Defective myogenic response of retinal vessels is associated with accelerated onset of retinopathy in type 1 diabetic individuals

PURPOSE: We seek to identify pathogenic mechanisms for diabetic retinopathy that can become therapeutic targets beyond hyperglycemia and hypertension. We investigated if a defective myogenic response of retinal arteries to increased perfusion pressure, which exposes capillaries to increased pressure and flow, is associated with the onset of clinical retinopathy. METHODS: We examined prospectively the incidence of retinopathy in type 1 diabetic individuals tested 4 years earlier for the retinal arterial myogenic response, and in a cross-sectional study the prevalence of defective myogenic response in type 1 patients who had diabetic retinopathy. Among these, we contrasted early-onset (after 15 \ub1 2 years of diabetes, E-DR; n = 5) to late-onset (after 26 \ub1 3 years of diabetes, L-DR; n = 7) retinopathy. We measured the myogenic response using a laser Doppler blood flowmeter after a change in posture from sitting to reclining, which increases retinal perfusion pressure. RESULTS: Five of seven participants who 4 years prior had a defective myogenic response had now developed clinical retinopathy; as compared with only one of six participants who 4 years prior had a normal response (P = 0.10). In the cross-sectional study, all participants had normal retinal hemodynamics at steady state. In response to the postural change, only the E-DR group showed defective myogenic response (P = 0.005 versus controls, P = 0.02 versus L-DR) and abnormally high retinal blood flow (P = 0.016 versus controls). CONCLUSIONS: In type 1 diabetic patients, a defective myogenic response of retinal arteries to pressure is not required for the development of clinical retinopathy, but is prominently associated with an accelerated onset of retinopathy

EFFECT OF AGING ON MACULAR FEATURES OF X-LINKED RETINOSCHISIS ASSESSED WITH OPTICAL COHERENCE TOMOGRAPHY

X-linked retinoschisis (XLRS) is one of the most common causes of macular degeneration in young men. The purpose of this study was to use optical coherence tomography combined with ophthalmoscopy to study the effects of aging on the morphologic changes associated with XLRS

Retinal blood flow in mild cognitive impairment and Alzheimer's disease

Background: Patients with Alzheimer's disease (AD) demonstrate the narrowing of retinal veins and decreased retinal venous blood flow compared with control subjects. We assessed whether these abnormalities are present in patients with mild cognitive impairment (MCI). Methods: After the determination of the global clinical dementia rating, 52 subjects (10 AD, 21 MCI, and 21 normal controls) underwent retinal hemodynamic profiling. Blood column diameter, blood speed, and blood flow were measured in a major temporal retinal vein using retinal laser Doppler flowmetry. In addition, peripapillary retinal nerve fiber layer (RNFL) thickness was measured using optical coherence tomography. Results: Blood column diameter in AD was narrower than in both MCI (P = .004) and controls (P = .002). However, blood speed in both AD (P = .024) and MCI (P = .005) was lower than in controls. As a result, the differences in blood flow between AD and MCI (P = .036), AD and controls (P < .0001), and MCI and controls (P = .009) were significant. Although there were no differences in RNFL thickness among the groups, blood flow was correlated (P = .047) with superior RNFL thickness in the AD group, but not in the MCI (P = .40) or control (P = .84) groups. Conclusions: Retinal blood flow in MCI is intermediate between what is measured in control subjects and in AD patients. Our findings suggest that blood flow abnormalities may precede the neurodegeneration in AD

Retinal Circulatory Abnormalities in Type 1 Diabetes

Purpose. To quantify retinal circulatory abnormalities in patients with type 1 diabetes; to compare blood speed and blood flow in major temporal retinal arteries as well as total retinal arterial cross-section measured in patients to that measured in controls without diabetes; to determine which factors are related to the measured abnormalities within the patient group. Methods. The laser Doppler technique and monochromatic fundus photography were used to measure retinal circulatory parameters in 39 patients with type 1 diabetes with duration of diabetes between 7 and 20 years and 13 age-matched controls without diabetes. Blood pressure, intraocular pressure, and heart rate were measured in all subjects. Glycosylated hemoglobin was measured in the patients. Retinopathy was assessed using standardized color fundus photography and fluorescein angiography. Results. Total retinal arterial cross-section was, on average, 17% higher (P = 0.007) in the patients than in the controls, and it increased with increasing duration of diabetes (P = 0.006). Arterial blood speed was, on average, 33% lower (P = 0.0001) in the patients than in the controls, and it decreased with increasing duration of diabetes (P = 0.03). Conclusions. The retinal circulation of patients with type 1 diabetes with no retinopathy or background retinopathy is characterized by dilated major arteries with reduced blood speeds. Dilation of the larger retinal arteries, with the accompanying decrease in vascular resistance to flow in those vessels, appears to counteract an increase in resistance to flow at the level of the smaller retinal vessels. Invest Ophthalmol Vis Sci. 1994;35:2968-2975 V&gt;«irculatory abnormalities in the diabetic retina are primarily influenced by changes in the resistance to flow through the retinal vascular network. Changes in resistance occur when vessels are either dilated or obstructed, or when blood rheologic properties are altered. There is evidence that each of these abnormalities occurs both before and during the development of clinically observable diabetic retinopathy. 1 Nonperfusion and obliteration of small blood vessels is a clinically observable feature of diabetic retinopathy that begins at an early stage. It is seen histologically as an increased prevalence of acellular capillaries. These acellular capillaries, which initially occur singly or in small groups, subsequently occur in larger clusters and are associated with atrophic arterioles. 2 As areas of nonperfusion become more extensive, they are traversed by a few tortuous, enlarged capillaries that ac

レーザードップラー法による網膜循環測定

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Ophthalmologic techniques to assess the severity of hyperviscosity syndrome and the effect of plasmapheresis in patients with Waldenström's macroglobulinemia

BACKGROUND: The aim of this study is to determine the serum immunoglobulin (Ig) M and serum viscosity (SV) levels at which retinal changes associated with hyperviscosity syndrome (HVS) as a result of Waldenström's macroglobulinemia (WM) occur. In addition, the effect of plasmapheresis on HVS-related retinopathy was tested. PATIENTS AND METHODS: A total of 46 patients with WM received indirect ophthalmoscopy, laser Doppler retinal blood flow measurements, serum IgM, and SV determinations. A total of 9 patients with HVS were studied before and after plasmapheresis. RESULTS: Mean IgM and SV levels of patients with the earliest retinal changes were 5442 mg/dL and 3.1 cp, respectively. Plasmapheresis improved retinopathy, decreased serum IgM (46.5 +/- 18%; P = .0009), SV (44.7 +/- 17.3%; P = .002), retinal venous diameter (15.3 +/- 5.8%; P = .0001), and increased venous blood speed by +55.2 +/- 22.5% (P = .0004). CONCLUSION: Examination of the retina is useful in identifying the symptomatic threshold of plasma viscosity levels in patients with HVS and can be used to gauge the effectiveness of plasmapheresis treatment

黄斑疾患 黄斑疾患に対する新しい検査法―診断と治療への応用―

黄斑疾患に対する新しい検査法に関し,診断と治療への応用に力点をおいて述べた.黄斑部の形態検査として,網膜厚と網膜の微細構造をretinal thickness analyzer,Heidelberg retina tomograph,optical coherence tomographyの3機種を用いて検討した.又,scanning laser ophthalmoscopeを用い,黄斑部における硝子体と網膜表層から深層迄の観察が可能なことを示した.黄斑部の機能検査としては,脈絡膜血流量,黄斑周囲の網膜血流量,中心窩脈絡毛細管板の血流量の測定を行った.黄斑浮腫の発症に血液網膜柵の障害が関与しているかを検討する為には,differential fluorophotometryを新しく開発した.治療法については,黄斑部光凝固法,黄斑変性に対する新しい治療法(光線力学療法),硝子体手術シミュレーションシステムについて述べ