Age-associated cardiac dysfunction in Drosophila melanogaster.

The fruit fly, Drosophila melanogaster, has served as a valuable model/organism for the study of aging and was the first organism possessing a circulatory system to have its genome completely sequenced. However, little is known about the function of the heartlike organ of flies during the aging process. We have developed methods for studying cardiac function in vivo in adult flies. Using 2 different cardiovascular stress methods (elevated ambient temperature and external electrical pacing), we found that maximal heart rate is significantly and reproducibly reduced with aging in Drosophila, analogous to observations in elderly humans. We also describe for the first time several other aspects of the cardiac physiology of young adult and aging Drosophila, including an age-associated increase in rhythm disturbances. These observations suggest that the study of declining cardiac function in aging flies may serve as a genetically tractable model for genome-wide mutational screening for genes that participate in or protect against cardiac aging and disease.

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.

Laser-tissue interaction and artifacts in confocal scanning laser ophthalmoscopy and tomography.

The goal of the present study was to analyze the interaction between incident laser light and retinal tissue in confocal scanning laser ophthalmoscopy and tomography. We examined the change in axial intensity distribution during evaluation of the retinal surface topography in macular and optic nerve head evaluation in normal volunteers and patients with different retinal diseases. Additionally, we examined a model eye with a model cyst and human globes in an eye mounting chamber. We found that confocal scanning laser tomographs record specular reflected light originating from intraocular surfaces as well as light scattering from deeper retinal structures. Concave and convex retinal surfaces and eye movements may influence accurate topographic detection. Knowledge of the exact mechanism of image formation in confocal tomography is of great importance for the understanding of validity of these measurements. Proper identification of observed artifacts and preventive measures will increase the utility, reproducibility, and validity of this technology.

Effect of repetitive imaging on topographic measurements of the optic nerve head.

OBJECTIVE: A confocal scanning diode laser ophthalmoscope was used to determine the number of examinations needed to obtain highly reproducible topographic measurements of the optic nerve head and peripapillary retina. DESIGN: Topographic images of the optic nerve head and peripapillary retina were obtained in one randomly selected eye on five separate visits. On each occasion the selected eye had five examinations. For each examination, one image was acquired (a total of 25 images per eye). Reproducibility was calculated as the average SD of all image elements (65,536 pixels). SETTING: Glaucoma referral center. SUBJECTS: Five normal subjects and five patients with glaucoma. INTERVENTION: Topographic imaging of the optic nerve head and peripapillary retina. MAIN OUTCOME MEASURE: Number of examinations needed to obtain highly reproducible topographic measurements. RESULTS: In healthy subjects, reproducibility with one examination per visit was 35.5 microns; this improved to 25.7 microns with three examinations and 22.5 microns with five examinations. In older patients with glaucoma, the reproducibility improved from 40.2 microns with one examination per visit to 28.5 and 24.1 microns with three and five examinations, respectively. CONCLUSION: We recommend a series of three examinations to provide high reproducibility with optimal efficiency in terms of time and materials used.

Simultaneous indocyanine green and fluorescein angiography using a confocal scanning laser ophthalmoscope.

BACKGROUND: Fluorescein and indocyanine green (ICG) angiography are both useful in the diagnosis and treatment of many retinal diseases. In some cases, both tests must be performed for diagnosis and treatment; however, performing both is time-consuming and may require multiple injections. METHODS: We designed a compact digital confocal scanning laser ophthalmoscope to perform true simultaneous fluorescein and ICG angiography. We report our experience using the instrument to perform 169 angiograms in 117 patients. RESULTS: There were no unexpected adverse effects from mixing the dyes and administering them in 1 injection. An entire examination, including fundus photography, fluorescein angiography, and ICG angiography, could be performed in 45 minutes. It was possible to study differences in fluorescein patterns by comparing identically timed frames and to find cases in which ICG or fluorescein was optimal in visualizing retinal and subretinal structures. Confocal optical sections in the depth (z) dimension allowed viewing in different planes. It was possible to overlay ICG and fluorescein images or compare them side-by-side using a linked cursor. Digital transmission of the images was also performed. CONCLUSIONS: Simultaneous ICG and fluorescein angiography can be performed rapidly, safely, and conveniently. The availability of simultaneous angiography will allow critical determination of the relative advantages and disadvantages of both types of angiography.

Imaging the microvasculature of choroidal melanomas with confocal indocyanine green scanning laser ophthalmoscopy.

OBJECTIVE: To image the microvasculature of choroidal melanoma with a new confocal scanning laser ophthalmoscope. METHODS: Eighteen consecutive patients, each with a unilateral choroidal melanoma, were examined prospectively. Indocyanine green angiography was performed with a new confocal scanning laser ophthalmoscope that enabled serial optical sectioning through the tumor. Two additional patients were studied with indocyanine green angiography and confocal scanning laser ophthalmoscopy just before enucleation for posterior choroidal melanomas. The histologic identification of microvasculature patterns was compared with the angiograms for these patients. RESULTS: In the series of 18 patients, 16 (89%) indocyanine green angiograms with optical sectioning revealed tubular structures within the melanoma that were identified as tumor vessels based on their angiographic appearance. The microvasculature patterns identified by indocyanine green angiography correlated well with the histologic appearance of these microvasculature patterns in both patients for whom histologic verification was available. CONCLUSIONS: This preliminary study suggests that indocyanine green angiography with confocal scanning laser ophthalmoscopy images the microvasculature of choroidal melanomas and may be capable of detecting microvasculature patterns that have been shown to be prognostically significant from histopathological studies.

Confocal scanning infrared laser ophthalmoscopy for indocyanine green angiography.

PURPOSE: We used indocyanine green to study wavelength-optimized confocal scanning infrared laser angiography in patients with retinal and choroidal disease. METHODS: A confocal scanning laser ophthalmoscope with an excitation wavelength of 795 nm was operated both in tight and wide confocal imaging modes. We examined 77 subjects with and without retinal and choroidal disease (including diabetic retinopathy, age-related macular degeneration, and subretinal neovascularization). RESULTS: The scanning laser ophthalmoscope allowed acquisition of images, in the wide confocal imaging mode, of the retinal circulation and late leakage sites without late injections of dye to outline the retinal vasculature. In the tight confocal imaging mode, optical subtraction of the light contribution of the retinal circulation allowed examination of the choroidal circulation, and vice versa. The wide confocal mode appears equivalent to other scanning laser ophthalmoscopes in recording images from retinal and choroidal layers. CONCLUSIONS: There are three differences between the confocal scanning laser ophthalmoscope and conventional instruments. First, the late images allow excellent visualization of the retinal circulation without a landmark injection. Second, confocal imaging allows optical subtraction of retinal circulation when focusing on the choroid and vice versa. Third, the instrument acquires and processes all data digitally, is personal computer-based, is compact, operates with a mouse-driven graphical user interface, and allows easy data exchange with conventional software. With further modifications in software and hardware, this device offers the possibility of producing a three-dimensional map of the retinal and choroidal vasculature.

Confocal laser tomographic analysis of the retina in eyes with macular hole formation and other focal macular diseases.

To study the retinal surface in the human eye in normal and diseased states we used laser scanning tomography. The confocal arrangement of the laser tomographic scanner permits examination of retinal topography in the axis perpendicular to the retinal surface. The eyes examined with the laser tomographic scanner included normal eyes, eyes with macular holes, impending macular holes, radiation retinopathy, macular edema, photocoagulation scars, subfoveal scars, and serous detachment of the fovea associated with subretinal neovascularization. The laser tomographic scanner is a new method that allows measurements of the topography of the internal limiting membrane in the macular area and may improve our understanding of the pathophysiologic characteristics and treatment of a variety of disorders of the macula.

Indocyanine green angiography of the peripapillary region in glaucomatous eyes by confocal scanning laser ophthalmoscopy.

PURPOSE: To investigate the peripapillary region in glaucomatous eyes by indocyanine green angiography. METHODS: Indocyanine green angiography of the optic disk and peripapillary region was evaluated by modified confocal scanning laser ophthalmoscopy in 22 eyes of 22 patients with glaucoma and in 10 normal eyes of 10 control patients with unilateral choroidal melanoma. The occurrence and extent of indocyanine green angiographic anomalies were correlated with optic disk morphology and the severity of glaucoma. RESULTS: In the 32 eyes of 32 patients, two types of peripapillary defects were identified in the late-phase angiograms. The first was hypofluorescent areas in the peripapillary region and was more common in eyes with glaucoma (P < .02); their occurrence and extent correlated with age (P < .01). In nine of the 17 eyes, alpha (peripheral) zone peripapillary atrophy corresponded with the areas of peripapillary indocyanine green hypofluorescene. The second defect, hypofluorescent halos adjacent to and extending around the full circumference of the optic disk margins, did not correlate with any of the study factors. CONCLUSIONS: Indocyanine green angiography showed areas of hypofluorescene in the peripapillary region in late-phase angiograms in 68% of glaucomatous eyes compared with 20% of control eyes. These hypofluorescent areas might be either of result of blockage of background fluorescence by pigment or caused by an absence of vascular tissue (choriocapillaris).

Retinal blood flow measurements in branch retinal vein occlusion using scanning laser Doppler flowmetry.

PURPOSE: To determine capillary blood flow measurements in eyes with branch retinal vein occlusion using a scanning laser Doppler flowmeter. METHODS: Retinal capillary blood flow in branch retinal vein occlusion areas and corresponding ipsilateral nonbranch retinal vein occlusion areas, 11 equivalent areas of the contralateral fellow eye of 12 consecutive untreated branch retinal vein occlusion patients, and 16 eyes of 11 age-matched normal control subjects were measured with scanning laser Doppler flowmetry. A template consisting of eight squares, each with a field of 100 x 100 microm (10 x 10 pixel) with space interval of 500 microm equidistant horizontally and vertically was used to obtain blood flow measurements in all subjects. Mean blood volume, flow, and velocity were obtained by averaging the mean values measured in each field. We avoided measurement over large retinal vessels to prevent the aliasing artifact of blood cells from moving faster than the sampling frequency. RESULTS: Branch retinal vein occlusion areas have significantly decreased microvascular blood volume (P = .0009), flow (P = .02), and velocity (P = .016) compared with ipsilateral nonbranch retinal vein occlusion areas in the same eye. Branch retinal vein occlusion areas also have decreased blood volume (P = .001), flow (P = .0042), and velocity (P = .0044) compared with areas of contralateral fellow eyes of branch retinal vein occlusion subjects. Branch retinal vein occlusion areas have significantly decreased blood volume (P = .0012), flow (P = .008), and velocity (P = .02) compared with age-matched normal areas. CONCLUSION: Average retinal blood volume, flow, and velocity in areas of branch retinal vein occlusion are significantly lower than in healthy retinas. The ability to noninvasively measure hemodynamic changes in the retinal capillary bed may be relevant to development of new therapies for retinovascular disease.

Retinal nerve fiber layer evaluation in human immunodeficiency virus-positive patients.

PURPOSE: To determine the effect of human immunodeficiency virus (HIV) infection on topographic measures of the optic disk and the retinal nerve fiber layer. METHODS: A cross-sectional study at the Acquired Immunodeficiency Syndrome (AIDS) Ocular Research Unit at the University of California, San Diego. Retinal nerve fiber layer thickness at the optic nerve head was evaluated using the Heidelberg Retinal Tomograph, a confocal scanning laser tomograph in 38 HIV-positive and 24 age-matched HIV-negative subjects. RESULTS: HIV-positive patients without CMV retinitis showed significant differences from HIV-negative normal controls in a number of measures of the retinal nerve fiber layer. This indicated a loss of retinal ganglion cells in HIV-positive patients without retinitis. HIV-positive patients with CMV retinitis were worse in most measurements than both HIV-negative controls and HIV-positive patients without CMV. CONCLUSIONS: Significant thinning of the retinal nerve fiber layer occurs in HIV-positive patients without infectious retinopathy, and there are further changes in the optic disk associated with CMV retinitis. Confocal scanning laser tomography may be of use in the diagnosis of early HIV-associated visual function loss.

Angiography of the glaucomatous optic nerve head.

An enhanced understanding of the microcirculation and blood flow in glaucoma is needed. Definitive study has been impaired by lack of a quantitative and objective clinical method to measure human optic nerve and peripapillary choroidal blood flow. Through optical sectioning of the optic nerve head and peripapillary retina, confocal scanning laser ophthalmoscopy offers the potential for angiographic examination of small vessels, particularly at the level of the lamina cribrosa.

Correlation of peripapillary retinal height and visual field in glaucoma and normal subjects.

PURPOSE: To investigate the relationship between peripapillary retinal height and visual field sensitivity. PATIENTS AND METHODS: Fourteen normal subjects and 25 primary open-angle glaucoma patients were examined using a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Visual fields (Humphrey program 24-2) were assessed with both standard achromatic automated perimetry and shortwavelength automated perimetry. The mean peripapillary retinal height was determined for superotemporal (60-90 degrees ), superonasal (91-120 degrees ), inferotemporal (271-300 degrees ), and inferonasal (240-270 degrees ) sectors. Based on Glaucoma Hemifield Test sector definitions, achromatic automated perimetry and short-wavelength automated perimetry fields were divided into each of four distinct regions. RESULTS: Significant differences in disc rim area, rim-disc area ratio, cup volume, and each papillary region were found between glaucoma patients and normal subjects. With both standard achromatic automated perimetry and short-wavelength automated perimetry, significant correlations (p < 0.05) were found between the mean peripapillary retinal height of the inferotemporal, inferonasal, superotemporal, and superonasal sectors and age-adjusted mean deviation of their respective anatomically matched visual field region. In addition, peripapillary retinal height was more highly correlated with ageadjusted mean deviation than disc rim area in glaucoma patients. CONCLUSIONS: We found that peripapillary height, particularly in the temporal region, showed the strongest association with visual field loss in glaucoma patients.

A new objective digital computerized vision screening system.

PURPOSE: Fewer than 40% of children in the crucial younger-than-4 age group are evaluated for visual problems by pediatricians. This is due to impracticality from either a clinical or practice efficiency standpoint. Current photoscreening methods require trained readers and suffer from significant subjectivity and interobserver variability. We report a cross-sectional, double-masked study using new digital imaging with objective, automated, computerized image analysis. METHODS: Two-hundred six children aged 9 months to 16 years were prospectively studied in a University-based pediatric ophthalmology practice. Images were taken by volunteers with a modified digital camera which, when downloaded, were analyzed within 35 seconds by new image analysis software. The analysis was compared to a masked review of a complete pediatric ophthalmic exam. RESULTS: Overall agreement between physician and the objective computerized analysis was 86.9%. Positive predictive value was 91%, sensitivity was 89%, and specificity was 83%. CONCLUSIONS: This automated digital imaging screening system eliminates human bias and provides accurate and immediate results. The system requires no special expertise.

[Correlation between ICG angiography verified networks in uveal melanomas and rate of tumor regression after brachytherapy]. / Zusammenhang von ICG-angiographisch nachgewiesenen "Networks" uvealer Melanome und Tumorrückbildungsgeschwindigkeit nach Brachytherapie.

INTRODUCTION: The post-irradiation regression rate of uveal melanomas is a prognostically significant factor for the development of metastases. Other predictive factors for metastases are histological networks which are imagable with confocal ICG angiography. The purpose of this study was to evaluate a possible connection of networks in the ICGA and tumor regression rates. METHODS: We compared the post-irradiation regression rates (as %) in 20 patients 1 year after brachytherapy with networks identified in pre-treatment indocyanine green angiography (ICGA). The ICG angiography was performed before irradiation, 10 patients were irradiated with Ru-106 and 10 were irradiated with Id-125. RESULTS: The mean preoperative maximum apical height was 5.2 mm [SD: 1.5 mm; Ru106 group: 5.7 mm (SD: 1.0 mm); Id-125 group: 5.0 mm (SD: 1.9 mm)]. In 11 patients (55%) (Ru-106: 5; Id-125: 6) we found networks in the preoperative ICG. The mean regression rate in tumors with networks was 51.3% (SD: 14.7%) and 28.0% (SD: 16.4%) in the group without networks. The difference between both groups was statistically significant (p = 0.003, Mann-Whitney test). No statistically significant difference in the regression rates was found between the two groups of brachytherapy Ru-106 and Id-125 (p = 0.165, Mann-Whitney test). DISCUSSION: Highly proliferative tumors are known to be more sensitive to irradiation. This may be one reason why tumors with a rapid post-irradiation regression are the more aggressive ones with regard to later development of metastases. Histopathological networks are also known to be a strong indication of more aggressive, metastasizing tumors. These networks are also imagable in ICG angiography. Our observation emphasizes a connection between networks in ICG angiography and regression rates of uveal melanomas after brachytherapy.

Visual function assessment in simulated real-life situations in patients with age-related macular degeneration compared to normal subjects.

PURPOSE: To evaluate visual function variations in eyes with age-related macular degeneration (AMD) compared to normal eyes under different light/contrast conditions using a time-dependent visual acuity testing instrument, the Central Vision Analyzer (CVA). METHODS: Overall, 37 AMD eyes and 35 normal eyes were consecutively tested with the CVA after assessing best-corrected visual acuity (BCVA) using ETDRS charts. The CVA established visual thresholds for three mesopic environments (M1 (high contrast), M2 (medium contrast), and M3 (low contrast)) and three backlight-glare environments (G1 (high contrast, equivalent to ETDRS), G2 (medium contrast), and G3 (low contrast)) under timed conditions. Vision drop across environments was calculated, and repeatability of visual scores was determined. RESULTS: BCVA significantly reduced with decreasing contrast in all eyes. M1 scores for BCVA were greater than M2 and M3 (P<0.001); G1 scores were greater than G2 and G3 (P<0.01). BCVA dropped more in AMD eyes than in normal eyes between M1 and M2 (P=0.002) and between M1 and M3 (P=0.003). In AMD eyes, BCVA was better using ETDRS charts compared to G1 (P<0.001). The drop in visual function between ETDRS and G1 was greater in AMD eyes compared to normal eyes (P=0.004). Standard deviations of test-retest ranged from 0.100 to 0.139 logMAR. CONCLUSION: The CVA allowed analysis of the visual complaints that AMD patients experience with different lighting/contrast time-dependent conditions. BCVA changed significantly under different lighting/contrast conditions in all eyes, however, AMD eyes were more affected by contrast reduction than normal eyes. In AMD eyes, timed conditions using the CVA led to worse BCVA compared to non-timed ETDRS charts.

Imaging vitreomacular interface abnormalities in the coronal plane by simultaneous combined scanning laser and optical coherence tomography.

AIM: To describe vitreoretinal imaging of eyes with vitreomacular abnormalities using high-resolution coronal-plane optical coherence tomography (OCT) scanning combined with simultaneous scanning laser ophthalmoscope (SLO) imaging. METHODS: A SLO-OCT (OTI, Canada) was used to scan 835 eyes in 736 patients with vitreomacular interface abnormalities including epiretinal membranes, macular hole, incomplete posterior vitreous detachment, vitreomacular traction syndromes and diabetic and cystoid macular oedema in a retrospective study. The longitudinal-B scan images and the transverse -C scan images in the coronal plane were used to describe vitreomacular interface abnormalities. The SLO-OCT simultaneously produces a confocal image of the retina. RESULTS: The longitudinal "B" scan and en-face "C" scan images allowed identification of tractive forces of epiretinal membrane, contour of the hyaloid membrane and changes in inner retinal surface. A simultaneously obtained OCT scan and SLO image of the fundus offered exact co-localisation of retinal structures and vitreomacular interface abnormalities. CONCLUSION: Scanning the vitreomacular interface by using combined OCT and SLO enables the visualisation and better understanding of various vitreomacular interface abnormalities, due to the ability to colocalise pathology on OCT with retinal vascular landmarks and the ability to visualise pathology from a new perspective, coronal plane parallel to retinal surface.

Colour versus grey-scale display of images on high-resolution spectral OCT.

AIM: To determine whether colour or grey-scale images from high-resolution spectral optical coherence tomography (OCT) are superior in visualising clinically important details of retinal structures. METHODS: Patients with macular pathologies were imaged using spectral OCT (OTI, Toronto, Canada). Two reviewers independently analysed the retinal structures and pathologies and graded them on a four-point scale on the basis of the visibility. A third reviewer masked to the results then reviewed images where there was a different score for colour versus grey scale. RESULTS: Statistical analysis showed the grey-scale image to be significantly better in visualising the details of epiretinal membrane, photoreceptor and retinal pigment epithelium layer morphology than the colour scale image (p = 0.00088-0.0006). In 16.17% of eyes, the colour image led to the false impression of photoreceptor disruption. CONCLUSION: Grey-scale images are qualitatively superior to the colour-scale images on high-resolution spectral OCT. Colour images can be misleading, as the displayed colours are false colours, and the observer may see a dramatic change in colour and interpret that as a large change in the OCT reflectivity.

Comparison of laser ray-tracing and skiascopic ocular wavefront-sensing devices.

PURPOSE: To compare two wavefront-sensing devices based on different principles. METHODS: Thirty-eight healthy eyes of 19 patients were measured five times in the reproducibility study. Twenty eyes of 10 patients were measured in the comparison study. The Tracey Visual Function Analyzer (VFA), based on the ray-tracing principle and the Nidek optical pathway difference (OPD)-Scan, based on the dynamic skiascopy principle were compared. Standard deviation (SD) of root mean square (RMS) errors was compared to verify the reproducibility. We evaluated RMS errors, Zernike terms and conventional refractive indexes (Sph, Cyl, Ax, and spherical equivalent). RESULTS: In RMS errors reading, both devices showed similar ratios of SD to the mean measurement value (VFA: 57.5+/-11.7%, OPD-Scan: 53.9+/-10.9%). Comparison on the same eye showed that almost all terms were significantly greater using the VFA than using the OPD-Scan. However, certain high spatial frequency aberrations (tetrafoil, pentafoil, and hexafoil) were consistently measured near zero with the OPD-Scan. CONCLUSION: Both devices showed similar level of reproducibility; however, there was considerable difference in the wavefront reading between machines when measuring the same eye. Differences in the number of sample points, centration, and measurement algorithms between the two instruments may explain our results.