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At least 235 records · Page 13Linked to original sources
PubMed1986

[Effect of decadron phosphate on ophthalmoscopic changes in the rat eye with intravitreal brass wires].

This paper reports on ophthalmoscopic findings after implantation of 0.3 mm2 copper-zinc wires (85:15) into the vitreous body of rat eyes (2 groups of 11 animals each) and the influence of daily administration of Decadron-Phosphate, equivalent to 0.05 mg dexamethasone. This drug, injected subconjunctivally over a period of 10 days, reduces the vitreal opacities and both retinal as well as vitreal vascularization, but increases the tendency of the foreign bodies to migrate. The dose-dependent decline in bodyweight gain is an indicator of the drug's systemic effect. In order to distinguish mechanical damage from the metal intoxication, glass splinters of the same size and shape were implanted in a further series of experiments, for the purpose of comparison.

Animals↗
PubMed1994

An algorithm for the fast registration of image sequences obtained with a scanning laser ophthalmoscope.

There is a need to quantify images of retinal pathology so that the natural progression and response to various forms of treatment such as laser therapy can be reliably monitored. The images obtained with a scanning laser ophthalmoscope are better than those from a traditional fundus camera, and the method of data collection leads naturally to digitization and quantitative techniques. However, during any angiographic sequence, there will inevitably be eye movement and it is essential that this be corrected for prior to the application of quantitative analysis. This article presents an algorithm (the smart localized binary correlation algorithm) for the automatic registration of fluorescein or indocyanine green angiograms which is based on localized correlation of binary templates in binary thresholded gradient images. The use of this algorithm decreases the calculation time up to 180 times when compared with the fastest applicable algorithm found in the literature. The algorithm only detects translational movement of the images but proves to be robust against rotational movement for the small angles (< 4 degrees) encountered in ophthalmic imaging. Registration accuracy is estimated to be +/- 2 pixels.

Algorithms↗
PubMed1997

The scanning laser ophthalmoscope.

The imaging of the fundus of the eye poses two major technical challenges. First, it is necessary for both the illuminating and reflected beams to pass through the same aperture, the iris. In some commonly used instruments this leads to the use of levels of illumination close to the maximum tolerable by a patient. Second, in order to visualize the different structures present in the various layers of the fundus it is necessary to perform tomographic imaging. The scanning laser ophthalmoscope provides an answer to these particular problems. By scanning the fundus with a narrow laser beam most of the area of the iris is then available for the reflected light and so the intensity of the illuminating beam can be kept low, making it more acceptable for patients. The use of confocal imaging allows 3D images to be produced. In this short review the performance of the instrument will be discussed and its application to a number of clinical problems in ophthalmology considered. Finally there will be a brief description of other instrumentation currently under development.

Diagnostic Imaging↗
PubMed1999

Tomographic reconstruction of the retina using a confocal scanning laser ophthalmoscope.

Retinal imaging with a confocal scanning laser ophthalmoscope (cSLO) involves scanning a small laser beam over the retina and constructing an image from the reflected light. By applying the confocal principle, tomographic images can be produced. However, the thickness of such slices, when compared with the retinal thickness, is too large to give useful 3D retinal images. In this study an algorithm has been developed which fits a double Gaussian curve to the axial intensity profiles generated from a stack of image slices. The underlying assumption is that the laser light has mainly been reflected by two structures in the retina, the internal limiting membrane and the retinal pigment epithelium. From the fitted curve, topographic images and novel thickness images of the retina can be generated. The technique has been applied to three normal volunteers and seven patients with macular pathology (cystoid macular oedema and macular hole) demonstrating the clinical value of the technique. The improvement in accuracy achieved by using a double rather than a single Gaussian is also demonstrated.

Humans↗
PubMed1998

Ophthalmoscopic abnormalities in adults with falciparum malaria.

We studied 424 adults with falciparum malaria admitted over 28 months. They were divided into three groups: cerebral malaria (n = 214); severe non-cerebral malaria (n = 58); and uncomplicated malaria (n = 152). Fundus examination was done daily from admission to discharge, and weekly thereafter in those with persistent changes. All patients were treated by a protocol based on WHO guidelines. Ophthalmoscopic abnormalities were: retinal haemorrhages, 40 (9.43%) (25 cerebral malaria, 10 severe non-cerebral and five uncomplicated malaria); papilloedema, 17 (7.94%) cerebral malaria and two uncomplicated malaria; blurring of disc margins, 25 (11.68%) cerebral and seven non-cerebral; retinal oedema, six (2.80%) cerebral and five non-cerebral malaria; disc pallor, five patients all with cerebral malaria; vitreous haemorrhage and hard exudate in one patient each, both cerebral malaria. Retinal haemorrhage was associated with cerebral malaria and severe non-cerebral malaria, especially with severe anaemia (p < 0.001), as compared to uncomplicated malaria (p < 0.01). The association of papilloedema and cerebral malaria was highly significant compared to severe non-cerebral malaria (p < 0.001). None of these findings was associated with statistically significant mortality, except disc pallor in cerebral malaria (p < 0.05).

Adolescent↗
PubMed2005

Digital simultaneous fluorescein and indocyanine green angiography, autofluorescence, and red-free imaging with a solid-state laser-based confocal scanning laser ophthalmoscope.

PURPOSE: To describe and to evaluate a novel confocal scanning laser ophthalmoscope (cSLO) for fluorescence angiography, fundus autofluorescence (FAF), and red-free imaging. METHODS: Digital infrared, red-free, FAF, fluorescein, and indocyanine green (ICG) angiography images were obtained with a cSLO in 766 patients. An optically pumped solid-state laser generates the excitation wavelength (488 nm) required for red-free, FAF, and fluorescein angiography images. For ICG angiography and infrared imaging, diode laser sources at 790 and 820 nm are used. Further features include an internal fixation control and a focus range of -24 to +30 diopters. RESULTS: High-image quality is achieved with a resolution of up to 5 microm per pixel in 30- x 30-degree images and allows for accurate delineation of normal and pathologic features. Simultaneous angiography offers high-contrast images. Corresponding display of quasi-simultaneous frames facilitates interpretation. A small focus difference between fluorescein and ICG scans occurs because of chromatic aberrations. Automated alignment and generation of mean images from several single frames allow for acquisition of high-resolution FAF images. CONCLUSION: Various laser-source related, optical, and electronic innovations improve cSLO fundus imaging for routine clinical application. A solid-state laser has advantages compared to argon gas laser sources, including less space occupation, heat emission, and noise production.

Adolescent↗
PubMed2005

Retinal location of the preferred retinal locus relative to the fovea in scanning laser ophthalmoscope images.

PURPOSE: It is difficult to determine the position of a preferred retinal locus (PRL) relative to the fovea in scanning laser ophthalmoscope (SLO) images as a result of disease-related retinal morphologic changes that obscure the fovea. To overcome this problem, we developed a method for determining retinal foveal position based on normal fixation position relative to the optic disk. The normal foveal position measurements can then be used to estimate the distance between a PRL and the fovea. METHODS: Using the SLO, foveal position was determined for 50 normal subjects by measuring the retinal locus of fixation relative to the optic disk in undistorted SLO images. The resulting normal foveal fixation area is described by a bivariate normal ellipse that can be plotted on any undistorted SLO image. Measurement reliability was assessed by repeated measurements. The PRL relative to the normal foveal fixation area was determined for 24 subjects with macular degeneration and bilateral central scotomas. RESULTS: The normal foveal fixation area based on all 50 subjects is described by a p = 0.9 bivariate ellipse whose centroid is located 12.6 degrees temporal to the temporal optic disk edge and 1.4 degrees inferior to a horizontal line bisecting the disk. PRL area is shown to increase with distance from the foveal fixation ellipse centroid. The shape of the PRL, characterized by the ratio of PRL ellipse major to minor axis, was found to depend on whether the PRL was vertically or horizontally aligned with the foveal fixation centroid. CONCLUSIONS: PRL position relative to the fovea can be reliably estimated by plotting the normal foveal fixation bivariate ellipse on undistorted SLO images of retinas in which the fovea is obscured as a result of the disease process.

Adult↗
PubMed1975

The ophthalmoscopic and fluorescein angiographic picture of diabetic retinopathy.

The ophthalmoscopic and fluorescein angiographic findings in diabetic retinopathy are reviewed. It is pointed out that the fundus lesions seen in diabetic retinopathy are characteristic, but not specific for diabetes. It is still not settled which role alterations in the microcirculation, alterations in the tissue metabolism, hypoxia or defects in the oxygen delivery system may play as provoking factors in the development of the diabetic retinopathy. Future investigations should concentrate on early diabetes and must include studies on the retinal blood-flow, electroretinographic and histopathologic changes.

Adolescent↗
PubMed2006

Ophthalmoscopic characteristics in sheep and goats: comparative study.

The ocular fundus was examined in 40 goat eyes and 40 sheep eyes by studying ophthalmoscopic characteristics and retinograms. Similarities and differing characteristics were described. In common: tapetal colour; peripheral yellowish area surrounding the Winslow stars; unpigmented areas in the non-tapetal zone; a great amount of myelin in the optic disc; the Bergmeister's papilla and the holoangiotic retinal vascular pattern. Differences: big size of the Winslow stars in goats; myelinizated fibre over the non-tapetal zone in sheep; shape, position and myelin distribution of the optic disc; and the presence of a 'primary artery' in goats.

Animals↗
PubMed2001

Changes in fixation in the presence of prism monitored with a confocal scanning laser ophthalmoscope.

BACKGROUND: The main optical effect of an ophthalmic prism is to deviate uniformly the entire field of view seen through the prism, resulting in an equal eye movement, if fixation on the same object is to be maintained. Conversely, it has been suggested that, in the case of low vision due to central scotoma, the eye changes its eccentric viewing behaviour when a prism is introduced, that is, the eye remains stationary with a change of retinal image location. METHOD: A new method is described in which retinal image position was recorded with a confocal scanning laser ophthalmoscope in four experimental conditions. RESULTS: Results showed that the normally-sighted eye rotates rapidly to compensate for the introduction of a prism. CONCLUSION: Future studies are required involving subjects with central scotoma but it is likely that many subjects with low vision will also refixate behind a prism and that the prescribing and wearing of bilateral prism in cases of central vision loss will have limited effectiveness in the demonstration or training of eccentric viewing.

Journal Article↗
PubMed2004

Ophthalmoscopic and morphogenetic changes in rat lens induced by galactose: attenuation by pyruvate.

BACKGROUND: Investigations have been conducted on the potential of pyruvate, a normal tissue metabolite, in the prevention of cataract formation. METHODS: Cataract was induced by maintaining young rats on a diet containing 30% galactose. The progress of cataract was monitored by visual inspection and ophthalmoscopic and slit-lamp examinations. The protective effect of pyruvate was assessed by incorporating it in the galactose diet and drinking water. The progress of cataract was substantially thwarted by this dietary regimen. RESULTS: Substantial morphogenetic changes in the lenses of the galactosaemic animals, which by themselves can offer obstruction to light penetration through the lens and scattering, were significantly attenuated. These changes were ascertained by histological detection of errors in cellular differentiation and their migration in unwanted areas. CONCLUSIONS: As per previous studies, the pyruvate effect is attributed to its direct effect on the biochemistry of lens related to the inhibition of oxidative stress, as well as to its effect on tissue physiology related to the lifelong process of organogenesis, characteristic of this tissue.

Animals↗
PubMed1982

The normal retinal fluorescein angiogram I. A study of the fluoresceinangiographic appearance of the retina in normal subjects without ophthalmoscopically obvious pathological changes.

Retinal fluorescein angiography and colour fundus photography was performed in the one eye of 48 clinically healthy middle aged subjects, 21 females and 27 males, without ophthalmoscopically obvious fundus abnormalities. A region of retina 45 degrees around the fovea was analysed for morphological elements in colour photographs, red-free photographs and fluorescein angiograms. Subtle morphological elements, small and 'large' fluorescent spots, were noted in 20 out of 48 subjects (= eyes) (42%) during the early and middle phases of the fluorescein angiogram. In 15 subjects the number and location of fluorescent spots (n = 40) corresponded to spots in the colour and red-free photographs. In 10 out of the 15 subjects (67%) with fluorescent spots the corresponding spots in the colour and red-free photographs were indistinctly outlined. Fluorescent spots without corresponding spots in colour and red-free photographs (n = 18) were found in 10 subjects. Thirty-eight per cent of all the fluorescent spots (n = 22) persisted with variable intensity in the late phases of the angiograms. Colour photographs disclosed variable numbers of yellowish spots in 34 subjects (71%). Sixty-four per cent of the spots (71 our of 111 spots) in colour photographs could not be visualized by fluorescein angiography. These spots were characteristically distinctly outlined. The retinal spots were chiefly located in the upper and lower regions temporal to the fovea both in colour photographs (71% of the spots) and the fluorescein angiograms (62% of the spots). The occurrence of morphological elements of the retina did not correlate with age or smoking habits. The appearance of minor morphological elements in the retina of normal subjects seems to variate widely as assessed by fluorescein angiography and fundus colour photography.

Adult↗
PubMed1991

Topographical analysis of peripheral vs central retina with pattern reversal visual evoked response and the scanning laser ophthalmoscope.

The contribution of the central and the surrounding peripheral retina to the pattern reversal visual evoked response (PVER) was analyzed simultaneously using double frequency stimulation and the Fast Fourier transform (FFT) method. The Scanning Laser Ophthalmoscope (SLO) was used to project the pattern stimulus, a square subtending 10 degrees on a side, on a specific location in the fundus and to monitor accurately the stimulus' position during PVER testing. When the stimulus area on the central retina was less than or equal to 50 min of arc on a side, or 0.69% of the total area was stimulated (a square of 10 degrees on a side), the contribution from the central retina was negligible, and the PVER was dominated by surrounding peripheral retinal activity. When the stimulus area of the central retina was greater than or equal to 100 min of arc on a side, or 2.78% of the whole area was stimulated, activity from the central retina became more evident. When the stimulus area projected on the central retina became 150 min on a side (6.25% of the area or greater), activity from the central retina showed an increase and exceeded that of the peripheral retina. When the central area became larger, its activity dominated the PVER, and the contribution from the peripheral retina became negligible at this stage. The PVER was highly dependent upon the activity of the central retina, and activity levels from the central and surrounding peripheral retina were correlated.

Adult↗
PubMed2005

Improved visualisation of choroidal neovascularisation by scanning laser ophthalmoscope using image averaging.

AIMS: To improve visualisation of angiographic features in patients with age related macular degeneration associated with choroidal neovascularisation (CNV) and related complications. To evaluate if image averaging can achieve this goal. METHODS: 27 eyes of 20 sequential patients with age related macular degeneration over a 3 month period were studied. Indocyanine green angiograms (ICGA), fluorescein angiograms (FA), and oral fluorescein angiograms were recorded with a confocal scanning laser ophthalmoscope. Software was used to average multiple images from a 10-20 image series (over 0.5-1.0 seconds). Image quality was assessed by two masked observers and graded on a scale of 0-3. A more quantifiable grading method was devised by adding a variable amount of Gaussian noise to the improved image until the original and image averaged image appeared equal. RESULTS: Masked review showed mild to strong improvement of visualisation of structures including borders of CNV. Improvement varied depending on the type and phase of the angiogram. Improvement was highest in late phase FA, mid and late phase ICGA, and all phases of oral FA. CONCLUSION: Image averaging using software based algorithms improves the quality of angiographic images, particularly late ICGA images and oral FAs. This method may assist in the visualisation of choroidal neovascularisation in age related macular degeneration.

Adult↗
PubMed1980

Experimental occlusion of the central artery of the retina. I. Ophthalmoscopic and fluorescein fundus angiographic studies.

Transient experimental occlusion of the central artery of the retina (OCAR), lasting from 15 to 270 minutes, was produced by clamping the artery in the orbit in 63 eyes of rhesus monkeys. Ophthalmoscopic and fluorescein angiographic studies were performed before and during clamping of the artery, as well as periodically after unclamping, for periods of up to 22 weeks. The effects of transient retinal ischaemia on the retina, optic disc, and retinal vascular bed were studied. 89% of the eyes showed a variable amount of residual retinal circulation on angiography during CAR clamping, but this did not exercise any protective action against ischaemic damage. Duration of the ischaemia was the principal factor determining severity of damage. OCAR for up to 98 minutes produced no significant permanent neural damage, but OCAR for 105 minutes or longer produced irreversible permanent neural damage. There was no significant permanent damage to the retinal vascular bed, though a transient fluorescein leakage was seen after OCAR for 2 1/2-3 hours or longer. The findings revealed that the normal red colour of the optic disc represents retinal vascular filling in the surface layer of the disc and not deeper vascular filling. The various factors influencing the retinal circulation and neural damage in OCAR are discussed.

Animals↗
PubMed1990

Argon indirect ophthalmoscopic photocoagulation: reduced potential phototoxicity with a fixed safety filter.

A new argon indirect ophthalmoscopic photocoagulator is presented which uses a red helium-neon laser aiming beam. An interference filter protects the operator from green or blue-green treatment beam reflections without impairing visualisation of the aiming beam or significant retinal anatomy. The protective filter is fixed in place, eliminating the weight, noise, and potential failure of mechanically switched filters. The red aiming beam has a negligible potential for producing photochemical retinal damage in the patient or operator.

Argon↗
PubMed1992

Confocal imaging of the fundus using a scanning laser ophthalmoscope.

A confocal scanning laser ophthalmoscope (cSLO) was used to examine the effects of confocal optics on the image of the human fundus in vivo. Patients from a retinal clinic and a glaucoma clinic were examined using the cSLO in the confocal mode. A degree of optical sectioning could be achieved, and the results agree with a best axial resolution of 300 microns measured in a model eye. The main advantage of using a confocal system was found to be the improved contrast of the images. This improved the resolution of structures such as the lamina cribrosa and optic disc drusen which are seen in low contrast in conventional images. The improved contrast of the confocal images is partly achieved by excluding light which has been scattered within the plane of focus. Structures which multiply scatter light will become less visible with confocal optics and hard exudates were found to be an example of such a structure. The cSLO and the fundus camera are seen as complementary instruments rather than as alternatives for imaging the fundus. It is envisaged that confocal imaging will enable details of the fundus to be revealed which are at present not seen in conventional images.

Fundus Oculi↗
PubMed1994

Clinical investigation of an infrared digital scanning laser ophthalmoscope.

An infrared scanning laser ophthalmoscope (SLO) has been custom built in order to investigate the application of confocal and indirect mode SLO imaging to patients with fundus disease. Infrared light is reflected from the fundus to a greater extent than visible light permitting lower illumination power and, as it penetrates the retinal pigment epithelium, choroidal structures can be readily imaged. Furthermore, as conventional infrared illumination and detection systems are not well suited to ophthalmoscopy, this area is underdeveloped as a potential source of useful clinical data. Confocal, direct and indirect imaging modes have been used to image fundi of normal volunteers and patients with fundus disease. In comparison with conventional fundus photography confocal infrared SLO imaging improves visualisation of choroidal vasculature, retinal pigment epithelial abnormalities, laser photocoagulation scars, and optic disc pores in the lamina cribrosa. Direct infrared SLO imaging enables fundus visualisation through nuclear lens opacities. Furthermore, indirect mode imaging enhances significantly the appearance of macular drusen. The potential clinical benefit of these observations is discussed.

Adult↗