Search

Purpose: To evaluate the relationship of neuroretinal layer thickness with sensitive measures of cardiovascular autonomic neuropathy in diabetic patients with non-proliferative diabetic retinopathy (NPDR)., Methods: Twenty-seven eyes of 27 patients with type 1 diabetes presenting with mild-to-moderate NPDR were compared to 27 healthy control (HC) eyes matched for age and gender. The total macular volume (TMV) and the volumes of individual neurosensory layers in the macula were analysed from spectral domain optical coherence tomography using automated layer segmentation. Cardiovascular autonomic regulation was assessed by short-term power spectrum analysis of heart rate variability (HRV) before, during and after an orthostatic challenge., Results: The patients had an age of 46 ± 12 years and diabetes since 28 ± 9 years. Diastolic and mean arterial pressure was lower in the patients compared to HCs. TMV (r = 0.58, p = 0.002), inner plexiform layer volume (IPLV; r = 0.39, p = 0.047) and inner nuclear layer volume (INLV; r = 0.60, p = 0.001) were associated with reduced recovery of low-frequency (LF) spectral power of HRV after orthostatic load in diabetic patients but not in HCs. The response of LF spectral power during the orthostatic manoeuvre was blunted in patients compared to HCs (p = 0.02). Diabetes duration was negatively associated with TMV and INLV, whereas IPLV was significantly reduced in eyes with moderate NPDR compared to HCs., Conclusion: The results indicate a correlation between inner retinal tissue loss and diminished autonomic regulation in type 1 diabetic patients with mild-to-moderate NPDR. The observed changes can be interpreted as congruent early signs of retinal and systemic neuropathy in diabetes., (© 2018 The Authors. Acta Ophthalmologica published by John Wiley & Sons Ltd on behalf of Acta Ophthalmologica Scandinavica Foundation.)

Purpose: To evaluate detailed changes in retinal layer thickness in spectral-domain optical coherence tomography (SD-OCT) images during a 1-year follow-up of patients treated for diabetic macula oedema (DME)., Methods: Post hoc analysis of retinal layer thickness changes applying the automated layer segmentation of SD-OCT images in eyes with DME that were randomly assigned to receive pro re nata (PRN) treatment with either 0.5 mg ranibizumab or 8 mg triamcinolone. In each patient, seven retinal layers were segmented in 49 scans covering a 20° × 20° area of the macula at baseline and after 1 year of treatment. Changes in individual layer thickness were correlated with visual acuity (VA) and compared between treatment arms., Results: Twenty-five patients (seven female, 60.2 ± 15.1 years) were evaluated. Thickness decrease of retinal nerve fibre layer (RNFL) was associated with a gain in VA over 12 months (r > 0.54; p < 0.05). Decrease in ganglion cell layer (GCL) and GCL+IPL thickness pooled for nasal Early Treatment of Diabetic Retinopathy Study (ETDRS) subfields correlated with VA as follows: ranibizumab r = 0.74 (GCL) and r = 0.63 (GCL+IPL); and triamcinolone r = 0.45 (GCL) and r = 0.46 (GCL+IPL)., Conclusion: In DME therapy, reduction in RNFL thickness may have a considerable impact on retinal function, unrelated to the type of pharmacological treatment. Precise morphologic quantification of neurosensory layers by SD OCT offers new insight into disease pathology and therapeutic targets., (© 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Purpose: To identify the effects of pan-retinal laser treatment on the integrity of neurosensory retinal layers., Methods: Patients were examined with fluorescence angiography after a standardized examination for diabetic retinopathy and a peripapillary ring scan with spectral domain optical coherence tomography. A single-session pan-retinal photocoagulation was performed using the PASCAL pattern scanning argon laser applying a minimum of 1,500 spots. Optical coherence tomography was evaluated more than 6 months., Results: Eighteen eyes of 12 consecutive patients with new onset, treatment-naive proliferative diabetic retinopathy secondary to diabetes Type 2 were treated and retinal optical coherence tomography morphology evaluated. Retinal nerve fiber layer thickness increased statistically significantly from baseline to week 1, when it reached its peak. The combined thickness of the outer plexiform and the inner nuclear layers and the combined thickness of the inner plexiform and the ganglion cell layers showed no relevant changes. The combined thickness of the retinal pigment epithelium and the photoreceptor cell layers decreased at month 1 followed by a steady increase in thickness, which remained below baseline values over time., Conclusion: Pan-retinal photocoagulation in proliferative diabetic retinopathy leads to a slowly reversible, marked biological response with statistically significant morphometric changes detected by spectral domain optical coherence tomography. Swelling of the retinal nerve fiber and outer nuclear layers induce an increase in peripapillary total retinal thickness. Simultaneously, the photoreceptor and retinal pigment epithelium layers decrease in thickness. These changes indicate diffuse retinal inflammation after pan-retinal laser therapy.

Purpose: To evaluate changes in the distribution and morphology of intraretinal microexudates and hard exudates (HEs) during intravitreal anti-vascular endothelial growth factor therapy in patients with persistent diabetic macular edema., Methods: Twenty-four patients with persistent diabetic macular edema after photocoagulation were investigated in this prospective cohort study. Each eye was assigned to a loading dose of three anti-vascular endothelial growth factor treatments at monthly intervals. Additional single treatments were performed if diabetic macular edema persisted or recurred. Intraretinal exudates were analyzed over 6 months using spectral domain optical coherence tomography (SD-OCT) and fundus photography., Results: Before treatment, microexudates were detected by SD-OCT as hyperreflective foci in 24 eyes, whereas HEs were seen in 22 eyes. During therapy, HE increased significantly in number and size. This was accompanied by accumulation of microexudates in the outer retina. Enlargement of hyperreflective structures in SD-OCT was accompanied by enlargement of HE at corresponding fundus locations. A rapid reduction in diabetic macular edema was seen in all patients, but to varying degrees. Patients with hemoglobin A1c levels <7% and serum cholesterol <200 mg/dL formed fewer HEs and featured more edema reduction and visual acuity gain., Conclusion: Diabetic macular edema reduction during intravitreal anti-vascular endothelial growth factor therapy was accompanied by dynamic rearrangement of intraretinal exudates at corresponding locations in fundus photography and SD-OCT. Intraretinal aggregates of microexudates detectable as hyperreflective foci by SD-OCT may compose and precede HE before they become clinically visible.

Purpose: The aim of the study was to compare the diameter of the central retinal artery (CRA) between patients with diabetes mellitus and healthy subjects in vivo. CRA diameters were calculated from retinal haemodynamic parameters measured with noninvasive measurement techniques., Methods: Sixteen patients with type 1 diabetes with no or mild diabetic retinopathy and 16 age-matched healthy controls were included in this study. Total retinal blood flow was assessed by combining bidirectional laser Doppler velocimetry in all veins entering the optic disc with measurements of retinal vessel diameters using a Dynamic Vessel Analyser. Blood flow velocity in the CRA was measured with colour Doppler imaging (CDI). The diameter of the CRA in the optic nerve was then calculated for each subject using the individual ocular haemodynamic data., Results: Calculated CRA diameters were significantly larger in patients with diabetes (180 ± 13 μm) compared with healthy controls (166 ± 10 μm, p = 0.001). No significant differences were found in retinal blood flow, retinal artery or vein diameters or mean flow velocity of the CRA., Conclusion: The data of the present study show increased calculated CRA diameter in patients with type 1 diabetes with no or mild retinopathy. Blood flow velocity measurements in retrobulbar vessels using CDI need to be interpreted with caution in terms of retinal blood flow, because no information about vessel diameters is obtained by this technique., (© 2013 The Authors. Acta Ophthalmologica © 2013 Acta Ophthalmologica Scandinavica Foundation. Published by Blackwell Publishing Ltd.)

Purpose: A variety of studies have shown that flicker-induced vasodilatation is reduced in patients with diabetes. It is, however, unclear whether reduced neural activity or abnormal neurovascular coupling is the reason for this phenomenon. In the present study, we hypothesized that retinal neurovascular dysfunction precedes neural dysfunction in patients with early type 1 diabetes., Methods: In the present study, 50 patients with type 1 diabetes without retinopathy and 50 healthy age- and sex-matched control subjects were included. The retinal vascular response to flicker stimulation was measured using the dynamic Retinal Vessel Analyzer. In addition, the response in retinal blood velocity to flicker stimulation as assessed with laser Doppler velocimetry was studied in a subgroup of patients. Pattern electroretinography (ERG) was used to measure neural retinal function., Results: The flicker responses of both retinal arteries and veins were significantly reduced in patients with diabetes (veins in the diabetic group: 3.5 ± 2.3% versus healthy control group: 4.6 ± 2.0%; P = 0.022 between groups, whereas arteries in the diabetic group: 2.0 ± 2.7% versus healthy control group: 3.8 ± 1.7%; P < 0.001 between groups). Likewise, the response of retinal blood velocity was reduced in patients with diabetes, although adequate readings could only be obtained in a subgroup of subjects (diabetic group [n = 22]: 19 ± 7%; healthy control group [n = 24]: 43 ± 19% P < 0.001 between groups). The parameters of pattern ERG were not different between the two groups., Conclusions: The study confirms that flicker responses are reduced early in patients with type 1 diabetes. This is seen before alterations in pattern ERG indicating abnormal neurovascular coupling.

Objective: To compare total retinal blood flow in diabetic patients with no or mild nonproliferative diabetic retinopathy and healthy control subjects and to investigate in patients whether there is a difference between retinal blood flow before morning insulin and under normoglycemic conditions using a glucose clamp., Research Design and Methods: Twenty patients with type 1 diabetes with no or mild diabetic retinopathy were included in this open parallel-group study, and 20 healthy age- and sex-matched subjects were included as control subjects. Retinal blood flow was assessed by combining velocity measurements using laser Doppler velocimetry and diameter measurements using a commercially available dynamic vessel analyzer. Measurements were performed before and during a euglycemic clamp., Results: Total retinal blood flow was higher in diabetic patients (53 +/- 16 microl/min) than in healthy subjects (43 +/- 16 microl/min; P = 0.034 between groups). When plasma glucose in diabetic patients was reduced from 9.3 +/- 1.7 to 5.3 +/- 0.5 mmol/l (P < 0.001) retinal blood flow decreased to 49 +/- 15 microl/min (P = 0.0003 vs. baseline). Total retinal blood flow during the glucose clamp was not significantly different from blood flow in normal control subjects (P = 0.161)., Conclusions: Type 1 diabetic patients with no or only mild diabetic retinopathy have increased retinal blood flow before their morning insulin dosage. Blood flow is reduced toward normal during euglycemic conditions. Retinal blood flow may fluctuate significantly with fluctuating plasma glucose levels, which may contribute to the microvascular changes seen in diabetic retinopathy.

Purpose: Various studies have shown that retinal vessels in patients with diabetes mellitus have a reduced capacity to adapt to changes in perfusion pressure and to stimulation with flickering light. Structural and functional changes in retinal vessels in diabetes could lead to a general reduction of vasodilator and/or vasoconstrictor capacity. To gain more insight into this topic, we compared the response of retinal vessel diameters to systemic glyceryl trinitrate (GTN) and stimulation with diffuse luminance flicker in patients with diabetes and healthy control subjects., Methods: Twenty patients with type 1 diabetes mellitus featuring no or mild nonproliferative diabetic retinopathy and 20 healthy, age-matched subjects were included in this study. A vessel analyzer was used for measurement of diameters of retinal arteries and veins. The response of diameters was measured continuously during stimulation with flickering light, as well as immediately after sublingual application of 0.8 mg GTN., Results: The response of retinal vessels to flickering light was significantly reduced in the patients with diabetes (arteries: 2.9% in diabetes versus 7.0% in control subjects, P < 0.002; veins: 4.6% in diabetes versus 6.8% in control subjects, P = 0.020). GTN-induced vasodilatation was not different between the patients with diabetes and the healthy control subjects (P >or= 0.70)., Conclusions: The present study confirmed reduced response of retinal vessels to stimulation with flickering light in diabetes. The response of retinal vessels to a direct NO-donor, however, was maintained. This result indicates that abnormal flicker-induced vasodilatation in diabetes is not a consequence of generally reduced retinal vascular reactivity (ClinicalTrials.gov number, NCT00432029).

The 2 leading causes of blindness in adults in the industrialized nations, diabetic retinopathy and age-related macular degeneration, have been investigated thoroughly with respect to their pathogenesis. In recent years, it has been discovered that dysfunctional ocular microcirculation appears to play a part in the development of both diseases. In diabetic retinopathy, it has been shown that the disease is associated with early retinal vascular dysregulation. In the later states of the disease, retinal tissue hypoxia is a major trigger of sight-threatening neovascularization. In age-related macular degeneration, there is increasing evidence that reduced blood flow in the choroid is associated with the development and progression of the disease. Knowledge of the pathophysiological vascular states underlying these diseases is essential for the assessment and development of future therapies.

Aims/Purpose: Neurovascular dysfunction and inner retinal layer thinning are among the earliest detectable retinal changes in diabetes, and both worsen during development and progression of diabetic retinopathy (DR). However, direct interactions between these features have not been investigated so far. Therefore, we aimed to analyse associations between the retinal functional hyperaemic response and thickness of the individual neuroretinal layers in eyes with non‐proliferative DR. Methods: Thirty patients with Type 1 diabetes featuring mild (n = 15) or moderate (n = 15) non‐proliferative DR and 14 healthy subjects were included in this cross‐sectional study. Retinal vessel diameters were measured before and during illumination with flickering light using a dynamic vessel analyser. Individual retinal layer thickness in the macula was analysed from spectral domain optical coherence tomography. Results: Flicker light‐induced vessel dilation was significantly reduced in diabetes patients compared to healthy controls (veins: 3.0% vs. 6.1%, p < 0.001; arteries: 1.3% vs. 5.1%, p = 0.005). Univariately, the response in retinal veins of diabetes patients correlated significantly with ganglion cell layer (GCL) thickness (r = 0.46, p = 0.010) and inner plexiform layer thickness (r = 0.40, p = 0.027), and negatively with haemoglobin A1c (HbA1c) levels (r = −0.41, p = 0.023) and age (r = −0.38, p = 0.037), but not with baseline diameters, glucose levels, or diabetes duration. In a multiple regression model only HbA1c (p = 0.027, β = −0.40) and GCL thickness (p = 0.030, β = 0.39) remained significantly associated with the vascular flicker light response. Conclusions: The results indicate that thinner GCL and worse glycaemic control both contribute to reduced neurovascular coupling in patients with clinical signs of DR. Progression of neurovascular dysfunction in DR might be related to structural degeneration of the neurovascular complex in the inner retina. [ABSTRACT FROM AUTHOR]