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PubMed1997

A new in vitro test method for calcification of bioprosthetic heart valves.

To investigate the calcification behavior of different bioprosthetic heart valves and verify possible hypotheses of the etiology of valve calcification, an accelerated pulse tester for bioprostheses was developed, whereby up to ten valves can be tested under identical test conditions. Each valve was mounted in a separate compartment on a piston and cyclically moved through a calcifying solution at frequencies of up to 800/min at 37 degrees C: An appropriate calcifying solution was evaluated by incubation tests of bovine and porcine tissue. Calcification was confirmed by measuring Ca and phosphate depletion by atomic absorption spectroscopy, von Kossa staining, EDAX, and microradiography. The first tests were successfully carried out on porcine valves that had been nondestructively assessed for tissue/stress anomalies by holographic interferometry prior to the calcification test. The tests showed that 75% of irregular fringe pattern areas corresponded to the calcification areas.

Animals↗
PubMed1997

[Effect of smoking on blood rheology].

The aim of this study was to compare the effects of cigarette smoking on biologic and rheologic tests, chiefly on the red blood cells (RBC) in measuring the deformability by the Cell Transit Analyser (CTA) and their aggregation by using an ultrasonic interferometry method based on A-mode echography allowed for the measurement of the accumulation rate of particles in a solid plate which is related to their sedimentation rate (Echo-Cell). Nine male smoker subjects with a high nicotine addiction measured by Fagerström questionnaire (> 8) and level of carbon monoxide (CM) in the breathed out air (> 20 ppm), have been compared with ten healthy no-smoker volunteers (CM < 3 ppm). One smoker has been eliminated of statistic evaluations because his glucose level showed a diabetes (10.5 mmol/l). A nailfold capillaroscopy performed in all subjects has eliminated the patterns of latent vasculitis or scleroderma. RBC and platelets counts, hemoglobin, ionogram, gamma GT, ASAT, ALAT, uric acid, total cholesterol and glucose levels were not significantly different between the two groups. On the other hand, in the smoker group, white blood cells count, serum triglycerides and especially fibrinogen values were higher than in the non-smoker's group. RBC sedimentation rate was normal in the two groups but was higher in smoker's group too. Without consumption of alcohol, the mean RBC volume was more important in smokers (91.9 +/- 1.2 versus 87.5 +/- 0.4, p = 0.003). Rheologic tests were more pathologic in smokers. The transit time or RBC by CTA was longer than in control group (1.6 ms +/- 0.02 versus 1.2 +/- 0.05, p = 0.0003). Echo-Cell technic showed a number and size of RBC aggregates more important with a rate of speed of accumulation higher than in the control group. These results demonstrated the toxic effects of smoking alone on blood toward a propensity for thrombotic status.

Adult↗
PubMed1997

[Interconnection of parameters of the mitochondrial and myofibrillar apparatus of cardiomyocytes and ploidy and hypertrophy in certain mammalian species, differing in body mass].

Using cytophotometry and interferometry, ploidy levels and dry weights were determined in cardiac atrium and ventricle myocytes in various mammalian species. Besides, in the same species, using electron microscopy and image analysis, myofibril volume density (MFVD) and mitochondrial volume density (MTVD), as well as the total length of internal mitochondrial membranes (IMM) per cell area unit were measured. The total of 14 mammalian species were studied, with approximately 100,000-fold interspecies differences in the body weight. The dry weights of the left ventricle myocytes in different mammalian species have been shown to vary from 3660 +/- 127 to 8890 +/- 160 pg. Somewhat smaller were the right ventricle myocytes; their dry weight varied from 3598 +/- 134 to 8189 +/- 160 pg. The atrium myocytes were significantly smaller than the ventricle myocytes in all the mammalian species studied. The lowest dry weight of the left atrium myocytes was revealed in the mouse (2415 +/- 96 pg), while the largest weights of the left atrium myocytes were found in the pig (5530 +/- 138 pg). Myocytes of the right atrium, with their mean dry weights in different species varying from 2379 +/- 93 (in the mouse) to 5123 +/- 124 pg (in the pig), were the smallest among all cardiac chamber myocytes. The data obtained indicate that differences in size between the ventricles and atria in mammals are owing predominantly to differences in the number of cardiomyocytes in different parts of the heart rather than to the size of these cells. The dry weight ratio between the right and left ventricle myocytes in various mammalian species was, on average, 0.937 +/- 0.02, and between the right and left atrium myocytes 0.938 +/- 0.04. This ratio between the left atrium and left ventricle myocytes was 0.717 +/- 0.03 and that between the right atrium and right ventricle was 0.722 +/- 0.02. The data obtained indicate that the ratios of cardiomyocyte sizes in different heart parts are rather stable parameters in the mammalian evolution. The mean ploidy levels in myocytes in different parts of the heart corresponded to the mean sizes of the cells. In all the species studied in this work, the ploidy of myocytes of the right ventricle was lower, on average, by 7% compared to myocytes of the left ventricle. The atrial cardiomyocytes had a markedly lower ploidy than the ventricular cardiomyocytes, the myocyte ploidy levels in the left atrium being in all the species higher than in the right atrium. In spite of a higher ploidy level in the ventricular than in the atrial myocytes, this difference in ploidy was less pronounced than the corresponding difference in the myocyte sizes in the same heart parts. In the majority of mammalian species studied, myocyte polyploidization in different parts of the heart combined two ways promoting the increase in the number of genomes in the cells: (1) acytokinetic mitoses in binuclear and multinuclear cells, i. e. mitotic divisions of diploid nuclei without cytoplasm division; in this case no increase in the tissue cell number occurred, (2) alternation of acytokinetic mitoses in mononuclear cells and of bimitoses in binuclear cells; in this case tissue cells increased in number. The ratio of these two ways of polyploid cell formation differed in various species. The former way appeared to be the only in the nutria and horse, whereas the latter way was found in the shrew and arctic fox. In pigs, whose polyploid cardiomyocytes are also formed mainly through the increase in number of diploid cell nuclei, the multinuclear cardiomyocytes contained, apart from diploid nuclei, a small amount of polyploid 4c and 8c nuclei. The formation of such cells is due presumably to the two mechanisms: the asynchronous DNA synthesis in one of the nuclei in a multinuclear cell, and the subsequent incomplete polyploidizing mitosis. (ABSTRACT TRUNCATED)

Animals↗
PubMed1976

[Holography and the possibility of its use in applied anatomy].

The article deals with some methods of holography (holograms with inclined reference beam, in three-dimensional media after Yu. N. Denisiuk, holographic interferometry) as applied to studying anatomical objects. Approximate optical schemes and photographic copies of holograms of separate objects are presented. The comparative analysis of different methods enabled the authors to recommened for practical use the method of obtaining holograms in three-dimensional media for documentation of anatomical investigation and storage of information, holographic method of obtaining contour maps of the surface for quantitative characteristics of individual properties of the object and the method of double exposure for studying static and dynamic deformities.

Anatomy↗
PubMed2000

Assessment of retinal nerve fiber layer internal reflectivity in eyes with and without glaucoma using optical coherence tomography.

OBJECTIVE: To assess the internal reflectivity of the retinal nerve fiber layer in normal, ocular hypertensive, and glaucomatous eyes using optical coherence tomography. METHODS: All patients underwent complete ophthalmic examination and achromatic automated perimetry. Intraocular pressure was 21 mm Hg or less for low-tension glaucoma and normal eyes and at least 25 mm Hg on 2 separate occasions in ocular hypertensive and high-tension glaucoma eyes. All glaucomatous eyes had characteristic glaucomatous optic neuropathy and associated achromatic automated perimetry defect. Relative retinal nerve fiber layer internal reflectivity was measured on optical coherence tomography images using a software program of our own design. RESULTS: We enrolled 98 eyes (19 normal, 34 ocular hypertensive, 17 high-tension glaucoma, and 28 low-tension glaucoma). Relative internal reflectivity was less in eyes with glaucoma than in normal (P<.001, t test) and ocular hypertensive eyes (P<.001, t test). There was no difference in relative internal reflectivity between normal and ocular hypertensive eyes (P =.32) and between eyes with high-tension glaucoma and low-tension glaucoma (P =.43). Internal reflectivity correlated with mean deviation on achromated automatic perimetry (r(2) = 0.49, P<.001, quadratic regression analysis). CONCLUSION: Relative retinal nerve fiber layer internal reflectivity may provide useful information about the extent of retinal nerve fiber layer injury in glaucoma. Arch Ophthalmol. 2000;118:1044-1047

Adult↗
PubMed2000

Watzke-Allen slit beam test in macular holes confirmed by optical coherence tomography.

OBJECTIVE: To examine the role, validity, and interpretation of Watzke-Allen slit beam testing in patients with idiopathic senile macular holes. METHODS: Thirty-seven consecutive patients with 40 full-thickness macular holes, confirmed on optical coherence tomography, were prospectively recruited. The Watzke-Allen slit beam test was used centrally and on the rim of the macular hole in both vertical and horizontal orientations. RESULTS: In 24 eyes, the beam was reported as thinned in both vertical and horizontal orientations when placed directly over the center of the macular hole. In 9 eyes, the Watzke-Allen slit was reported as broken in both vertical and horizontal orientations. In 6 eyes, the beam was reported as broken in one orientation and thinned in the other. In 1 eye, the beam was reported as kinked but not thinned or broken. When the beam was placed on the edge of the macular hole, all patients reported a displacement or bowing of the beam away from the center of the hole. CONCLUSIONS: These findings confirm tangential traction of photoreceptors from a central foveal dehiscence as the causative mechanism in the development of the majority of macular holes. Careful interpretation of the Watzke-Allen sign may offer a technique for preoperatively determining visual prognosis. Arch Ophthalmol. 2000;118:1059-1063

Aged↗
PubMed2001

Initial stages of posterior vitreous detachment in healthy eyes of older persons evaluated by optical coherence tomography.

OBJECTIVE: To promote understanding of the development of posterior vitreous detachment (PVD) in healthy eyes using optical coherence tomography (OCT). METHODS: We studied 209 eyes of 209 healthy volunteers (165 men and 44 women; mean age, 52.3 years [range, 31-74 years]). In addition to biomicroscopy and ophthalmoscopy, OCT was performed to obtain high-resolution cross-sectional images of the vitreoretinal interface in the posterior fundus. RESULTS: The condition of the posterior vitreoretinal interface was classified as 1 of 5 stages, according to biomicroscopic findings and OCT images relative to discrete linear signals indicating a detached posterior vitreous face: stage 0, no PVD (61 eyes [29.2%]); stage 1, incomplete perifoveal PVD in up to 3 quadrants (100 eyes [47.8%]); stage 2, incomplete perifoveal PVD in all quadrants, with residual attachment to the fovea and optic disc (26 eyes [12.4%]); stage 3, incomplete PVD over the posterior pole, with residual attachment to the optic disc (4 eyes [1.9%]); or stage 4, complete PVD identified with biomicroscopy, but not with OCT because of instrument limitations (18 eyes [8.6%]). Stage 1, 2, and 3 incomplete PVD without subjective symptoms was not recognizable on contact lens biomicroscopy. There was a significant age-related progression in the condition of the vitreoretinal interface from stage 0 to stage 4. The superior quadrant was usually the initial site of incomplete PVD. CONCLUSIONS: Optical coherence tomography demonstrates that healthy human eyes have incomplete or partial PVD beginning as early as the fourth decade of life. Age-related PVD occurs initially as a focal detachment in the perifovea of 1 quadrant, with persistent attachment to the fovea and optic nerve head, with a predilection for the superior quadrant. It extends its range slowly for years and eventually results in complete PVD, associated with release of vitreopapillary adhesion.

Adult↗
PubMed2001

Discriminating between normal and glaucomatous eyes using the Heidelberg Retina Tomograph, GDx Nerve Fiber Analyzer, and Optical Coherence Tomograph.

OBJECTIVE: To compare the ability of 3 instruments, the Heidelberg Retina Tomograph (HRT), the GDx Nerve Fiber Analyzer (GDx), and the Optical Coherence Tomograph (OCT), to discriminate between healthy eyes and eyes with early to moderate glaucomatous visual field loss. SUBJECTS AND METHODS: Forty-one patients with early to moderate glaucomatous visual field loss and 50 healthy subjects were included in the study. The HRT, GDx, and OCT imaging and visual field testing were completed on 1 eye from each subject within a 6-month interval. Statistical differences in sensitivity at fixed specificities of 85%, 90%, and 95% were evaluated. In addition, areas under the receiver operating characteristic (ROC) curve were compared. RESULTS: No significant differences were found between the area under the ROC curve and the best parameter from each instrument: OCT thickness at the 5-o'clock inferior temporal position (mean +/- SE, 0.87 +/- 0.04), HRT mean height contour in the nasal inferior region (mean +/- SE, 0.86 +/- 0.04), and GDx linear discriminant function (mean +/- SE, 0.84 +/- 0.04). Twelve HRT, 2 GDx, and 9 OCT parameters had an area under the ROC curve of at least 0.81. At a fixed specificity of 90%, significant differences were found between the sensitivity of OCT thickness at the 5-o'clock inferior temporal position (71%) and parameters with sensitivities less than 52%. Qualitative assessment of stereophotographs resulted in a sensitivity of 80%. CONCLUSION: Although the area under the ROC curves was similar among the best parameters from each instrument, qualitative assessment of stereophotographs and measurements from the OCT and HRT generally had higher sensitivities than measurements from the GDx.

Adult↗
PubMed2001

Reproducibility of retinal mapping using optical coherence tomography.

OBJECTIVE: To assess the reproducibility of retinal thickness measurement using commercially available mapping software of optical coherence tomography (OCT). METHODS: Six radial scans, 6 mm long and centered on the fixation point, were performed on 10 eyes of 10 healthy volunteers and 10 eyes of 10 diabetic patients with clinically significant macular edema. Retinal thickness was measured automatically using the mapping software of OCT in the 9 macular Early Treatment Diabetic Retinopathy Study areas and in a central area 500 microm in diameter. Measurement reproducibility was tested by means of 3 series of scans performed by 2 different observers on 2 different days. Results were assessed by their repeatability and intraclass correlation coefficients (ICCs). RESULTS: In healthy subjects, intraobserver, interobserver, and intervisit reproducibility of retinal thickness measurements were excellent, with a repeatability coefficient of less than 7 microm and ICCs of greater than 0.89. In diabetic patients, the repeatability coefficient was less than 21 microm in all areas of the macula except one, with an ICC of greater than 0.98. Relative variations in measurements were small in both healthy and diabetic subjects, with reproducibilities of +/- 5% and +/- 6%, respectively. CONCLUSION: Retinal mapping software of OCT allows reproducible measurement of retinal thickness in both healthy subjects and diabetic patients with macular edema.

Adult↗
PubMed2001

Real-time optical coherence tomography of the anterior segment at 1310 nm.

BACKGROUND: Recent advances in high-speed scanning technology have enabled a new generation of optical coherence tomographic (OCT) systems to perform imaging at video rate. Here, a handheld OCT probe capable of imaging the anterior segment of the eye at high frame rates is demonstrated for the first time. OBJECTIVE: To demonstrate real-time OCT imaging of anterior segment structures. DESIGN: Survey of anterior segment structures in normal human subjects. SETTING: Laboratory. MAIN OUTCOME MEASURES: Achieving real-time imaging of the anterior segment, satisfactory image quality, and convenience of a handheld probe. RESULTS: Optical coherence tomographic imaging of the anterior segment of the eyes of human subjects was performed using 1310-nm wavelength light with an image rate of 8 frames per second. Imaging trials demonstrated clear resolution of corneal epithelium and stroma, sclerocorneal junction, sclera, iris pigment epithelium and stroma, and anterior lens capsule. The anterior chamber angle was clearly visualized. Limited imaging of the ciliary body was performed. Real-time imaging of pupillary constriction in response to light stimulus was also performed. CONCLUSION: High-speed OCT at 1310-nm wavelength is a potentially useful technique for noninvasive assessment of anterior segment structures. CLINICAL RELEVANCE: Our results suggest that real-time OCT has potential applications in glaucoma evaluation and refractive surgery.

Anterior Chamber↗
PubMed2001

Optical coherence tomography demonstrates subretinal macular edema from papilledema.

OBJECTIVE: To evaluate macular changes in eyes with papilledema from increased intracranial pressure using optical coherence tomography (OCT). METHODS: Fifty-five patients with papilledema seen during 1998 and 1999 were studied with OCT of the optic nerve and retinal nerve fiber layer. Nineteen of these also had OCT of the macula during periods of acute, subacute, or recurrent papilledema and were evaluated in detail for this report. RESULTS: Seven patients had OCT evidence of subretinal fluid involving the macula. All had some reduction in visual acuity. The subretinal fluid appeared to arise from the peripapillary region, and all showed some improvement in central vision as the fluid resolved. CONCLUSIONS: Subretinal fluid accumulations can cause decreased visual acuity in patients with papilledema. Optical coherence tomography can demonstrate subretinal fluid and can be used to follow the course of this important visual complication of papilledema.

Acute Disease↗
PubMed2001

Progressive change of optical coherence tomography scans in retinal degeneration slow mice.

OBJECTIVE: To study whether optical coherence tomography (OCT) scans correlate retinal histologic findings with the progression of retinal degeneration in retinal degeneration slow (rds) mice. METHODS: Sensory retinal thickness (SRT) and outer retinal thickness (ORT), representing photoreceptor cell layer, in temporal retina at a distance 1 to 2 disc diameters from the optic disc were measured using scan profile in OCT from 6 healthy mice (16 weeks old) and 2-week-old (n = 6), 6-week-old (n = 4), and 60-week-old (n = 2) rds mice. Histologic sections were obtained from Epon-embedded retinas from the corresponding location. RESULTS: Cross-sectional OCT images correlated to the corresponding histologic sections in each mouse. Both SRT and ORT of 2-week-old rds mice (150 +/- 4 microm and 28 +/- 4 microm, respectively) lacking photoreceptor outer segments were already shorter than those of healthy mice (174 +/- 5 microm and 37 +/- 6 microm, respectively) (P<.001). In 6-week-old mice, microscopic findings revealed a decreased number of nuclei in the outer nuclear layer, and SRT and ORT (136 +/- 2 microm and 20 +/- 1 microm, respectively) were shorter than those of 2-week-old rds mice (P<.001). The SRT of 60-week-old rds mice without a photoreceptor layer was remarkably reduced (120 +/- 7 microm), and no ORT could be measured. CONCLUSION: Our findings suggest a possible relationship between SRT and ORT, as measured by OCT, and histologic change in retinal degenerative diseases. CLINICAL RELEVANCE: The quantitative analysis obtained by OCT scans may have potential to detect progressive change in degenerative retina and may be used in studying human retinal degeneration.

Animals↗
PubMed2002

Partial antagonism of endothelin 1-induced vasoconstriction in the human choroid by topical unoprostone isopropyl.

BACKGROUND: There is increasing evidence that reduced ocular blood flow plays a role in the pathogenesis of glaucoma. In patients with normal-tension glaucoma, ocular blood flow abnormalities may be associated with dysfunction of the endothelin 1 (ET-1) regulation system. OBJECTIVE: To test the hypothesis that unoprostone, a topical docosanoid, may affect ET-1--induced vasoconstriction in the human choroid. METHODS: In a placebo-controlled, randomized, double-masked, 2-way crossover design, ET-1 (2.5 ng/kg per minute for 150 minutes) was administered intravenously to 24 healthy individuals. Thirty minutes after the start of ET-1 infusion, 1 drop of unoprostone or placebo was instilled into the right eye. After another 30 minutes, 2 drops of unoprostone or placebo was topically administered. This procedure was continued and the dose was increased further until 4 drops of unoprostone or placebo was reached. Subfoveal and pulsatile choroidal blood flow were assessed using laser Doppler flowmetry and laser interferometric measurement of fundus pulsation amplitude, respectively. RESULTS: Administration of exogenous ET-1 decreased choroidal blood flow (mean +/- SEM, 17% +/- 2%; P<.001) and fundus pulsation amplitude (mean +/- SEM, 19% +/- 2%; P<.001). This effect was significantly blunted when topical unoprostone was coadministered (mean +/- SEM decrease in choroidal blood flow, 7% +/- 2%; P =.04 vs. placebo; mean +/- SEM decrease in fundus pulsation amplitude, 12% +/- 2%; P<.001 vs. placebo). CONCLUSION: There is a functional antagonism between ET-1 and topical unoprostone in the choroidal vasculature. CLINICAL RELEVANCE: Our findings of a functional antagonism between ET-1 and topical unoprostone in the choroidal vasculature may be important in vascular eye diseases associated with increased ET-1.

Administration, Topical↗
PubMed2002

Decreased visual acuity associated with cystoid macular edema in neovascular age-related macular degeneration.

OBJECTIVE: To determine the prevalence and visual significance of cystoid macular edema (CME) in eyes with subfoveal neovascular age-related macular degeneration using optical coherence tomography (OCT). MATERIALS AND METHODS: The medical records of 61 consecutive patients initially seen with nondisciform subfoveal neovascular age-related macular degeneration were retrospectively reviewed. All patients underwent fluorescein angiography and OCT imaging. Eyes with intraretinal hyporeflective spaces in the macula in the OCT images were considered to have CME. RESULTS: Twenty-eight (46%) of 61 eyes demonstrated CME on the OCT images. The presence of CME and increased foveal thickness correlated with decreased visual acuity, but not with the duration of symptoms. Twenty-six (93%) of 28 eyes with CME contained classic choroidal neovascularization, whereas 16 (48%) of 33 eyes without CME contained classic choroidal neovascularization. CONCLUSIONS: Cystoid macular edema is a common finding in patients with choroidal neovascularization associated with age-related macular degeneration. The presence of CME and foveal thickening is associated with worse visual acuity in these patients. Cystoid macular edema is more common with choroidal neovascularization containing classic component. The OCT is a useful test to detect the presence of CME in these patients since CME may be difficult to identify on fluorescein angiogram.

Aged↗
PubMed2002

Transscleral optical coherence tomography: a new imaging method for the anterior segment of the eye.

OBJECTIVE: To present a new imaging method for the anterior segment of the eye. METHODS: Transscleral optical coherence tomographic images were generated in healthy volunteers using a slitlamp-adapted prototype equipped with a superluminescence diode with an infrared wavelength of 1310 nm. RESULTS: The optical coherence tomographic system used allowed penetration of human sclera in vivo and high-resolution, cross-sectional imaging of the anterior chamber angle and the ciliary body. CONCLUSION: The 1310-nm optical coherence tomographic image shows a significant potential as a noninvasive diagnostic tool for the anterior segment of the eye.

Anatomy, Cross-Sectional↗
PubMed2003

Macular thickness changes in glaucomatous optic neuropathy detected using optical coherence tomography.

OBJECTIVE: To correlate macular thickness and retinal nerve fiber layer (RNFL) thickness in normal and glaucomatous eyes using optical coherence tomography. METHODS: Complete examination, automated achromatic perimetry, and optical coherence tomography of the peripapillary RNFL and macula were performed. Exclusion criteria were visual acuity of less than 20/40, diseases other than glaucoma, and unreliable automated achromatic perimetry. Macular thickness measurements were generated using 6 radial optical coherence tomographic scans (5.9 mm) centered on the fovea, and mean and quadrantic macular thickness values were calculated. RESULTS: Fifty-nine eyes of 59 patients (29 normal and 30 glaucomatous) were enrolled (mean +/- SD age, 56.7 +/- 20.3 years; range, 20-91 years). All eyes with glaucoma had associated visual field loss (mean +/- SD mean defect, -8.4 +/- 5.8 dB). Mean macular thickness was significantly associated with visual field mean defect (R2 = 0.47; P<.001), pattern standard deviation (R2 = 0.32; P<.001), and mean RNFL thickness (R2 = 0.38; P<.001). In glaucomatous eyes with visual field loss localized to 1 hemifield (n = 11), mean +/- SD macular thickness in the quadrant associated with the field defect (277 +/- 28 micro m) was significantly less (P =.005) than in the unaffected quadrant (286 +/- 27 micro m). Mean RNFL thickness in the affected quadrant (89 +/- 53 micro m) was significantly thinner (P =.009) than in the unaffected quadrant (121 +/- 39 micro m). MAIN OUTCOME MEASURES: Mean total and quadrantic macular and RNFL thickness measurements. CONCLUSIONS: Macular thickness changes are well correlated with changes in visual function and RNFL structure in glaucoma and may be a surrogate indicator of retinal ganglion cell loss.

Adult↗