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Purpose: Instillation of topical anesthetics with or without preservatives in normal persons has been shown to enhance the effect of mydriatic eye drops. The purpose of the present investigation was to study whether a similar effect can be observed in diabetic patients screened for retinopathy and whether the effect depends on the presence of retinopathy. Methods: Thirty-six patients attending a screening programme for diabetic retinopathy were randomized to receive local anesthetic eye drops on one eye, followed by instillation of both a sympathomimetic and a parasympatholytic eye drop in both eyes, which was repeated after 20 minutes. The pupil diameter in both eyes was measured with 5 minutes intervals until 35 minutes after the first application of mydriatics, and the responses in the two eyes were compared. Results: The pupil diameter increased significantly throughout the observarion period in both eyes (p

Purpose To establish a quality indicator that could be used in optimizing treatment for rhegmatogenous retinal detachment (RRD). Methods The Danish National Patient Registry was used to identify surgery conducted in Denmark for RRD in the period 01 January 2001–31 December 2009. Cases were identified by diagnosis and surgical codes. Results A total of 6522 cases were operated for a primary RRD in the study period, and 22% (1434 patients) were reoperated for a redetachment. A Cox regression analysis showed that the risk of redetachment was equal to or less than detachment on the fellow eye 1 year after primary surgery with techniques not using silicone oil. The same was true 1.5 years after surgery for techniques using silicone oil. Based on this, we established a quality indicator defining failure as the need for operation for redetachment within 1 year from initial surgery when using techniques without oil and after 1.5 years for techniques using oil. Also the lack of oil removal within 1 year from initial surgery should be noted as an operational failure. We applied the quality indicators on the cohort of 6522 RRDs and found that in Denmark the need for redetachment surgery has decreased over time and also that high-volume departments have better outcome compared to smaller ones. Conclusions The risk of reoperation for redetachment after initial surgery fulfils the criteria for a good quality indicator and can be used in RRD surgery. This indicator could aid in optimizing the management of RRD patients to minimize morbidity.

Purpose: Inhibition of cyclooxygenase (COX) and nitric oxide synthesis (NOS) has previously been shown to modify hypoxia-induced relaxation of retinal arterioles in vitro. The purpose of the present study was to investigate whether these findings can be reproduced in vivo. Methods: Twenty healthy persons aged 20-55 years were examined. Using the dynamic vessels analyzer (DVA), the resting diameter and diameter changes during isometric exercise and flicker stimulation were studied before and during breathing of a hypoxic gas mixture. The examinations were carried out before and during intravenous infusion of the NOS-inhibitor l-NMMA, and were repeated on a second study day after topical administration of the COX-inhibitor diclofenac. Results: The resting diameter of retinal arterioles increased significantly during hypoxia and decreased significantly during l-NMMA infusion (p

The cellular basis for the regulation of retinal blood flow is unknown, but recently a new type of perivascular cell (PVC) with pericyte characteristics was identified in the retinal arterial vascular wall located immediately external to the vascular smooth muscle cells. A possible involvement of this cell type in the regulation of retinal vascular tone might be elucidated by studying differences in the response after the addition of compounds stimulating respectively relaxation and contraction. The effects of PGE2 and PGF2α on vascular tone and calcium activity in PVCs in porcine retinal arterioles were studied in a confocal myograph after the addition of the ryanodine receptor blocker ryanodine, the L-type Ca2+ channel blocker nifedipine, the non-specific cation channel blocker LOE908, the sarcoplasmic reticulum Ca2+-ATPase (SERCA) blocker CPA, and the inositol triphosphate receptor (IP3R) and transient receptor potential (TRP) ion channel blocker 2-APB. The Ca2+ channel blockers nifedipine and LOE908 induced significant relaxation of retinal arterioles. After the addition of both PGE2 and PGF2α calcium activity in the PVCs was significantly reduced by both the SERCA inhibitor CPA and the IP3R antagonist 2-APB, but the changes in calcium activity were unrelated to the changes in tone induced by PGE2 and PGF2α. Changes in the tone of porcine retinal arterioles in vitro induced by PGE2 and PGF2α involve other factors than calcium activity in the perivascular cells.

Lentivirus-based gene delivery vectors carrying multiple gene cassettes are powerful tools in gene transfer studies and gene therapy, allowing coexpression of multiple therapeutic factors and, if desired, fluorescent reporters. Current strategies to express transgenes and microRNA (miRNA) clusters from a single vector have certain limitations that affect transgene expression levels and/or vector titers. In this study, we describe a novel vector design that facilitates combined expression of therapeutic RNA- and protein-based antiangiogenic factors as well as a fluorescent reporter from back-to-back RNApolII-driven expression cassettes. This configuration allows effective production of intron-embedded miRNAs that are released upon transduction of target cells. Exploiting such multigenic lentiviral vectors, we demonstrate robust miRNA-directed downregulation of vascular endothelial growth factor (VEGF) expression, leading to reduced angiogenesis, and parallel impairment of angiogenic pathways by codelivering the gene encoding pigment epithelium-derived factor (PEDF). Notably, subretinal injections of lentiviral vectors reveal efficient retinal pigment epithelium-specific gene expression driven by the VMD2 promoter, verifying that multigenic lentiviral vectors can be produced with high titers sufficient for in vivo applications. Altogether, our results suggest the potential applicability of combined miRNA- and protein-encoding lentiviral vectors in antiangiogenic gene therapy, including new combination therapies for amelioration of age-related macular degeneration.

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.

Purpose: Vasomotion refers to periodic oscillations in vascular tone that ensure the intermittent supply of blood to adjacent microvascular units. Previous evidence from vessels outside the eye suggests that cyclic guanosine-monophosphate (cGMP) is involved in the regulation of vasomotion, but it is unknown whether this compound has an effect on vasomotion in retinal vessels. Methods: Retinal arterioles from porcine eyes were studied in a wire myograph. After initiation of vasomotion, the vessels were stimulated with increasing concentrations of the cGMP agonist 8-Br-cGMP (n = 6), the phosphodiesterase inhibitor zaprinast (n = 6) and the cGMP synthesis inhibitor L-NAME (n = 6). High concentrations of L-NAME blocked vasomotion, and control experiments (n = 20) using 8-Br-cGMP, S-nitroso-N-acetylpenicillamine (SNAP), adenosine and pinacidil were carried out to elucidate whether this effect was related to changes in the general tone of the vessel. Additionally, the relationship between oscillations in vascular tone and intracellular calcium concentration was studied. Results: Induction of cGMP agonistic activity with either 8-Br-cGMP or zaprinast lowered the vasomotion frequency significantly, whereas L-NAME-induced inhibition of cGMP increased this frequency. Neither of the agents affected the amplitude of the oscillations. The control experiments indicated that the effect of cGMP on vasomotion frequency was independent of the accompanying increase in tone. The oscillations in tone during vasomotion were accompanied by similar oscillations in intracellular calcium concentration. Conclusion: Cyclic GMP lowers the frequency without affecting the amplitude of vasomotion in isolated porcine retinal arterioles.

To study the effect of normocapnic (NA) and hypercapnic acidosis (HA) on the tone, the intracellular calcium level ([Ca(2 +)](i)), and the membrane potential of smooth muscle cells in porcine retinal arterioles.Twenty-four porcine retinal arterioles were mounted in a wire myograph for isometric recording of the wall tension. The vessels were precontracted with 0.3 microM U46619 and were exposed to NA (pH = 7.0) and HA (pH = 7.0). Intracellular calcium was measured using the fluorophore Fura-2AM (n = 12). In six vessels, 0.1 mM NG-nitroarginine methyl ester (L-NAME) was added to block NO synthesis. The membrane potential of smooth muscles cells was measured in situ with sharp glass electrodes (n = 12).NA and HA induced both a decrease in wall tension from 1.04 +/- 0.06 N/m to 0.65 +/- 0.1 N/m (p0.01) (NA) and 0.56 +/- 0.1 N/m (p0.01) (HA) and a decrease in [Ca(2 +)](i) as evidenced from the change in the Fura-2 fluorescence emission ratio from 0.66 +/- 0.03 to 0.57 +/- 0.05 (p = 0.005) (NA) and 0.56 +/- 0.05 (p = 0.002) (HA). These results were unaffected by inhibition of NO-synthesis. NA and HA also both induced hyperpolarization of the smooth muscle membrane from -18 +/- 0.7 mV during precontraction to -26 +/- 1.9 mV (p = 0.002) (NA) and -24 +/- 2.6 mV (p = 0.02) (HA).Acidosis-induced relaxation of the tone in preconstricted isolated porcine retinal arterioles is associated with a decrease in intracellular calcium and a hyperpolarization of the smooth muscle cells. The acidosis-induced relaxation is independent of CO(2) and is not mediated through NO.

Introduction: Proliferative diabetic retinopathy is treated with panretinal photocoagulation, which improves the visual prognosis in this complication considerably. The visual acuity (VA) and grade of retinopathy before treatment are known indicators of the visual prognosis after treatment, but the prognostic value of other clinical background and treatment parameters is unknown. Methods: The study reports predictors for visual outcome identified among retrospective clinical background data and treatment parameters from 4422 panretinal photocoagulation sessions for proliferative diabetic retinopathy in 1013 eyes of 601 patients performed at the Department of Ophthalmology, Arhus University Hospital between 1985 and 2002. Results: High pretreatment VA and low age were strong positive predictors of post-treatment VA (p < 0.0001). However, diabetes type, diabetes duration and calendar year of treatment showed no influence on post-treatment VA (p = 0.7829, 0.1782, and 0.3747, respectively). The visual prognosis was inversely related to the number of treatment sessions (p = 0.0259) and the number of vitrectomies (OR = 2.66 [1.24; 5.69], p = 0.0117, for more than two operations). However, the visual prognosis was unrelated to any of the other parameters studied. Conclusions: Pretreatment VA, age and the number of panretinal photocoagulation treatment sessions and vitrectomies necessary to halt the disease are indicators of the visual prognosis after panretinal laser photocoagulation for proliferative diabetic retinopathy.

Aims The TOSCA project was set up to establish a tele-ophthalmology service to screen for diabetic retinopathy (DR) in Europe. The aim of this study was to determine the feasibility of establishing telemedicine-based digital screening for detecting DR and to evaluate the satisfaction of both patients and healthcare professionals with the screening procedures used within the TOSCA project. Methods The study was a non-randomized, multicentre study carried out in four different countries over a period of 3 months. Patients (n = 390) with diabetes aged > 12 years were included. Two digital retinal images per eye (macular and nasal) were taken and exported to a central server. Patients were asked to complete a questionnaire to assess satisfaction. Accredited graders carried out grading remotely and the results were reported back to the referring centre. Previously graded patient data chosen randomly to represent examples of both DR and no DR were also sent anonymously to the grading centre at a frequency of approximately every 10 patients. Results Most (99%) of the images were assessable enabling a retinopathy grade to be assigned to the patient. Patients found the retinal photography procedures acceptable; only 6% in one centre would not recommend the procedure. Healthcare professionals (photographers and graders) were also satisfied with the overall procedures. The average time taken to grade each patient was approximately 5 min. Conclusions This study demonstrated that it is feasible to electronically transmit and grade retinal images remotely using the TOSCA process. Built-in quality assurance procedures proved acceptable.

Purpose: To report the occurrence of registered blindness among diabetes patients in Arhus County, Denmark during 1993−2002. Methods: Data were obtained from a database of 7527 diabetes patients, which included all patients in the county who had been treated for or had experienced visual loss due to diabetic retinopathy since 1992. Of these, 1949 had type 1 diabetes and represented 90% of the type 1 diabetes patient population in the county, and 5459 had type 2 diabetes and represented 40% of the type 2 diabetes patient population in the county. Results: The point prevalence of legal blindness was 0.6% for type 1 and 1.5% for type 2 diabetes patients at January 1st, 2003. In type 1 diabetes patients, the major cause of blindness was proliferative diabetic retinopathy (PDR) (66.2% of all blind eyes); in type 2 diabetes patients the major causes were age-related macular degeneration (21.9%), PDR (18.0%) and diabetic maculopathy (DMac) (18.5%). During 1993−2002 there was a significant decrease in the number of blind eyes secondary to PDR (p = 0.008) in type 1 diabetes patients, and a significant increase in the number of blind eyes secondary to DMac (p = 0.005) in type 2 diabetes patients. Conclusion: The major challenge in reducing diabetes-related blindness is related to the detection and treatment of an increased incidence of diabetic maculopathy in type 2 diabetes patients.

PURPOSE: To study the age-dependent change in myogenic response of retinal arterioles.METHODS: Fifty-one healthy volunteers with at least ten persons in each of the five age decades (I-V) between 20 and 69 years were subjected to diameter measurement of retinal arterioles using the Retinal Vessel Analyzer (RVA) during rest and during an increase in the systemic blood pressure when lifting hand weights. The transmural pressure in the retinal arterioles during the procedures was estimated from the blood pressure and the intraocular pressure and was compared to the accompanying diameter response.RESULTS: The retinal arteriolar diameter showed a significant decrease as a function of increasing weight for the two younger age groups below the age of 40 years (P=0.007, group I, and P=0.049, group II), compatible with perfect autoregulation, whereas no such change was observed in persons above this age (P=0.41, 0.053, 0.29 for groups III-V, respectively).CONCLUSION: Studies on autoregulation in retinal disease should consider the normal age-related decrease in diameter response of retinal arterioles when the blood pressure is changed.

Knudsen ST, Bek T, Logstrup Poulsen P, Norgaard Hove M, Rehling M, Mogensen CE (Aarhus Kommunehospital, Aarhus, Denmark). Effects of losartan on diabetic maculopathy in type 2 diabetic patients: a randomized, double-masked study. J Intern Med 2003; 254: 147–158. Objective. Diabetic maculopathy (DMa) is a leading cause of visual loss in the western world. Preliminary studies have suggested that angiotensin converting enzyme inhibitors might be effective in preventing the progression of diabetic retinopathy, but no studies have quantitatively assessed the effect of this treatment on macular oedema in patients with DMa. We evaluated the effect of treatment with the angiotensin II receptor antagonist losartan on macular oedema and hard exudates in patients with an advanced stage of DMa. Design. Randomized, placebo-controlled, double-masked and parallel-group trial. Setting. Academic medical centre. Subjects. Twenty-four type 2 diabetic patients with DMa. Intervention. Subjects were randomly assigned to a 4-month treatment with either losartan (50 mg o.d.) or placebo. Main outcome measures. (i) Degree of macular oedema as estimated by optical coherence tomography scanning of the retina; (ii) fundus photography and flourescein angiography; (iii) 24-h ambulatory blood pressure (BP); (iv) urinary albumin excretion (UAE); and (v) transcapillary escape rate of albumin (TERalb). Results. Central retinal thickness increased from 244 ± 16 to 256 ± 31 μm in the losartan group, whilst there was no change in the placebo group (245 ± 36 μm vs. 242 ± 30 μm), P = 0.017. Day BP were lowered in the losartan group (from 144/83 ± 17/10 to 138/78 ± 20/11 mmHg) compared with the placebo group (140/81 ± 14/5 to 139/82 ± 13/9 mmHg), P = 0.27 for systolic and P = 0.009 for diastolic BP. Importantly, there were no changes in night BP in any of the groups. We found no changes in the number of hard exudates, semiquantitative retinopathy grade, visual acuity, UAE, or TERalb in any of the groups. Conclusions. Type 2 diabetic patients with maculopathy do not seem to benefit from short-term treatment with losartan (50 mg once daily) as far as retinal thickness is concerned, as this dose may increase retinal thickness in the central macular area. Long-term studies are required to assess the clinical implications of these findings.

Purpose: To characterize vasomotion in porcine retinal arterioles in vitro using isobaric (pressure myograph) and isometric (wire myograph) methods. Methods: Pressure myograph: 208 small porcine retinal arterioles (outer diameter 68 ± 4 μm) were studied under isobaric conditions in a double-barrelled pipette system. Diameter changes of the arterioles were registered by video recordings. Wire myograph: 60 large porcine retinal arterioles (inner diameter 147 ± 1.6 μm) were studied under isometric conditions in a small vessel myograph for force measurements. Results: The rates of success in initiating vasomotion were 7.2% using the pressure myograph and 43% using the wire myograph (p

Introduction: The morphological appearance of the ocular fundus is one of the key parameters used in the diagnosis and management of retinal disease. However, optical imperfections in the refractive media result in blurring, low luminance and contrast, and changes in the colour composition of the image which can be seen as an increasing yellowish appearance with age. The introduction of a method for quantifying this age-related change in colour content may help in diagnosing and grading pathological changes in the eye lens which are secondary to ocular and systemic diseases. Methods:A total of 102 digitized fundus images from 102 healthy subjects (mean age = 50.4 years, range 7.0–94.3 years) were used to build a model for estimating the age of the subject from the colour content of the images. Results:Estimation of age from the fundus images could be done within approximately 16 years. This variation could be reduced considerably by analysis of repeated photographs from the same examination. Conclusion: The colour content of fundus images can be used to estimate the ages of healthy subjects. Furthermore, when the colour content of fundus images deviates from that expected according to subject age, this may indicate causes other than age of increased light absorption in the lens, such as cumulative exposure to hyperglycaemia in diabetic patients. This could potentially be used to identify patients with undiagnosed type 2 diabetes in the general population and help to establish their risk of developing late diabetic complications as the cumulative exposure to hyperglycaemia is unknown at the time of diagnosis of the disease.

Purpose: To study possible causes of the gradual venous occlusion that precedes the formation of venous loops and reduplications in diabetic retinopathy using histopathological techniques. Methods: Casts of the retinal vascular system from six eyes of five diabetic patients were used to identify venous loops and reduplications. Subsequently the lesions were studied by immunohistochemistry using antibodies against cellular and non-cellular components previously shown to be disturbed in the diabetic retina. Results: In all eyes the venous abnormalities identified on the casts were accompanied by abnormal wall partitions dividing the venous lumen. These partitions consisted of a double layer of flat cells displaying immunoreactivity to von Willebrand factor and actin (endothelial cells), but not to glial fibrillary acid protein or S-100 protein (glial cells), CD3, CD20, CD68, or neutrophil elastase (leucocytes). Neutrophile granulocytes adhering to the walls of larger retinal venules were unrelated to the venous partition and to capillary occlusion in the adjacent retinal areas. Conclusions: Venous loops and reduplications are associated with partitions of the larger retinal venules consisting of a double layer of endothelial cells anchored to a thin basement membrane. An elucidation of the factors distinguishing this endothelial cell proliferation from preretinal new vessel formation may be important for understanding the pathophysiology of proliferative diabetic retinopathy.

To study the effect of Na-K pump and K(ATP) channel inhibition on the diameter and the adenosine-induced vasodilation of small retinal arterioles.Thirty isolated porcine arterioles with a diameter of approximately 70 microm were mounted in a double-barrelled pipette system placed in an organ bath, and diameter changes were studied under isobaric no-flow conditions. After an equilibration period, the arterioles were incubated with the Na-K pump inhibitors ouabain and low K(+) medium or the K(ATP) channel inhibitor glibenclamide, and spontaneous diameter changes were studied. Subsequently, the arterioles were precontracted and the adenosine concentration response curve was measured with and without the presence of inhibitors.Inhibition of the Na-K pump elicited a significant decrease in the spontaneous diameter of the vessels (P = 0.047), whereas no change in the spontaneous diameter was induced by inhibition of the K(ATP) channels (P = 0.754). Inhibition of the Na-K pump with ouabain or with low K(+) medium, as well as inhibition of the K(ATP) channels with glibenclamide, both diminished the adenosine induced vasodilation (P = 0.003, P = 0.01, and P = 0.003, respectively).The adenosine-induced vasodilation of small retinal arterioles involves the K(ATP) channels and the Na-K pump. Changes in the metabolism of adenosine as well as the activity of the K(ATP) channels or the Na-K pump can be expected to influence the retinal blood flow.

Purpose: Occlusion of the central retinal vein (CRVO) is a frequent cause of visual loss. The occlusion induces hypoxia in the retina and the larger retinal veins, but the significance of retinal oxygen saturation for visual acuity at diagnosis and after anti-VEGF treatment for CRVO has not been studied in detail.Methods: Retinal oximetry was performed in 91 patients consecutively referred for specialist evaluation of CRVO. The correlation between oxygen saturation in larger retinal vessels and visual acuity at the primary examination and the predictive value of oxygen saturation for visual prognosis after three monthly intravitreal injections with anti-VEGF medication were studied.Results: At referral, the oxygen saturation in larger retinal vessels of the affected eye was significantly higher in arterioles (100.7 ± 1.4% vs. 96.3 ± 0.6%) and significantly lower in venules (37.8 ± 2.6% vs. 58.2 ± 1.3%) than in the unaffected eye (P < 0.001 for both comparisons). Best-corrected visual acuity (BCVA) showed a significant negative correlation with the oxygen saturation in retinal arterioles (P = 0.002) and a significant positive correlation with the saturation in retinal venules (P = 0.013). Multiple linear regression showed that BCVA, but not oxygen saturations, contributed significantly to predicting visual outcome after three monthly intravitreal injections with VEGF inhibitor.Conclusions: The correlation between retinal oxygen saturation and BCVA at the time of diagnosis of CRVO may help understanding hemodynamic and visual changes in the acute stages of the disease. However, retinal oximetry cannot replace measures of retinal function as a predictive parameter for the visual outcome in CRVO after three monthly intravitreal anti-VEGF injections.

Background: Crosstalk between large and small arteries has been suggested to partake in the microvascular complication development in patients with type 2 diabetes mellitus (T2DM). Yet, data are scarce. In the present study, we aimed to elucidate the crosstalk between large and small arteries in T2DM. Methods: Twenty patients with T2DM and 20 sex- and age matched controls were included. Arterial stiffness was assessed by carotid-femoral Pulse Wave Velocity (cfPWV) using the SphygmoCor. Endothelial function was assessed using EndoPAT. Retinal blood supply regulation was examined by retinal arteriolar diameter change during i) exposure to flickering lights, ii) isometric exercise (hand-weight lifting), and iii) a combined stimulus of i) + ii) using the Retinal Vessel Analyzer (RVA). Results: T2DM patients had higher cfPWV than controls (9.3±1.8 m/s vs. 8.3±2.2 m/s, p = .049). No group difference was observed in endothelial function (0.71±0.30 vs. 0.81±0.30, p = .32) or in response to intervention with flicker, exercise or the combination (all p > 0.05). Endothelial function was associated with mean arteriolar diameter change for the combination intervention (Beta = 0.033 [0.0013; 0.064], p = .042) in patients and controls. No association was observed between cfPWV and retinal arteriolar %-diameter change in patients or controls. Conclusion: Peripheral endothelial function was associated with retinal arteriolar diameter change. Our findings may indicate a contribution of macro-microvascular crosstalk in diabetes complication development.

Aquaporins (AQP) are channels in the cell membrane that mainly facilitate a passive transport of water. In the eye, AQPs are expressed in the ciliary body and retina and may contribute to the pathogenesis of glaucoma and optic neuropathy. We investigated the expression of AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9 in human glaucoma eyes compared with normal eyes. Nine glaucoma eyes were examined. Of these, three eyes were diagnosed with primary open angle glaucoma; three eyes had neovascular glaucoma; and three eyes had chronic angle-closure glaucoma. Six eyes with normal intraocular pressure and without glaucoma were used as control. Immunohistochemistry was performed using antibodies against AQP1, AQP3, AQP4, AQP5, AQP7 and AQP9. For each specimen, optical densities of immunoprecipitates were measured using Photoshop and the staining intensities were calculated. Immunostaining showed labelling of AQP7 and AQP9 in the nonpigmented ciliary epithelium and the staining intensities were significantly decreased in glaucoma eyes (p = 0.003; p = 0.018). AQP7 expression in the Müller cell endfeet was increased (p = 0.046), and AQP9 labelling of the retinal ganglion cells (RGC) showed decreased intensity (p = 0.037). No difference in AQP1, AQP4 and AQP9 expression was found in the optic nerve fibres. This study is the first investigating AQPs in human glaucoma eyes. We found a reduced expression of AQP9 in the retinal ganglion cells of glaucoma eyes. Glaucoma also induced increased AQP7 expression in the Müller cell endfeet. In the ciliary body of glaucoma eyes, the expression of AQP7 and AQP9 was reduced. Therefore, the expression of AQPs seems to play a role in glaucoma.

Hypoxia-induced relaxation of porcine retinal arterioles has been shown to be reduced during inhibition of prostaglandin synthesis and nitric oxide synthase (NOS). The purpose of this study was to identity the specific prostaglandin receptor(s) and source(s) of NO mediating this effect.Porcine retinal arterioles with preserved perivascular retinal tissue were mounted in a myograph and were exposed to hypoxia in the presence of one of the following: the general NO synthase inhibitor L-NAME, the selective iNOS inhibitor 1400W, the selective nNOS inhibitor 7-nitroindazole, the general cyclooxygenase (COX) inhibitor ibuprofen or an antagonist to the FP- (AL 8810), DP- (BWA868C), EP1 - (SC-19220), EP2 - (PF-044189) or EP4 receptors (GW627368X). The experiments were repeated after removal of the perivascular retinal tissue.Hypoxia induced relaxation of retinal arterioles with preserved perivascular retinal tissue. This relaxation was significantly reduced in the presence of L-NAME, 1400W, ibuprofen and the EP4 receptor antagonist GW627368X. The simultaneous addition of L-NAME or 1400W in combination with ibuprofen, but not GW627368X, reduced hypoxia-induced vasorelaxation additively as compared to the effect of the compounds individually.Hypoxia-induced vasorelaxation of porcine retinal arterioles is mediated by inducible NOS and stimulation of EP4 receptors acting through separate pathways, but mechanisms unrelated to the studied prostaglandin receptors and NOS products are also involved.

Purpose Retinal hypoxia with consequent changes in blood perfusion is a central feature in common vision threatening diseases. The aim of this study was to examine the effects of inhibiting COX and NO-synthesis on hypoxia-induced relaxation of retinal vessels in humans Methods Twenty healthy persons aged 20-55 years were examined on two days separated by 4-7 days. The resting diameter and the diameter response to isometric exercise and flicker stimulation of retinal vessels were studied using the Dynamic Vessel Analyzer before and during breathing a hypoxic gas mixture and before and during intravenous infusion with the NOS inhibitor L-NMMA and were repeated on a second day after topical administration of the COX-inhibitor diclofenac Results The resting diameter of arterioles increased significantly during hypoxia and decreased significantly during L-NMMA infusion (p

Purpose Disturbances in the regulation of retinal blood flow are a hallmark of vision threatening diseases. Retinal blood flow is controlled by autoregulation, which involves Ca2+ activity in a recently identified population of perivascular cells with pericyte characteristics (PVCs). The purpose of the study was to identify the sources of Ca2+ recruitment in these PVCs during stimulation of porcine retinal arterioles in vitro with PGE2 and PGF2a. Methods Porcine retinal arterioles with preserved perivascular retinal tissue were mounted in a confocal myograph, placed in a confocal microscope and loaded with Oregon Green. After addition of PGE2 (10-5 M) or PGF2a (10-5 M) arteriolar tone and fluorescence from PVCs were recorded simultaneously in the absence and in the presence of Ca2+ channel blockers (ryanodine, nifedipine, LOE908, CPA, 2-APB). Results PGE2 induced significant relaxation of preconstricted retinal arterioles and Ca2+ activity in PVCs. The percentage of active PVCs, and the number but not the amplitude of Ca2+ oscillations were significantly reduced by CPA and 2-APB, but not by ryanodine, nifedipine and LOE908. PGF2acaused arteriolar contraction and the percentage of active PVCs, the number and the amplitude of Ca2+ oscillations were significantly reduced by CPA and 2-APB. Conclusion Ca2+ activity in PVCs accompanies porcine retinal arterioles responses to PGE2 and PGF2aSarcoplasmic reticulum and inositol triphosphate receptors are important sources of this Ca2+ activity. The amplitude of Ca2+ oscillations seems to play a particular role in contraction of retinal arterioles.

Purpose Studies of diameter regulation in retinal arterioles in vitro have mostly been performed on larger vessels, but evidence suggests that perturbations in the retinal microcirculation may also play a role in the development of vision threatening retinal diseases. Therefore, the purpose of the present study was to develop an in vitro technique for studying diameter regulation in both larger and smaller vessels. Methods A special tissue chamber was developed for mounting, cannulating and perfusing porcine hemiretinas while controlling temperature, pH and oxygen saturation. The chamber was mounted in a flourescens microscope, and the effect on the diameter of larger arterioles, pre-capillary arterioles and capillaries was studied after intravascular and extravascular addition of the thromboxane analogue U46619 and lactate (n=6 for each variable) and NMDA (preliminary). Results In all vessel calibers the thromboxane analogue U46619 induced a significant contraction after extraluminal application (p 0.13). Lactate had no effect on the diameter of non-precontracted vessels (p>0.21), but in pre-contracted vessels lactate relaxed the vessel diameter. Conclusion The response to vasoactive compounds is different after intraluminal and extraluminal application, and the diameter response of vasoactive compounds is different in larger and smaller retinal vessels. The dilating effect of lactate depends on the state of contraction of the retinal vessel.

PURPOSE Diabetic retinopathy is characterized by retinal vascular impairment resulting in retinal hypoxia. The disease can be treated by retinal photocoagulation, but the mechanism of action of this treatment is unknown. Therefore, it is of interest to investigate whether the effects of retinal photocoagulation are related to changes in oxygen saturation. METHODS Retinal oximetry and diameter measurements were performed on larger retinal arterioles and venules in 220 eyes from 149 patients with diabetic maculopathy (DM) and proliferative diabetic retinopathy (PDR) before, immediately after, and 3 months after photocoagulation treatment. RESULTS Before treatment oxygen saturation was increased in retinal venules in DM patients to result in reduced arteriovenous (AV) saturation difference, and was increased in arterioles and venules in PDR patients to result in a normal AV saturation difference. Immediately after treatment the oxygen saturation in both groups was unchanged in retinal arterioles and increased in retinal venules resulting in a reduced AV saturation difference. Three months after treatment arterial and venous saturations were increased, but the AV saturation difference was not different from the pretreatment level. In both patient groups vascular diameters had decreased 3 months after treatment, which was significant for venules in the PDR group. CONCLUSIONS The effects of retinal photocoagulation on diabetic retinopathy are not correlated with changes in oxygen saturation in larger retinal vessels.

PURPOSE: Diabetic retinopathy is one of the leading causes of blindness in the Western world. The disease is characterized by morphological lesions secondary to disturbances in retinal blood flow assumed to be related to disturbances in retinal autoregulation. However, there is a need for elucidating the relation between disturbances in diameter regulation of retinal vessels and the development of diabetic retinopathy in longitudinal studies.METHODS: Sixty-four patients with type 2 diabetes mellitus were subjected to measurement of pressure autoregulation of retinal arterioles using the Dynamic Vessel Analyzer (DVA) and measurement of retinal thickness using OCT scanning, and after a mean of 6.8 years, 42 of the patients were re-examined. The vascular response was compared in patients in whom retinopathy had disappeared, was unchanged, or had worsened.RESULTS: At baseline, hemoglobin A1c (HbA1c) was significantly higher in the patients who would later experience worsening of diabetic retinopathy than in the other groups, but had been reduced at the follow-up examination. During the follow-up period, the resting diameter of retinal arterioles decreased significantly in the patients who experienced improvement in diabetic retinopathy but was unchanged in the other groups, whereas both the diameter response of retinal arterioles to isometric exercise and retinal thickness increased non-significantly with worsening of retinopathy.CONCLUSIONS: The development of diabetic retinopathy is related to the diameter of retinal arterioles. Future clinical intervention studies should aim at investigating the effects of normalizing arteriolar diameters in diabetic retinopathy.

The carbonic anhydrase inhibitor dorzolamide can induce relaxation of retinal arterioles with a consequent increase in blood flow and oxygenation of the retina. It has been shown that the mechanisms underlying this relaxation are independent of extracellular acidosis and CO2. The purpose of the present study was to investigate the possible involvement of nitric oxide (NO) and intracellular acidosis in dorzolamide-induced relaxation of retinal arterioles. Porcine retinal arterioles were mounted in a wire myograph and dorzolamide induced relaxation was studied after 1) the addition of the NO synthase inhibitor l-NAME (3 × 10(-4) M) or the guanylyl cyclase inhibitor ODQ (3 × 10(-6) M), and 2) after loading the smooth muscle cells with the pH sensitive fluorophore SNARF-1-AM and studying changes in vascular tone and intracellular fluorescence after the induction of hypoxia, addition of lactate (10(-2) M), and extracellular acidification (pH = 7.0) alone and in the presence of dorzolamide (10(-3) M). Dorzolamide significantly relaxed retinal arterioles (p < 0.03), and the effect was significantly higher in the presence of perivascular tissue than in isolated vessels at the highest concentration (p < 0.01). In the presence of perivascular tissue dorzolamide-induced relaxation could be reduced by NO inhibition (p < 0.02). Dorzolamide increased intracellular acidification (p < 0.02) during extracellular acidosis, but there was no relation between relaxation and intracellular acidosis. In conclusion, dorzolamide-induced vasorelaxation depends on NO and the perivascular retinal tissue, but is independent of acidification in the extracellular and the intracellular space of retinal vascular smooth muscle cells. Other factors than NO and acidification are involved in dorzolamide-induced relaxation of retinal arterioles.

PURPOSE: Diabetic retinopathy is diagnosed by fundus photography and optical coherence tomography (OCT) scanning. However, adaptive optics (AO) imaging can be expected to add new aspects to the knowledge of diabetic retinopathy because photographic resolution is improved by reducing the influence of optical aberrations on retinal imaging.METHODS: Nineteen patients with diabetes mellitus were subjected to fundus photography, OCT scanning and AO imaging. The fundus photographs were scaled to the same magnification as that of the AO image, and qualitative aspects of AO images of each retinopathy lesion observed on fundus photographs and OCT scans were assessed.RESULTS: All red lesions on fundus photographs appeared on AO images as dark hyporeflective elements, but it could not be verified whether lesions represented haemorrhages or microaneurysms. The smallest of these lesions were circular with a size corresponding to that of blood cells. Hard exudates had irregular surfaces with buddings of various sizes protruding from the lesions. Areas of retinal oedema observed by fundus imaging and OCT scanning resulted in blurring of AO images, but cystoid spaces observed by OCT could be seen on AO images to have a sharp delimitation with a darker hyporeflective rim at the internal lining of the cyst wall.CONCLUSION: AO imaging may potentially assist in detecting diabetic retinopathy at an earlier stage, may help elucidating the pathophysiology of the diseases and may be used for evaluating the effects of clinical interventions on diabetic retinopathy and other retinal vascular diseases.

Background: Diabetic retinopathy is graded by semi-quantitative assessment of the morphological lesions as seen on fundus photographs. This grading method mainly considers the type and number of retinopathy lesions, implying that the diagnostic value of the regional distribution of retinopathy lesions is largely unknown. Design and methods: Case control design. The study group consisted of fifteen diabetic patients successively examined in a screening clinic, with retinopathy lesions predominantly around the larger vascular arcades. The control group consisted of fifteen patients pairwise matched with the patients in the study group regarding sex, age, diabetes type, and diabetes duration. The two groups were compared with respect to the distribution of individual retinal lesions (microaneurysms/dot haemorrhages, blot haemorrhages, cotton wool spots, and hard exudates) around the larger vascular arcades and in the macular area, hypertensive vascular abnormalities (crossing phenomena, arteriolar narrowing, arteriolar light reflex), metabolic regulation, and blood pressure. Results: The patients in the study group had significantly more microaneurysms and haemorrhages around the larger vascular arcades than had the control group, but there was no difference between the vascular changes in the two groups. The study group had significantly higher blood pressure than had the control group, whereas there was no significant difference in metabolic regulation between the two groups. Conclusions: The findings suggest the existence of a hypertensive-like retinopathy in diabetic patients with lesions mainly around the larger vascular arcades, but with no increase in hypertensive vascular changes. This pattern is not identified with current semi-quantitative grading methods. Further improvement of clinical decisions made from fundus photographs of diabetic retinopathy requires the development of computerised methods for quantitative assessment of retinal lesions.

Udgivelsesdato: 2001-Apr Two fundamentally different methods are currently used for the determination of free insulin-like growth factor-I (IGF-I): ultrafiltration by centrifugation (UF) and direct immunoradiometric assay (IRMA). The aim was to evaluate a commercial IRMA (DSL, Webster, TX, USA) and to compare it with UF. In the IRMA it is recommended that samples be incubated for 2 h at 5;C. When comparing samples (n = 8) incubated for 1 and 2 h, levels increased by 27 +/- 5% (P< 0.0001). When incubating samples at 22;C instead of 5;C, levels increased by 192 +/- 32% (P< 0.0001). Addition of IGF-binding protein-1 (IGFBP-1) to normal sera (n = 6) dose-dependently decreased ultrafiltered free IGF-I only (P< 0.0007). Similarly, UF was more sensitive than IRMA to addition of IGFBP-2 (P< 0.05). In healthy subjects (n = 35) IRMA yielded 20% higher levels than UF (1.09 +/- 0.09 vs 0.91 +/- 0.12 microg/L; P< 0.0001). IRMA and UF yielded similar results in healthy subjects treated with IGF-I (n = 5) or growth hormone (n = 7) and in acromegalic patients (n = 6) before and after somatostatin analogue treatment. However, marked differences were observed in conditions with elevated IGFBP-1 and -2. In type-1 diabetics (n = 23) ultrafiltered free IGF-I was more reduced than IRMA free IGF-I (38 +/- 9 vs 76 +/- 7% of matched controls (n = 13); P< 0.0001). In patients with chronic renal failure (n = 25), IRMA free IGF-I was identical to control levels (n = 13), whereas ultrafiltered free IGF-I was decreased by 51 +/- 7% (P< 0.0001). Similarly, women with anorexia nervosa (n = 9) studied before and after weight gain showed significant changes in ultrafiltered free IGF-I only (P< 0.03). In conclusion, IRMA was not very robust with respect to variations in sample incubation and this may bias results. IRMA generally yielded higher levels than UF, in accordance with the knowledge that IRMA measures free plus readily dissociable IGF-I. IRMA was less affected than UF by added IGFBP-1 and -2, and reductions in free IGF-I were better revealed by UF than IRMA.

BACKGROUND Heredo-oto-ophthalmo-encephalopathy (HOOE) is a dominantly inherited disease characterised by gradual loss of vision from the age of 20, progressive hearing loss from the late 20s, cerebellar ataxia in the 30s, and death in dementia in the fourth or fifth decade. Currently, no detailed description has been given of the ocular changes seen in HOOE. Therefore, the ocular changes of HOOE were described on the basis of clinical and histological data from six affected family members. METHODS Three members of the family affected by HOOE were subjected to a full ophthalmological re-examination, and postmortem examination was done on three eyes from two affected family members. RESULTS Visual loss in HOOE was caused by posterior subcapsular cataract and retinal neovascularisations leading to vitreous haemorrhages and neovascular glaucoma. In the retina there was extensive accumulation of an amyloid material, both diffusely and in the walls of the retinal vessels. The retinal glial cells showed extensive pathological changes and retinal Muller cells were seen to occlude the lumen of retinal vessels. CONCLUSION Heredo-oto-ophthalmo-encephalopathy is a familial amyloidosis of the central nervous system which is different from previously reported cases of amyloidosis by including cataract and retinal neovascularisations. The disease is accompanied by extensive changes in retinal glial cells that may play a part in the pathophysiology of the ocular complications of the disease.

Purpose: Retinal photocoagulation can improve the visual prognosis of patients with diabetic maculopathy complicated with clinically significant macular oedema. However, this effect covers a wide variation of visual outcome with some patients improving and other patients worsening several visual acuity steps. Therefore, parameters are needed that can be used to ensure that treatment is modified or avoided in those patients who are at risk of experiencing visual loss. Methods: The change in visual acuity shortly after laser photocoagulation for diabetic maculopathy was assessed in 95 eyes of 79 patients as a part of a routine quality assessment programme, and was compared to the age at onset of diabetes, the pre-treatment duration of diabetes, the number of retinopathy lesions and the number of laser applications given to treat the maculopathy. Results: On average visual acuity was unchanged at the post treatment control (mean=−0.04, SD=0.15), however, with a wide variation (range: −0.44 to 0.33). There was no correlation between the change in visual acuity and any of the studied background parameters. Conclusions: It is concluded that the treatment intervention rather than the general disease state is the main determining factor for the visual prognosis after laser photocoagulation for diabetic maculopathy. Other parameters should be identified to act as a basis for differentiating and improving laser photocoagulation of diabetic maculopathy. One such possible parameter might be the distance of retinopathy lesions and laser applications from the retinal fixation area.

Background. The relation between retinopathy and the parameters: 24-h blood pressure, glucose control, albuminuria, and outcome of pregnancy was studied before, during, and after pregnancy in women with insulin-dependent diabetes mellitus on tight metabolic control during pregnancy. Methods. Prospective study of 112 pregnant women with insulin-dependent diabetes mellitus followed with fundus photography at the Department of Ophthalmology, Arhus University Hospital. Changes in retinopathy were related to 24-h blood pressure, blood glucose, albuminuria, and adverse perinatal outcome. Results. There was an association between grade of retinopathy and HbA1c before (Spearman's rho=0.49, p

Familial Danish dementia (FDD), also known as heredopathia ophthalmo-oto-encephalica, is an autosomal dominant disorder characterized by cataracts, deafness, progressive ataxia, and dementia. Neuropathological findings include severe widespread cerebral amyloid angiopathy, hippocampal plaques, and neurofibrillary tangles, similar to Alzheimer's disease. N-terminal sequence analysis of isolated leptomeningeal amyloid fibrils revealed homology to ABri, the peptide originated by a point mutation at the stop codon of gene BRI in familial British dementia. Molecular genetic analysis of the BRI gene in the Danish kindred showed a different defect, namely the presence of a 10-nt duplication (795–796insTTTAATTTGT) between codons 265 and 266, one codon before the normal stop codon 267. The decamer duplication mutation produces a frame-shift in the BRI sequence generating a larger-than-normal precursor protein, of which the amyloid subunit (designated ADan) comprises the last 34 C-terminal amino acids. This de novo- created amyloidogenic peptide, associated with a genetic defect in the Danish kindred, stresses the importance of amyloid formation as a causative factor in neurodegeneration and dementia.

Background: Haemorrhages from retinal vessels is one of the major clinical characteristics of diabetic retinopathy. Vitreous haemorrhages from retinal neovascularizations may extend to the visual axis and disturb central vision, whereas asymptomatic intraretinal haemorrhages may develop from ruptures of smaller retinal vessels. On rare occasions, however, smaller intraretinal haemorrhages may develop in the fovea, and consequently lead to a reduction in central vision. The clinical characteristics and visual outcome of these lesions have not been described in detail. Methods: Clinical data of 4724 diabetic patients (31.4% with type 1 diabetes and 68.6% with type 2 or other diabetes types) examined in the screening clinic for diabetic retinopathy at the Department of Ophthalmology, Arhus University Hospital, 1993–1998 were reviewed. Patients who had had a previous foveal haemorrhage were subjected to a full ophthalmological reexamination. Results: Six eyes of six patients with type 1 diabetes had previously had a foveal haemorrhage. The lesion had resulted in a visual reduction of on the average 1.4 visual acuity steps (SD=0.5, range:1–2, n=5), and resolution of the lesion was accompanied by an increase in visual acuity of on the average 1.2 visual acuity steps (SD=0.4, range: 1–2, n=6). Four of the patients had progressed to proliferative diabetic retinopathy and had received pan-retinal photocoagulation. Conclusions: Foveal haemorrhages in diabetic retinopathy are accompanied by a mild and transient reduction in central vision. The lesions predominate in patients with type 1 diabetes of long duration, and may indicate that retinopathy has developed into a moderate or severe stage.

Purpose Venous loops and reduplications are rare manifestations of diabetic retinopathy, and knowledge of their natural history is therefore limited to descriptions from a few casuistic reports. The purpose of the present study was to describe the prevalence and clinical characteristics of venous loops and reduplications based on a large data material from the screening clinic for diabetic retinopathy at the Department of Ophthalmology, Arhus University Hospital. Methods Fundus photographs of 4418 patients were reassessed for the presence of venous loops or reduplications. Results Venous loops or reduplications occurred in 29 (0.66%) of the examined patients, and in 26 of 338 patients with proliferative diabetic retinopathy (7.7%). The abnormalities were most frequent on the larger retinal veins, and in advanced retinopathy, but were unlinked to the development of the proliferative retinopathy. The development of the venous abnormalities was seen to be preceded by a gradual occlusion of a larger vein with the formation of multiple smaller collateral vessels, one or some of which to become the venous loop or reduplication. The epidemiology, localization, and pattern of development of the occlusion preceding the formation of loops or reduplications was different from that of retinal vein thrombosis. Conclusion The findings suggest that retinal venous loops and reduplications secondary to diabetic retinopathy are shunt vessels developed to bypass a nonthrombotic occlusion of a larger retinal vein.

Background The mechanisms underlying capillary closure leading to neovascularisation in retinal disease are unknown. In order to further characterize these mechanisms morphological, histopathological, and immunohistochemical changes in areas of capillary closure secondary to retinal vein occlusion were studied. Material The retina from four eyes of two patients with evidence of previous retinal vein occlusion were cast for demonstrating the morphology of capillary closure. Subsequent histological sections through these areas were stained with periodic acid Schiff, Sirius red, and Alcian blue (basement membranes), and by immunohistochemistry to type IV collagen (basement membranes), von Willebrand factor (endothelial cells), glial fibrillary acid protein (GFAP) and vimentin (glial cells), S-100 protein (perivascular glial cells), carbonic anhydrase isoenzyme II (CAH-II) and CD-57 antigen (Muller cells), and CD-68 antigen (microglia). Results Retinal capillary closure was most prominent on the venous side of microvascular units. The material which was accumulated to occlude the lumen of retinal capillaries displayed immunoreactivity to GFAP, vimentin, CD-57 antigen, and CAH-II, but not to S-100 protein, suggesting that this material represents invaded Muller cells. The perivascular glial cells displayed continuous bands of immunoreactivity to S-100 protein corresponding to border zones of retinal areas affected by retinal vein occlusion, but this immunoreactivity was absent inside areas of capillary closure. The histopathological and immunohistochemical appearance of vascular basement membranes was similar in areas of capillary occlusion and outside these areas. Conclusions The findings in areas of capillary closure secondary to retinal vein occlusion showed both similarities to and differences from capillary closure in other retinal disease such as diabetic retinopathy. This evidence may act as a basis for further elucidation of the pathophysiology of capillary closure in retinal disease.

The role of blood pressure elevation in the incidence and progression of diabetic retinopathy is not clearly established and results have been conflicting. Blood pressure and urinary albumin excretion (UAE) are closely related. In order to evaluate the independent relationship between retinopathy and blood pressure elevation, precise information on UAE is essential, as confounding by renal disease (incipient or overt), cannot otherwise be excluded. The aim of the present study was to evaluate the association between diabetic retinopathy and 24-h ambulatory blood pressure (AMBP) in a group of well-characterized normoalbuminuric IDDM patients. In 65 normoalbuminuric (UAE < 20 microg/min) IDDM patients we performed 24-h AMBP (Spacelabs 90207) with readings at 20-min intervals. Fundus photographs were graded independently by two experienced ophthalmologists. UAE was measured by RIA and expressed as geometric mean of three overnight collections made within 1 week. HbA1c was determined by HPLC. Tobacco use and level of physical activity were assessed by questionnaire. Fifteen patients had no detectable retinal changes [grade 1], 35 had grade 2 retinopathy; and 15 had more advanced retinopathy [grade 3-6]. Diastolic night blood pressure was significantly higher in patients with diabetic retinopathy compared to patients without retinopathy (68 +/- 8 mmHg [grade 3-6] and 65 +/- 6 mmHg [grade 2], compared to 61 +/- 4 mmHg [grade 1], p = 0.02). Diurnal blood pressure variation was significantly blunted in the patients with retinopathy as indicated by a higher night/day ratio of diastolic blood pressure (84.6% +/- 4 [grade 3-6], and 81.2% +/- 6 [grade 2] compared to 79.1% +/- 4 [grade 1], p = 0.01). Heart rate tended to be higher in patients in group 2 and 3-6 compared to patients without retinopathy with p values of 0.07 and 0.11 for day-time and 24 h values, respectively. Mean HbA1c increased significantly with increasing levels of retinopathy (p < 0.01). Patients were similar regarding sex, age, tobacco use, and level of physical activity. Notably, UAE was almost identical in the three groups (5.0 x /divided by 1.7 [grade 1], 3.9 x /divided by 1.8 [grade 2], and 5.1 x /divided by 1.6 microg/min [grade 3-6]). In conclusion, night blood pressure is higher and circadian blood pressure variation blunted in patients with retinopathy compared to patients without retinopathy despite strict normoalbuminuria and similar UAE levels in the groups compared. Our data suggest that the association between blood pressure and diabetic retinopathy is present also when coexisting renal disease is excluded. Disturbed diurnal variation of blood pressure is a pathophysiological feature related to the development of both retinopathy and nephropathy in IDDM patients.

Purpose: To compare the induced regular and irregular astigmatism after scleral and corneal tunnel incision. Setting: University hospital outpatient cataract clinic. Methods: One hundred phacoemulsification patients with less than 1.0 diopter (D) of preoperative astigmatism were randomly assigned to have a clear corneal incision (50 patients) or a scleral tunnel incision (50 patients). All incisions were 3.5 to 4.0 mm wide and were made in the steepest axis of the corneal astigmatism. The surgically induced astigmatism was analyzed by vector analysis from keratometric data, as well as by Fourier harmonic series analysis of the topographic data. Results: One day after surgery, the surgically induced astigmatism (vector analysis, keratometry) was 1.41 D ± 0.66 (SD) and 0.55 ± 0.31 D in the corneal incision group and the scleral incision group, respectively (P < .01). Six months after surgery, the induced astigmatism was 0.72 ± 0.35 D and 0.36 ± 0.21 D in the two groups, respectively (P < .01). The corneal topography data confirmed the regular astigmatism changes found by conventional keratometry. However, in addition, Fourier harmonic series analysis of the topography data showed significantly more irregular induced astigmatism with the corneal approach than with the scleral approach. Conclusion: The clear corneal incision induces significantly more regular as well as irregular astigmatism than the scleral tunnel incision.

Diabetic retinopathy is accompanied by disturbances in retinal blood flow, which is assumed to be related to the diabetic metabolic dysregulation. It has previously been shown that normoinsulinemic hyperglycemia has no effect on the diameter of retinal arterioles at rest and during an increase in the arterial blood pressure induced by isometric exercise. However, the influence of hyperinsulinemia on this response has not been studied in detail. In seven normal persons, the diameter response of retinal arterioles to an increased blood pressure induced by isometric exercise, to stimulation with flickering light, and to the combination of these stimuli was studied during euglycemic normoinsulinemia (protocol N) on one examination day, and euglycemic hyperinsulinemia (protocol H) on another examination day. Isometric exercise induced significant contraction of retinal arterioles at all examinations, but during a repeated examination the diameter response was significantly reduced in the test persons following the N protocol and increased in the persons following the H protocol. Flicker stimulation induced a significant dilatation of retinal arterioles at all examinations, and the response was significantly higher during a repeated examination, irrespective of the insulin level. Repeated exposure to isometric exercise reduces contraction, whereas repeated exposure to flickering light increases dilatation of retinal arterioles in vivo. Hyperinsulinemia increases contraction of retinal arterioles induced by isometric exercise.

Purpose: Aquaporins (AQPs) are widely expressed and have diverse distribution patterns in the eye. AQPs 0–5 have been localized at the cellular level in human eyes. We investigated the presence of the more recently discovered AQPs 6–12 in the human eye. Methods: RT-PCR was performed on fresh tissue from two human eyes divided into the cornea, corneal limbus, ciliary body and iris, lens, choroid, optic nerve, retina and sclera. Each structure was examined to detect the mRNA of AQPs 6–12. Twenty-one human eyes were examined using immunohistochemical and immunofluorescence techniques to determine the topographical localization of AQPs 6–12. Results: mRNA transcripts of AQP7, AQP9 and AQP11 were found in the ciliary body, corneo-limbal tissue, optic nerve, retina and sclera. AQP9 and AQP11 mRNA was also detected in the choroid. No mRNA of AQP6, AQP8, AQP10 or AQP12 was detected. Anti-AQP7 immunolabelling was detected in the corneal epithelium, corneal endothelium, trabecular meshwork endothelium, ciliary epithelia, lens epithelium, the inner and outer limiting membrane of the retina, the retinal pigment epithelium and the capillary endothelium of all parts of the eye. AQP9 immunolabelling was detected in the nonpigmented ciliary epithelium and retinal ganglion cells. AQP11 immunolabelling was detected in the corneo-limbal epithelium, nonpigmented ciliary epithelium and inner limiting membrane of the retina. Conclusion: Selective expression of AQP7, AQP9 and AQP11 was found within various structures of the human eye. The detection of these aquaporins in the eye implies a role that may be related not only to water transport but also to the transport of glycerol, lactate and ammonia, with importance for metabolism, especially in the retina.

Purpose: The retinal blood flow depends on the diameter of retinal arterioles, but diameter changes in these vessels have hitherto only been assessed in vessels larger than approximately 100 μm. Therefore, a new method was developed for studying diameter changes along the vascular tree of arterioles in whole perfused segments of porcine retinas, and the effect of known vasoconstrictors on the diameter of retinal arterioles at different branching levels were studied. Methods: Thirty-four whole-mounted porcine retinas were placed in a specially designed tissue chamber. On the basis of video recordings through an inverted microscope, the diameter of retinal arterioles was measured at five different branching levels before and after addition of a high potassium concentration, or increasing concentrations of endothelin-1, the prostaglandin analogue U46619, noradrenaline or none (time controls). Results: The baseline diameter ranged from 136 μm (95% CI 132–140 μm) for 1st order arterioles to 33 μm (95% CI 21–44 μm) for 5th order arterioles. In 1st order arterioles, endothelin produced 56.6% (95% CI 47.6–64.0) and U46619 14.6% (95% CI 5.7–22.6) relative constriction compared with baseline, which for both compounds decreased significantly with increasing branching level (p

Disturbances in the retinal vascular supply are involved in the pathophysiology of the most frequent diseases causing visual impairment and blindness in the Western World. These diseases are diagnosed by noting how morphological lesions in the retina vary in shape, size, location and dynamics, and subsequently concluding the presence of a specific disease entity. This diagnostic approach can be used to identify the site of a retinal vascular occlusion, to assess whether retinal diseases are primarily due to changes in the larger retinal vessels or the microcirculation, and to differentiate the relative involvement of the choroidal and the retinal vascular systems. However, a number of morphological manifestations of retinal vascular disease cannot presently be related to the underlying pathophysiology. The review concludes that there is a need for developing new methods for assessing vascular structure and function in the ciliary vascular system supplying the choroid and the optic nerve head. Presently, the study of these structures relies on imaging techniques with limited penetration and resolution into the tissue. Secondly, there is a need for studying oscillations in retinal vascular function occurring within days to weeks, and for studying regional manifestations of retinal vascular disease. This may constitute the basis for future research in retinal vascular pathophysiology and for the development of new treatment modalities to reduce blindness secondary to retinal vascular disease.

Purpose Relaxation of porcine retinal arterioles in vitro has been shown to be preceded by calcium activity in a population of perivascular cells that cannot be classified as neurons, glial cells, or vascular smooth muscle cells. The purpose of the present investigation was to study calcium activity in these perivascular cells during ATP- and PGE2-induced vasorelaxation, and to identify pericyte markers and other cellular constituents characterizing these cells. Methods Porcine arterioles were loaded with a calcium-sensitive fluorophore and mounted in a myograph. Simultaneous measurements of calcium activity and vascular tone during stimulation with ATP and PGE2 were performed before and after addition of specific antagonists to these compounds and to nitric oxide. Additionally, immunohistochemistry was performed on whole mounts of porcine retina using antibodies to known markers of vascular pericytes and cellular components of the vascular wall. Results Relaxation of retinal arterioles with both ATP and PGE2 was preceded by a significant increase in the number of perivascular cells displaying calcium activity. The effect of ATP was inhibited by the adenosine receptor antagonist 8-PSPT, whereas the effect of PGE2 was inhibited by the EP1 receptor antagonist SC19220 and the NO-synthesis inhibitor L-NAME. The perivascular cells had morphological features in common with pericytes and displayed immunoreactivity to the pericyte markers NG2 and CD-13, but not to markers of glial cells, neurons, or vascular smooth muscle cells. Conclusions The perivascular cell type located external to the smooth muscle cells in porcine retinal arterioles shows calcium activity during relaxation with ATP and PGE2 and has morphological properties in common with pericytes. Future studies should focus on the role of this cell type for regulating retinal blood flow and for retinal vascular disease.