Hypertensive retinopathy revisited: some answers, more questions

Central serous chorioretinopathy: An evidence-based treatment guideline

Central serous chorioretinopathy (CSC) is a relatively common disease that causes vision loss due to macular subretinal fluid leakage and it is often associated with reduced vision-related quality of life. In CSC, the leakage of subretinal fluid through defects in the retinal pigment epithelial layer's outer blood-retina barrier appears to occur secondary to choroidal abnormalities and dysfunction. The treatment of CSC is currently the subject of controversy, although recent data obtained from several large randomized controlled trials provide a wealth of new information that can be used to establish a treatment algorithm. Here, we provide a comprehensive overview of our current understanding regarding the pathogenesis of CSC, current therapeutic strategies, and an evidence-based treatment guideline for CSC. In acute CSC, treatment can often be deferred for up to 3-4 months after diagnosis; however, early treatment with either half-dose or half-fluence photodynamic therapy (PDT) with the photosensitive dye verteporfin may be beneficial in selected cases. In chronic CSC, half-dose or half-fluence PDT, which targets the abnormal choroid, should be considered the preferred treatment. If PDT is unavailable, chronic CSC with focal, non-central leakage on angiography may be treated using conventional laser photocoagulation. CSC with concurrent macular neovascularization should be treated with half-dose/half-fluence PDT and/or intravitreal injections of an anti-vascular endothelial growth factor compound. Given the current shortage of verteporfin and the paucity of evidence supporting the efficacy of other treatment options, future studies-ideally, well-designed randomized controlled trials-are needed in order to evaluate new treatment options for CSC.

Retinal image registration method for myopia development

OBJECTIVE

The development of myopia is usually accompanied by changes in retinal vessels, optic disc, optic cup, fovea, and other retinal structures as well as the length of the ocular axis. And the accurate registration of retinal images is very important for the extraction and analysis of retinal structural changes. However, the registration of retinal images with myopia development faces a series of challenges, due to the unique curved surface of the retina, as well as the changes in fundus curvature caused by ocular axis elongation. Therefore, our goal is to improve the registration accuracy of the retinal images with myopia development.

METHOD

In this study, we propose a 3D spatial model for the pair of retinal images with myopia development. In this model, we introduce a novel myopia development model that simulates the changes in the length of ocular axis and fundus curvature due to the development of myopia. We also consider the distortion model of the fundus camera during the imaging process. Based on the 3D spatial model, we further implement a registration framework, which utilizes corresponding points in the pair of retinal images to achieve registration in the way of 3D pose estimation.

RESULTS

The proposed method is quantitatively evaluated on the publicly available dataset without myopia development and our Fundus Image Myopia Development (FIMD) dataset. The proposed method is shown to perform more accurate and stable registration than state-of-the-art methods, especially for retinal images with myopia development.

SIGNIFICANCE

To the best of our knowledge, this is the first retinal image registration method for the study of myopia development. This method significantly improves the registration accuracy of retinal images which have myopia development. The FIMD dataset we constructed has been made publicly available to promote the study in related fields.

Association Between Cardiovascular Health and Retinopathy in US Adults: From NHANES 2005-2008

PURPOSE

Investigating the relationship between cardiovascular health (CVH) and retinopathy in the adult population of the United States.

DESIGN

The cross-sectional study.

METHODS

The study utilized samples, including the diabetes population, from the National Health and Nutrition Examination Survey (NHANES) conducted between 2005 and 2008 (N= 4249), to assess cardiovascular health (CVH) using the Life's Essential 8 (LE8) assessment. Retinopathy is determined through imaging assessment by professionals independently grading fundus photographs. Univariable and multivariable weighted logistic regression models, restricted cubic splines (RCS), subgroup analysis and weighted quantile sum (WQS) regression approaches were employed to assess the association between LE8 score-based CVH status and retinopathy. The mediation analysis was conducted to investigate whether serum albumin levels mediated the relationship between LE8 score and retinopathy.

RESULTS

In a fully adjusted logistic regression model, participants in the moderate and high CVH groups had a 39% (odds ratio (OR) 0.61, 95% confidence interval (CI) 0.43-0.87, P-value = 0.01) and 56% (OR 0.44, 95% CI 0.25-0.77, P-value < 0.001) lower odds of developing retinopathy compared to the low CVH group. The RCS model indicates a significant non-linear relationship between CVH and retinopathy. The WQS regression analysis suggests that blood glucose (47.65%) and blood pressure (19.41%) have the highest weights in relation to retinopathy. Mediation analysis suggests that serum albumin partially mediates the relationship between LE8 scores and retinopathy.

CONCLUSION

This study demonstrates a significant negative correlation between overall cardiovascular health measured by LE8 scores and retinopathy. Public health strategies that promote achieving optimal cardiovascular health indicators may help reduce the burden of retinal microvascular diseases.

Case report: The role of hypertension retinopathy graduation in the management of systemic cardiovascular disease

Moderate to severe hypertensive retinopathies are more likely to correlate with uncontrolled blood pressure in all ages. Mild microvascular changes are expected with natural aging and are therefore more concerning in patients younger than 40. Risk assessment is subsequently determined based on blood pressure measurements and patient symptoms. The goal of this paper is to discuss current opinions regarding the role of grading hypertensive retinopathy in the risk assessment of systemic cardiovascular disease in the context of a clinical case. Management and referral recommendations for clinicians will be summarized. Emergent referral for hospital-based care is indicated in any patient with severe hypertensive retinopathy; pregnant women with moderate hypertensive retinopathy; patients younger than 55 with blood pressure greater than Grade 2; any patient with blood pressure greater than grade Severe; any patient with symptoms of chest pain, headache, dyspnea, or dizziness; and any patient with a symptomatic retinal plaque.

Computer-aided diagnostic system for hypertensive retinopathy: A review

Hypertensive Retinopathy (HR) is a retinal disease caused by elevated blood pressure for a prolonged period. There are no obvious signs in the early stages of high blood pressure, but it affects various body parts over time, including the eyes. HR is a biomarker for several illnesses, including retinal diseases, atherosclerosis, strokes, kidney disease, and cardiovascular risks. Early microcirculation abnormalities in chronic diseases can be diagnosed through retinal examination prior to the onset of major clinical consequences. Computer-aided diagnosis (CAD) plays a vital role in the early identification of HR with improved diagnostic accuracy, which is time-efficient and demands fewer resources. Recently, numerous studies have been reported on the automatic identification of HR. This paper provides a comprehensive review of the automated tasks of Artery-Vein (A/V) classification, Arteriovenous ratio (AVR) computation, HR detection (Binary classification), and HR severity grading. The review is conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. The paper discusses the clinical features of HR, the availability of datasets, existing methods used for A/V classification, AVR computation, HR detection, and severity grading, and performance evaluation metrics. The reviewed articles are summarized with classifiers details, adoption of different kinds of methodologies, performance comparisons, datasets details, their pros and cons, and computational platform. For each task, a summary and critical in-depth analysis are provided, as well as common research issues and challenges in the existing studies. Finally, the paper proposes future research directions to overcome challenges associated with data set availability, HR detection, and severity grading.

Determinants of diabetic retinopathy in Ethiopia: A systematic review and meta-analysis

INTRODUCTION

Diabetic retinopathy (DR) is the primary retinal vascular complication of diabetes mellitus and a leading cause of visual impairment and blindness. It affects the global diabetic population. In Ethiopia, about one-fifth of diabetic patients were affected by DR, but there were inconsistent finding across studies about the determinants factors of DR. Therefore, we aimed to identify the risk factors for DR among diabetic patients.

METHODS

We have accessed previous studies through an electronic web-based search strategy using PubMed, Google (Scholar), the Web of Science, and the Cochrane Library with a combination of search terms. The quality of each included article was assessed using the Newcastle Ottawa Assessment Scale. All statistical analyses were carried out using Stata version 14 software. The odds ratios of risk factors were pooled using a fixed-effect meta-analysis model. Heterogeneity was assessed using the Cochrane Q statistics and I-Square (I2). Furthermore, publication bias was detected based on the graphic asymmetry test of the funnel plot and/or Egger's test (p< 0.05).

RESULTS

The search strategy retrieved 1285 articles. After the removal of duplicate articles, 249 articles remained. Following further screening, about 18 articles were assessed for eligibility, of which three articles were excluded because of reporting without the outcome of interest, poor quality, and not full text. Finally, fifteen studies were reviewed for the final analysis. Co-morbid hypertension (HTN) (AOR 2.04, 95%CI: 1.07, 3.89), poor glycemic control (AOR = 4.36, 95%CI: 1.47, 12.90), and duration of diabetes illness (AOR = 3.83, 95%CI: 1.17, 12.55) were found to be confirmed associated factors of diabetic retinopathy.

CONCLUSION

In this study, co-morbid HTN, poor glycemic control, and longer duration of diabetes illness were found to be the determinant factors of DR. Aggressive treatment of co-morbid HTN and blood glucose, and regular eye screening should be implemented to reduce the occurrence of DR.

TRIAL REGISTRATION

The review protocol was registered in the international prospective register of systematic reviews (PROSPERO) with registration number PROSPERO: CRD42023416724.

Seeing Red: Associations between Historical Redlining and Present-Day Visual Impairment and Blindness

PURPOSE

Redlining was a discriminatory housing policy in the United States that began in 1933 and denoted neighborhoods with high proportions of Black individuals as "undesirable" and a high risk for lending, which therefore excluded people from obtaining traditional insured mortgages to purchase a home. Simultaneously, realtors discouraged Black individuals from purchasing homes in predominantly non-Black neighborhoods. This resulted in decreased home ownership and wealth accumulation among Black individuals and neighborhoods with high proportions of Black individuals. This study investigated rates of visual impairment and blindness (VIB) in neighborhoods that at one time were graded for redlining.

DESIGN

Secondary data analysis of American Community Survey data and historical grades for redlining.

PARTICIPANTS

United States census tracts (CTs) from 2010 with historical grades for redlining.

METHODS

One-way analysis of variance, Kruskal-Wallis test, chi-square test, and logistic regression modeling.

MAIN OUTCOME MEASURES

The main outcome was CT percentage of residents reporting VIB and the association with historical grades for redlining. Grades were converted to numeric values (1 to 4, with higher values indicating worse grade) and aggregated over a CT based on the distribution of grades within to obtain a redlining score. Logistic regression was used to model the effect of redlining on the probability of having VIB.

RESULTS

Eleven thousand six hundred sixty-eight CTs were analyzed. Logistic regression found that a 1-unit increase in average redlining score was associated with a 13.4% increased odds of VIB after controlling for CT measures of age, sex, people of color (any non-White race), state, and population size (odds ratio [OR], 1.134; 95% confidence interval [CI], 1.131-1.138; P < 0.001). Similar results were observed for an additional model that adjusted for the estimated percentage of Black residents within a CT (OR, 1.180; 95% CI, 1.177-1.183; P < 0.001).

CONCLUSIONS

Historical government-sanctioned residential segregation through redlining was found to be associated with higher proportions of people living with VIB in these neighborhoods today. Understanding how neighborhood segregation impacts eye health is important for planning improved mechanisms of eye care delivery to mitigate health disparities.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Recent trends and advances in fundus image analysis: A review

Automated retinal image analysis holds prime significance in the accurate diagnosis of various critical eye diseases that include diabetic retinopathy (DR), age-related macular degeneration (AMD), atherosclerosis, and glaucoma. Manual diagnosis of retinal diseases by ophthalmologists takes time, effort, and financial resources, and is prone to error, in comparison to computer-aided diagnosis systems. In this context, robust classification and segmentation of retinal images are primary operations that aid clinicians in the early screening of patients to ensure the prevention and/or treatment of these diseases. This paper conducts an extensive review of the state-of-the-art methods for the detection and segmentation of retinal image features. Existing notable techniques for the detection of retinal features are categorized into essential groups and compared in depth. Additionally, a summary of quantifiable performance measures for various important stages of retinal image analysis, such as image acquisition and preprocessing, is provided. Finally, the widely used in the literature datasets for analyzing retinal images are described and their significance is emphasized.

Hypertensive eye disease

Hypertensive eye disease includes a spectrum of pathological changes, the most well known being hypertensive retinopathy. Other commonly involved parts of the eye in hypertension include the choroid and optic nerve, sometimes referred to as hypertensive choroidopathy and hypertensive optic neuropathy. Together, hypertensive eye disease develops in response to acute and/or chronic elevation of blood pressure. Major advances in research over the past three decades have greatly enhanced our understanding of the epidemiology, systemic associations and clinical implications of hypertensive eye disease, particularly hypertensive retinopathy. Traditionally diagnosed via a clinical funduscopic examination, but increasingly documented on digital retinal fundus photographs, hypertensive retinopathy has long been considered a marker of systemic target organ damage (for example, kidney disease) elsewhere in the body. Epidemiological studies indicate that hypertensive retinopathy signs are commonly seen in the general adult population, are associated with subclinical measures of vascular disease and predict risk of incident clinical cardiovascular events. New technologies, including development of non-invasive optical coherence tomography angiography, artificial intelligence and mobile ocular imaging instruments, have allowed further assessment and understanding of the ocular manifestations of hypertension and increase the potential that ocular imaging could be used for hypertension management and cardiovascular risk stratification.

Improving U-Net architecture and graph cuts optimization to classify arterioles and venules in retina fundus images

The central retinal artery and its branches supply blood to the inner retina. Vascular manifestations in the retina indirectly reflect the vascular changes and damage in organs such as the heart, kidneys, and brain because of the similar vascular structure of these organs. The diabetic retinopathy and risk of stroke are caused by increased venular caliber. The degrees of these diseases depend on the changes of arterioles and venules. The ratio between the calibers of arterioles and venules (AVR) is various. AVR is considered as the useful diagnostic indicator of different associated health problems. However, the task is not easy because of the lack of information of the features being used to classify the retinal vessels as arterioles and venules. This paper proposed a method to classify the retinal vessels into the arterioles and venules based on improving U-Net architecture and graph cuts. The accuracy of the proposed method is about 97.6%. The results of the proposed method are better than the other methods in RITE dataset and AVRDB dataset.

Prevalence of Risk Factors of Retinal Diseases among Patients in Madang Province, Papua New Guinea

PURPOSE

To explore the prevalence of risk factors of retinal diseases among patients seeking services from Madang Provincial Hospital Eye Clinic in Papua New Guinea.

MATERIALS AND METHODS

A hospital-based retrospective study was conducted at the only eye clinic serving the entire Madang province of Papua New Guinea. Purposive sampling was used to obtain data from patients' record cards at the eye clinic from January to June 2021. The data collected included gender, age, presenting visual acuity, blood pressure, blood sugar level, body mass index, smoking habits, and history of cataract surgery. The data was analyzed using the International Business Machines Corporation's Statistical Package for Social Sciences version 21. A p-value of <0.05 was considered statistically significant.

RESULTS

Two hundred and fifty-five (255) patients went through diabetes and hypertension screening during the period of the study (January to June 2021). The mean age of the patients was 53.14 ± 11.20 years and there were more males (56.86%) than females. Nearly half of the patients (43.6%) were either visually impaired or blind. More than half (52.6%) had diabetes mellitus. Majority of the patients (73.3%) were hypertensive and more than half (57.0%) of the patients had unhealthy body mass index (BMI <18.525 kg/m² or > 25 kg/m²). Overweight was significantly associated with hypertension (p < 0.001) and diabetes mellitus (p < 0.001). A few of them were smokers or had a history of cataract surgery (13.7% and 2.0%, respectively).

CONCLUSION

There is a high prevalence of diabetes, hypertension, and overweight among ophthalmic patients in Madang. It is important that measures are put in place to eliminate barriers to health care and to strengthen eye care services in Papua New Guinea.

Evaluation of the prevalence of non-diabetic eye disease detected at first screen from a single region diabetic retinopathy screening program: a cross-sectional cohort study in Auckland, New Zealand

OBJECTIVES

To evaluate the prevalence of incidental non-diabetic ocular comorbidities detected at first screen in a large diabetic retinopathy (DR) screening programme.

DESIGN

Cross-sectional cohort study.

SETTING

Single large metropolitan diabetic eye screening programme in Auckland, New Zealand.

PARTICIPANTS

Twenty-two thousand seven hundred and seventy-one participants who attended screening from September 2008 to August 2018.

RESULTS

Hypertensive retinopathy (HTR) was observed in 14.2% (3236/22 771) participants. Drusen were present in 14.0% participants under the age of 55 years, increasing to 20.5% in those 55 years and older. The prevalence of neovascular age-related macular degeneration (AMD) was 0.5% in participants aged<55 years, 2.4% in participants aged 55-75 years and 16% in participants aged>75 years. Retinal vein occlusion and retinal arterial embolus were prevalent in 0.7% and 0.02%, respectively, in participants aged<55 years, increasing to 2.2% and 0.4%, respectively, in those >75 years. Cataracts were common being present in 37.1% of participants over the age of 75 years. Only 386 individuals (1.7%) were labelled as glaucoma suspects. Geographic atrophy, epiretinal membrane, choroidal nevi and posterior capsular opacification had an increased prevalence in older individuals.

CONCLUSIONS

Our data suggest that AMD, HTR and cataracts are routinely detected during DR screening. The incorporation of the detection of these ocular comorbidities during DR screening provide opportunities for patients to modify risk factors (smoking cessation and diet for AMD, blood pressure for HTR) and allow access to cataract surgery.

Novel surgical approach for removing intraretinal loculated foveal hemorrhage in a patient with hypertensive retinopathy

Purpose

To present a surgical approach for removing intra-retinal loculated foveal hemorrhage due to hypertensive retinopathy (HR) in a patient with uncontrolled hypertension (HTN).

Observations

A 67-year-old man presented to a tertiary retina clinic with the complaint of decreased vision in his left eye (OS) for the past six months. He had a history of uncontrolled HTN, which caused HR; otherwise, his past medical and ocular history were insignificant. His best-corrected visual acuity (BCVA) was 20/20 right eye (OD) and 20/400 OS. Fundus examination of OD did not show significant pathology except mild arterial narrowing. Fundus examination of OS revealed arterial narrowing and multiple areas of small retinal hemorrhage. Old, organized hemorrhage with a yellow foveal centered lesion appearance was detected on fundus examination. Spectral-domain optical coherence tomography (SD-OCT) showed a dense hyper-reflective intra-retinal lesion at the fovea. Pars plana vitrectomy was performed. Internal limiting membrane (ILM) was stained with Brilliant Blue G (BBG) and peeled off around the lesion using ILM forceps. Attempts to remove the lesion with cannula-assisted active backflush and aspiration were unsuccessful. Therefore, the lesion was gently dissected and extracted by using 41-gauge needle. After removing the clot, the rotational ILM flap technique was used to repair the developed macular hole-like tissue defect. At the two-month follow-up visit, BCVA improved considerably to 20/50, and significant anatomical restoration was observed.

Conclusion and Importance

HR is relatively common among patients with elevated blood pressure. To date, management of HR and its complications such as retinal hemorrhage is limited to non-surgical methods. For the first time, a surgical approach is utilized to manage one of the HR's complications with prominent visual and structural improvement. The index case report presents a new management option for hypertensive retinal hemorrhage, but only in appropriate patients with ocular indications and understanding of the potential adverse events associated with the surgical procedure.

Polarization properties of retinal blood vessel walls measured with polarization sensitive optical coherence tomography

A new method based on polarization-sensitive optical coherence tomography (PS-OCT) is introduced to determine the polarization properties of human retinal vessel walls, in vivo. Measurements were obtained near the optic nerve head of three healthy human subjects. The double pass phase retardation per unit depth (DPPR/UD), which is proportional to the birefringence, is higher in artery walls, presumably because of the presence of muscle tissue. Measurements in surrounding retinal nerve fiber layer tissue yielded lower DPPR/UD values, suggesting that the retinal vessel wall tissue near the optic nerve is not covered by retinal nerve fiber layer tissue (0.43°/µm vs. 0.77°/µm, respectively). Measurements were obtained from multiple artery-vein pairs, to quantify the different polarization properties. Measurements were taken along a section of the vessel wall, with changes in DPPR/UD up to 15%, while the vessel wall thickness remained relatively constant. A stationary scan pattern was applied to determine the influence of involuntary eye motion on the measurement, which was significant. Measurements were also analyzed by two examiners, with high inter-observer agreement. The measurement repeatability was determined with measurements that were acquired during multiple visits. An improvement in accuracy can be achieved with an ultra-broad-bandwidth PS-OCT system since it will provide more data points in-depth, which reduces the influence of discretization and helps to facilitate better fitting of the birefringence data.

An O-shape Neural Network With Attention Modules to Detect Junctions in Biomedical Images Without Segmentation

Junction plays an important role in biomedical research such as retinal biometric identification, retinal image registration, eye-related disease diagnosis and neuron reconstruction. However, junction detection in original biomedical images is extremely challenging. For example, retinal images contain many tiny blood vessels with complicated structures and low contrast, which makes it challenging to detect junctions. In this paper, we propose an O-shape Network architecture with Attention modules (Attention O-Net), which includes Junction Detection Branch (JDB) and Local Enhancement Branch (LEB) to detect junctions in biomedical images without segmentation. In JDB, the heatmap indicating the probabilities of junctions is estimated and followed by choosing the positions with the local highest value as the junctions, whereas it is challenging to detect junctions when the images contain weak filament signals. Therefore, LEB is constructed to enhance the thin branch foreground and make the network pay more attention to the regions with low contrast, which is helpful to alleviate the imbalance of the foreground between thin and thick branches and to detect the junctions of the thin branch. Furthermore, attention modules are utilized to introduce the feature maps from LEB to JDB, which can establish a complementary relationship and further integrate local features and contextual information between the two branches. The proposed method achieves the highest average F1-scores of 0.82, 0.73 and 0.94 in two retinal datasets and one neuron dataset, respectively. The experimental results confirm that Attention O-Net outperforms other state-of-the-art detection methods, and is helpful for retinal biometric identification.

Glutathione-related antioxidant defense system in patients with hypertensive retinopathy

Objective: To analyze the glutathione antioxidant defense system changes in the tear and serum of patients with hypertensive retinopathy (HR) and to establish whether there is an interdependence between their levels and HR degree.

Methods: 90 patients were split into three groups according to the Keith-Wagner-Barker grading of HR: GI–36 patients; GII–35 patients; GIII–19 patients. The concentration of reduced glutathione (GSH) and activities of glutathione peroxidase (GPx) and glutathione reductase (GR) in tear and serum were measured. Results were analyzed by ANOVA, followed by Bonferroni post hoc test. The Spearman correlation coefficient was calculated (p≤0.05 statistically significant).

Results: In serum, the GSH level and GPx activity were not statistically changed between groups with HR degree advancement, unlike the GR activity that was statistically diminished (p=0.018). The values of the studied markers in the tear showed a decrease with the progression of the HR degree. Only serum GSH level correlated with the tear one (r=-0.361, p=0.000), while the enzymes activity did not. A correlation of GPx and GR activity (r=0.417, p=0.000) was identified in tear, while in serum - of GPx activity and GSH level (r=409, p=0.000). Tear GPx and GR levels correlated significantly but with low power with HR degree (r=0.299, p=0.004/ r=0.299, p=0.004).

Conclusion: Statistically significant elevation in tear GPx and GR activity and a tendency of GSH level increase was revealed, being attested, and a direct correlation between GPx and GR activity, as well as of their activity with the HR degree. In serum, the GSH level and the GPx activity did not change accurately, while the GR activity diminished significantly, the identified decrease being correlated with the HR degree.

Abbreviations: HR = hypertensive retinopathy, HTN = hypertension, GSH = reduced glutathione, GPx = glutathione peroxidase, GR = glutathione reductase, GGR = gamma-glutamyl transferase, ROSs = reactive species of oxygen, OS = oxidative stress

Serous business: Delineating the broad spectrum of diseases with subretinal fluid in the macula

A wide range of ocular diseases can present with serous subretinal fluid in the macula and therefore clinically mimic central serous chorioretinopathy (CSC). In this manuscript, we categorise the diseases and conditions that are part of the differential diagnosis into 12 main pathogenic subgroups: neovascular diseases, vitelliform lesions, inflammatory diseases, ocular tumours, haematological malignancies, paraneoplastic syndromes, genetic diseases, ocular developmental anomalies, medication-related conditions and toxicity-related diseases, rhegmatogenous retinal detachment and tractional retinal detachment, retinal vascular diseases, and miscellaneous diseases. In addition, we describe 2 new clinical pictures associated with macular subretinal fluid accumulation, namely serous maculopathy with absence of retinal pigment epithelium (SMARPE) and serous maculopathy due to aspecific choroidopathy (SMACH). Differentiating between these various diseases and CSC can be challenging, and obtaining the correct diagnosis can have immediate therapeutic and prognostic consequences. Here, we describe the key differential diagnostic features of each disease within this clinical spectrum, including representative case examples. Moreover, we discuss the pathogenesis of each disease in order to facilitate the differentiation from typical CSC.

Could aortic arch calcification help in detection of hypertensive retinopathy?

OBJECTIVE

Hypertension-induced end-organ damage is one of the important determinants of morbidity and mortality in patients with hypertension. All types of hypertension-induced end-organ damages start with vascular damage. Vascular calcification is a marker of vascular damage and aortic arch calcification (AAC) is one of the easily identifiable types of vascular calcification. We hypothesized that AAC predicts retinopathy in hypertensive patients.

METHODS

Consecutive hypertensive patients without diabetes mellitus were included. Chest radiography in the posterior-anterior was used to assess the presence of AAC. All patients underwent ophthalmologic examination for retinopathy.

RESULTS

We included 495 hypertensive patients in this study. Of these, 306 (62%) had hypertensive retinopathy. Patients with hypertensive retinopathy had significantly higher prevalence of AAC as compared to the patients without hypertensive retinopathy (88% vs. 22%, P < 0.001). We found a strong and positive correlation between hypertensive retinopathy and AAC grades (r = 639, P < 0.001). Receiver operator characteristics curve analysis yielded a strong predictive ability of AAC for the presence of hypertensive retinopathy [area under curve = 0.814, 95% confidence interval (CI): 0.775-0.853, P < 0.0001]. In multivariate logistic regression analysis, presence of AAC [odds ratio (OR) 13.128; CI: 7.894-21.832] and serum glucose levels (OR 1.020; CI: 1.003-1.037) were strongly and independently associated with hypertensive retinopathy.

CONCLUSION

Presence of AAC on chest radiograph is strongly and independently associated with retinopathy in nondiabetic hypertensive patients. This simple, inexpensive and widely available tool may help in early detection of retinopathy in patients with hypertension.

Retinal image registration as a tool for supporting clinical applications

BACKGROUND AND OBJECTIVE

The study of small vessels allows for the analysis and diagnosis of diseases with strong vasculopathy. This type of vessels can be observed non-invasively in the retina via fundoscopy. The analysis of these vessels can be facilitated by applications built upon Retinal Image Registration (RIR), such as mosaicing, Super Resolution (SR) or eye shape estimation. RIR is challenging due to possible changes in the retina across time, the utilization of diverse acquisition devices with varying properties, or the curved shape of the retina.

METHODS

We employ the Retinal Image Registration through Eye Modelling and Pose Estimation (REMPE) framework, which simultaneously estimates the cameras' relative poses, as well as eye shape and orientation to develop RIR applications and to study their effectiveness.

RESULTS

We assess quantitatively the suitability of the REMPE framework towards achieving SR and eye shape estimation. Additionally, we provide indicative results demonstrating qualitatively its usefulness in the context of longitudinal studies, mosaicing, and multiple image registration. Besides the improvement over registration accuracy, demonstrated via registration applications, the most important novelty presented in this work is the eye shape estimation and the generation of 3D point meshes. This has the potential for allowing clinicians to perform measurements on 3D representations of the eye, instead of doing so in 2D images that contain distortions induced because of the projection on the image space.

CONCLUSIONS

RIR is very effective in supporting applications such as SR, eye shape estimation, longitudinal studies, mosaicing and multiple image registration. Its improved registration accuracy compared to the state of the art translates directly in improved performance when supporting the aforementioned applications.

Retinal Neurovascular Impairment in Patients with Essential Hypertension: An Optical Coherence Tomography Angiography Study

Purpose

To investigate retinal neurovascular structural changes in patients with essential hypertension.

Methods

This observational cross-sectional study consisted of 199 right eyes from 169 nondiabetic essential hypertensive patients, divided into groups as follows: group A, 113 patients with hypertensive retinopathy (HTNR); group B, 56 patients without HTNR; and a control group of 30 healthy subjects. Peripapillary retinal nerve fiber layer (RNFL), radial peripapillary segmented (RPC), ganglion cell–inner plexiform layer (GC-IPL), and superficial (SVP) and deep (DVP) vascular plexus density at the macula (6 × 6 mm²) were measured by optical coherence tomography angiography (OCTA).

Results

DVP density was significantly reduced in groups A and B compared to the control group (group A DVP, P = 0.001; group B DVP P = 0.002). GC-IPL, RNFL thickness, and RPC and SVP density in group A were significantly decreased compared to the control group or group B (all P < 0.05). In hypertensive patients, GC-IPL and RNFL thickness were negatively correlated with severity of HTNR (GC-IPL, r = –0.331, P < 0.001; RNFL, r = –0.583, P < 0.001) and level of home blood pressure monitoring (HBPM) (GC-IPL, r = –0.160, P = 0.050; RNFL, r = –0.282, P = 0.001) and were positively correlated with SVP (GC-IPL, r = 0.267, P = 0.002; RNFL, r = 0.361, P < 0.001) and RPC density (GC-IPL, r = 0.298, P < 0.001; RNFL, r = 0.663, P < 0.001). Among subjects with grade 2 or 3 retinopathy, the superior RNFL was significantly thinner in patients with high HBPM level than in those with normal HBPM level (grade 2, P = 0.016; grade 3, P = 0.006).

Conclusions

Reduction of retinal vessel density and RNFL thickness is observed in patients with HTNR and is inversely associated with level of HBPM.

Systemic Disease and Ocular Comorbidity Analysis of Geographically Isolated Federally Recognized American Indian Tribes of the Intermountain West

BACKGROUND

The American Indian Navajo and Goshute peoples are underserved patient populations residing in the Four Corners area of the United States and Ibupah, Utah, respectively.

METHODS

We conducted a cross-sectional study of epidemiological factors and lipid biomarkers that may be associated with type II diabetes, hypertension and retinal manifestations in tribal and non-tribal members in the study areas (n = 146 participants). We performed multivariate analyses to determine which, if any, risk factors were unique at the tribal level. Fundus photos and epidemiological data through standardized questionnaires were collected. Blood samples were collected to analyze lipid biomarkers. Univariate analyses were conducted and statistically significant factors at p < 0.10 were entered into a multivariate regression.

RESULTS

Of 51 participants for whom phenotyping was available, from the Four Corners region, 31 had type II diabetes (DM), 26 had hypertension and 6 had diabetic retinopathy (DR). Of the 64 participants from Ibupah with phenotyping available, 20 had diabetes, 19 had hypertension and 6 had DR. Navajo participants were less likely to have any type of retinopathy as compared to Goshute participants (odds ratio (OR) = 0.059; 95% confidence interval (CI) = 0.016-0.223; p < 0.001). Associations were found between diabetes and hypertension in both populations. Older age was associated with hypertension in the Four Corners, and the Navajo that reside there on the reservation, but not within the Goshute and Ibupah populations. Combining both the Ibupah, Utah and Four Corners study populations, being American Indian (p = 0.022), residing in the Four Corners (p = 0.027) and having hypertension (p < 0.001) increased the risk of DM. DM (p < 0.001) and age (p = 0.002) were significantly associated with hypertension in both populations examined. When retinopathy was evaluated for both populations combined, hypertension (p = 0.037) and living in Ibupah (p < 0.001) were associated with greater risk of retinopathy. When combining both American Indian populations from the Four Corners and Ibupah, those with hypertension were more likely to have DM (p < 0.001). No lipid biomarkers were found to be significantly associated with any disease state.

CONCLUSIONS

We found different comorbid factors with retinal disease outcome between the two tribes that reside within the Intermountain West. This is indicated by the association of tribe and with the type of retinopathy outcome when we combined the populations of American Indians. Overall, the Navajo peoples and the Four Corners had a higher prevalence of chronic disease that included diabetes and hypertension than the Goshutes and Ibupah. To the best of our knowledge, this is the first study to conduct an analysis for disease outcomes exclusively including the Navajo and Goshute tribe of the Intermountain West.

The association of primary aldosteronism with glaucoma-related fundus abnormalities

Purpose

To elucidate glaucoma-related fundus abnormalities in patients with primary aldosteronism (PA).

Methods

The study compared 272 eyes from 137 PA patients and 352 eyes from 177 control subjects selected randomly from 1173 participants of a public glaucoma screening. The presence of glaucomatous optic disc appearance (rim thinning and cup enlargement) and retinal nerve fiber layer defects (RNFLDs) was determined independently from fundus photographs. The results were compared between the PA and control groups.

Results

There were 9 patients (6.6%) with glaucomatous optic disc abnormalities in the PA group and 10 cases (5.6%) identified in the control group (p = 0.92). RNFLDs were detected more frequently in the PA group (55 eyes, 20.2%) than in the control group (26 eyes, 7.4%; p<0.001). The two types of RNFLDs were classified as either having their central ends at the disc margin (D) or away from the disc margin and around the retinal vessels (V). Type D and V RNFLDs were detected in 35 (12.9%) and 26 (9.6%) eyes in the PA group and in 25 (7.1%) and 4 (1.1%) eyes in the control group, respectively. Both types of RNFLDs were more frequent in the PA group than in the control group (Type D and V, p = 0.03, <0.001, respectively).

Conclusion

Although the prevalence of glaucomatous optic disc appearance did not differ between the two groups, RNFLDs were more frequent in PA patients than in the control group. Moreover, RNFLDs with their central ends located around retinal vessels were characteristic of PA patients.

The Schlager mouse as a model of altered retinal phenotype

Hypertension is a risk factor for a large number of vision-threatening eye disorders. In this study, we investigated for the first time the retinal neural structure of the hypertensive BPH/2J mouse (Schlager mouse) and compared it to its control counterpart, the normotensive BPN/3J strain. The BPH/2J mouse is a selectively inbred mouse strain that develops chronic hypertension due to elevated sympathetic nervous system activity. When compared to the BPN/3J strain, the hypertensive BPH/2J mice showed a complete loss of outer layers of the neural retina at 21 weeks of age, which was indicative of a severe vision-threatening disease potentially caused by hypertension. To elucidate whether the retinal neural phenotype in the BPH/2J strain was attributed to increased BP, we investigated the neural retina of both BPN/3J and BPH/2J mice at 4 weeks of age. Our preliminary results showed for the first time that the BPH/2J strain develops severe retinal neural damage at a young age. Our findings suggest that the retinal phenotype in the BPH/2J mouse is possibly due to elevated blood pressure and may be contributed by an early onset spontaneous mutation which is yet to be identified or a congenital defect occurring in this strain. Further characterization of the BPH/2J mouse strain is likely to i) elucidate gene defects underlying retinal disease; ii) understand mechanisms leading to neural retinal disease and iii) permit testing of molecules for translational research to interfere with the progression of retinal disease. The animal experiments were performed with the approval of the Royal Perth Hospital Animal Ethics Committee (R535/17-18) on June 1, 2017.

Genetic Epidemiologic Analysis of Hypertensive Retinopathy in an Underrepresented and Rare Federally Recognized Native American Population of the Intermountain West

Understanding disease risk is challenging in multifactorial conditions as it can differ by environment, ethnicity and race. The Confederated Tribes of the Goshute Reservation are one of the most isolated populations in the United States. Retinal changes are a reliable indicator for systemic disease. We conducted a cross-sectional study to identify correlations between genetic data and epidemiological risk factors for blinding retinal disease in this tribe. As part of the "Supporting Prediction and Prevention Blindness Project (SPBPP)" in the Native American Population of the Intermountain West, we found that hypertensive retinopathy was the most prevalent retinal disease. We found that forty-two percent of the Goshute population was affected. Blood samples, fundus photos and intraocular pressure were obtained for all participants. In addition, a standardized questionnaire was administered. DNA and total cholesterol, HDL, LDL, VLDL, triglycerides and HbA1c were also evaluated. Our study interrogated genetic variants from the PAGE study (ARMS2 rs10490924, CFH rs800292, rs1061170) and additional studies that looked at previously associated genetic variants with retinal disease associated with cardiovascular disease. We conducted univariate and multivariate logistic regression in Stata v15.0. We found an association between hypertriglyceridemia and HTR (adjp = .05) within the Goshute population. To the best of our knowledge, this is the first study to demonstrate the prevalence of hypertensive retinopathy in a Native American population. Moreover, our study is the first to demonstrate an independently predictive relationship between hypertriglyceridemia and hypertensive retinopathy in an American Indian population. This study furthers our knowledge about prevalent blinding eye disease within the most geographically isolated federally recognized native United States American tribe, for which nothing has been published with respect to any disease. Although, this study furthers our understanding about the prevalence of genetic epidemiological risk factors within this population, it has greater implications for the screening of blinding diseases in underserved populations in general. This study can inform public health on planning and delivering of quality, accessible and relevant care to this population.

Prevalence and clinical spectrum of hypertensive retinopathy among hypertension clinic patients at Queen Elizabeth Central Hospital in Malawi

Background

Prevalence and spectrum of hypertensive retinopathy in the population reflects the status of hypertension control and the associated risks for cardiovascular events. We investigated the prevalence and clinical spectrum of hypertensive retinopathy among patients attending hypertension clinic at a tertiary hospital in Malawi.

Methods

This was a cross-sectional study of systematically selected patients attending hypertension clinic at Queen Elizabeth Central Hospital. Patient interviews using a structured questionnaire and review of patients' medical records (health passports) were done to obtain the following information: demographics, duration since the diagnosis of hypertension, history of stroke and blood pressure measurements. The presence and severity of hypertensive retinopathy was determined by dilated fundoscopy through slit lamp biomicroscopy.

Results

We recruited 104 patients. Women outnumbered men by 3:1. Women tended to be younger compared to men (mean ages 54 and 61 years respectively). Of the surveyed patients, 80% had sub-optimal blood pressure control and 75% had evidence of hypertensive retinopathy. History of stroke was associated with hypertensive retinopathy.

Conclusions

Hypertensive retinopathy is very common in patients attending the hypertension clinic at Queen Elizabeth Central Hospital in Blantyre, Malawi. This may be a reflection of sub-optimal blood pressure control in this patient population. There is a need to identify the actual reasons, rectify them and intensify intervention in control of hypertension in this patient population.

Risk factors for hypertensive retinopathy in a Chinese population with hypertension: The Beijing Eye study

Hypertensive retinopathy (HRP) is a clinical feature and systemic manifestation of hypertension. There have been few reports on the risk factors for hypertensive retinopathy in China. The aim of the present study was to describe risk factors associated with HRP in a population-based sample of Chinese patients with hypertension in Beijing. The clinical data of 228 hypertensive patients was retrospectively studied, including 112 patients with retinopathy for the HRP group and 116 patients without retinopathy for the NO-HRP group. Basic clinical data and plasma clinical indicators of the two groups were compared. Logistic regression models were used to assess risk factors associated with HRP. Duration of hypertension, smoking habits, family history of hypertension, plasma level of endothelin-1 (ET-1) and systolic and diastolic blood pressure were significantly increased in the HRP group compared with the NO-HRP group (P<0.05). No significant differences were identified between the two groups for other factors. Logistic regression models indicated that hypertension duration (P<0.001, 95% CI: 0.962-0.988) and ET-1 level (P<0.001, 95% CI: 1.144-1.278) were significantly associated with HRP. The diagnostic threshold of ET-1 to diagnosis HRP was 43.5 ng/l. Of the factors studied, longer hypertension duration and elevated ET-1 level were identified to be risk factors for HRP in patients with hypertension from Beijing. Detecting the plasma level of ET-1 in patients with hypertension may be a useful diagnostic indicator for HRP.

Double trouble: exudative hypertensive retinopathy in a patient with retinitis pigmentosa

A young female suffering from chronic kidney disease presented with retinal features suggestive of retinitis pigmentosa (RP). Cystoid intraretinal changes were noted at the macula in both eyes on optical coherence tomography. Careful clinical examination and fluorescein angiography revealed disc oedema, macular hard exudates and flower petal leakage in both eyes. A clinical diagnosis of RP with leaking cystoid macular oedema (CMO) because of hypertensive retinopathy was made. Exudation and macular oedema subsided with hypertension control and posterior sub-Tenon steroid injection. Although CMO does not typically leak on fluorescein angiography in RP, this need not always be true. Clinical signs and fluorescein angiography help in the differentiation of macular oedema when more than one aetiology may be responsible.

Retinal vessel morphology in rheumatoid arthritis: Association with systemic inflammation, subclinical atherosclerosis, and cardiovascular risk

OBJECTIVE

Quantification of retinal vessel morphology has emerged as a marker of cardiovascular health. We examined retinal microvascular diameters in RA, particularly in regard to systemic inflammation, subclinical atherosclerosis, and cardiovascular risk.

METHODS

Retinal images from RA patients and controls were processed using computerized software, to obtain CRAE and CRVE and AVR. Subclinical atherosclerosis was assessed with cIMT, and 10-year risk of general cardiovascular disease was calculated.

RESULTS

Both CRAE (78.8 ± 8.9 vs 90.2 ± 9.9 μm, P < .001) and AVR (0.69 ± 0.09 vs 0.81 ± 0.09, P < .001) were decreased in RA patients (n = 87) compared to controls (n = 46), whereas CRVE did not differ. Among RA patients, CRAE and AVR were inversely associated with both cIMT and CRP, whereas CRVE positively correlated with CRP (P < .05 for all). CRAE additionally correlated with cardiovascular risk score (r = -.396, P = .001). In the multivariate analysis, cardiovascular risk was associated with CRAE; age with CRVE, while CRP independently predicted AVR.

CONCLUSIONS

Our study shows altered retinal microvascular morphology in RA patients. Inflammation appears as the biological link for the observed association between retinal microvascular abnormalities and subclinical atherosclerosis. Retinal arteriolar narrowing might play its own role in cardiovascular risk prediction in RA.

A Review on the Extraction of Quantitative Retinal Microvascular Image Feature

Digital image processing is one of the most widely used computer vision technologies in biomedical engineering. In the present modern ophthalmological practice, biomarkers analysis through digital fundus image processing analysis greatly contributes to vision science. This further facilitates developments in medical imaging, enabling this robust technology to attain extensive scopes in biomedical engineering platform. Various diagnostic techniques are used to analyze retinal microvasculature image to enable geometric features measurements such as vessel tortuosity, branching angles, branching coefficient, vessel diameter, and fractal dimension. These extracted markers or characterized fundus digital image features provide insights and relates quantitative retinal vascular topography abnormalities to various pathologies such as diabetic retinopathy, macular degeneration, hypertensive retinopathy, transient ischemic attack, neovascular glaucoma, and cardiovascular diseases. Apart from that, this noninvasive research tool is automated, allowing it to be used in large-scale screening programs, and all are described in this present review paper. This paper will also review recent research on the image processing-based extraction techniques of the quantitative retinal microvascular feature. It mainly focuses on features associated with the early symptom of transient ischemic attack or sharp stroke.

Retinal image registration based on keypoint correspondences, spherical eye modeling and camera pose estimation

In this work, an image registration method for two retinal images is proposed. The proposed method utilizes keypoint correspondences and assumes a spherical model of the eye. Image registration is treated as a pose estimation problem, which requires estimation of the rigid transformation that relates the two images. Using this estimate, one image can be warped so that it is registered to the coordinate frame of the other. Experimental evaluation shows improved accuracy over state-of-the-art approaches as well as robustness to noise and spurious keypoint correspondences. Experiments also indicate the method's applicability to diagnostic image enhancement and comparative analysis of images from different examinations.

Hypertension and its severity in children with steroid sensitive nephrotic syndrome during remission

BACKGROUND AND OBJECTIVE

Hypertension is not a typical feature of steroid sensitive nephrotic syndrome (SSNS) and the presence of persistent hypertension is suggestive of significant renal lesion. There is paucity of data regarding occurrence and severity of hypertension in SSNS in pediatric population during remission and was the main objective of this study. In addition, correlation with factors like family history, BMI, and lipid profile was studied.

METHODS

Cross-sectional study conducted at tertiary care center in India including 81 children of infrequent relapsing SSNS between 1 and 10 years in remission and was off steroids. Grading and severity of hypertension were assessed. Statistical analysis was done using SPSS version 21.0.

RESULTS

Median age of presentation was 5 years, with male:female ratio of 1.3:1. Out of 81 infrequent relapsing SSNS children, 23.45% (19) had hypertension. Among those children with hypertension (n = 19), 73.68% (14) had positive family history compared to 32.25% (20) in those without hypertension. Positive correlation was found between BP and serum cholesterol and LDL. Of the hypertensive patients, 1 (5.26%) had fundus changes, 2 (10.52%) had features of left ventricular hypertrophy, and 13 (68.42%) had non-nephrotic range proteinuria.

CONCLUSION

There is high incidence of hypertension in NS children during remission. Though significant positive correlation was found with positive family history of hypertension and deranged lipid profile highlighting possibility of essential hypertension in them, there is need for close active monitoring and management of hypertension in them as untreated cases may have significant target organ damage.

Bilateral papillary oedema - case report

OBJECTIVE

We report one case of malignant high blood pressure with no systemic signs but with ocular complaints.

METHODS

The paper presents the case of a 31-year-old male who complained of sudden loss of visual acuity in both eyes. The ophthalmological examination revealed bilateral papillary oedema. General and cardiological examinations revealed he was suffering from malignant high blood pressure.

RESULTS

The pathogenic treatment resulted in resolution of signs and symptoms with favourable ophthalmological evolution and almost entirely functional recovery. Clinical, paraclinical and imagistic data suggested the diagnosis of pheochromocytoma.

CONCLUSION

This case highlighted ocular complications of high blood pressure. The paper summarizes the differential diagnosis and management of high blood pressure and reviews the most common causes of secondary hypertension in young patients.

Review of the association between retinal microvascular characteristics and eye disease

Computerized retinal imaging technologies enable the static and dynamic measurement of a range of retinal microvascular parameters. Large population-based studies have reported associations between these microvascular indices and various ophthalmic diseases including diabetes, age-related macular degeneration, retinal artery embolism, retinal vein occlusion, glaucoma and non-glaucomatous optic neuropathies. Increasingly, sophisticated imaging and analysis techniques have the potential to provide relevant clinical information regarding disease risk and progression; however, further studies are required to verify associations and strengthen the predictive power of these techniques. We summarize the current state of knowledge regarding retinal microvascular characteristics and eye disease.

An experimental evaluation of the accuracy of keypoints-based retinal image registration

This work regards an investigation of the accuracy of a state-of-the-art, keypoint-based retinal image registration approach, as to the type of keypoint features used to guide the registration process. The employed registration approach is a local method that incorporates the notion of a 3D retinal surface imaged from different viewpoints and has been shown, experimentally, to be more accurate than competing approaches. The correspondences obtained between SIFT, SURF, Harris-PIIFD and vessel bifurcations are studied, either individually or in combinations. The combination of SIFT features with vessel bifurcations was found to perform better than other combinations or any individual feature type, alone. The registration approach is also comparatively evaluated against representative methods of the state-of-the-art in retinal image registration, using a benchmark dataset that covers a broad range of cases regarding the overlap of the acquired images and the anatomical characteristics of the imaged retinas.

Retinal image registration through simultaneous camera pose and eye shape estimation

In this paper, a retinal image registration method is proposed. The approach utilizes keypoint correspondences and assumes that the human eye has a spherical or ellipsoidal shape. The image registration problem amounts to solving a camera 3D pose estimation problem and, simultaneously, an eye 3D shape estimation problem. The camera pose estimation problem is solved by estimating the relative pose between the views from which the images were acquired. The eye shape estimation problem parameterizes the shape and orientation of an ellipsoidal model for the eye. Experimental evaluation shows 17.91% reduction of registration error and 47.52% reduction of the error standard deviation over state of the art methods.

Retinal image registration under the assumption of a spherical eye

We propose a method for registering a pair of retinal images. The proposed approach employs point correspondences and assumes that the human eye has a spherical shape. The image registration problem is formulated as a 3D pose estimation problem, solved by estimating the rigid transformation that relates the views from which the two images were acquired. Given this estimate, each image can be warped upon the other so that pixels with the same coordinates image the same retinal point. Extensive experimental evaluation shows improved accuracy over state of the art methods, as well as robustness to noise and spurious keypoint matches. Experiments also indicate the method's applicability to the comparative analysis of images from different examinations that may exhibit changes and its applicability to diagnostic support.

Pharmacology of the retinal pigment epithelium, the interface between retina and body system

The retinal pigment epithelium (RPE) is a close, interactive partner to the photoreceptors as well as an interface with the endothelium of the choroid and thus with the body's circulatory system. To fulfill these roles, the RPE communicates with neighboring tissue by secretion of a large variety of factors and is able to react to secreted factors via a plethora of transmembrane receptors. Clinically relevant local pharmacological effects are caused by anti-VEGF-A treatment in choroidal neovascularization or by carboanhydrase inhibitors reducing fluid accumulation in the macula. Being exposed to the bloodstream, the RPE reacts to systemic disease, such as diabetes or hypertension, but also to systemic pharmacological intervention, for example to hypotensive drugs acting on the renin-angiotensin-system. Sustained pharmacological treatments, in particular, cause side effects at the RPE with consequences for both RPE function and photoreceptor survival. Among these are systemic inhibition of angiotensin-converting enzyme, insulin treatment in diabetes and anti-VEGF-A therapy. Given the special anatomical and functional relationships of the RPE, pharmacological intervention targeting either the eye or the body systemically should take potential alteration of RPE and subsequently photoreceptor function into account.

Hypertensive retinopathy in a transgenic angiotensin-based model

Severe hypertension destroys eyesight. The RAS (renin-angiotensin system) may contribute to this. This study relied on an established angiotensin, AngII (angiotensin II)-elevated dTGR (double-transgenic rat) model and same-background SD (Sprague-Dawley) rat controls. In dTGRs, plasma levels of AngII were increased. We determined the general retinal phenotype and observed degeneration of ganglion cells that we defined as vascular degeneration. We also inspected relevant gene expression and lastly observed alterations in the outer blood-retinal barrier. We found that both scotopic a-wave and b-wave as well as oscillatory potential amplitude were significantly decreased in dTGRs, compared with SD rat controls. However, the b/a-wave ratio remained unchanged. Fluorescence angiography of the peripheral retina indicated that exudates, or fluorescein leakage, from peripheral vessels were increased in dTGRs compared with controls. Immunohistological analysis of blood vessels in retina whole-mount preparations showed structural alterations in the retina of dTGRs. We then determined the general retinal phenotype. We observed the degeneration of ganglion cells, defined vascular degenerations and finally found differential expression of RAS-related genes and angiogenic genes. We found the expression of both human angiotensinogen and human renin in the hypertensive retina. Although the renin gene expression was not altered, the AngII levels in the retina were increased 4-fold in the dTGR retina compared with that in SD rats, a finding with mechanistic implications. We suggest that alterations in the outer blood-retinal barrier could foster an area of visual-related research based on our findings. Finally, we introduce the dTGR model of retinal disease.

The association of severity of retinal vascular changes and cardiac remodelling in systemic hypertension

OBJECTIVES

The aim of the study was to explore the association between hypertensive retinopathy, grades of retinopathy and cardiac remodelling.

METHODS

This was a cross-sectional observational study. A total of 500 consecutive hypertensive adults from the in-patient population were studied for the presence of hypertensive retinopathy by dilated fundoscopy. The presence of cardiac remodelling due to hypertension was studied both by electrocardiography (ECG) and echocardiography. Hypertensive target organ damage in other organs was also screened. In addition, the association of grades of hypertensive retinopathy with target organ damage was also analyzed.

RESULTS

Systolic blood pressure (BP) at presentation and duration of hypertension showed no relationship with markers of hypertensive heart disease. However, diastolic BP was significantly higher in patients with retinopathy. Hypertensive retinopathy was diagnosed in 324 subjects of whom 90 had grades 3 and 4 retinopathy. Patients with grades 3 and 4 retinopathy had significant associations with ECG evidence of left ventricular (LV) strain pattern and left atrial enlargement, and a weaker association with left ventricular hypertrophy (LVH) using QRS voltage criteria (Sokolov-Lyon). On echocardiography, grades 3 and 4 retinopathy were significantly associated with LVH, left atrial enlargement and reduced left ventricular ejection fraction (LVEF), as well as with higher creatinine values. A large number of these patients presented with heart failure. Cardiac remodelling was not seen in patients without retinopathy and was uncommon in patients with grades 1 and 2 retinopathy.

CONCLUSION

Grades 3 and 4 retinopathy demonstrated a significant association with LV strain pattern and left atrial enlargement on ECG, LVH and reduced LVEF on echocardiography as well as with heart failure. There was no relationship with systolic BP and duration of hypertension, while diastolic BP showed a significant positive correlation. Signs of hypertensive heart disease were practically absent in patients without hypertensive retinopathy and uncommon in those with grade 1-2 alterations.

Super resolution for fundoscopy based on 3D image registration

An approach to the generation of super-resolution (SR) images from fundoscopy images is proposed that is based on the 3D registration of the original fundoscopy images. The proposed approach utilizes a simple 3D registration method to enable the application of conventional SR techniques which, otherwise, employ 2D image registration. Qualitative and quantitative comparative evaluation shows that the obtained results improve image definition and alleviate noise.

Influence of refractive condition on retinal vasculature complexity in younger subjects

OBJECTIVE

The aim of this study was to compare the retinal vasculature complexity between emmetropia, and myopia in younger subjects.

METHODS

A total of 82 patients (24.12 ± 1.25 years) with two types of refractive conditions, myopia and emmetropia were enrolled in this study. Refraction data were converted to spherical equivalent refraction. These retinal images (right eyes) were obtained from NAVIS Lite Image Filing System and the vasculature complexity was measured by fractal dimension (D f ), quantified using a computer software following a standardized protocol.

RESULTS

There was a significant difference (P < 0.05) in the value of D f between emmetropic (1.5666 ± 0.0160) and myopic (1.5588 ± 0.0142) groups. A positive correlation (rho = 0.260, P < 0.05) between the D f and the spherical equivalent refraction was detected in this study. Using a linear model, it was estimated that 6.7% of the variation in D f could be explained by spherical equivalent refraction.

CONCLUSIONS

This study provides valuable findings about the effect of moderate to high myopia on the fractal dimension of the retinal vasculature network. These results show that myopic refraction in younger subjects was associated with a decrease in D f , suggesting a loss of retinal vessel density with moderate to high myopia.

Effect of dietary nickel deprivation on vision, olfaction, and taste in rats

Early studies on dietary nickel deprivation found decreased reproduction rate in pigs and decreased insemination and conception rates in goats. Studies from our laboratory demonstrated that nickel deprivation impaired male reproductive function of rats. A physiological amount of nickel modulates the function of cyclic nucleotide-gated cation channels (CNG channels) in vitro. Thus, because CNG channels have important roles in spermatozoa function, it was speculated that the impairment of reproduction by nickel deprivation was through an effect on CNG channels. Because CNG channels are found in retinal photoreceptor, olfactory receptor, and taste receptor cells, we hypothesized that nickel deprivation would also alter light/dark preference, odor preference to female rat urine, and taste preference/aversion in rats. In the light/dark Y-maze, nickel deprivation significantly decreased time spent in the dark arm by rats. The number of sniffs to estrous female urine was significantly increased only in nickel-supplemented rats. The number of licks at the saccharin bottle was significantly decreased by dietary nickel deprivation. These findings suggest that nickel has a biological role in the special senses: vision, olfaction and taste.

Assessing the role of optometrists in the control of systemic hypertension in Saudi Arabia

The low level of awareness, treatment, and control of systemic hypertension is a global problem, but it is much more serious in Saudi Arabia. This study examines the contribution made by Saudi optometrists in detection and management of patients with systemic hypertension. We surveyed a sample of 250 optometrists practicing in Saudi Arabia to evaluate the level of knowledge and awareness of their role in combating systemic hypertension. A 48.4% response rate was obtained from practicing optometrists. Of those responding, optometrists were very positive towards the use of blood pressure (BP) monitors in optometric practice on a routine basis. Forty-six percent of the optometrists had access to a BP monitor, and about 93% of these respondents actually used the monitors during clinic consultations. Automated monitors were the most common (54%). Fifty-one percent and 49% of the optometrists reported that they did routinely question their patients about high BP and about their current BP medications, respectively. The less frequently asked question concerned the cholesterol level of the patient (21%). The tests most widely used by the optometrists while examining hypertensive patients was direct ophthalmoscopy with red free filter (56%) and the least was binocular indirect ophthalmoscopy (21%). Optometrists were more likely to refer patients suspected of systemic hypertension on the basis of elevated BP (74%) and presence of retinal hemorrhages (72%), but were less likely to refer patients with changes in arteriolar reflex (41%). The opinions were very positive towards the routine monitoring of BP within the Saudi optometry profession, as optometrists indicated that they had time within an eye examination to measure BP, it was financially rewarding (56% of respondents), and patients appreciated it (64% of respondents). Despite half of the optometrists having access to BP monitors (predominantly automated devices), many of the optometrists were unsure if they were trained enough to monitor BP in such patients. There is urgent need to train optometrists on the use of BP devices, interpretation of readings, and use of additional diagnostic tests during such eye examinations.

Hypertension

Hypertension is the most common modifiable risk factor for cardiovascular disease. Antihypertensive treatment substantially reduces the risk of heart failure, stroke, and myocardial infarction. Current guidelines recommend screening all adults for high blood pressure (BP). Lifestyle modifications to help control high BP include weight loss, exercise, moderation of alcohol intake, and a diet low in sodium and saturated fats and high in fruits and vegetables. Out-of-office BP monitoring should be used to confirm suspected white coat effect, especially in patients with apparent resistant hypertension.