51 research outputs found
Ocular pulse amplitude in diabetes mellitus
BACKGROUND—The influence of diabetes mellitus on ocular pulse amplitude (OPA), an indirect measure of choroidal perfusion, is unclear.
METHODS—OPA, using the Langham ocular blood flow (OBF) system, applanation intraocular pressure (IOP), systemic blood pressure (BP), heart rate, and haemoglobin (Hb) A(1c) were measured in patients with insulin dependent diabetes mellitus (IDDM) with no (DR-0, n = 22) non-proliferative (DR-1, n = 24), and proliferative (DR-2, n = 18) diabetic retinopathy.
RESULTS—Neither local (OPA, IOP) nor systemic perfusion parameters (BPs, HR) nor HbA(1c) were significantly altered in DR-0, DR-1, or DR-2 IDDM patients.
CONCLUSION—Choroidal circulation remains unaffected as diabetic retinopathy advances.
First-order optimality conditions in generalized semi-infinite programming
Abstract. In this paper, we consider a generalized semi-infinite optimization problem where the index set of the corresponding inequality constraints depends on the decision variables and the involved functions are assumed to be continuously differentiable. We derive first-order necessary optimality conditions for such problems by using bounds for the upper and lower directional derivatives of the corresponding optimal value function. In the case where the optimal value function is directly differentiable, we present first-order conditions based on the linearization of the given problem. Finally, we investigate necessary and sufficient first-order conditions by using the calculus of quasidifferentiable functions. Key Words. Generalized semi-infinite programming, necessary and sufficient first-order optimality condition, optimal value function, directional differentiability, quasidifferentiability. 1
Comparison of fundus autofluorescence images acquired by the confocal scanning laser ophthalmoscope (488 nm excitation) and the modified Topcon fundus camera (580 nm excitation).
To compare autofluorescence (AF) images obtained with the confocal scanning laser ophthalmoscope (using the Heidelberg retina angiograph; HRA) and the modified Topcon fundus camera, in a routine clinical setting. A prospective comparative study conducted at the Jules-Gonin Eye Hospital. Fifty-six patients from the medical retina clinic. All patients had complete ophthalmic slit-lamp and fundus examinations, colour and red-free fundus photography, AF imaging with both instruments, and fluorescein angiography. Cataract and fixation were graded clinically. AF patterns were analyzed for healthy and pathological features. Differences of image noise were analyzed by cataract grading and fixation. A total of 105 eyes were included. AF patterns discovered by the retina angiograph and the fundus camera images, respectively, were a dark optic disc in 72 % versus 15 %, a dark fovea in 92 % versus 4 %, sub- and intraretinal fluid visible as hyperautofluorescence on HRA images only, lipid exudates visible as hypoautofluorescence on HRA images only. The same autofluorescent pattern was found on both images for geographic atrophy, retinal pigment changes, drusen and haemorrhage. Image noise was significantly associated with the degree of cataract and/or poor fixation, favouring the fundus camera. Images acquired by the fundus camera before and after fluorescein angiography were identical. Fundus AF images differ according to the technical differences of the instruments used. Knowledge of these differences is important not only for correctly interpreting images, but also for selecting the most appropriate instrument for the clinical situation
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