ABSTRACT
OBJECTIVE: Coronary microvascular dysfunction (CMD) is a cause of ischaemia with non-obstructive coronary arteries (INOCA). It is notoriously underdiagnosed due to the need for invasive microvascular function testing. We hypothesized that systemic microvascular dysfunction could be demonstrated non-invasively in the microcirculation of the bulbar conjunctiva in patients with CMD. METHODS: Patients undergoing coronary angiography for the investigation of chest pain or dyspnoea, with physiologically insignificant epicardial disease (fractional flow reserve ≥0.80) were recruited. All patients underwent invasive coronary microvascular function testing. We compared a cohort of patients with evidence of CMD (IMR ≥25 or CFR <2.0); to a group of controls (IMR <25 and CFR ≥2.0). Conjunctival imaging was performed using a previously validated combination of a smartphone and slit-lamp biomicroscope. This technique allows measurement of vessel diameter and other indices of microvascular function by tracking erythrocyte motion. RESULTS: A total of 111 patients were included (43 CMD and 68 controls). There were no differences in baseline demographics, co-morbidities or epicardial coronary disease severity. The mean number of vessel segments analysed per patient was 21.0 ± 12.8 (3.2 ± 3.5 arterioles and 14.8 ± 10.8 venules). In the CMD cohort, significant reductions were observed in axial/cross-sectional velocity, blood flow, wall shear rate and stress. CONCLUSION: The changes in microvascular function linked to CMD can be observed non-invasively in the bulbar conjunctiva. Conjunctival vascular imaging may have utility as a non-invasive tool to both diagnose CMD and augment conventional cardiovascular risk assessment.
Subject(s)
Coronary Artery Disease , Fractional Flow Reserve, Myocardial , Myocardial Ischemia , Humans , Cross-Sectional Studies , Prospective Studies , Hemodynamics , Coronary Angiography/methods , Coronary Vessels , Microcirculation , Conjunctiva , Coronary CirculationABSTRACT
BACKGROUND: Atherosclerotic heart disease often remains asymptomatic until presentation with a major adverse cardiovascular event. Primary preventive therapies improve outcomes, but conventional screening often misattributes risk. Vascular imaging can be utilised to detect atherosclerosis, but often involves ionising radiation. The conjunctiva is a readily accessible vascular network allowing non-invasive hemodynamic evaluation. AIM: To compare conjunctival microcirculatory function in patients with and without obstructive coronary artery disease. METHODS: We compared the conjunctival microcirculation of myocardial infarction patients (MI-cohort) to controls with no obstructive coronary artery disease (NO-CAD cohort). Conjunctival imaging was performed using a smartphone and slit-lamp biomicroscope combination. Microvascular indices of axial (Va) and cross-sectional (Vcs) velocity; blood flow rate (Q); and wall shear rate (WSR) were compared in all conjunctival vessels between 5 and 45 µm in diameter. RESULTS: A total of 127 patients were recruited (66 MI vs 61 NO-CAD) and 3602 conjunctival vessels analysed (2414 MI vs 1188 NO-CAD). Mean Va, Vcs and Q were significantly lower in the MI vs NO-CAD cohort (Va 0.50 ± 0.17 mm/s vs 0.55 ± 0.15 mm/s, p < 0.001; Vcs 0.35 ± 0.12 mm/s vs 0.38 ± 0.10 mm/s, p < 0.001; Q 154 ± 116 pl/s vs 198 ± 130 pl/s, p < 0.001). To correct for differences in mean vessel diameter, WSR was compared in 10-36 µm vessels (3268/3602 vessels) and was lower in the MI-cohort (134 ± 64 s-1 vs 140 ± 63 s-1, p = 0.002). CONCLUSIONS: Conjunctival microcirculatory alterations can be observed in patients with obstructive coronary artery disease. The conjunctival microvasculature merits further evaluation in cardiovascular risk screening.
Subject(s)
Coronary Artery Disease , Humans , Coronary Artery Disease/diagnostic imaging , Blood Flow Velocity , Microcirculation/physiology , Cross-Sectional Studies , Conjunctiva/blood supply , Coronary Vessels/diagnostic imaging , Coronary AngiographyABSTRACT
Microvascular haemodynamic alterations are associated with coronary artery disease (CAD). The conjunctival microcirculation can easily be assessed non-invasively. However, the microcirculation of the conjunctiva has not been previously explored in clinical algorithms aimed at identifying patients with CAD. This case-control study involved 66 patients with post-myocardial infarction and 66 gender-matched healthy controls. Haemodynamic properties of the conjunctival microcirculation were assessed with a validated iPhone and slit lamp-based imaging tool. Haemodynamic properties were extracted with semi-automated software and compared between groups. Biomarkers implicated in the development of CAD were assessed in combination with conjunctival microcirculatory parameters. The conjunctival blood vessel parameters and biomarkers were used to derive an algorithm to aid in the screening of patients for CAD. Conjunctival blood velocity measured in combination with the blood biomarkers (N-terminal pro-brain natriuretic peptide and adiponectin) had an area under receiver operator characteristic curve (AUROC) of 0.967, sensitivity 93.0%, specificity 91.5% for CAD. This study demonstrated that the novel algorithm which included a combination of conjunctival blood vessel haemodynamic properties, and blood-based biomarkers could be used as a potential screening tool for CAD and should be validated for potential utility in asymptomatic individuals.
Subject(s)
Algorithms , Conjunctiva , Biomarkers , Blood Flow Velocity , Case-Control Studies , Conjunctiva/blood supply , Humans , MicrocirculationABSTRACT
OBJECTIVE: To evaluate the dynamics and longevity of the humoral immune response to SARS-CoV-2 infection and assess the performance of professional use of the UK-RTC AbC-19 Rapid Test lateral flow immunoassay (LFIA) for the target condition of SARS-CoV-2 spike protein IgG antibodies. DESIGN: Nationwide serological study. SETTING: Northern Ireland, UK, May 2020-February 2021. PARTICIPANTS: Plasma samples were collected from a diverse cohort of individuals from the general public (n=279), Northern Ireland healthcare workers (n=195), pre-pandemic blood donations and research studies (n=223) and through a convalescent plasma programme (n=183). Plasma donors (n=101) were followed with sequential samples over 11 months post-symptom onset. MAIN OUTCOME MEASURES: SARS-CoV-2 antibody levels in plasma samples using Roche Elecsys Anti-SARS-CoV-2 IgG/IgA/IgM, Abbott SARS-CoV-2 IgG and EuroImmun IgG SARS-CoV-2 ELISA immunoassays over time. UK-RTC AbC-19 LFIA sensitivity and specificity, estimated using a three-reference standard system to establish a characterised panel of 330 positive and 488 negative SARS-CoV-2 IgG samples. RESULTS: We detected persistence of SARS-CoV-2 IgG antibodies for up to 10 months post-infection, across a minimum of two laboratory immunoassays. On the known positive cohort, the UK-RTC AbC-19 LFIA showed a sensitivity of 97.58% (95.28% to 98.95%) and on known negatives, showed specificity of 99.59% (98.53 % to 99.95%). CONCLUSIONS: Through comprehensive analysis of a cohort of pre-pandemic and pandemic individuals, we show detectable levels of IgG antibodies, lasting over 46 weeks when assessed by EuroImmun ELISA, providing insight to antibody levels at later time points post-infection. We show good laboratory validation performance metrics for the AbC-19 rapid test for SARS-CoV-2 spike protein IgG antibody detection in a laboratory-based setting.
Subject(s)
COVID-19 , Immunoglobulin G , Antibodies, Viral , Antibody Formation , COVID-19/therapy , Cross-Sectional Studies , Humans , Immunization, Passive , Immunoassay , Northern Ireland/epidemiology , SARS-CoV-2 , Sensitivity and Specificity , Spike Glycoprotein, Coronavirus , COVID-19 SerotherapyABSTRACT
PURPOSE: Congenital heart disease (CHD) is the most common live birth defect and a proportion of these patients have chronic hypoxia. Chronic hypoxia leads to secondary erythrocytosis resulting in microvascular dysfunction and increased thrombosis risk. The conjunctival microcirculation is easily accessible for imaging and quantitative assessment. It has not previously been studied in adult CHD patients with cyanosis (CCHD). METHODS: We assessed the conjunctival microcirculation and compared CCHD patients and matched healthy controls to determine if there were differences in measured microcirculatory parameters. We acquired images using an iPhone 6s and slit-lamp biomicroscope. Parameters measured included diameter, axial velocity, wall shear rate and blood volume flow. The axial velocity was estimated by applying the 1D + T continuous wavelet transform (CWT). Results are for all vessels as they were not sub-classified into arterioles or venules. RESULTS: 11 CCHD patients and 14 healthy controls were recruited to the study. CCHD patients were markedly more hypoxic compared to the healthy controls (84% vs 98%, p = 0.001). A total of 736 vessels (292 vs 444) were suitable for analysis. Mean microvessel diameter (D) did not significantly differ between the CCHD patients and controls (20.4 ± 2.7 µm vs 20.2 ± 2.6 µm, p = 0.86). Axial velocity (Va) was lower in the CCHD patients (0.47 ± 0.06 mm/s vs 0.53 ± 0.05 mm/s, p = 0.03). Blood volume flow (Q) was lower for CCHD patients (121 ± 30pl/s vs 145 ± 50pl/s, p = 0.65) with the greatest differences observed in vessels >22 µm diameter (216 ± 121pl/s vs 258 ± 154pl/s, p = 0.001). Wall shear rate (WSR) was significantly lower for the CCHD group (153 ± 27 s-1 vs 174 ± 22 s-1, p = 0.04). CONCLUSIONS: This iPhone and slit-lamp combination assessment of conjunctival vessels found lower axial velocity, wall shear rate and in the largest vessel group, lower blood volume flow in chronically hypoxic patients with congenital heart disease. With further study this assessment method may have utility in the evaluation of patients with chronic hypoxia.
Subject(s)
Conjunctiva/blood supply , Cyanosis/diagnosis , Heart Defects, Congenital/diagnosis , Microcirculation , Slit Lamp Microscopy , Adult , Blood Flow Velocity , Case-Control Studies , Cyanosis/etiology , Cyanosis/physiopathology , Female , Heart Defects, Congenital/complications , Heart Defects, Congenital/physiopathology , Humans , Male , Middle Aged , Predictive Value of Tests , Regional Blood Flow , Slit Lamp , Slit Lamp Microscopy/instrumentation , Smartphone , Stress, Mechanical , Young AdultABSTRACT
Microcirculatory dysfunction occurs early in cardiovascular disease (CVD) development. Acute myocardial infarction (MI) is a late consequence of CVD. The conjunctival microcirculation is readily-accessible for quantitative assessment and has not previously been studied in MI patients. We compared the conjunctival microcirculation of acute MI patients and age/sex-matched healthy controls to determine if there were differences in microcirculatory parameters. We acquired images using an iPhone 6s and slit-lamp biomicroscope. Parameters measured included diameter, axial velocity, wall shear rate and blood volume flow. Results are for all vessels as they were not sub-classified into arterioles or venules. The conjunctival microcirculation was assessed in 56 controls and 59 inpatients with a presenting diagnosis of MI. Mean vessel diameter for the controls was 21.41 ± 7.57 µm compared to 22.32 ± 7.66 µm for the MI patients (p < 0.001). Axial velocity for the controls was 0.53 ± 0.15 mm/s compared to 0.49 ± 0.17 mm/s for the MI patients (p < 0.001). Wall shear rate was higher for controls than MI patients (162 ± 93 s-1 vs 145 ± 88 s-1, p < 0.001). Blood volume flow did not differ significantly for the controls and MI patients (153 ± 124 pl/s vs 154 ± 125 pl/s, p = 0.84). This pilot iPhone and slit-lamp assessment of the conjunctival microcirculation found lower axial velocity and wall shear rate in patients with acute MI. Further study is required to correlate these findings further and assess long-term outcomes in this patient group with a severe CVD phenotype.
Subject(s)
Conjunctiva/blood supply , Microcirculation , Non-ST Elevated Myocardial Infarction/physiopathology , ST Elevation Myocardial Infarction/physiopathology , Adult , Aged , Case-Control Studies , Female , Humans , Male , Middle Aged , Prospective StudiesABSTRACT
PURPOSE: The conjunctival microcirculation is a readily-accessible vascular bed for quantitative haemodynamic assessment and has been studied previously using a digital charge-coupled device (CCD). Smartphone video imaging of the conjunctiva, and haemodynamic parameter quantification, represents a novel approach. We report the feasibility of smartphone video acquisition and subsequent haemodynamic measure quantification via semi-automated means. METHODS: Using an Apple iPhone 6â¯s and a Topcon SL-D4 slit-lamp biomicroscope, we obtained videos of the conjunctival microcirculation in 4 fields of view per patient, for 17 low cardiovascular risk patients. After image registration and processing, we quantified the diameter, mean axial velocity, mean blood volume flow, and wall shear rate for each vessel studied. Vessels were grouped into quartiles based on their diameter i.e. group 1 (<11⯵m), 2 (11-16⯵m), 3 (16-22⯵m) and 4 (>22⯵m). RESULTS: From the 17 healthy controls (mean QRISK3 6.6%), we obtained quantifiable haemodynamics from 626 vessel segments. The mean diameter of microvessels, across all sites, was 21.1µm (range 5.8-58⯵m). Mean axial velocity was 0.50mm/s (range 0.11-1mm/s) and there was a modestly positive correlation (r 0.322) seen with increasing diameter, best appreciated when comparing group 4 to the remaining groups (pâ¯<â¯.0001). Blood volume flow (mean 145.61pl/s, range 7.05-1178.81pl/s) was strongly correlated with increasing diameter (r 0.943, pâ¯<â¯.0001) and wall shear rate (mean 157.31â¯s-1, range 37.37-841.66â¯s-1) negatively correlated with increasing diameter (râ¯-â¯0.703, pâ¯<â¯.0001). CONCLUSIONS: We, for the first time, report the successful assessment and quantification of the conjunctival microcirculatory haemodynamics using a smartphone-based system.
Subject(s)
Cardiovascular Diseases/diagnosis , Conjunctiva/blood supply , Diagnostic Techniques, Ophthalmological/instrumentation , Hemodynamics , Microcirculation , Slit Lamp , Smartphone , Adult , Blood Flow Velocity , Cardiovascular Diseases/physiopathology , Case-Control Studies , Feasibility Studies , Female , Hemorheology , Humans , Image Interpretation, Computer-Assisted , Male , Middle Aged , Mobile Applications , Models, Cardiovascular , Predictive Value of Tests , Regional Blood FlowABSTRACT
PURPOSE: To study the time course (onset, time and duration of maximal cycloplegia, and the full duration) of cycloplegic action of 1% Cyclopentolate - 1% Tropicamide. METHODS: Seventy-seven students, aged 15-24 years were purposively sampled from the University of Cape Coast and Cape Coast Technical Institute. Subjective near addition (ADD) determination and pupil diameter measurement before and after a drop of the test agent (1% Cyclopentolate - 1% Tropicamide combination in the right eye) and the control (1% Cyclopentolate in the left eye) were performed. Measurements of subjective near ADD and pupil diameter were made after the initial reading at 5 minutes interval for the first hour and every 30 minutes for the next 7 hours for each participant. Time of onset, time of peak cycloplegia, duration of peak cycloplegia and duration of total cycloplegic effect was indirectly determined. RESULTS: 1% Cyclopentolate - 1% Tropicamide combination had rapid onset of cycloplegia (5-10 minutes), shorter time of maximal cycloplegia (55 versus 90 minutes), and recovery (7 versus ≥ 8hours) in the majority (79.2%) of subjects. CONCLUSION: Cyclopentolate -Tropicamide combination was comparable to Cyclopentolate in depth of cycloplegia produced, and clinically superior to 1% Cyclopentolate in rapidity of cycloplegic onset, time of maximal cycloplegia and recovery from cycloplegia.
Subject(s)
Accommodation, Ocular/drug effects , Cyclopentolate/administration & dosage , Mydriatics/administration & dosage , Pupil/drug effects , Tropicamide/administration & dosage , Dose-Response Relationship, Drug , Female , Humans , Male , Ophthalmic Solutions/administration & dosage , Time FactorsABSTRACT
BACKGROUND: Ocular allergy is a growing public health problem that greatly impacts the day-to-day life of sufferers and their families. Other aspects of their activities of daily living such as schooling, professional, and social life are affected hence an increased awareness and knowledge of ocular allergies, their detection and treatment is paramount. This study was to assess the level of knowledge and awareness of ocular allergy among undergraduate students of public universities in Ghana. METHODS: A descriptive cross sectional survey was conducted among 1000 students from three selected public universities in Ghana. Each respondent completed a questionnaire that had questions concerning awareness and knowledge of ocular allergy. RESULTS: Out of the 1000 students, 347 (34.7 %) were aware of ocular allergy. Of these 347 students, the level of knowledge of ocular allergy was generally low. Majority of the students had their source of information about ocular allergy from the media and the internet. There was statistical significant association among awareness of ocular allergy, sources of information and programme of study (p < 0.001). CONCLUSION: Level of awareness among university students is generally low. Students' programmes of study influenced their knowledge of ocular allergy. Public health measures are recommended to help educate students on the prevention and control of ocular allergy as well as the complications associated with this condition.
Subject(s)
Conjunctivitis, Allergic , Health Knowledge, Attitudes, Practice , Adolescent , Adult , Awareness , Conjunctivitis, Allergic/diagnosis , Conjunctivitis, Allergic/etiology , Conjunctivitis, Allergic/prevention & control , Cross-Sectional Studies , Eye Infections/complications , Female , Ghana , Humans , Male , Students , Young AdultABSTRACT
Aim: To determine the relationship between some visual functions: colour vision defects, abnormal stereopsis, visual acuity and the occurrence of road traffic accident (RTAs) among commercial vehicle drivers in the central region of Ghana, and to assess their knowledge of these anomalies. Method: A descriptive cross-sectional study employing a multi-stage random sampling approach was conducted in the major commercial towns within the central region of Ghana. Participants were taken through a comprehensive eye examination after the administration of a structured questionnaire. Results: 520 male commercial vehicle drivers were enrolled for this study with a mean age of 39.23years ±10.96 years and mean visual acuity of 0.02±0.08 logMAR. Protans were more likely to be involved in RTAs (χ2=6.194, p=0.034). However, there was no statistically significant association between abnormal stereopsis (OR=0.89 95% CI: 0.44-1.80, p=0.56), poor vision due to refractive error (χ2=3.090, p=0.388) and the occurrence of RTAs. While 86.9% were aware of abnormal stereopsis, only 45% were aware of colour vision defects. There was a statistically significant association between stereopsis anomaly and colour vision defect (r=0.371, p<0.005). Conclusion: The study found an association between protanopia and RTAs but none between stereopsis anomalies, refractive errors and the occurrence of RTAs. Drivers were less knowledgeable on colour vision defects as compared to stereopsis anomalies (AU)
Objetivo: Determinación de la relación entre algunas funciones visuales -alteraciones de la visión cromática, alteraciones de la estereopsis y agudeza visual- y la ocurrencia de accidentes de tráfico entre los conductores de vehículos comerciales en la región central de Ghana, así como evaluación de su conocimiento sobre estas anomalías. Método: Se realizó un estudio descriptivo cruzado, utilizando una muestra aleatoria de múltiples fases, en las principales ciudades comerciales de la región central de Ghana. A los participantes se les realizó un amplio examen visual tras la entrega de un cuestionario estructurado. Resultados: Se incluyó en este estudio a 520 varones conductores de vehículos comerciales, con una edad media de 39,23 años ±10,96 años, y una agudeza visual de 0,02±0,08 logMAR. Los sujetos con protanopia tuvieron más probabilidad de sufrir un accidente de tráfico (χ2=6,194, p= 0,034). Sin embargo, no se produjo una asociación estadísticamente significativa entre las alteraciones de la estereopsis (OR=0,89 95% IC: 0,44-1,80, p = 0,56), la baja visión debida a error refractivo (χ2=3,090, p=0,388), y la ocurrencia de accidentes de tráfico. Aunque el 86,9% eran conscientes de las alteraciones de la estereopsis, sólo el 45% estaba al corriente de las alteraciones de la visión cromática. Se produjo una asociación estadísticamente significativa entre las alteraciones de la estereopsis y las alteraciones de la visión cromática (r = 0,371, p < 0,005). Conclusión: El estudio halló una asociación entre la protanopia y los accidentes de tráfico, y ninguna asociación entre las alteraciones de la estereopsis, los errores refractivos y la ocurrencia de accidentes de tráfico. Los conductores eran menos conscientes de las alteraciones de la visión cromática que de las alteraciones de la estereopsis (AU)
Subject(s)
Humans , Vision Disorders/epidemiology , Vision Tests , Visual Acuity/physiology , Automobile Driving/standards , Depth Perception/physiology , Cross-Sectional Studies , Color Vision Defects/epidemiologyABSTRACT
Reported case of leukemic retinopathy mimicking common ischemic retinopathies in a young adult where ophthalmic visit was the first step to the diagnosis of chronic myeloid leukemia. It highlights the importance of routine eye exams and that clinicians should suspect leukemia in an otherwise healthy patient presenting with ischemic retinopathy.
ABSTRACT
AIM: To determine the relationship between some visual functions: colour vision defects, abnormal stereopsis, visual acuity and the occurrence of road traffic accident (RTAs) among commercial vehicle drivers in the central region of Ghana, and to assess their knowledge of these anomalies. METHOD: A descriptive cross-sectional study employing a multi-stage random sampling approach was conducted in the major commercial towns within the central region of Ghana. Participants were taken through a comprehensive eye examination after the administration of a structured questionnaire. RESULTS: 520 male commercial vehicle drivers were enrolled for this study with a mean age of 39.23 years ±10.96 years and mean visual acuity of 0.02±0.08 logMAR. Protans were more likely to be involved in RTAs (χ(2)=6.194, p=0.034). However, there was no statistically significant association between abnormal stereopsis (OR=0.89 95% CI: 0.44-1.80, p=0.56), poor vision due to refractive error (χ(2)=3.090, p=0.388) and the occurrence of RTAs. While 86.9% were aware of abnormal stereopsis, only 45% were aware of colour vision defects. There was a statistically significant association between stereopsis anomaly and colour vision defect (r=0.371, p<0.005). CONCLUSION: The study found an association between protanopia and RTAs but none between stereopsis anomalies, refractive errors and the occurrence of RTAs. Drivers were less knowledgeable on colour vision defects as compared to stereopsis anomalies.
Subject(s)
Accidents, Traffic/statistics & numerical data , Automobile Driving , Vision Disorders/epidemiology , Visual Acuity/physiology , Adult , Aged , Color Vision Defects/epidemiology , Cross-Sectional Studies , Depth Perception/physiology , Female , Ghana/epidemiology , Humans , Male , Middle Aged , Refractive Errors/epidemiology , Vision Disorders/physiopathology , Young AdultABSTRACT
AIM: The aim was to investigate the antiallergic effect of an aqueous leaf extract of Pistia stratiotes (ALPS) in a murine model of ovalbumin (OVA)-induced allergic conjunctivitis (AC). MATERIALS AND METHODS: Prior to topical challenge (instillation of 1.5 mg OVA in 10 µL phosphate buffered saline into their conjunctival sacs) to induce AC, groups of sensitized Imprinting Control Region mice (injected IP, on day 1 and 7, with 0.2 ml solution of 100 µg OVA and 0.01 mg aluminum hydroxide in phosphate buffered saline), were treated with 5 mg/kg cetirizine, 10, 50 or 100 mg/kg of ALPS, or 2 ml/kg normal saline per os. Conjunctival redness, lid edema, tearing and lid scratching (clinical symptoms of AC) were scored. Serum OVA specific immunoglobulins were determined using ELISA. Histopathological assessment of the conjunctival mucosal tissue was conducted. The extract was screened for secondary plant metabolites. RESULTS: Pretreatment with the extract significantly (P ≤ 0.05-0.01) and dose-dependently reduced the scores for clinical symptoms, which were marked in vehicle-pretreated mice. Pretreatment also lowered (P ≤ 0.01-0.001) serum OVA specific immunoglobulins. Mast cell infiltration and degranulation in conjunctival stroma (measured by an inflammatory score) in histopathological studies was also significantly low (P ≤ 0.05-0.01) on pretreatment. CONCLUSION: The ALPS exhibited interesting antiallergic activity and hence could be useful in managing AC.