nerve head parameters. This is to ensure that subsequent clinical decisions are not influenced by an apparent change in these parameters, especially cup-to-disk ratio as different methods might give different values.

Retinal microvascular abnormalities in neurofibromatosis type 1

PURPOSE

The aim of this study was to provide a classification of the different retinal vascular arrangements in neurofibromatosis 1 (NF1), with appropriate qualitative and quantitative information.

METHODS

This study was conducted on 334 consecutive patients with NF1 and 106 sex-matched and age-matched healthy control subjects. Each patient underwent a comprehensive ophthalmological examination inclusive of near-infrared reflectance retinography by using the spectral domain Optical coherence tomography (OCT), a complete dermatological examination and 1.5 T MRI scan of the brain to assess the presence of optic nerve gliomas. To evaluate the predictability and the diagnostic accuracy of our identified retinal microvascular arrangements, we calculated the diagnostic indicators for each pattern of pathology, with corresponding 95% CI. In addition, we evaluated the association between the microvascular arrangements and each National Institutes of Health diagnostic criteria.

RESULTS

Microvascular abnormalities were detected in 105 of 334 NF1 patients (31.4%), the simple vascular tortuosity was recognised in 78 of 105 cases (74.3%) and whether the corkscrew pattern and the moyamoya-like type showed a frequency of 42.8% (45 of 105 cases) and 15.2% (16 of 105 cases), respectively. We found a statistically significant correlation between the presence of retinal microvascular abnormalities and the patient age (p=0.02) and between the simple vascular tortuosity, the patient age and the presence of neurofibromas (p=0.002 and p=0.05, respectively).

CONCLUSIONS

We identified microvascular alterations in 31.4% of patients and a statistically significant association with patient age. Moreover, the most frequent type of microvascular alterations, the simple vascular tortuosity, resulted positively associated with age and with the presence of neurofibromas.

Agreement between retinal images obtained via smartphones and images obtained with retinal cameras or fundoscopic exams - systematic review and meta-analysis

Background

Smartphone fundoscopy is a new option for visualizing the ocular fundus but must be validated before being included in population-based examinations. Our aim was to evaluate the quality of fundoscopic images obtained via smartphone and to compare their agreement with retinal camera images or clinical examination.

Methods

The database for this study included all observational studies with smartphone fundoscopy that have comparative analyses with the gold standard methods.

Results

Out of 121 potentially relevant studies, nine were included in this analysis, comprising a total of 4,219 eyes. Mean age was 56.6 years (SD±8.5). Combined kappa (κ) agreement statistics were equal to 77.77% (95% CI: 70.34%, 83.70%). No heterogeneity was measured by random effects (I²=zero).

Conclusion

Fundoscopic images obtained by using smartphones have substantial agreement with gold standards for clinical or photographic exams.

A Smartphone-Based Tool for Rapid, Portable, and Automated Wide-Field Retinal Imaging

Purpose

High-quality, wide-field retinal imaging is a valuable method for screening preventable, vision-threatening diseases of the retina. Smartphone-based retinal cameras hold promise for increasing access to retinal imaging, but variable image quality and restricted field of view can limit their utility. We developed and clinically tested a smartphone-based system that addresses these challenges with automation-assisted imaging.

Methods

The system was designed to improve smartphone retinal imaging by combining automated fixation guidance, photomontage, and multicolored illumination with optimized optics, user-tested ergonomics, and touch-screen interface. System performance was evaluated from images of ophthalmic patients taken by nonophthalmic personnel. Two masked ophthalmologists evaluated images for abnormalities and disease severity.

Results

The system automatically generated 100° retinal photomontages from five overlapping images in under 1 minute at full resolution (52.3 pixels per retinal degree) fully on-phone, revealing numerous retinal abnormalities. Feasibility of the system for diabetic retinopathy (DR) screening using the retinal photomontages was performed in 71 diabetics by masked graders. DR grade matched perfectly with dilated clinical examination in 55.1% of eyes and within 1 severity level for 85.2% of eyes. For referral-warranted DR, average sensitivity was 93.3% and specificity 56.8%.

Conclusions

Automation-assisted imaging produced high-quality, wide-field retinal images that demonstrate the potential of smartphone-based retinal cameras to be used for retinal disease screening.

Translational Relevance

Enhancement of smartphone-based retinal imaging through automation and software intelligence holds great promise for increasing the accessibility of retinal screening.

In vivo super-resolution imaging of transient retinal phototropism evoked by oblique light stimulation

Rod-dominated transient retinal phototropism (TRP) has been observed in freshly isolated retinas, promising a noninvasive biomarker for objective assessment of retinal physiology. However, in vivo mapping of TRP is challenging due to its subcellular signal magnitude and fast time course. We report here a virtually structured detection-based super-resolution ophthalmoscope to achieve subcellular spatial resolution and millisecond temporal resolution for in vivo imaging of TRP. Spatiotemporal properties of in vivo TRP were characterized corresponding to variable light intensity stimuli, confirming that TRP is tightly correlated with early stages of phototransduction.

Sub-Airy Confocal Adaptive Optics Scanning Ophthalmoscopy

Purpose

To demonstrate the viability of improving transverse image resolution in reflectance scanning adaptive optics ophthalmoscopy using sub-Airy disk confocal detection.

Methods

The foveal cone mosaic was imaged in five human subjects free of known eye disease using two custom adaptive optics scanning light ophthalmoscopes (AOSLOs) in reflectance with 7.75 and 4.30 mm pupil diameters. Confocal pinholes of 0.5, 0.6, 0.8, and 1.0 Airy disk diameters (ADDs) were used in a retinal conjugate plane before the light detector. Average cone photoreceptor intensity profile width and power spectrum were calculated for the resulting images. Detected energy using a model eye was recorded for each pinhole size.

Results

The cone photoreceptor mosaic is better resolved with decreasing confocal pinhole size, with the high spatial frequency content of the images enhanced in both the large- and small-pupil AOSLOs. The average cone intensity profile width was reduced by ∼15% with the use of a 0.5 ADD pinhole when compared to a 1.0 ADD, with an accompanying reduction in signal greater than a factor of four.

Conclusions

The use of sub-Airy disk confocal pinhole detection without increasing retinal light exposure results in a substantial improvement in image resolution at the cost of larger than predicted signal reduction.

Translational Relevance

Improvement in transverse resolution using sub-Airy disk confocal detection is a practical and low-cost approach that is applicable to all point- and line-scanning ophthalmoscopes, including optical coherence tomographers.

Dysflective cones: Visual function and cone reflectivity in long-term follow-up of acute bilateral foveolitis

Purpose

Confocal adaptive optics scanning laser ophthalmoscope (AOSLO) images provide a sensitive measure of cone structure. However, the relationship between structural findings of diminished cone reflectivity and visual function is unclear. We used fundus-referenced testing to evaluate visual function in regions of apparent cone loss identified using confocal AOSLO images.

Methods

A patient diagnosed with acute bilateral foveolitis had spectral-domain optical coherence tomography (SD-OCT) (Spectralis HRA + OCT system [Heidelberg Engineering, Vista, CA, USA]) images indicating focal loss of the inner segment-outer segment junction band with an intact, but hyper-reflective, external limiting membrane. Five years after symptom onset, visual acuity had improved from 20/80 to 20/25, but the retinal appearance remained unchanged compared to 3 months after symptoms began. We performed structural assessments using SD-OCT, directional OCT (non-standard use of a prototype on loan from Carl Zeiss Meditec) and AOSLO (custom-built system). We also administered fundus-referenced functional tests in the region of apparent cone loss, including analysis of preferred retinal locus (PRL), AOSLO acuity, and microperimetry with tracking SLO (TSLO) (prototype system). To determine AOSLO-corrected visual acuity, the scanning laser was modulated with a tumbling E consistent with 20/30 visual acuity. Visual sensitivity was assessed in and around the lesion using TSLO microperimetry. Complete eye examination, including standard measures of best-corrected visual acuity, visual field tests, color fundus photos, and fundus auto-fluorescence were also performed.

Results

Despite a lack of visible cone profiles in the foveal lesion, fundus-referenced vision testing demonstrated visual function within the lesion consistent with cone function. The PRL was within the lesion of apparent cone loss at the fovea. AOSLO visual acuity tests were abnormal, but measurable: for trials in which the stimulus remained completely within the lesion, the subject got 48% correct, compared to 78% correct when the stimulus was outside the lesion. TSLO microperimetry revealed reduced, but detectible, sensitivity thresholds within the lesion.

Conclusions and importance

Fundus-referenced visual testing proved useful to identify functional cones despite apparent photoreceptor loss identified using AOSLO and SD-OCT. While AOSLO and SD-OCT appear to be sensitive for the detection of abnormal or absent photoreceptors, changes in photoreceptors that are identified with these imaging tools do not correlate completely with visual function in every patient. Fundus-referenced vision testing is a useful tool to indicate the presence of cones that may be amenable to recovery or response to experimental therapies despite not being visible on confocal AOSLO or SD-OCT images.

Wide-field fundus imaging with trans-palpebral illumination

In conventional fundus imaging devices, transpupillary illumination is used for illuminating the inside of the eye. In this method, the illumination light is directed into the posterior segment of the eye through the cornea and passes the pupillary area. As a result of sharing the pupillary area for the illumination beam and observation path, pupil dilation is typically necessary for wide-angle fundus examination, and the field of view is inherently limited. An alternative approach is to deliver light from the sclera. It is possible to image a wider retinal area with transcleral-illumination. However, the requirement of physical contact between the illumination probe and the sclera is a drawback of this method. We report here trans-palpebral illumination as a new method to deliver the light through the upper eyelid (palpebra). For this study, we used a 1.5 mm diameter fiber with a warm white LED light source. To illuminate the inside of the eye, the fiber illuminator was placed at the location corresponding to the pars plana region. A custom designed optical system was attached to a digital camera for retinal imaging. The optical system contained a 90 diopter ophthalmic lens and a 25 diopter relay lens. The ophthalmic lens collected light coming from the posterior of the eye and formed an aerial image between the ophthalmic and relay lenses. The aerial image was captured by the camera through the relay lens. An adequate illumination level was obtained to capture wide angle fundus images within ocular safety limits, defined by the ISO 15004-2: 2007 standard. This novel trans-palpebral illumination approach enables wide-angle fundus photography without eyeball contact and pupil dilation.

In vivo super-resolution retinal imaging through virtually structured detection

High resolution is important for sensitive detection of subtle distortions of retinal morphology at an early stage of eye diseases. We demonstrate virtually structured detection (VSD) as a feasible method to achieve in vivo super-resolution ophthalmoscopy. A line-scanning strategy was employed to achieve a super-resolution imaging speed up to 127 ?? frames / s with a frame size of 512 × 512 ?? pixels . The proof-of-concept experiment was performed on anesthetized frogs. VSD-based super-resolution images reveal individual photoreceptors and nerve fiber bundles unambiguously. Both image contrast and signal-to-noise ratio are significantly improved due to the VSD implementation.

In Vivo Imaging of the Human Retinal Pigment Epithelial Mosaic Using Adaptive Optics Enhanced Indocyanine Green Ophthalmoscopy

PURPOSE

The purpose of this study was to establish that retinal pigment epithelial (RPE) cells take up indocyanine green (ICG) dye following systemic injection and that adaptive optics enhanced indocyanine green ophthalmoscopy (AO-ICG) enables direct visualization of the RPE mosaic in the living human eye.

METHODS

A customized adaptive optics scanning light ophthalmoscope (AOSLO) was used to acquire high-resolution retinal fluorescence images of residual ICG dye in human subjects after intravenous injection at the standard clinical dose. Simultaneously, multimodal AOSLO images were also acquired, which included confocal reflectance, nonconfocal split detection, and darkfield. Imaging was performed in 6 eyes of three healthy subjects with no history of ocular or systemic diseases. In addition, histologic studies in mice were carried out.

RESULTS

The AO-ICG channel successfully resolved individual RPE cells in human subjects at various time points, including 20 minutes and 2 hours after dye administration. Adaptive optics-ICG images of RPE revealed detail which could be correlated with AO dark-field images of the same cells. Interestingly, there was a marked heterogeneity in the fluorescence of individual RPE cells. Confirmatory histologic studies in mice corroborated the specific uptake of ICG by the RPE layer at a late time point after systemic ICG injection.

CONCLUSIONS

Adaptive optics-enhanced imaging of ICG dye provides a novel way to visualize and assess the RPE mosaic in the living human eye alongside images of the overlying photoreceptors and other cells.

OPHTHALMIC REFERENCE VALUES AND LESIONS IN TWO CAPTIVE POPULATIONS OF NORTHERN OWLS: GREAT GREY OWLS (STRIX NEBULOSA) AND SNOWY OWLS (BUBO SCANDIACUS)

This study established ophthalmic reference values and characterized ocular lesions in two captive populations of boreal owls, including 46 eyes of 23 great grey owls (Strix nebulosa) and 38 eyes from 19 snowy owls (Bubo scandiacus). A complete ophthalmologic exam was conducted, including neuro-ophthalmic reflexes, Schirmer tear test I (STT-I), intraocular pressure (IOP) using rebound tonometry, fluorescein staining, horizontal corneal measurements using Jameson calipers, direct and indirect ophthalmoscopy, and ocular ultrasound biometry. Eyes with an STT of <5 mm/min, outliers, and eyes with severe diseases were excluded from reference value analysis. No statistically significant differences were found between right or left eyes in either species or among individuals in different age groups and sexes. Mean intraocular pressures and Schirmer tear tests were also not statistically significantly different between great grey owls and snowy owls (IOP: 9.6 ± 2.6 mm Hg and 9.1 ± 1.9 mm Hg, respectively, and STT-I: 9.8 ± 2.8 mm/min and 9.8 ± 2.4 mm/min, respectively). However, snowy owls overall had a significantly larger eye than did great grey owls, reflected in corneal diameters (23.4 ± 1 vs. 20.0 ± 0.8 mm, respectively) and sonographic biometry. In both species, the most common ocular lesions included keratitis, cataracts, chorioretinal lesions, and abnormal pecten. Establishment of reference ocular parameters will help wildlife veterinarians and rehabilitators determine an appropriate treatment plan and will aid in correctly identifying the presence of ocular disease.

Clinical study of fundus findings in pregnancy induced hypertension

BACKGROUND AND OBJECTIVES

To study the role of ophthalmoscopy in pregnancy induced hypertension (PIH) in diagnosis, prognosis, differential diagnosis, line of treatment and effect of treatment.

MATERIALS AND METHODS

An observational study in which all the patients for the study are selected from antenatal clinic, antenatal wards and preeclampsia and eclampsia room in Department of Obstetrics and Gynecology, General Ophthalmic Out Patient Department (OPD) in case of ambulatory patients, during the period of Nov. 2003 to June 2006 randomly. In every case detail obstetric history, general examination and relevant pathological investigations were carried out. In every case, pupil was dilated with homatropine (2%) eye drops and detailed ophthalmic examination was carried out.

RESULTS

In our study out of 300 cases of PIH, there are 182 cases of mild preeclampsia and 76 cases of severe preeclampsia and 42 cases of eclampsia. Among these, 37 cases (20.33%) of mild preeclampsia and 75 cases (98.68%) of severe preeclampsia and 41 cases (97.62%) of eclampsia show positive fundus changes. The incidence of pre-term babies, intra uterine death, still birth and low birth weight infants is high in mothers having positive fundus changes, i.e. for pre-term infant (72.46%), still birth (62%) and low birth weight (45.56%) in our series The perinatal mortality is higher in patients having Grade II (33.85%), Grade III (54.29%), Grade IV (100%) hypertensive retinopathy.

CONCLUSION

Retinal examination reveals important objective information in PIH, furthers their accurate diagnosis and refines their management.

The Diabetic Retinopathy Screening Workflow: Potential for Smartphone Imaging

Complications of diabetes mellitus, namely diabetic retinopathy and diabetic maculopathy, are the leading cause of blindness in working aged people. Sufferers can avoid blindness if identified early via retinal imaging. Systematic screening of the diabetic population has been shown to greatly reduce the prevalence and incidence of blindness within the population. Many national screening programs have digital fundus photography as their basis. In the past 5 years several techniques and adapters have been developed that allow digital fundus photography to be performed using smartphones. We review recent progress in smartphone-based fundus imaging and discuss its potential for integration into national systematic diabetic retinopathy screening programs. Some systems have produced promising initial results with respect to their agreement with reference standards. However further multisite trialling of such systems' use within implementable screening workflows is required if an evidence base strong enough to affect policy change is to be established. If this were to occur national diabetic retinopathy screening would, for the first time, become possible in low- and middle-income settings where cost and availability of trained eye care personnel are currently key barriers to implementation. As diabetes prevalence and incidence is increasing sharply in these settings, the impact on global blindness could be profound.

Adaptive optics ophthalmoscopy

This review starts with a brief history and description of adaptive optics (AO) technology, followed by a showcase of the latest capabilities of AO systems for imaging the human retina and an extensive review of the literature on where AO is being used clinically. The review concludes with a discussion on future directions and guidance on usage and interpretation of images from AO systems for the eye.

Diagnostic Accuracy of Optic Nerve Ultrasonography and Ophthalmoscopy in Prediction of Elevated Intracranial Pressure

INTRODUCTION

Elevated intracranial pressure (ICP) is a major and potentially lethal disorder in patients admitted to the emergency department (ED). Several methods are being used to investigate for elevated ICP. Here we assessed and compared the diagnostic accuracy of two existing tools of ophthalmoscopy and optic nerve ultrasonography in detection of elevated ICP.

METHODS

131 participants with probable elevation of ICP referred to the emergency department of Al-Zahra Hospital, Isfahan, Iran, from 2012 to 2014, were enrolled. Brain computed tomography (CT) scan, ultrasonography of optic nerve sheath, and ophthalmoscopy were performed for them. The optic nerves sheath with diameter more than 5 millimeters was considered as elevated ICP. Widening of optic nerve, ocular venous engorgement, blurring, hemorrhage over optic disk, elevation of optic disk, and retinal venous tortuosity were recorded as evidences of ICP rising in ophthalmoscopy. Diagnostic accuracy of the two tools in prediction of ICP rising were compared with the results of brain CT scan as a gold standard.

RESULTS

The mean age of participants was 46.29 ± 10 years (77% male). The number of diagnosed elevated ICPs with ophthalmoscopy and ultrasound were 98 (74.8%) and 102 (77.9%) cases, respectively. The calculated sensitivity and specificity of ophthalmoscopy and ultrasonography in detection of ICP rising were 100.0% (95% CI: 88.6-100.0) and 35.4% (95% CI: 26.0-46.2), 100.0% (95% CI: 84.0-100.0) and 31.9% (95% CI: 23.0-41.7), respectively.

CONCLUSION

The present study revealed that bedside ultrasonography of optic nerve sheath and ophthalmoscopy have enough accuracy for the screening of patients with probable elevation of ICP. Of course, it should be considered that despite the high sensitivity of both tools, their specificity is low.

Microscopic inner retinal hyper-reflective phenotypes in retinal and neurologic disease

PURPOSE

We surveyed inner retinal microscopic features in retinal and neurologic disease using a reflectance confocal adaptive optics scanning light ophthalmoscope (AOSLO).

METHODS

Inner retinal images from 101 subjects affected by one of 38 retinal or neurologic conditions and 11 subjects with no known eye disease were examined for the presence of hyper-reflective features other than vasculature, retinal nerve fiber layer, and foveal pit reflex. The hyper-reflective features in the AOSLO images were grouped based on size, location, and subjective texture. Clinical imaging, including optical coherence tomography (OCT), scanning laser ophthalmoscopy, and fundus photography was analyzed for comparison.

RESULTS

Seven categories of hyper-reflective inner retinal structures were identified, namely punctate reflectivity, nummular (disc-shaped) reflectivity, granular membrane, waxy membrane, vessel-associated membrane, microcysts, and striate reflectivity. Punctate and nummular reflectivity also was found commonly in normal volunteers, but the features in the remaining five categories were found only in subjects with retinal or neurologic disease. Some of the features were found to change substantially between follow up imaging months apart.

CONCLUSIONS

Confocal reflectance AOSLO imaging revealed a diverse spectrum of normal and pathologic hyper-reflective inner and epiretinal features, some of which were previously unreported. Notably, these features were not disease-specific, suggesting that they might correspond to common mechanisms of degeneration or repair in pathologic states. Although prospective studies with larger and better characterized populations, along with imaging of more extensive retinal areas are needed, the hyper-reflective structures reported here could be used as disease biomarkers, provided their specificity is studied further.

[Hypertension-related eye disorders]

Hypertension affects a significant proportion of the population, however, it is often diagnosed with a delay. The aim of this article is to review the well known and less known eye abnormalities related to hypertension, and place them in the context of population based studies. Hypertension affects various parts of the eye. The originally classified hypertensive retinopathy (retinal microvascular changes) is still relevant, but new features are visible in cases of controlled hypertension. Signs of mild hypertensive retinopathy are more common than expected occurring in nearly 10-15% of the adult non-diabetic population. Hypertensive retinopathy can be an indicator of other hypertensive complications such as neurologic and cardiac complications. Microvascular changes are reversible in well controlled hypertension. Proper treatment of hypertension can reduce the development and progression of diabetic retinopathy and, thus, visual loss due to severe retinal diseases such as retinal vascular occlusion (artery and vein), retinal arteriolar emboli, macroaneurysm, ischemic optic neuropathy and age-related macular degeneration.

Simultaneous in vivo imaging of melanin and lipofuscin in the retina with photoacoustic ophthalmoscopy and autofluorescence imaging

We combined photoacoustic ophthalmoscopy (PAOM) with autofluorescence imaging for simultaneous in vivo imaging of dual molecular contrasts in the retina using a single light source. The dual molecular contrasts come from melanin and lipofuscin in the retinal pigment epithelium (RPE). Melanin and lipofuscin are two types of pigments and are believed to play opposite roles (protective versus exacerbate) in the RPE in the aging process. We have successfully imaged the retina of pigmented and albino rats at different ages. The experimental results showed that multimodal PAOM system can be a potentially powerful tool in the study of age-related degenerative retinal diseases.