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PubMed1995

Distribution of fundus autofluorescence with a scanning laser ophthalmoscope.

BACKGROUND: Variation of fluorescence derived from lipofuscin in the retinal pigment epithelium has been recorded with age and in retinal diseases. Studies have been based largely on in vitro observations on eye bank eyes which has placed severe limitations on the data available. METHODS: A technique is described whereby in vivo imaging of autofluorescence of the fundus was achieved using a scanning laser ophthalmoscope. RESULTS: The optical characteristics, distribution, and variation with disease imply that the fluorescence is derived from lipofuscin in the pigment epithelium. Autofluorescence is shown to be abnormally high in certain inherited diseases, and low in the presence of retinal atrophy. CONCLUSION: This technique may be useful both in clinical practice and research. It may allow the detection of the abnormal phenotype in genetically determined disease at a time when other techniques may not. Longitudinal studies of age related macular disease would permit correlation between changes in the pigment epithelium and Bruch's membrane to be established.

Adolescent↗
PubMed1997

Imaging of optic nerve head drusen with the scanning laser ophthalmoscope.

BACKGROUND: Optic nerve head drusen may present diagnostic difficulties in cases of disc swelling. Imaging of the nerve in a search for drusen is often inconclusive, especially in children, where drusen may be buried below the surface of the nerve head. METHODS: A small study was carried out using a scanning laser ophthalmoscope (SLO) with an infrared confocal facility to scan deep within optic discs in an attempt to image drusen. RESULTS: The SLO was able to demonstrate superficial and buried drusen (using the infrared confocal facility). The superiority of the SLO over ultrasound in the presence of lens opacity was revealed, as the SLO simultaneously demonstrated both drusen and the associated anomalous disc features which are not detected by ultrasound. CONCLUSION: The SLO can help in the diagnosis of optic disc drusen especially in difficult cases where lens opacity or buried drusen hinders their definitive diagnosis.

Adolescent↗
PubMed1998

Novel approach towards colour imaging using a scanning laser ophthalmoscope.

AIMS: Conventional fundus imaging using a fundus camera produces colour fundus pictures. The scanning laser ophthalmoscope (SLO) has the advantages of lower levels of light exposure, improved contrast, and direct digital imaging but until now has produced monochromatic images as a laser of single wavelength is used. True representation of the fundus is possible by combining images taken using blue, green, and red lasers. METHODS: A custom built SLO was used to capture blue, green, and red fundus images from suitable volunteers and patients with fundus disease. Images were corrected for eye movement and combined to form a colour image. Colour fundus photographs were taken using a fundus camera for comparison with the SLO image. RESULTS: The background fundus and retinal vasculature had similar appearances with the two imaging modalities. Internal limiting membrane reflections were prominent with the SLO. Identification of new vessels in the diabetic fundus was easier with the SLO than the colour fundus photographs. CONCLUSION: A colour SLO offers all the advantages of the present monochromatic imaging system with the added advantage of true colour representation of the fundus.

Adult↗
PubMed1998

Fundus autofluorescence in patients with macular holes imaged with a laser scanning ophthalmoscope.

AIM: To demonstrate the usefulness of a recently developed technique of imaging fundus autofluorescence and to compare it with the results of fluorescein angiography in the diagnosis and staging of macular holes. METHODS: The intensity and distribution of fundus autofluorescence was studied in 51 patients with idiopathic macular holes and pseudoholes using a confocal laser scanning ophthalmoscope (cLSO) and the images were compared with those obtained by fundus fluorescein angiography. RESULTS: Autofluorescence imaging demonstrated bright fluorescence of macular holes with appearance similar to that obtained by fluorescein angiography. In contrast macular pseuodoholes showed no such autofluorescence. The attached operculum in stage 2 macular holes and the preretinal operculum in stage 3 macular holes showed focal decreased autofluorescence. The associated retinal elevation and the cuff of subretinal fluid were less fluorescent compared with the background autofluorescence of the normal fellow eyes. Following successful surgical treatment the autofluorescence of the macular holes was no longer visible. CONCLUSION: Autofluorescence imaging with the cLSO makes the assessment of macular holes possible with an accuracy comparable with that of fluorescein angiography. Being non-invasive and rapid, autofluorescence imaging may become a useful alternative to fluorescein angiography in the assessment and the differential diagnosis of full thickness macular holes.

Aged↗
PubMed2003

Fundus autofluorescence imaging compared with different confocal scanning laser ophthalmoscopes.

BACKGROUND: With the advent of confocal scanning laser ophthalmoscopes (cSLO), fundus autofluorescence (FAF) resulting mainly from lipofuscin accumulation on the level of the retinal pigment epithelium can be visualised in vivo. Various cSLOs are available to document FAF. The authors analysed and compared results of FAF using three different instruments. METHODS: Eight eyes of eight normal volunteers and 18 eyes of 12 patients with different retinal diseases (age related macular degeneration, macular dystrophy, central serous retinopathy) were examined. FAF images were recorded from each subject with the Heidelberg retina angiograph (HRA), the Rodenstock cSLO (RcSLO) and the Zeiss Prototype SM 30-4024 (ZcSLO). For excitation an argon laser (488 nm) was used (barrier filter: HRA 500 nm; RcSLO 515 nm; ZcSLO 521 nm). 32 FAF images were aligned and averaged using the same software for all cSLOs. FAF distribution was measured and grey scale values as well as root mean square (RMS) contrast were compared. RESULTS: Mean age of all subjects was 55.5 (SD 21.4) years. The maximum grey scale value averaged across all eyes was 76.19 (39.34) for the HRA, 61.44 (22.12) for the ZcSLO and 37.0 (9.97) for the RcSLO. The RMS contrast was 0.46 (0.20) for the ZcSLO, 0.40 (0.12) for the HRA, and 0.13 (0.05) for the RcSLO. The differences between the cSLOs were statistically significant with higher grey scale levels and more contrast for the HRA and ZcSLO than the RcSLO (repeated measures ANOVA; p<0.0001). The differences between the HRA and the ZcSLO were not significant (post hoc comparisons; p<0.05). CONCLUSIONS: All cSLOs allow clinically useful FAF imaging in retinal diseases. However, grey scale levels and contrast were much lower on the RcSLO. Therefore, RcSLO images appear much darker than HRA or ZcSLO images. Furthermore, not all cSLOs have a fixed photodetector gain and a standardised value for the argon laser amplification, which is mandatory for an absolute comparison of FAF imaging results.

Aged↗
PubMed1975

A new indirect ophthalmoscope.

A hand-instrument is described, which serves the purpose of direct and indirect ophthalmoscopy. One part of the instrument, which may be used alone, is a direct ophthalmoscope; it comprises as a distinctive feature a mirror which is vertically movable. The other part is an attachment comprising magnifying lenses, a system for viewing the fundus periphery, a movable fixation target, a system for seeing the patient's eye, and a demonstration mirror. Both parts together form a light, easy-to-handle unit for monocular indirect ophthalmoscopy.

Eye Diseases↗
PubMed2006

In vivo imaging and counting of rat retinal ganglion cells using a scanning laser ophthalmoscope.

PURPOSE: To determine whether a scanning laser ophthalmoscope (SLO) is useful for in vivo imaging and counting of rat retinal ganglion cells (RGCs). METHODS: RGCs of Brown Norway rats were retrogradely labeled bilaterally with the fluorescent dye 4-(4-(dihexadecylamino)styryl)-N-methylpyridinium iodine (DiA). The unilateral optic nerve was crushed intraorbitally with a clip. RGCs were imaged in vivo with an SLO with an argon blue laser (488 nm) and optical filter sets for fluorescein angiography, before and 1, 2, and 4 weeks after the crush. Fluorescent cells were also counted in retinal flatmounts at baseline and 1, 2, and 4 weeks after the crush. An image overlay analysis was performed to check cell positions in the SLO images over time. Lectin histochemical analysis was performed to determine the relationship of microglia to the newly emerged DiA fluorescence detected by image overlay analysis after the optic nerve crush. RESULTS: Fluorescent RGCs were visible in vivo with an SLO. RGC survival decreased gradually after the crush. In the retina after the optic nerve crush, newly emerged DiA fluorescence detected by image overlay analysis corresponded to fluorescent cells morphologically different from RGCs in the retinal flatmount and was colocalized mostly with lectin-stained microglial processes. RGC counts by SLO were comparable to those in retinal flatmounts. CONCLUSIONS: The SLO is useful for in vivo imaging of rat RGCs and therefore may be a valuable tool for monitoring RGC changes over time in various rat models of RGC damage.

Animals↗
PubMed2005

Directional light scanning laser ophthalmoscope.

The cone photoreceptor mosaic of the living human eye has in a limited number of cases been imaged without the use of wavefront-correction techniques. To accomplish this, the directionality of the photoreceptors, as manifested by their waveguiding properties, may be used to advantage. In the present paper we provide a model of our recently proposed directional light scanning laser ophthalmoscope [Opt. Lett. 29, 968 (2004)] together with a detailed numerical analysis of the device. The outcome is compared with experimental results.

Computer Simulation↗
PubMedDate not supplied

Tracking retinal motion with a scanning laser ophthalmoscope.

The vast majority of people with low vision retain some functional vision to perform everyday tasks. To study the effectiveness and efficiency of the visual tasks performed by people with low vision, knowing the movement patterns of their preferred retinal locus (PRL) used for fixation, saccade, and pursuit is critical. The scanning laser ophthalmoscope (SLO) has been used to acquire retinal images while a subject is performing a visual tracking exercise. SLO data has traditionally been analyzed with the use of manual techniques that are both time-consuming and prone to errors due to operator fatigue. To improve the speed and accuracy of the analysis of retinal motion from SLO image sequences, we developed an automated image processing technique and tested it using MATLAB(TM) (The MathWorks, Natick, MA) software. The new software technique was experimentally tested on both normal- and low-vision subjects and compared with the results obtained using manual techniques. The findings indicate that the new technique works very well for most subjects, fairing poorly only in subjects where the quality of the SLO images was substandard.

Adult↗
PubMedDate not supplied

Dynamic visual stimulus presentation in an adaptive optics scanning laser ophthalmoscope.

PURPOSE: To demonstrate the technology and application of synchronized laser modulation in the adaptive optics scanning laser ophthalmoscope (AOSLO), which makes it possible to deliver adaptive optics (AO) corrected stimuli to the retina of a living eye and to record the precise retinal location where the stimulus has landed. METHODS: The modification involves the development of custom software to control a high frequency pixel clock and a waveform generator board in synchrony with the scanning mirrors. The experiment involves a measurement of visual acuity with and without aberrations correction with AO. RESULTS: The system can project stimuli at a frame rate of 30 Hz with high sampling resolution (7.5 seconds of arc), thereby limiting the quality of the retinal image to the level of AO correction. Visual acuity in six subjects is improved on average by 33% after aberration correction across a 5.89-mm pupil. CONCLUSIONS: Dynamic visual stimulus presentation in an AOSLO works effectively and expands the scope of AOSLO applications. S5

Adult↗
PubMed1976

Modification of Welch-Allyn "11500 ophthalmoscope for visuoscopy.

Visuoscopy is an indispensable test in the evaluation of the monocular fixation pattern. Unfortunately, the instrumentation needed to accurately perform the test is often costly. A procedure describing how the Welch-Allyn "11500 ophthalmoscope may be inexpensively modified for the routine performance of visuoscopy is presented.

Fixation, Ocular↗
PubMed1992

Indirect ophthalmoscope argon laser treatment of retinoblastoma.

We describe our use of an indirect ophthalmoscope argon laser for the treatment of selected retinoblastomas. The essential aspect of the technique is the creation, using the "continuous" exposure setting, of a confluent white laser burn completely around the tumor base. This procedure results in the prompt regression of most tumors, although several sessions, 1 to 4 weeks apart, are usually necessary for all but the smallest lesions. This method of laser treatment is applicable to retinoblastoma tumors located anywhere in the ocular fundus, including ones adjacent to the ora serrata.

Child, Preschool↗
PubMed2004

[Use of scanning laser ophthalmoscope and scanning laser polarimeter in diagnosis and monitoring of early stages of primary open-angle glaucoma].

PURPOSE: To evaluate the usefulness of scanning laser ophthalmoscope (TopSS) and scanning laser polarimeter (GDx) in diagnosis and monitoring patients suspected of primary open angle glaucoma (POAG). MATERIAL AND METHODS: In eighty eyes of 40 patients, we performed TopSS, GDx and static perimetry (Octopus 123) in the time period of three years. RESULTS: The GDx analysis showed progression of changes in the retinal fiber thickness in 28 (35%) eyes (p<0.05). In 18 eyes we found non-specific changes in GDx examinations, which were related to no glaucomatous reason. TopSS analysis of the optic nerve head revealed progression in c/d in 16 (20%) eyes (p<0.05). In seven eyes we detected changes in the visual field, which were more strongly connected with changes in TopSS than GDx. CONCLUSIONS: 1. The TopSS and GDx examinations enabled diagnosis and monitoring of early glaucomatous changes in the period of observation. 2. The GDx examination seems to be more sensitive, and TopSS more specific to glaucoma.

Adult↗
PubMed1992

[Indocyanine green angiography with an infrared scanning laser ophthalmoscope. Initial clinical experiences].

This report summarizes our first clinical results with indocyanine green angiography using an infrared scanning laser ophthalmoscope (IR-SLO) is equipped with an infrared laser diode of 780 nm and a barrier filter of 830 nm. Angiographies are recorded on videotape and images simultaneously digitized and saved on the disk. For each examination, 25 mg of Indocyanine Green (ICG), dissolved in 5 ml aqueous solvent, is injected into a cubital vein. We came to the following conclusions: First, the detection of subretinal neovascular membranes is certainly improved, especially for ill-defined membranes when the exact demarcation cannot be seen either because of diffuse exudation of fluorescein or because of the pigment epithelium. Second, we were able to demonstrate the lobular structure of the choriocapillary layer and prove that the acute form of posterior multifocal placoid pigment epitheliopathy is derived from a defect in this layer. Third, examination of the meaning sites of retinal and choroidal vessels revealed the additive fluorescence of ICG, which had not previously been known and which is bound to complicate tremendously the analysis of quantitative measurements. Our results prove that this new method is a useful diagnostic procedure for both the clinical routine and research. The different properties of fluorescein and indocyanine green prevent competition of these dyes. ICG represents a true completion.

Adult↗
PubMed1991

[Image of the cornea with the scanning laser ophthalmoscope].

With a scanning laser ophthalmoscope (SLO), a hexagonal reflex phenomenon can be observed, which originates from the tear film and corneal tissue layers. Time motion analysis verifies that it is possible to discriminate between the cornea and tear film.

Cornea↗
PubMed1990

[Imaging the optic papilla with the laser scanning ophthalmoscope].

The laser scanning ophthalmoscope offers tissue examination and support of papillometrical evaluations as a result of different forms of illumination. Confocal, mixed, and Tyndall light are used in the differential diagnosis and identification of the scleral rim. With highpower mixed light under miotic conditions, imaging of the excavation is possible.

Glaucoma↗