Ocular and systemic vascular alterations in overweight and obese individuals undergoing weight-loss interventions

Obesity and its accompanying comorbidities play a crucial role in the pathogenesis of endothelial function which is a pre-cursor to atherosclerosis, subsequently leading to increases in cardiovascular risk. However, amelioration of these risk factors and improvements in endothelial function have never been fully explored in functional assessments of the retinal and peripheral microcirculations.The aim of this thesis was therefore to investigate the presence and impact of weight-loss interventions in overweight and obese individuals and also the relationships between functional measurements of different vascular beds. The principle findings of this work were:1. The relationship between retinal and peripheral vascular function in healthy individuals with low cardiovascular risk• Participants with higher peripheral vascular reactivity indices had a higher amplitude change from maximum to minimum and also showed enhanced reaction times to flicker provocation, which correlated to the degree of peripheral vascular function. 2. The effects of physical training on retinal and systemic microvascular function• Physical exercise positively influenced the retinal microcirculation through improvements in dilation and constriction reaction times to flicker provocation. 3. The long-lasting effects of fasting during the month of Ramadan on retinal and peripheral vascular function• Participants during fasting had a higher capacity to reach maximum dilation and also a greater percentage increase from baseline diameters. The retinal veins were also significantly less variable during baseline corrected measurements. 4. The effect of bariatric surgery on retinal vessels structure and systemic microvascular function• Increases were recorded for the diameter of retinal arteries but also for the veins. Peripheral vascular function was significantly improved and arterial stiffness was decreased. CVD risk was significantly decreased and also correlated with retinal vessel calibre measurements. 5. Is there an improvement in anterior ocular health after bariatric surgery?• Anterior surface health doesn’t necessarily cause ocular health problems in obese individuals nor can it be improved or ameliorated through bariatric surger

Impact of Bariatric Surgery-Induced Weight Loss on Anterior Eye Health in Patients with Obesity

The aim of the present research was to assess the effect of bariatric surgery-induced weight loss on the tear film and ocular surface of patients with obesity. A total of 29 participants with obesity (aged 47.2 10.1 years, 8 male) were measured at baseline and followed up one year after Roux-en-Y gastric bypass (RYGB) surgery. General anthropometric data, as well as serum lipid markers of cholesterol, were assessed in all individuals. Bilateral anterior eye measurements of tear meniscus height (TMH), non-invasive tear breakup time, bulbar and limbal redness and infrared meibography were captured using the Keratograph K5M (Oculus) and ocular surface damage was evaluated using fluorescein sodium and lissamine green staining. Bariatric surgery resulted in significant loss of weight (body mass index p 0.05). Although there were trends for a reduced TMH and a decrease in meibomian gland dropout after bariatric surgery, these differences were also insignificant (p > 0.05). In conclusion, weight reduction through bariatric surgery did not have an effect on the tear film or ocular surface in unselected patients with obesity

Retinal and peripheral vascular function in healthy individuals with low cardiovascular risk

Objective: To assess retinal and peripheral microvascular function in individuals with low cardiovascular risk. Methods and results: Retinal microvascular function was assessed using the dynamic vessel analyser (DVA) and peripheral vascular reactivity was measured using the digital thermal monitor (DTM) in 136 healthy participants. In addition, systemic blood pressure (BP) profiles, blood analyses for glucose and lipid metabolism markers (CHOL, HDL-c, LDL-c), as well as the Framingham Risk Score (FRS) were assessed in all participants. Based on peripheral vascular reactivity scores, participants were separated into 3 groups: high, intermediate and low risk. Participants with high risk showed a significant higher retinal arteriolar time to reach maximum dilation (tMD) than those with intermediate and low risk (p < 0.001). In addition, retinal arterial dilation amplitude (DA), and constriction slope (SlopeAC) were higher in subjects with low risk (p = 0.006, p = 0.019). Only in high risk participants, peripheral vascular reactivity parameters correlated with retinal arterial functional parameters DA, (r = 0.3800, p = 0.029) and tMD (r = −0.5904, p < 0.001). Conclusion: We conclude that signs of abnormal vascular function are similarly present and detectable in various microvascular beds, despite existing differences in their anatomical and physiological properties

The Effect of Bariatric Surgery on Microvascular Structure and Function, Peripheral Pressure Waveform and General Cardiovascular Risk: A Longitudinal Study

Purpose: This study aims to assess the effect of bariatric surgery on retinal microvascular calibre, peripheral microvascular function, peripheral pressure waveforms, and the general cardiovascular disease (CVD) risk in obese individuals after undergoing Roux-en-Y gastric bypass (RYGB) surgery. Methods: A total of 29 obese participants were included in the study. All of the measurements were conducted at two time points: before and one year following the bariatric surgery procedure. General anthropometric data, as well as blood markers for glucose, cholesterol, and triglycerides were assessed in all individuals. In all participants, the Framingham risk score (FRS), and retinal vessel calibre measurements, using a Zeiss fundus camera and VesselMap software (ImedosSystems, Jena, Germany), were performed. Systemic arterial stiffness was measured by pulse wave analysis (PWA), and peripheral microvascular reactivity by way of digital thermal monitoring (DTM) in all participants. Results: As expected, various general anthropometric parameters, including body mass index (BMI), waist circumference and neck circumference, were significantly decreased post-surgery comparing to baseline in all individuals (all p < 0.001). In addition, their general CVD risk, as measured using FRS, was significantly improved (p < 0.001). At the retinal vascular level, central retinal artery equivalent (CRAE) as well as, central retinal vein equivalent (CRVE) had increased after surgery comparing to the baseline values (p = 0.003 and p = 0.007, respectively). In addition, both systemic arterial stiffness and peripheral microvascular reactivity had improved in all participants (p < 0.001 and p = 0.008 respectively). Conclusions: Our findings suggest that bariatric surgery has a positive effect on the overall vascular health, as well as on the general CVD risk of the obese patients undergoing this procedure