ABSTRACT.Purpose: To measure the oxygen saturation (SO 2 ) in retinal arterioles and venules in patients with glaucomatous optic neuropathy. Methods: We examined SO 2 in retinal arterioles and venules simultaneously by imaging spectrometry. Oxygen saturation was evaluated according to the difference of the extinction spectra of haemoglobin and oxyhaemoglobin. The arteriovenous difference (avD) was calculated by (SO 2art -SO 2ven ). The optic nerve head topography was estimated by Heidelberg retinal tomography and the visual field using the Octopus G1. We examined one eye in each of 58 healthy persons (mean age 58.6 ± 10.7 years; mean rim area 1.52 ± 0.33 mm 2 ; mean defect 0.65 ± 1.31 dB; mean intraocular pressure [IOP] 18.5 ± 2.7 mmHg), 49 patients with normal-tension primary open-angle glaucoma (NTG) (mean age 63.0 ± 8.5 years; mean rim area 0.89 ± 0.34 mm 2 ; mean defect 5.4 ± 4.1 dB; mean IOP 19.2 ± 2.9 mmHg), and 45 patients with high-tension primary openangle glaucoma (POAG) (mean age 62.6 ± 10.3 years; mean rim area 0.97 ± 0.47 mm 2 ; mean defect 7.1 ± 6.4 dB; mean IOP 31.6 ± 10.8 mmHg). Results: The intraclass correlation coefficients of the SO 2 measurement were 0.82 (arteriole) and 0.59 (venule). In normal eyes, the SO 2art , SO 2ven and avD were 92.3 ± 3.4%, 55.7 ± 6.8% and 36.6 ± 7.0%, respectively. Equivalent data were 89.7 ± 5.4%, 56.0 ± 8.3% and 33.7 ± 10.6%, respectively, in NTG eyes and 91.4 ± 4.0%, 58.3 ± 10.5% and 33.1 ± 11.5%, respectively, in POAG eyes. Over all examined eyes, the arteriolar SO 2 and the retinal arterio-venous difference correlated significantly with the rim area. Conclusion: Eyes with NTG showed significantly decreased arteriolar SO 2 . These changes were not seen in POAG patients.
Background and Purpose-In acute stroke care, rapid but careful evaluation of patients is mandatory but requires an experienced stroke neurologist. Telemedicine offers the possibility of bringing such expertise quickly to more patients. This study tested for the first time whether remote video examination is feasible and reliable when applied in emergency stroke care using the National Institutes of Health Stroke Scale (NIHSS). Methods-We used a novel multimedia telesupport system for transfer of real-time video sequences and audio data. The remote examiner could direct the set-top camera and zoom from distant overviews to close-ups from the personal computer in his office. Acute stroke patients admitted to our stroke unit were examined on admission in the emergency room. Standardized examination was performed by use of the NIHSS (German version) via telemedicine and compared with bedside application. Results-In this pilot study, 41 patients were examined. Total examination time was 11.4 minutes on average (range, 8 to 18 minutes). None of the examinations had to be stopped or interrupted for technical reasons, although minor problems (brightness, audio quality) with influence on the examination process occurred in 2 sessions. Unweighted coefficients ranged from 0.44 to 0.89; weighted coefficients, from 0.85 to 0.99. Conclusions-Remote examination of acute stroke patients with a computer-based telesupport system is feasible and reliable when applied in the emergency room; interrater agreement was good to excellent in all items. For more widespread use, some problems that emerge from details like brightness, optimal camera position, and audio quality should be solved.
Introduction: While there are several studies on reliability of telemedicine in assessing stroke scales, little is known about the validity of a general neurological examination performed via telemedicine. Therefore, we sought to test the agreement between bedside and remote examination in acute patients of the emergency room. Methods: Acute patients at the emergency room of a 450-bed academic teaching hospital were included in this study. A clinical neurological examination consisting of 22 items was performed at bedside and also remotely via an audio-visual link by a different neurologist; both were experienced clinicians at the consultant level. Kappa statistics were calculated for each item of the examination. Results: Forty three patients completed both examinations (mean age 58.3 years, 56% female). Patients were seen between 8 and 72 min after admission (mean 36.3 min). Total time for remote examination was 12.6 min (8–21 min) and 8.9 min (5–18 min) for bedside examination. K-coefficients ranged from 0.32 (muscle tone) – 0.82 (language) indicating a fair to excellent agreement in most items. Conclusions: Remote examination via an audio-visual link produces comparable results to bedside performance even in acute patients of the emergency room. Compared to the scarce data available, inter-observer agreement is about the same as that between 2 examiners at bedside. However, more studies on reliability and validity of clinical neurological examination are required.
Audiovisual consultation seems to be a feasible and useful support in routine neurology back-up service of an acute care hospital. Better mobility of devices and flexibility of service is needed to improve availability and quality of this valuable tool.
Imaging spectrometry is a new technique that permits simultaneous measurements of reflectance spectra at different locations along a line. Results are three-dimensional images, whose coordinates are location, wavelength, and reflectance. A conventional fundus camera is adapted to a spectrograph and an intensified charge coupled device (CCD) matrix detector system. The spectral resolution of this spectrometer is lower than 2 nm within a spectral range between 395 and 710 nm. The local resolution is lower than 23 µm along a line of 1.5 mm. From an imaging spectrum, the extinction spectrum of blood in vessels can be calculated. Also, in case of a noisy extinction spectrum of blood, its approximation by a model function results in calibration-free measurement of the oxygen saturation. Considering the radiation transport in single fundus layers, the local distribution of the concentration-thickness product of xanthophyll, melanin, and choroidal blood can be calculated.
Conclusions Certified quality management within a large stroke network using telemedicine is possible and might improve stroke care procedures and thrombolysis rates. Outcome studies comparing conventional stroke care and telestroke care are inevitable.
Spectroscopic measurement of light that is reflected from biological tissue in vivo is being investigated for various clinical applications. One special object of investigation using optical methods is the human ocular fundus. A fundus reflectometer that enables the simultaneous acquisition of up to 192 spectra arranged in a horizontal line across the fundus is described. The underlying optical principle of the device is the confocal imaging of an illuminated narrow, slitlike field at the fundus to the entrance slit of a spectrograph. This is imaged by the grating of the spectrograph onto a two-dimensional CCD chip that records the local distribution of ocular fundus reflectance spectra within a wavelength range of 400 up to 710 nm with a resolution better than 2 nm and a local resolution of 23 m in a field dimension of 1.5 mm. The performance of the device was investigated, the effects of confocal and nonconfocal imaging are discussed, and some representative measurements are presented.
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