Change in retinal blood flow and retinal arterial diameter after intraocular pressure reduction in glaucomatous eyes.

PURPOSE: To study retinal blood flow and vessel diameter after intra-ocular pressure (IOP) reduction in high- and low-pressure glaucomas, that is, exfoliation glaucoma (ExG) and normal-tension glaucoma (NTG). METHODS: The study included 17 eyes with ExG and 20 with NTG. A minimum of 25% IOP reduction was achieved by deep sclerectomy. Blood flow in the temporal peripapillary retina was measured with scanning laser Doppler flowmetry (Heidelberg Retina Flowmeter, HRF), and retinal vessel diameters were evaluated with the retinal vessel analyser (RVA). Examinations were carried out before and 3 months after the operation. RESULTS: Pre-operative IOP was significantly higher in ExG than in NTG (median 26 mmHg, range 20-33 mmHg versus 15 mmHg, 12-20; p < 0.001). Surgery reduced IOP significantly both in ExG eyes (postoperative IOP 13 mmHg, 5-17; p < 0.001) and NTG eyes (9 mmHg, 3-13; p < 0.001). After the operation, systolic retinal flow was significantly reduced in ExG eyes, whereas in NTG, HRF parameters remained unchanged. Pre-operatively, the central retinal artery equivalent (CRAE) and arteriovenous ratio (AVR) were higher in ExG than in NTG eyes. After IOP reduction, both CRAE and AVR were reduced in ExG eyes, but remained unchanged in NTG. CONCLUSION: The study showed that before IOP reduction, arterial diameter was larger in ExG eyes than in NTG eyes. IOP reduction resulted in vasoconstriction and reduction of flow in ExG, whereas in NTG, both vessel diameter and retinal flow remained unchanged.

Effects of a single bout of interval hypoxia on cardiorespiratory control in patients with type 1 diabetes.

Hypoxemia is common in diabetes, and reflex responses to hypoxia are blunted. These abnormalities could lead to cardiovascular/renal complications. Interval hypoxia (IH) (5-6 short periods of hypoxia each day over 1-3 weeks) was successfully used to improve the adaptation to hypoxia in patients with chronic obstructive pulmonary disease. We tested whether IH over 1 day could initiate a long-lasting response potentially leading to better adaptation to hypoxia. In 15 patients with type 1 diabetes, we measured hypoxic and hypercapnic ventilatory responses (HCVRs), ventilatory recruitment threshold (VRT-CO2), baroreflex sensitivity (BRS), blood pressure, and blood lactate before and after 0, 3, and 6 h of a 1-h single bout of IH. All measurements were repeated on a placebo day (single-blind protocol, randomized sequence). After IH (immediately and after 3 h), hypoxic and HCVR increased, whereas the VRT-CO2 dropped. No such changes were observed on the placebo day. Systolic and diastolic blood pressure increased, whereas blood lactate decreased after IH. Despite exposure to hypoxia, BRS remained unchanged. Repeated exposures to hypoxia over 1 day induced an initial adaptation to hypoxia, with improvement in respiratory reflexes. Prolonging the exposure to IH (>2 weeks) in type 1 diabetic patients will be a matter for further studies.

Decline in the cumulative incidence of severe diabetic retinopathy in patients with type 1 diabetes.

OBJECTIVE: To determine if the cumulative incidence of severe retinopathy in patients with type 1 diabetes has changed. RESEARCH DESIGN AND METHODS: The study looked at 3,781 patients diagnosed with type 1 diabetes (1939-2005), median age at onset 13 (interquartile range [IQR] 9-21) years, and duration of diabetes 19 (IQR 13-27) years. The severe retinopathy was based on a history of laser treatment. Patients were divided into <1975, 1975-1979, 1980-1984, and ≥1985 cohorts according to the diagnosis of diabetes. RESULTS: The cumulative incidence of severe retinopathy has declined (P < 0.0001). After 20 years of duration, the cumulative incidence was 23% (95% CI 21-25) and 33 (30-35) in the earliest cohorts, 18 (15-21) in the next cohort, and 6 (4-9) in the recent cohort. After 30 years, the cumulative incidence was 52 and 48% in the earliest cohorts, while it was 62% after 40 years in the earliest cohort. CONCLUSIONS: The cumulative incidence of severe retinopathy has declined in patients with type 1 diabetes.

Intravitreal triamcinolone acetonide as an adjuvant therapy to panretinal photocoagulation for proliferative retinopathy with high risk characteristics in type 1 diabetes: case report with 22 weeks follow-up.

PURPOSE: To describe a new treatment protocol to deliver panretinal photocoagulation that may avoid further deterioration of vision in patients with type 1 diabetes mellitus with proliferative retinopathy with high risk characteristics for severe visual loss and cystoid macular oedema. METHODS: Fundus photography, measurement of foveal thickness with optical coherence tomography and best corrected visual acuity (BCVA) determined by Snellen and ETDRS charts were measured before and after treatment in a 28-year-old man. RESULTS: Over 9 weeks, BCVA improved from 0.05 to 0.25 and the number of letters read at 2 metres from four to 39 after panretinal photocoagulation and adjuvant intravitreal triamcinolone injection under intraconal anaesthesia. Foveal thickness decreased from 691 microm to 239 microm and cysts disappeared by 15 weeks. By 22 weeks, foveal thickness had increased to 282 microm and small cysts had reappeared, but BCVA remained at 0.2 and the number of letters read at 30. CONCLUSION: Proliferative retinopathy regressed, cystoid macular oedema disappeared and vision improved after panretinal photocoagulation and adjuvant intravitreal triamcinolone acetonide injection under intraconal anaesthesia. This represents a feasible option in cases where pain during laser treatment and impairment of vision afterwards due to cystoid macular oedema result in poor compliance with standard laser treatment under topical anaesthesia.