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Translational Vision Science &... Oct 2021To evaluate a region of interest (ROI) method of analyzing anterior segment optical coherence tomography (AS-OCT) corneal densitometry (CD) in the setting of Descemet...
PURPOSE
To evaluate a region of interest (ROI) method of analyzing anterior segment optical coherence tomography (AS-OCT) corneal densitometry (CD) in the setting of Descemet membrane endothelial keratoplasty (DMEK) dehiscence.
METHODS
Retrospective chart review of eyes that underwent (1) DMEK for Fuchs dystrophy (2) between 2018 to 2020 with (3) a partial DMEK dehiscence on AS-OCT, (4) involvement of only one side of the graft, (5) high-quality corneal AS-OCT scan, and (6) location of dehiscence within the central 5.5 mm of the cornea. Image analysis of the ROIs with ImageJ compared the total edematous area, mean stromal CD, and ratio of anterior-to-posterior (A/P) stromal CD for regions of DMEK dehiscence compared to the contralateral side with an attached DMEK graft. Control regions (with no dehiscence) and postdehiscence resolution images were also analyzed.
RESULTS
Seventy sectors of the 21 images from 21 eyes with DMEK dehiscence were included. Compared to the contralateral side, regions of DMEK dehiscence had larger total areas (P < 0.0001), lower mean stromal CD (P = 0.0003), and higher A/P stromal CD (P < 0.0001). All control regions and postdehiscence resolution images did not show any significant differences compared to the contralateral sides.
CONCLUSIONS
This technique to analyze multiple ROIs on AS-OCT can be useful to evaluate CD of specific regions of corneal pathology. Lower mean stromal CD and higher A/P stromal CD may specify corneal edema.
TRANSLATIONAL RELEVANCE
Analyzing CD via multiple specific ROIs may be more suitable than measuring the CD of the full cornea and has broader applications extending to other corneal pathologies.
Topics: Densitometry; Descemet Membrane; Descemet Stripping Endothelial Keratoplasty; Retrospective Studies; Tomography, Optical Coherence; Visual Acuity
PubMed: 34609477
DOI: 10.1167/tvst.10.12.6 -
Atherosclerosis Jul 2013Abnormalities in retinal vessels are frequent, but its association with findings in other vascular sites has been scarcely investigated. This study aimed to examine the...
OBJECTIVE
Abnormalities in retinal vessels are frequent, but its association with findings in other vascular sites has been scarcely investigated. This study aimed to examine the association between ultrasound-measured carotid intima-media thickness (IMT) and retinal arteriolar and venular diameters, in hypertensive patients.
METHODS
In this cross-section study, 173 hypertensive patients had both retinography taken and digitized to determine vessel diameters by an edge-detecting computerized method and carotid ultrasound for semi-automated carotid IMT measurement. The association between the mean common carotid IMT and retinal arterioles and venules diameters was assessed by using multiple linear regression models.
RESULTS
The mean (±SD) arteriolar and venular diameters were 102. 8 (±11.6) μm and 128.9 (±15.5) μm, respectively, and common carotid IMT was 0.87 (±0.19) mm. A significant and independent association was demonstrated for carotid IMT and retinal arteriolar caliber (adjusted β -0.245, p = 0.001) and for carotid IMT and retinal venular caliber (adjusted β 0.191, p = 0.009) after controlling for age, gender, systolic blood pressure, total cholesterol and HDL (high-density lipoprotein) cholesterol, prior cardiovascular disease, carotid plaque and the retinal fellow vessel.
CONCLUSION
In patients with hypertension, carotid intima-media thickness, a marker of macrovascular damage, is significantly and independently associated with microvascular damage, determined by retinal arteriolar and venular calibers.
Topics: Aged; Arterioles; Carotid Artery, Common; Carotid Intima-Media Thickness; Cross-Sectional Studies; Densitometry; Female; Humans; Hypertension; Linear Models; Male; Middle Aged; Observer Variation; Radiography; Reproducibility of Results; Retinal Vessels; Risk Factors; Venules
PubMed: 23664203
DOI: 10.1016/j.atherosclerosis.2013.04.019 -
The American Journal of Clinical... Mar 2010Hydrometry and densitometry are widely used to assess pediatric body composition due to their ease of application. The accuracy of these techniques depends on the...
BACKGROUND
Hydrometry and densitometry are widely used to assess pediatric body composition due to their ease of application. The accuracy of these techniques depends on the validity of age- and sex-specific constant values for lean tissue hydration or density. Empirical data on these constants, and their variability between individuals, are lacking.
OBJECTIVES
The objectives were to measure lean tissue hydration and density in a large sample of children and adolescents and to derive prediction equations.
DESIGN
Body composition was measured in 533 healthy individuals (91% white) aged 4-23 y by using the 4-component model. Age- and sex-specific median values for hydration and density were obtained by using the LMS (lambda, mu, sigma) method. Regression analysis was used to generate prediction equations on the basis of age, sex, and body mass index SD score (BMI SDS). Values were compared with those in previously published predictions.
RESULTS
Age-associated changes in density and hydration differed between the sexes. Compared with our empirical values, use of published values resulted in a mean bias of 2.1% fat (P < 0.0001). Age, sex, and BMI SDS were all significant predictors of lean tissue hydration and density. With adjustment for age and sex, hydration was higher, and density lower, in higher-BMI SDS individuals.
CONCLUSIONS
The chemical maturation of lean tissue is not a linear process and proceeds differently in males and females. Previously published reference values are inaccurate and induce clinically significant bias in percentage fat. New empirical reference values are provided for use in pediatric hydrometry and densitometry. Further research that extends to cover nonwhite ethnic groups is needed.
Topics: Adipose Tissue; Adolescent; Age Factors; Body Composition; Body Fluid Compartments; Body Mass Index; Child; Child, Preschool; Densitometry; Female; Humans; Male; Muscle, Skeletal; Obesity; Prevalence; Reference Values; Sex Factors; Water; Young Adult
PubMed: 20089731
DOI: 10.3945/ajcn.2009.28428 -
Vision Research Oct 1999To test the feasibility of scanning laser densitometry with a modified Rodenstock scanning laser ophthalmoscope (SLO) to measure the rod and cone photopigment...
PURPOSE
To test the feasibility of scanning laser densitometry with a modified Rodenstock scanning laser ophthalmoscope (SLO) to measure the rod and cone photopigment distribution in patients with retinal diseases.
METHODS
Scanning laser densitometry was performed using a modified Rodenstock scanning laser ophthalmoscope. The distribution of the photopigments was calculated from dark adapted and bleached images taken with the 514 nm laser of the SLO. This wavelength is absorbed by rod and cone photopigments. Discrimination is possible due to their different spatial distribution. Additionally, to measure retinal sensitivity profiles, dark adapted two color static perimetry with a Tübinger manual perimeter was performed along the horizontal meridian with 1 degree spacing.
RESULTS
A patient with retinitis pigmentosa had slightly reduced photopigment density within the central +/- 5 degrees but no detectable photopigment for eccentricities beyond 5 degrees. A patient with cone dystrophy had nearly normal pigment density beyond +/- 5 degrees, but considerably reduced photopigment density within the central +/- 5 degrees. Within the central +/- 5 degrees, the patient with retinitis pigmentosa had normal sensitivity for the red stimulus and reduced sensitivity for the green stimulus. There was no measurable function beyond 7 degrees. The patient with cone dystrophy had normal sensitivity for the green stimulus outside the foveal center and reduced sensitivity for the red stimulus at the foveal center. The results of color perimetry for this patient with a central scotoma were probably influenced by eccentric fixation.
CONCLUSION
Scanning laser densitometry with a modified Rodenstock SLO is a useful method to assess the human photopigment distribution. Densitometry results were confirmed by dark adapted two color static perimetry. Photopigment distribution and retinal sensitivity profiles can be measured with high spatial resolution. This may help to measure exactly the temporal development of retinal diseases and to test the success of different therapeutic treatments. Both methods have limitations at the present state of development. However, some of these limitations can be overcome by further improving the instruments.
Topics: Adult; Densitometry; Female; Humans; Lasers; Middle Aged; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinal Rod Photoreceptor Cells; Retinitis Pigmentosa; Visual Field Tests
PubMed: 10746133
DOI: 10.1016/s0042-6989(99)00090-5 -
Revista Da Associacao Medica Brasileira... Apr 2016Vertebral fracture assessment (VFA) is a test technique that can be used to detect asymptomatic vertebral fractures (AVF). It uses dual energy X-ray bsorptiometry (DXA)... (Observational Study)
Observational Study
OBJECTIVE
Vertebral fracture assessment (VFA) is a test technique that can be used to detect asymptomatic vertebral fractures (AVF). It uses dual energy X-ray bsorptiometry (DXA) and can be performed concurrently with bone densitometry. This study aims to assess the prevalence of AVF in patients with low bone mass.
METHODS
Cross-sectional study including 135 individuals with low bone mineral density (BMD) with a T-score < -2.0 standard deviation (SD) in a densitometry clinic located in the city of Blumenau (state of Santa Catarina). Anthropometric, clinical and lifestyle variables were obtained from history-taking and physical examination. Densitometric variables were obtained by bone mineral densitometry and VFA (Explorer, Hollogic®). Vertebral fractures were classified according to the Genant criteria. Student's t, chi-square and logistic regression were performed for statistical analysis.
RESULTS
AVFs occurred in 24.4% of the subjects. They were older compared to those without AVF (65±9.25 versus 60.1±8.66; p=0.005), and had a history of lowimpact fractures (38.24% versus 19.8%; OR 2.5; p=0.03). Half of the patients that reported steroid therapy had AVFs, compared to one fifth of those who did not use steroids (50% versus 21.49%; OR 3.6; p=0.01).
CONCLUSION
Asymptomatic vertebral fractures were present in approximately one fourth of patients. The risk factors associated were history of low-impact fracture, use of steroids and age > 61 years.
Topics: Absorptiometry, Photon; Adult; Aged; Aged, 80 and over; Asymptomatic Diseases; Bone Density; Brazil; Cross-Sectional Studies; Densitometry; Female; Humans; Logistic Models; Male; Middle Aged; Osteoporotic Fractures; Prevalence; Reference Values; Retrospective Studies; Risk Factors; Spinal Fractures
PubMed: 27167544
DOI: 10.1590/1806-9282.62.02.145 -
Molecules (Basel, Switzerland) Nov 2018A new, simple, and cost-effective TLC-densitometric method has been established for the simultaneous quantitative determination of acetylsalicylic acid and ascorbic acid...
A new, simple, and cost-effective TLC-densitometric method has been established for the simultaneous quantitative determination of acetylsalicylic acid and ascorbic acid in combined effervescent tablets. Separation was performed on aluminum silica gel 60F plates using chloroform-ethanol-glacial acid at a volume ratio of 5:4:0.03 as the mobile phase. UV densitometry was performed in absorbance mode at 200 nm and 268 nm for acetylsalicylic acid and ascorbic acid, respectively. The presented method was validated as per ICH guidelines by specificity, linearity, accuracy, precision, limit of detection, limit of quantification, and robustness. Method validations indicate a good sensitivity with a low value of LOD and LOQ of both examined active substances. The linearity range was found to be 1.50⁻9.00 μg/spot and 1.50⁻13.50 μg/spot for acetylsalicylic and ascorbic acid, respectively. A coefficient of variation that was less than 3% confirms the satisfactory accuracy and precision of the proposed method. The results of the assay of combined tablet formulation equal 97.1% and 101.6% in relation to the label claim that acetylsalicylic acid and ascorbic acid fulfill pharmacopoeial requirements. The developed TLC-densitometric method can be suitable for the routine simultaneous analysis of acetylsalicylic acid and ascorbic acid in combined pharmaceutical formulations. The proposed TLC-densitometry may be an alternative method to the modern high-performance liquid chromatography in the quality control of above-mentioned substances, and it can be applied when HPLC or GC is not affordable in the laboratory.
Topics: Ascorbic Acid; Aspirin; Densitometry; Sensitivity and Specificity
PubMed: 30487409
DOI: 10.3390/molecules23123115 -
Anais Brasileiros de Dermatologia 2024To evaluate the effects of rosacea on ocular surface changes such as alterations in dry eye parameters, corneal densitometry, and aberrations, in comparison with healthy...
OBJECTIVE
To evaluate the effects of rosacea on ocular surface changes such as alterations in dry eye parameters, corneal densitometry, and aberrations, in comparison with healthy controls.
METHODS
A total of 88 eyes of 44 patients diagnosed with rosacea and 88 eyes of 44 healthy controls were enrolled in this cross-sectional study. All participants underwent a comprehensive dermatologic and ophthalmic examination and Tear Break-Up Time (TBUT) and Schirmer-1 tests were performed. The rosacea subtype and Demodex count and OSDI scores of all participants were recorded. Corneal topographic, densitometric, and aberrometric measurements were obtained using the Scheimpflug imaging system.
RESULTS
The mean age of the 44 patients was 41.2 ± 11.0 years of whom 31 (70.5%) were female. The mean TBUT and Schirmer-1 test values were significantly decreased and OSDI scores were significantly increased in the rosacea group compared to healthy controls (p < 0.01 for all). The most common subtype of rosacea was erythematotelangiectatic rosacea (70.4%). The severity grading of rosacea revealed that 18 (40.9%) patients had moderate erythema. The median (min-max) Demodex count was 14.0 (0-120) and the disease duration was 24.0 (5-360) months. The comparison of the corneal densitometry values revealed that the densitometry measurements in all concentric zones, especially in central and posterior zones were higher in rosacea patients. Corneal aberrometric values in the posterior surface were also lower in the rosacea group compared to healthy controls. The topographic anterior chamber values were significantly lower in the rosacea group.
STUDY LIMITATIONS
Relatively small sample size, variable time interval to hospital admission, and lack of follow-up data are among the limitations of the study. Future studies with larger sample sizes may also enlighten the mechanisms of controversial anterior segment findings by evaluating rosacea patients who have uveitis and those who do not.
CONCLUSION
Given the fact that ocular signs may precede cutaneous disease, rosacea is frequently underrecognized by ophthalmologists. Therefore, a comprehensive examination of the ocular surface and assessment of the anterior segment is essential. The main priority of the ophthalmologist is to treat meibomian gland dysfunction and Demodex infection to prevent undesired ocular outcomes.
Topics: Humans; Rosacea; Female; Cross-Sectional Studies; Adult; Male; Middle Aged; Cornea; Case-Control Studies; Corneal Topography; Densitometry; Severity of Illness Index; Anterior Eye Segment; Dry Eye Syndromes; Reference Values; Statistics, Nonparametric
PubMed: 38614939
DOI: 10.1016/j.abd.2023.07.005 -
Journal of Clinical Pathology Jun 1981
Review
Topics: Animals; Biological Assay; Densitometry; Guinea Pigs; Histocytochemistry; Hormones; Radioimmunoassay; Rats; Reference Standards
PubMed: 7019259
DOI: 10.1136/jcp.34.6.575 -
Medical Principles and Practice :... 2007To develop a TLC-densitometric method for the determination of barakol content in Senna siamea leaf and flower extracts, and to compare the barakol content in mature...
OBJECTIVE
To develop a TLC-densitometric method for the determination of barakol content in Senna siamea leaf and flower extracts, and to compare the barakol content in mature leaves, young leaves and young flowers of the plant which are consumed as a vegetable in curry.
MATERIALS AND METHODS
The extraction of pure barakol was performed by boiling the fresh young leaves of S. siamea with 0.5% sulfuric acid followed by chloroform extraction. The extract was further purified and recrystallized from absolute ethanol. Authentic sample of barakol was used for the validation of the TLC-densitometric method. Chromatography was performed on a TLC aluminium plate precoated with silica gel 60 F(254)as a stationary phase and chloroform-methanol (85:15 v/v) as a solvent system. Fifteen percent ethanolic extracts of mature leaves, young leaves and flowers of S. siamea were analyzed and compared for barakol content using the validated TLC-densitometric method. Both the validation and analysis of barakol by TLC-densitometry were carried out at the absorbance mode of 366 nm.
RESULTS
Barakol was extracted as pure lemon-yellow crystals from young S. siamea leaves with 0.1% yield. Linearity was found over the range of 200-900 ng/spot (r(2) = 0.997). The developed method gave high precision (%RSD < 0.50) and accuracy (average 101.12%). The limit of detection and limit of quantitation were 8 and 50 ng, respectively. Barakol content in young leaves, mature leaves and young flowers were 1.67, 0.78 and 1.43% dry weight, respectively. R(f) value of the barakol in young leaves, young flowers and authentic sample was the same: 0.45 +/- 0.03.
CONCLUSION
The TLC-densitometric method was simple, precise and convenient; hence it is an effective procedure for the simultaneous determination of barakol in plant extracts.
Topics: Benzopyrans; Chromatography, Thin Layer; Densitometry; Flowers; Humans; Molecular Structure; Phenalenes; Plant Leaves; Senna Plant
PubMed: 17159364
DOI: 10.1159/000096140 -
The Journal of Nutrition Aug 2011The respective contribution of fat-free mass (FFM) and fat mass to body weight (Wgt) is a relevant indicator of risk for major public health issues. In an earlier study,... (Comparative Study)
Comparative Study
The respective contribution of fat-free mass (FFM) and fat mass to body weight (Wgt) is a relevant indicator of risk for major public health issues. In an earlier study, a Bayesian Network (BN) was designed to predict FFM from a DXA database (1999-2004 NHANES, n = 10,402) with easily accessible variables [sex, age, Wgt, and height (Hgt)]. The objective of the present study was to assess the robustness of these BN predictions in different population contexts (age, BMI, ethnicity, etc.) when covariables were stochastically deduced from population-based distributions. BN covariables were adjusted to 82 published distributions for age, Wgt, and Hgt from 16 studies assessing body composition. Anthropometric adjustments required a surrogate database (n = 23,411) to get the missing correlation between published Wgt and Hgt distributions. Published BMI distributions and their predicted BN counterparts were correlated (R(2) = 0.99; P < 0.001). Predicted FFM distributions were closely adjusted to their published counterparts for both sexes between 20 and 79 y old, with some discrepancies for Asian populations. In addition, BN predictions revealed a very good agreement between FFM assessed in different population contexts. The mean difference between published FFM values (61.1 ± 3.44 and 42.7 ± 3.32 kg for men and women, respectively) and BN predictions (61.6 ± 3.11 and 42.4 ± 2.76 kg for men and women, respectively) was <1% when FFM was assessed by DXA; the difference rose to 3.6% when FFM was assessed by bioelectric impedance analysis or by densitometry methods. These results suggest that it is possible, within certain anthropometric limitations, to use BN predictions as a complementary body composition analysis for large populations.
Topics: Absorptiometry, Photon; Adipose Tissue; Bayes Theorem; Body Composition; Humans
PubMed: 21715469
DOI: 10.3945/jn.111.137935