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Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children
摘要： Macular pigment optical density (MPOD)—assessed using customized heterochromatic flicker photometry (cHFP)—is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7–10-year-olds (n = 66) underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46) with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59—session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27). There was no significant difference in the MPOD of boys vs. girls (p = 0.56). There was a significant correlation between sessions (Y = 0.52x + 0.31; R2 = 0.29, p ≤ 0.005), with a reliability of 0.70 (Cronbach’s α). Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R2 = 0.32, p < 0.005), with a reliability of 0.72 (Cronbach’s α). In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood.
关键词： retinal lutein,heterochromatic flicker photometry,macular pigment optical density
更新于2025-09-23 15:22:29
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Subretinal Fluid Optical Density and Spectral-Domain Optical Coherence Tomography Characteristics for the Diagnosis of Circumscribed Choroidal Hemangioma
摘要： Purpose: To investigate spectral domain-optical coherence tomography (SD-OCT) features of untreated circumscribed choroidal hemangioma (CCH), and the optical density (OD) of the associated subretinal fluid (SRF). Procedures: This international retrospective multicenter study conducted at 5 tertiary retina referral centers included 34 patients with symptomatic CCH imaged on SD-OCT. CCH surface, size, and overlying retinal changes and OD ratio (ODR) were evaluated. Results: The mean ODR of the SRF was 0.808 ± 0.287. Tumor base measured on ultrasound correlated significantly with the ODR (p = 0.012). ODR values in cases of CCH were similar to those of choroidal metastasis, but significantly lower than those of choroidal melanoma (p = 0.006). Thirty-two out of 34 cases (94%) presented with a regular smooth choroidal surface. OCT demonstrated SRF overlying the CCH in 29 eyes (85%). The presence of SRF correlated significantly with a larger basal tumor diameter (p = 0.035). OCT displayed sub- and intraretinal hyperreflective foci, correlating with both larger maximal retinal thickness overlying the tumor (p = 0.031) and the amount of SRF (p = 0.016) in 29 eyes (85%). Conclusion: CCH displays typical findings on SD-OCT. ODR is a new important tool in the differential diagnosis of choroidal tumors and should be considered for enhancing the accuracy of diagnosing CCH. This benefit is especially relevant for cases in which the presentation of CCH is atypical.
关键词： Optical density,Optical coherence tomography,Ocular tumors,Circumscribed choroidal hemangioma
更新于2025-09-23 15:21:01
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Evolution of visual acuity, flap thickness, and optical density after laser in situ keratomileusis performed with a femtosecond laser
摘要： To describe the postoperative evolution of visual acuity, flap morphology, and stromal optical density femtosecond laser-assisted laser in situ keratomileusis (FS-LASIK). The study comprised 44 consecutive eyes that had FS-LASIK performed with the WaveLight FS200 and the Allegretto excimer laser to correct myopia. Visual outcomes, flap thickness, and stromal optical density were assessed 1 day, 1 week, 1 month, and 3 months postoperatively. A statistically significant improvement in the mean uncorrected distance visual acuity at 1 day (0.94 ± 0.2) and 1 week (0.93 ± 0.2) to 1 month (1.04 ± 0.2) and 3 months (1.11 ± 0.1) postoperatively (P < .05). At 3 months postoperatively, the femtosecond laser had good outcomes in efficacy (0.98 ± 0.1), safety (0.98 ± 0.1), and predictability (100% of eyes were within ± 0.5 D of emmetropia). The femtosecond-created flaps were slightly thicker than intended, the mean SD intraflap was 7.1 μm, the range between the thickest and thinnest points in each flap was 25.4 μm, and the mean flap thickness homogeneity was 7.6 μm at 3 months postoperatively. A progressive decrease in the optical density of the flap stroma and the residual stromal bed was detected during follow-up. The femtosecond laser study appears to be a safe, effective, and predictable platform to obtain LASIK flaps. The flaps were planar and homogeneous but slightly thicker than intended. The optical density of the flap stroma was slightly higher at early follow-up and decreased over time.
关键词： visual acuity,femtosecond laser,LASIK,flap thickness,optical density
更新于2025-09-16 10:30:52
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A New Process to Synthesize CrSe Thin Films with Nanosize by CBD Method
摘要： In this study, CrSe thin films were produced by using a new variation of chemical bath deposition (CBD) on glass substrates at different pH values, namely pH: 8, 9, 10 and 11. Some optical properties of these films including T% (transmittance), R% (reflectance), n (refractive index), k (extinction coefficient) and ?1 and ?2 (real and imaginary parts of dielectric constants) for pH: 8, 9, 10 and 11 were found as (82.89, 80.00, 78.54, 79.05%), (3.76, 5.32, 4.08, 5.44), (1.48, 1.59, 1.48, 1.60), (0.055, 0.079, 0.127, 0.116) and (1.33, 1.47, 1.21,1.52) and (0.87, 0.33, 0.12, 0.14) at 550 nm wavelength. Surface morphologies of thin films were examined by SEM. Film thicknesses were measured to be 34, 44, 50 and 104 nm by AFM, and the optical band gap (Egap) were calculated as 3.14; 3.72; 3.71 and 3.74 eV for pH: 8, 9, 10 and 11, respectively. Optical conductivity variation of CrSe thin films were calculated as a function of frequency for pH: 8, 9, 10 and 11, respectively. The usage areas of these films in optoelectronic applications were discussed.
关键词： Thin Film,CBD Method,Optical density,CrSe,Optical conductivity
更新于2025-09-09 09:28:46
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Enhanced method for determining the low-LET saturation dose of PRESAGE?
摘要： An accurate value for the saturation dose of PRESAGE? is important in elucidating the mechanism of the so-called quenching phenomenon in the 3-D dosimetry of proton beams. This quantity is difficult to obtain, because it involves measuring the optical density of a set of very highly attenuating samples. We present a novel method that makes use of the ability to irradiate microscopically-thin “slices” of a cuvette using microplanar beams from a synchrotron. Using the new method, we were able to measure optical densities of up to 50 cm-1 using a standard spectrophotometer, and we derived a value 14000 Gy for the saturation parameter D37.
关键词： 3-D dosimetry,synchrotron,quenching phenomenon,saturation dose,PRESAGE?,optical density,proton beams,microplanar beams
更新于2025-09-09 09:28:46