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Retinal Vessels (retinal + vessel)
Selected AbstractsNon-viral gene therapy for diabetic retinopathyDRUG DEVELOPMENT RESEARCH, Issue 11 2006*Article first published online: 9 FEB 200, Toshiyuki Oshitari Abstract Diabetic retinopathy results from vascular abnormalities, such as an increase in the permeability of retinal vessels, and retinal neurodegeneration, which are irreversible changes that occur early in the course of diabetic retinopathy. To block the vascular and neuronal complications associated with the development and progression of diabetic retinopathy, a reasonable strategy would be to prevent the increased vascular permeability and to block the neuronal cell death. The purpose of this review is to present the non-viral strategies being used to block the neurovascular abnormalities and neuronal cell death that are observed in the early stages of diabetic retinopathy in order to prevent the onset or the progression of the diabetic retinopathy. Some of the non-viral gene therapeutic techniques being used are electroporation of selected genes, injections of antisense oligonucleotides, and injections of small interference RNAs. The results obtained by these methods are discussed as is the potential of these therapeutic strategies to prevent the onset or the progression of the neurovascular abnormalities in diabetic retinopathy. Drug Dev. Res. 67:835,841, 2006. © 2007 Wiley-Liss, Inc. [source] A comparison of manual and automated methods of measuring conjunctival vessel widths from photographic and digital imagesOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 2 2004Christopher G. Owen Abstract We investigated the application of a fully automated computer algorithm for identifying vessels of the conjunctiva from their scleral surround, and compared measures of vessel width with established methods. Vessel widths at 101 locations (ranging from 20 to 140 ,m), from 12 patients, were measured from film and digital images, using a variety of methods, and compared. Widths were measured manually, by semi-automated methods using grey level (densitometric) profiles taken from digital images, and by automated techniques set at different operating levels. Good intra-session repeatibility was obtained using the automated method with an operating sigma value of 3 pixels (16 ,m) (mean difference 0.5 ,m, 95% CI ,8.5 to 9.4 ,m) and manual calliper measurements from digitally created photographic slides (mean difference 0.4 ,m, ,9.3 to 10.1 ,m). For comparison with other measures of width, the latter was used as the gold standard. Widths measured from film were slightly larger than those measured directly from digital images, although this effect was small (5 ,m) for most vessels. Overall widths measured using the automated method, with a sigma value of 3 pixels, agreed best with the gold standard (inter-method repeatibility; mean difference 1.4 ,m, ,32.5 to 35.2 ,m) although the automated method overestimated small widths (<40 ,m) and underestimated larger vessel widths (>40 ,m). Automated detection of vessels of the conjunctiva from digital images avoids manual and operator involved measures which are time consuming, and which preclude large patient studies. The resulting data may help in monitoring the vascular response of the conjunctiva to surgical or pharmacological intervention, and in describing vascular changes in response to ocular or systemic disease. The application of this algorithm to the study of retinal vessels is yet to be realised. [source] 2421: Wall-to-lumen ratio of retinal vessels in patients with cerebrovascular damageACTA OPHTHALMOLOGICA, Issue 2010G MICHELSON Purpose There is evidence that generalized retinal arteriolar narrowing, which can be measured by the arteriole-to-venule ratio (AVR) of retinal vessels, predicts cerebrovascular events. The wall-to-lumen ratio (WLR) and wall cross-sectional area (WCSA) of retinal arterioles reflect structural arteriolar parameters. The primary objective was to test the association between WLR and AVR in patients with cerebrovascular damage. Methods In this cross-sectional study, 23 patients (57.5 +/- 9.4 years) with acute transitory ischemic attack or lacunar cerebral infarct were compared with two age-matched control groups: 83 subjects with essential hypertension (53.7 +/- 5.5 years) and 16 normotensive subjects (52.2 +/- 8.3 years). Retinal arteriolar parameters (WLR, WTH, and WCSA) were assessed in vivo with scanning laser Doppler flowmetry (SLDF). AVR and a qualitative evaluation of retinal vessels were obtained from digital retinal color photographs. The intima-media thickness (IMT) of the carotid artery was measured. Results WLR (0.44 +/- 0.1 vs. 0.34 +/- 0.1 vs. 0.30 +/- 0.1, P < 0.001) and carotid IMT (P < 0.05) were significantly greater in the cerebrovascular event group compared with normotensive subjects. WLR and WCSA were significantly higher in the cerebrovascular event group compared with subjects with mild arterial hypertension. AVR was similar in all three study groups. Conclusion The increase in WLR and WCSA of retinal arterioles, as well as in IMT in patients with cerebrovascular damage suggests vascular hypertrophy in the microvascular and macrovascular bed. The lack of association between AVR of retinal vessels and WLR of retinal arterioles [source] 3253: Ocular neurovascular coupling in glaucoma patientsACTA OPHTHALMOLOGICA, Issue 2010K GUGLETA Purpose Defining property of glaucoma, cupping of the optic disc in parallel to loss of retinal ganglion cells and their axon, implies tissue remodeling of the optic nerve head which in turns requires involvement of astrocytes. Their malfunction may lead not only to cupping, but also to disturbance in ocular neurovascular coupling. Methods We analyzed 122 glaucoma patients, ocular hypertensives and healthy controls who all received no IOP-lowering therapy at least four weeks prior to the study examination. One eye per subject entered the primary analysis: in the POAG group, an eye with the biggest damage, in the OHT group an eye with the highest average IOP was selected. Relative vessel diameter increase in response to flicker light was used as the measure of neurovascular coupling. Results This response was impaired in untreated POAG patients, affecting both superior and inferior temporal retinal vessels. In general, inferior vessel dilated more than superior ones. The dilation amplitude was inversely correlated to the level of morphological (retinal nerve fiber layer thickness) and functional (visual field mean defect) glaucomatous damage. Despite the relatively high level of inter- and intraocular correlation of vessel responses, in a separate analysis of contralateral eyes, they seem to display higher dilation amplitudes than the more damaged eyes which were included in the original analysis. Conclusion Neurovascular coupling is impaired in untreated glaucoma patients. Prospective studies are underway in an attempt to clarify the cause versus consequence relationship between the glaucomatous damage and disturbance of neurovascular coupling. [source] 3122: Regulation of retinal tissue oxygenationACTA OPHTHALMOLOGICA, Issue 2010CJ POURNARAS Purpose To evaluate the changes in the retinal oxygen partial pressure (PO2) following physiological stimuli. Methods Evaluation of either the preretinal and intraretina partial pressure of oxygen (PO2) distribution, using oxygen sensitive microelectrodes, in various animal models. Measurements were obtained during changes of the perfusion pressure, systemic hyperoxia, hypoxia, hypercapnia, carbogen breathing and following carbonic anydrase inhibitors use. Results The oxygen tension (PO2) in the inner half of the retina remains largely unaffected by moderate changes in perfusion pressure. The increase of the systemic PaO2 through breathing of 100% O2 (hyperoxia) induces endothelin (ET) mediated marked vasoconstriction of the inner retinal arterioles in both anesthetized animals and normal human subjects. The regulatory vasoconstriction maintains the PO2 in retinal tissue constant. A decrease in PaO2 (hypoxia) induces a vasodilation of the retinal arterioles through endothelium-derived NO release. As a result, trans-retinal PO2 profiles made during steps of systemic hypoxia have shown that the values measured in the inner retina up to half of its thickness, remain rather stable. By contrast, the PO2 values, measured close to the choroid and in the outer retina, decrease in a linear manner with the decrease of the PaO2. An increase in the PaCO2 (hypercapnia) of arteriolar blood, produces an increase in retinal blood flow and retinal tissue PO2. Intravenous injection of acetazolamide (carbonic anhydrase inhibitor) produces an increase in preretinal PO2 due to dilation of the retinal vessels Conclusion Thanks to the autoregulatory capability of the retinal circulation, the oxygen tension (PO2) in the inner half of the retina, remains largely unaffected during physiological stimuli. [source] 3123: Non-invasive measurement of retinal oxygenation: principles and expectationsACTA OPHTHALMOLOGICA, Issue 2010M HAMMER Purpose To determine oxygen saturation (SO2) of blood inside retinal vessels which is an essential measure for the estimation of oxygen supply to the tissue as well as its oxygen consumption. Methods Two-, four-, and multiple - wavelength approaches to the non-invasive measurement of SO2 will be discussed. The dual wavelength technique, imaging the fundus at 548 and 610 nm, showed to be most appropriate for clinical routine investigations. The SO2 of the hemoglobin in retinal arterioles and venules is calculated from the ratio of the optical densities of the vessels at both wavelengths. Results From a healthy control population, mean arterial and venous SO2 were measured to be 98±10.1% and 65±11.7% with reproducibility of 2.52% and 3.25% respectively. In a cohort of 41 patients (mean age: 65±12.3 years) with diabetic retinopathy (DR), we found an increase of the venous SO2 with the severity of DR: Mild non-proliferative DR 69±7%, moderate non-proliferative DR 70±5%, severe non-proliferative DR, 75±5%, and proliferative DR 75±8%. Measurements of SO2 in accordance with vessel diameters revealed a correlation of the venous SO2 with arterial as well as venous diameters in 159 diabetic patients (mean age: 55.8±13.9 years) with no or non , proliferative DR. Increased venous SO2 is an indicator of insufficient oxygen supply to the retinal tissue. The correlation of the vessel diameters with venous SO2 may point to compensatory mechanisms of retinal blood flow regulation. Conclusion Accurate retinal vessel oximetry is possible by non , invasive optical methods. Combined with measurements characterising the retinal blood flow, it is a powerful tool for the estimation of retinal oxygen supply and consumption. Commercial interest [source] 2321: Retinal vessel diameter affects oxygen saturation measurementsACTA OPHTHALMOLOGICA, Issue 2010SH HARDARSON Purpose To test whether retinal vessel oxygen saturation measurements are affected by vessel diameter and to compare saturation between the temporal and nasal retina. Methods The Oxymap retinal oximeter is based on a fundus camera. It measures light absorbance at two wavelengths of light and calculates oxygen saturation in retinal vessels as well as vessel diameter. Measurements were performed on 12 healthy individuals. The effect of vessel diameter on saturation measurements was tested by measuring before and after the first bifurcation in the retina (1st degree parent vessels and 2nd degree daughter vessels). Arteriolar saturation can be assumed to be equal before and after bifurcation. Results The ratio between oxygen saturation in 1st degree parent arteriole and 2nd degree daughter arteriole was 0.97±0.02 (mean±SD). The ratio was significantly lower than the theoretical value of 1.00 (p<0.001, n=12) The corresponding ratio for venules was 0.90±0.04 (p<0.001). Oxygen saturation was 94±6% in 1st degree superotemporal arterioles and 99±6% in superonasal arterioles (p=0.057). Oxygen saturation in inferotemporal arterioles was 89±6% and 95±4% in inferonasal arterioles (p=0.009). There was no significant difference in venous saturation between temporal and nasal quadrants. Conclusion Measured oxygen saturation is lower in 1st degree parent vessels than in their 2nd degree daughter branches. This indicates that retinal vessel diameter affects oxygen saturation measurements. The higher measured saturation in the nasal arterioles, compared to temporal arterioles, may also be due to the fact that the nasal vessels are narrower. A correction for the effect of vessel diameter should be incorporated into oxygen saturation measurements. Commercial interest [source] 2322: Reproducibility of retinal vessel hemoglobin oxygenation saturation in healthy subjectsACTA OPHTHALMOLOGICA, Issue 2010M LASTA Purpose Only recently systems for the measurement of hemoglobin oxygenation saturation in retinal vessels became commercially available. In the present study a fundus camera equipped with a dual wavelength transmission filter and a CCD camera was used (Imedos, Jena, Germany). Two monochromatic fundus images at 548 and 610 nm were recorded simultaneously and the oxygen saturation (SaO2) was calculated based on the optical density ratio. Methods A study on test/retest, short-term and day-to-day reproducibility of the technique was done in 14 healthy subjects. To assess test/retest variability fundus images were taken at each measurement cycle. To assess short-term reproducibility 2 such cycles of 3 fundus images were done within 15 minutes. Finally, this cycle of measurements was done on the next day to assess day-to-day reproducibility. Data were evaluated separately for retinal branch arteries and branch veins. The reproducibility was calculated using the standard deviation (SD) of the measurements. Results In retinal branch veins the SaO2 was 49±9% (range 32-69%, 38 vessels) and in retinal branch arteries 91±8% (range 77-112%, 40 vessels). The test/retest SD was 5.4±3.7% in retinal veins and 3.0±2.3% in retinal arteries. The short term SD was 4.7±3.7% in retinal veins and 2.9±2.1% in retinal arteries. The day-to-day SD was 6.2±4.1% in retinal veins and 4.0±2.8% in retinal arteries. Conclusion Our data indicate that the test/retest, short-term and day-to-day reproducibility of the technique is acceptable. Hence, the system may be adequate to follow oxygen saturation during disease processes. The data obtained in retinal branch arteries indicates, however, that the validity of measurements requires further studies. [source] 2325: Dynamic retinal vessel analysis , how different parameters create the whole pictureACTA OPHTHALMOLOGICA, Issue 2010I LANZL Purpose Dynamic vessel analysis is usually associated with the observation of the reaction of retinal vessels to a defined stimulus. The data which is generated this way may be further analysed with respect to the dynamic unstimulated and stimulated vessel behaviour. Assessment of different parameters may highlight different aspects of the underlying disease. Methods Vessel diameters of retinal vessel segments were assessed by Dynamic Vessel Analyzer (DVA) in healthy volunteers of different age groups and patients with diabetes, glaucoma and systemic hypertension. Mathematical analysis of unstimulated vessels was used to describe vessel wall characteristics. Methods of signal analysis including Fourier Transformation, spectral filtration, auto- and cross correlation were applied to evaluate characteristic oscillations and pulse wave propagation along the vessel. Results Characteristic different vessel behaviour and vessel wall conformation are obtained by dynamic quantitative evaluations from the unstimulated vessels in physiologic aging and disease. Conclusion Dynamic vessel analysis includes information which may lead to further understanding of the vascular status and underlying disease pathology. It is also feasible to assess pulse wave velocities in retinal arterioles und thus clinically characterize the elasticity of the upstream vasculature in health and disease. [source] Retinal oxygenation in diabetic retinopathyACTA OPHTHALMOLOGICA, Issue 2009SH HARDARSON Purpose Diabetic retinopathy (DR) is believed to cause retinal tissue hypoxia by damaging retinal capillaries. The purpose of this study was to examine the effect of diabetic retinopathy on oxygen saturation in retinal arterioles and venules. Methods The retinal oximeter (Oxymap ehf., Reykjavik, Iceland) is composed of a fundus camera, beam splitter and light filters. Specialized software calculates relative oxygen saturation from light absorption at two wavelengths of light (605nm and 586nm). One first or second degree temporal arteriole and venule were measured in one eye of 31 healthy individual and 28 patients with diabetic retinopathy. The diabetic patients had background DR (n=6), macular oedema (n=7), untreated preproliferative or proliferative DR (n=7) or stable proliferative DR after treatment (n=8). Statistical analyses were performed with an unpaired t-test, one-way ANOVA and Dunnett's post test. Results Retinal arteriolar saturation was 93±4% (n=31, mean±SD) in healthy subjects and 101±6% (n=28) in patients with DR (p<0.0001). Retinal venular saturation was 58±6% in healthy subjects and 67±8% in diabetic patients (p<0.0001). Arteriolar and venular saturation was higher in all subgroups of diabetic patients (see methods) than in healthy subjects. Conclusion Increased oxygen saturation in retinal vessels in diabetic retinopathy, also found by other researchers, is consistent with poor distribution of blood and oxygen to the retinal tissue rather than decreased total retinal blood flow. Poor distribution of oxygen may be caused by capillary dropouts and shunts as well as thickening of the capillary walls. Commercial interest [source] Retinal photocoagulation and oxygenationACTA OPHTHALMOLOGICA, Issue 2009CJ POURNARAS Purpose The clinical role of photocoagulation for the treatment of hypoxia related complications of retinal ischemic microangiopathies is well established. Methods Measurements of the partial pressure of oxygen (PO2) distribution within the the retina in various animal species using oxygen sensitive microelectrodes and evaluation of the retinal vessels reactivity by laser doppler velocimetry gave additional insights concerning photocoagulation mechanisms. Results The PO2 within the vitreo-retinal interface is heterogeneous. Preretinal and trans-retinal PO2 profiles indicate that the preretinal PO2 far away from vessels remain constant in all retinal areas. Intervascular intraretinal PO2 gradually decreases from both the vitreo-retinal interface and the choroid towards the mid-retina. Close to the pigment epithelium, it is significantly higher than at the vitreoretinal interface due to the much higher O2 supply provided by choroidal compaires to retinal circulation. Laser photocoagulation reduces the outer retina O2 consumption and allows O2 diffusion into the inner retina from the choroid raising the PO2 in the inner healthy retinal layers and in the preretinal intervascular normal areas. In this way laser treatment relieves retinal hypoxia in experimental branch vein occlusion (BRVO). In patients with diabetic retinopathy (DR), the retinal PO2 is higher in areas previously treated with laser. Following photocoagulation, the resulting reversal of hypoxia, the retinal vasculature constriction and the improvement of the regulatory response to hyperoxia all affect favorably both the retinal neovascularisation and macular edema. Conclusion Photocoagulation induces an increase of the inner retinal oxygenation reversing the retinal hypoxia and improving the regulatory response of the retinal vessels [source] Retinal vessel oximetry using sequential and 'snapshot' hyperspectral imagingACTA OPHTHALMOLOGICA, Issue 2009A MCNAUGHT Purpose Use of sequential, and 'snapshot' hyperspectral imagers to measure oxygen saturation in retinal vessels in normals, and examples of eye disease, eg glaucoma, and retinovascular diseases. Validation of estimated oximetry values using a model eye. Methods A sequential hyperspectral imager was constructed using a fundus camera with built-in liquid-crystal tuneable filter. Images of normals,and ocular disease are presented. A novel 'snapshot' hyperspectral imager is also described: this produces images in a single exposure. Validation of both devices using an artificial eye with capillary tubes containing human blood of known oxygen saturation, placed in front of an 'artificial retina' is described. The image analysis used to detect retinal vessels, and generate oximetric values is detailed. Results Both the sequential, and 'snapshot' retinal imagers produced accurate estimations of retinal vessel oxygen saturation, when compared with the model eye. Imaging of a small group of glaucoma eyes showed abnormally elevated venous oxygen saturation. In proliferative diabetic retinopathy, abnormally elevated venular saturation was found in areas of capillary loss on FFA. In vein occlusion, elevated venous saturation was found in eyes with ischaemic FFAs. Conclusion Both the sequential and 'snapshot' hyperspectral imagers deliver useful oximetric maps of the retina. The 'snapshot' device allows more rapid imaging. The elevated venular oxygen saturation seen in both glaucoma, and retinovascular disease, is perhaps evidence of reduced oxygen consumption in damaged inner retina in glaucoma, and/or vascular 'shunting' in retinovascular disease. [source] Appraisal and management of subclinical choroidal inflammation: the iceberg phenomenonACTA OPHTHALMOLOGICA, Issue 2009CP HERBORT Purpose To explore further the ocular fundal structures after funduscopy has been performed in intraocular inflammatory diseases, we have at our disposal among other investigational imaging methods, fluorescence angiography comprising fluorescein angiography (FA) and indocyanine green angiography (ICGA). In most cases dual FA & ICGA is necessary as the two methods image completely different structures. Fluorescein angiography is giving information on superficial structures including the optic disc, the retinal vessels and the retina as well as on the RPE, whereas ICGA is exploring the choroidal compartment. In contrast to FA that usually does not furnish additional information but is only giving more precise images of the superficial structures explored, ICGA is revealing elements, in case of choroidal inflammatory involvement, that no other method can show. The choroidal inflammatory lesions can be very extensive while often causing only faint or no signs during clinical examination and with other investigational imaging methods, a phenomenon which corresponds to the so-called "iceberg effect". This aptitude of ICGA to show lesions that are otherwise inaccessible make it an essential method to detect and follow choroidal lesions. Methods Cases where diagnosis cannot be made without ICGA or cases where inflammation can only be followeb by ICGA, the so-called iceberg constellation because other methods show only faint or no signs, will be presented. Conclusion Inflammatory lesions limited to the choroid cannot be detected without performing ICGA which is indispensible to diagnose purely choroidal diseae and to monitor the evolution of choroidal inflammation. [source] Effect of breathing a mixture of 92% O2 + 8% CO2 on flicker induced vasodilatationACTA OPHTHALMOLOGICA, Issue 2009M LASTA Purpose It has been shown that increased neural activity evoked by stimulation with diffuse luminance flicker increases retinal and optic nerve head blood flow. Beside others, an increased oxygen demand has been attributed to evoke the flicker response. This study seeks to investigate whether the flicker light induced increase in retinal vessel diameters is different in subjects breathing 92% O2 + 8% CO2 compared to breathing room air. Methods 24 healthy volunteers were included in the study. Diameters of retinal vessels were recorded continuously with a Retinal Vessel Analyzer. During this measurement flicker stimulation was applied at a frequency of 8 Hz. Subjects were breathing a combination of 92% O2 + 8% CO2 and room air in a randomized, two way cross over design. Flicker responses were assessed during the two breathing periods. Blood gas values were determined from capillary blood samples. Results Under room air conditions flicker stimulation significantly increased retinal venous diameters (p<0.05). Breathing of 92% O2 + 8% CO2 increased pO2 from 88±18 mmHg to 277±71 mmHg (p<0.05) and pCO2 from 37±3 mmHg to 46±6 mmHg (p<0.05). Breathing a combination of 92% O2 + 8% CO2 significantly increased flicker induced vasodilatation in retinal veins compared to room air (p<0.05). Conclusion Breathing of a combination of 92% O2 + 8% CO2 increases the response of retinal venous diameters to stimulation with flicker light. The reason for this effect has, however, yet to be clarified. [source] Is there a role for dynamic retinal vessel analysis in internal medicine?ACTA OPHTHALMOLOGICA, Issue 2008IM LANZL Purpose Human retinal vessels and their reaction to stimuli change during life and in disease due to physiological, genetic and pathological influences. Using the Dynamic Vessel Analyzer (DVA, Fa. IMEDOS, Jena) it is possible to assess changes in retinal vessel diameters in response to vasoactive stimuli in real time and non-invasively. Methods Retinal arterial vessel reaction in the natural time course and to the average of 3 consecutive monochromatic flicker stimulations (530-600 nm, 12,5 Hz, 20 s) with a 80 s observation pause between stimulations was investigated in healthy volunteers of different age groups, obese patients, diabetes type 1 patients, systemic hypertensive patients and patients with lysosomal storage disease. Statistical data analysis of vessel reactions independent from the DVA program was performed. Results There is a statistically significant difference in retinal vascular behaviour in different age groups in a healthy population. The same is true between a healthy population and each of the diseases investigated. Lysosomal storage disease however demonstrated an increase in dilation following flicker stimulation compared to normal persons. Conclusion Flicker stimulation of the retina light evokes a prompt vessel reaction in all healthy subjects. We could demonstrate an age dependence of the retinal arterial reaction in medically healthy persons and in hypertension, diabetes and obese patients. From the increased reaction in lysosomal storage disease further understanding of different factors leading to the vascular reaction to stimuli may be derived. Application of flicker stimulus to retinal vessels represents a method to assess the endothelial function of vessels which is important to understand in systemic disease. [source] Response of retinal arteriole diameter to increased blood pressure during acute hyperglycaemiaACTA OPHTHALMOLOGICA, Issue 3 2007Peter Jeppesen Abstract. Purpose:, To study retinal response in terms of arteriole diameter and retinal thickness secondary to an increase in arterial blood pressure during acute hyperglycaemia. Methods:, In a randomized, double-blinded, cross-over study, nine healthy persons were subjected to clamping of blood glucose to either 5 mmol/l or 15 mmol/l using somatostatin to control endogenous insulin secretion. The response of retinal arterioles in terms of diameter as determined with the retinal vessel analyser (RVA) and retinal thickness as assessed by optical coherence tomography (OCT) were measured after an increase in arterial blood pressure induced by isometric exercise. Arterial feeding pressure in the eye was assessed from the ophthalmic artery pressure and pulse amplitude measured by ophthalmodynamometry. Results:, Isometric exercise induced a significant increase in mean arterial blood pressure and a significant contraction of the retinal arterioles. An acute increase in blood glucose from 5 mmol/l to 15 mmol/l did not affect either the diameter of retinal vessels or retinal thickness. Conclusions:, Acute hyperglycaemia per se does not change isometric exercise-induced retinal arteriolar contraction. Metabolic factors other than blood glucose are suspected to be involved in the impairment of retinal autoregulation as seen in hyperglycaemia induced by oral glucose intake. [source] New insights into the development of retinopathy of prematurity , importance of early weight gainACTA PAEDIATRICA, Issue 4 2010A Hellström Abstract Evidence is accumulating that one of the strongest predictors of retinopathy of prematurity (ROP), in addition to low gestational age, is poor weight gain during the first weeks of life. In infants born preterm, the retina is not fully vascularised. The more premature the child, the larger is the avascular area. In response to hypoxia, vascular endothelial growth factor (VEGF) is secreted. For appropriate VEGF-induced vessel growth, sufficient levels of insulin-like growth factor I (IGF-I) in serum are necessary. IGF-I is a peptide, related to nutrition supply, which is essential for both pre- and post-natal general growth as well as for growth of the retinal vasculature. In prematurely born infants, serum levels are closely related to gestational age and are lower in more prematurely born infants. At preterm birth the placental supply of nutrients is lost, growth factors are suddenly reduced and general as well as vascular growth slows down or ceases. In addition, the relative hyperoxia of the extra-uterine milieu, together with supplemental oxygen, causes a regression of already developed retinal vessels. Postnatal growth retardation is a major problem in very preterm infants. Both poor early weight gain and low serum levels of IGF-I during the first weeks/months of life have been found to be correlated with severity of ROP. Conclusion: This review will focus on the mechanisms leading to ROP by exploring factors responsible for poor early weight gain and abnormal vascularisation of the eye of the preterm infant. [source] Abnormal vessel morphology in boys born after intracytoplasmic sperm injectionACTA PAEDIATRICA, Issue 11 2008Margareta Hök Wikstrand Abstract Aim: Children born after intracytoplasmic sperm injection (ICSI) are at risk of preterm birth, low birth weight and perinatal morbidity which may predispose for diseases of the central nervous and vascular systems. Our aim was to investigate the ocular fundus morphology in children born after ICSI. Method: Children born after ICSI (n = 82) had ocular fundus photographs taken at the age of 5 years and results were compared with those of a control group (n = 203). The ocular fundus morphology with the central retinal vessels was evaluated by digital image analysis. Results: Children born after ICSI (n = 57) had abnormal retinal vascularization as evidenced by a lower number of vascular branching points compared with the control group (n = 181) (p = 0.0002). A gender difference was found whereby the ICSI boys (n = 35) had significantly fewer retinal branching points (median 24, range 19,29.5) compared with the control boys (median 27.5, range 20,37) (p < 0.0001). Conclusion: Our findings showed that ICSI boys have abnormal vessel morphology as demonstrated by a reduced number of central retinal branching points. The difference still remained after elimination of factors earlier shown to be associated with a low number of vascular branching points, i.e. low birth weight and preterm, suggesting other mechanisms responsible for the low number of vascular branching points. [source] | ||||||||||