Forward Light Scatter Research Articles

Ocular forward light scattering and corneal backward light scattering in patients with dry eye.

To evaluate ocular forward light scattering and corneal backward light scattering in patients with dry eye. Thirty-five eyes in 35 patients with dry eye and 20 eyes of 20 healthy control subjects were enrolled. The 35 dry eyes were classified into two groups according to whether superficial punctate keratopathy in the central 6-mm corneal zone (cSPK) was present or not. Ocular forward light scattering was quantified with a straylight meter. Corneal backward light scattering from the anterior, middle, and posterior corneal parts was assessed with a corneal densitometry program using the Scheimpflug imaging system. Both dry eye groups had significantly higher intraocular forward light scattering than the control group (both P<0.05). The dry eye group with cSPK had significantly higher values in anterior and total corneal backward light scattering than the other two groups. Moderate positive correlations were observed between the cSPK score and corneal backward light scattering from the anterior cornea (R=0.60, P<0.001) and corneal backward light scattering from the total cornea (R=0.54, P<0.001); however, no correlation was found between cSPK score and ocular forward light scattering (R=0.01, P=0.932). Ocular forward light scattering and corneal backward light scattering from the anterior cornea were greater in dry eyes than in normal eyes. Increased corneal backward light scattering in dry eye at least partially results from cSPK overlying the optical zone.

Using holography to measure extinction.

This work presents a new concept to measure the extinction cross section for a single particle in situ. The concept involves recording the hologram produced by the interference of a particle's forward-scattered light with the incident light. This interference pattern is fundamentally connected to the energy flow that gives rise to extinction, and, by integrating this measured pattern, one obtains an approximation for the cross section. Mie theory is used to show that this approximation can be as little as 1% in error of the true value for many cases of practical interest. Moreover, since an image of the particle can be computationally reconstructed from a measured hologram using the Fresnel-Kirchhoff diffraction theory, one can obtain the cross section simultaneously with the particle shape and size.

Development of a flow cytometry–based pulse-width assay for detection of aggregates in cellular therapeutics to be infused by catheter

Background aimsDelivery of cell-based therapies through the carotid artery with the use of an intra-arterial catheter could introduce aggregates and cause focal ischemia in the brain. We developed a pulse-width flow cytometry method for aggregate detection and quantification. The assay was designed to be used as a cell product release assay in a clinical trial seeking to treat ischemic stroke with sorted cells brightly expressing aldehyde dehydrogenase (ALDHbr cells) delivered through intra-arterial catheters. MethodsThe forward light scatter pulse-width axis of a flow cytometer was calibrated for particle diameter measurements through the use of traceable standard microspheres and linear regression. As a positive control, Concanavalin A–aggregated cells were counted manually and sorted onto slides to compare with pulse width–determined values. Known numbers of aggregates were spiked into purified singlet cells for quantification. A clinical standard for aggregate count and diameter was determined. The assay was used to qualify catheters with the use of ALDHbr cells. ResultsThe pulse-width axis was highly linear for microsphere diameter (r2 > 0.99), which allowed for size calibration. Microscopically determined counts and diameters corresponded to pulse width-determined values. Known aggregate counts were linear with pulse width–determined aggregate counts (r2 = 0.98). The limit of detection was determined to be 0.004%. Flow of ALDHbr cells through catheters did not generate aggregates. The final method to be used as a release assay for the stroke clinical trial was tested successfully on samples from volunteer donors. ConclusionsThe pulse-width aggregate detection assay provides a reliable, reproducible, accurate and rapid means of detection, classification and quantification of aggregates in cell therapy products.

Monitoring growth and lipid production of new isolated oleaginous yeast Cryptococcus aerius UIMC65 on glucose and xylose cultures

Process monitoring is one of the most important factors affecting production efficiency at industrial scale bioprocesses. In the present work, Flow-cytometric analysis has been employed to monitor and determine neutral lipid cell droplets, granularity and size of the cells of the new oleaginous yeast, Cryptococcus aerius UIMC65. It has been shown that, differences of fluorescent intensity as well as side and forward scatter light properties have close correlations with the differences in lipid production by these yeast cells. The lipid content-related fluorescent intensity versus forward scatter parameter has been used to monitor and compare different subpopulations during growth phases on both glucose and xylose in batch cultures. Flow cytometric results have revealed that the observed differences in the proportion of each subpopulation were related to the specific growth phase and lipid content of the cells. The highest lipid content and lipid productivity were attained at 82.62%, 4.47 g/L (at 72 h) and 78.41%, 6.21 g/L (at 60 h) on glucose and xylose growth cultures, respectively. The highest biomass, lipid yield and biomass yield were found to be 7.92 g/L (on glucose culture, at 60 h), 20.92% (on glucose culture, at 48 h) and 50.71% (on glucose culture, at 24 h), respectively.

Relationship between halo size and forward light scatter

PurposeTo determine the relationship between the size of a halo induced by a glare source and forward scatter or visual acuity (VA) in healthy eyes.MethodMeasurements were made in the right...

Detection of Fluorescent Nanoparticle Interactions with Primary Immune Cell Subpopulations by Flow Cytometry

Engineered nanoparticles are endowed with very promising properties for therapeutic and diagnostic purposes. This work describes a fast and reliable method of analysis by flow cytometry to study nanoparticle interaction with immune cells. Primary immune cells can be easily purified from human or mouse tissues by antibody-mediated magnetic isolation. In the first instance, the different cell populations running in a flow cytometer can be distinguished by the forward-scattered light (FSC), which is proportional to cell size, and the side-scattered light (SSC), related to cell internal complexity. Furthermore, fluorescently labeled antibodies against specific cell surface receptors permit the identification of several subpopulations within the same sample. Often, all these features vary when cells are boosted by external stimuli that change their physiological and morphological state. Here, 50 nm FITC-SiO2 nanoparticles are used as a model to identify the internalization of nanostructured materials in human blood immune cells. The cell fluorescence and side-scattered light increase after incubation with nanoparticles allowed us to define time and concentration dependence of nanoparticle-cell interaction. Moreover, such protocol can be extended to investigate Rhodamine-SiO2 nanoparticle interaction with primary microglia, the central nervous system resident immune cells, isolated from mutant mice that specifically express the Green Fluorescent Protein (GFP) in the monocyte/macrophage lineage. Finally, flow cytometry data related to nanoparticle internalization into the cells have been confirmed by confocal microscopy.

Detection of Fluorescent Nanoparticle Interactions with Primary Immune Cell Subpopulations by Flow Cytometry

Engineered nanoparticles are endowed with very promising properties for therapeutic and diagnostic purposes. This work describes a fast and reliable method of analysis by flow cytometry to study nanoparticle interaction with immune cells. Primary immune cells can be easily purified from human or mouse tissues by antibody-mediated magnetic isolation. In the first instance, the different cell populations running in a flow cytometer can be distinguished by the forward-scattered light (FSC), which is proportional to cell size, and the side-scattered light (SSC), related to cell internal complexity. Furthermore, fluorescently labeled antibodies against specific cell surface receptors permit the identification of several subpopulations within the same sample. Often, all these features vary when cells are boosted by external stimuli that change their physiological and morphological state. Here, 50 nm FITC-SiO2 nanoparticles are used as a model to identify the internalization of nanostructured materials in human blood immune cells. The cell fluorescence and side-scattered light increase after incubation with nanoparticles allowed us to define time and concentration dependence of nanoparticle-cell interaction. Moreover, such protocol can be extended to investigate Rhodamine-SiO2 nanoparticle interaction with primary microglia, the central nervous system resident immune cells, isolated from mutant mice that specifically express the Green Fluorescent Protein (GFP) in the monocyte/macrophage lineage. Finally, flow cytometry data related to nanoparticle internalization into the cells have been confirmed by confocal microscopy.

Comparison of methods to quantify posterior capsule opacification using forward and backward light scattering

To compare forward and backward light scattering measurements to quantify posterior capsule opacification (PCO). Vienna Institute for Research in Ocular Surgery, Vienna, Austria. Prospective single-center study. This observational study comprised consecutive patients scheduled for neodymium:YAG (Nd:YAG) capsulotomy for regeneratory PCO. The corrected distance visual acuity (CDVA) using Early Treatment of Diabetic Retinopathy Study charts and the contrast sensitivity under mesopic and photopic conditions using Pelli-Robson charts were assessed before an Nd:YAG capsulotomy was performed. Retroillumination images, rotating Scheimpflug scans (Pentacam HR), and straylight meter (C-Quant) and point-spread function (PSF) meter (Optical Quality Analysis System) measurements were performed before and after Nd:YAG capsulotomy. The study enrolled 50 eyes of 50 patients. The mean uncorrected distance visual acuity and CDVA were 0.76 logMAR ± 0.18 (SD) and 0.68 ± 0.2 logMAR, respectively. The mean log contrast sensitivity (logCS) was 1.2 ± 0.15 logCS under photopic conditions and 1.05 ± 0.15 logCS under mesopic conditions. There was a moderate correlation between the Scheimpflug score and the Automated Quantification of After-Cataract score (r(2) = 0.37, P=.03). Furthermore, a moderate and close to significant correlation between the PSF meter and the straylight meter was observed (r(2) = 0.32; P=.07). Each of the 4 devices assesses different aspects of a patient's quality of vision. Further developments should focus on methods that measure forward scatter of light in a large visual angle and are not too patient or examiner dependent.

Optimization of forward-scattered light energy and de-coherence of Mie scattering for speckle suppression

Reducing the coherence of laser light without energy loss is critical for speckle suppression in laser projectors. In this paper, it is shown that more than 90 % of incident light is forward-scattered with complete de-coherence. We modeled a scattering volume with particles in ZEMAX as a scattering medium and studied the forward-scattered light energy and de-coherence dependence on the following three parameters: particle concentration, normalized radius of particles $$\upalpha $$ and refractive index ratio m. By varying all three parameters, a number of parameter combinations to achieve complete de-coherence are obtained, and which are utilized for speckle suppression. The forward-scattered light energy loss is up to 60–70 % of incident light at these combinations. But, at smaller particle concentration, the loss drops quickly. When setting the particle concentration at $$1\times 10^{8}\,\hbox {cm}^{-3}$$ , the forward-scattered light energy can be more than 90 % of incident light by adjusting $$\upalpha $$ and m according to Mie scattering theory. The structure parameter L of the scattering volume is also analyzed to collect forward-scattered light more than 90 % of incident light. These results can benefit the parameters’ choice of scattering particles and the design of a scattering volume used for speckle suppression.

Forward light scatter and visual acuity through scratched protective eyewear

BackgroundScratches and other surface abrasions on protective eyewear can shorten their life cycle by scattering light from the image, which will compromise visual performance. Although scratch and abrasion resistance testing is well developed, there is little information available regarding visual acuity through lenses scratched in an actual work environment.MethodsWe collected protective eyewear from mine and smelting operations that had been returned because vision through the lenses was unacceptable due to scratches and abrasions. Forward scattered light was measured on both cleaned and partially cleaned lenses using both haze and light diffusion measurements. Visual acuity through a selection of lenses was determined for both high and low contrast letters under photopic light levels.ResultsLenses with scratches in the central region had haze values ranging from one to 30 per cent. The highest haze values were measured on lenses that were both scratched and covered with dirt, whereas haze values less than 10 per cent were measured on lenses that had the dirt removed and just had scratches in the central region. Light diffusion values were highly correlated with haze. Visual acuity for high and low contrast letters became worse as the percentage haze increased but the linear correlation was only moderate.ConclusionThe appearance of the scratches on the lens surfaces strongly suggests that they were a result of improper lens cleaning. The findings also suggest that haze values less than two per cent or a luminance reduction factor less than 3.0-cd/(m2 lx) are unlikely to affect high and low contrast acuity.

基于CMOS探测模拟气泡幕前向光散射动态特性

The concepst of Vertical-plane and Horizontal-plane scattering angle of forward laser paraxial were proposed based on CMOS.The dynamic image sequence of light scattering by simulated bubble film,which was captured by CMOS,can be expressed by an image sequence matrix whose line vector and column vector represented one frame image through computing gray average of column pixel and line pixel of the frame image.The gray distribution and evolution characteristics of 100frame image sequence of forward light scattering by bubble film generated under presser 0.005and 0.01MPa,was analyzed qualitatively through calculating the mean horizontal and vertical gray,as the dynamic range and correlation of 5frame image was analyzed quantitatively.Through analyzed the dynamic image scattered by bubble film with the increasing pressure on CMOS,the range and amplitude of horizontal and vertical gray of forward light scattering image sequence increased as the increasing scale,number density and rising speed of bubble film.

基于CMOS探测模拟气泡幕前向光散射动态特性

The concepst of Vertical-plane and Horizontal-plane scattering angle of forward laser paraxial were proposed based on CMOS.The dynamic image sequence of light scattering by simulated bubble film,which was captured by CMOS,can be expressed by an image sequence matrix whose line vector and column vector represented one frame image through computing gray average of column pixel and line pixel of the frame image.The gray distribution and evolution characteristics of 100frame image sequence of forward light scattering by bubble film generated under presser 0.005and 0.01MPa,was analyzed qualitatively through calculating the mean horizontal and vertical gray,as the dynamic range and correlation of 5frame image was analyzed quantitatively.Through analyzed the dynamic image scattered by bubble film with the increasing pressure on CMOS,the range and amplitude of horizontal and vertical gray of forward light scattering image sequence increased as the increasing scale,number density and rising speed of bubble film.

Suppression of forward-scattered light using high-frequency intensity modulation

Laser imaging through a turbid medium is complicated by scattering. Backscattered photons reduce image contrast as weak target returns compete against a large background of backscattered light. Forward scattering broadens the interrogating laser beam, thereby reducing the spatial resolution of the target. Prior research has shown that intensity modulation (<100 MHz ) can be used to “wash-out” the backscatter, resulting in better discrimination of the target and higher contrast. We show that the higher modulation frequencies (>100 MHz ) can be also used to suppress forward scattered light, thereby increasing spatial resolution.

PU.1 promotes cell cycle exit in the murine myeloid lineage associated with downregulation of E2F1

Acute myeloid leukemia (AML) is characterized by increased proliferation and reduced differentiation of myeloid lineage cells. AML is frequently associated with mutations or chromosomal rearrangements involving transcription factors. PU.1 (encoded by Sfpi1) is an E26 transformation-specific family transcription factor that is required for myeloid differentiation. Reduced PU.1 levels, caused by either mutation or repression, are associated with human AML and are sufficient to cause AML in mice. The objective of this study was to determine whether reduced PU.1 expression induces deregulation of the cell cycle in the myeloid lineage. Our results showed that immature myeloid cells expressing reduced PU.1 levels (Sfpi1(BN/BN) myeloid cells) proliferated indefinitely in cell culture and expanded invivo. Transplantation of Sfpi1(BN/BN) cells induced AML in recipient mice. Cultured Sfpi1(BN/BN) cells expressed elevated messenger RNA transcript and protein levels of E2F1, an important regulator of cell cycle entry. Restoration of PU.1 expression in Sfpi1(BN/BN) myeloid cells blocked proliferation, induced differentiation, and reduced E2F1 expression. Taken together, these data show that PU.1 controls cell cycle exit in the myeloid lineage associated with downregulation of E2F1 expression.

Association Of Platelet Function Markers, Independent Of Platelet Count, With Bleeding Score In Patients With Immune Thrombocytopenia

BackgroundImmune thrombocytopenia (ITP) patients with similarly low platelet counts differ in their tendency to bleed. AimTo determine if differences in platelet function in ITP patients with similarly low platelet counts partly account for the variation in bleeding tendency. MethodsThe relationship between bleeding scores and platelet function markers was investigated in a single center cross-sectional study of pediatric patients with ITP. Following informed consent, blood was collected from ITP patients and bleeding was graded using the Buchanan and Adix Score (J Pediatr 2002) at routine clinic visits or while admitted to the hospital. Bleeding scores were obtained by one of three hematologists blinded to platelet function results, and investigators performing platelet function tests were blinded to clinical results. Platelet function was assessed by whole blood flow cytometric measurement of unstimulated, ADP- or TRAP-stimulated platelet surface activated GPIIb-IIIa (as measured by PAC1 binding), P-selectin, and GPIb and by unstimulated, convulxin-, or ADP plus TRAP-stimulated platelet surface phosphatidylserine expression (as determined by annexin V binding). Platelet count, immature platelet fraction (IPF) and mean platelet volume (MPV) were determined by a Sysmex XE-2100, and platelet forward angle light scatter (FSC) was measured by flow cytometry. ResultsPlatelet function and bleeding scores were evaluated in 34 consecutive consenting pediatric ITP patients (16 female, 18 male, age 9.7 ± 5.7 years [mean ± SD]). ITP was newly diagnosed (< 3 months) in 10 patients, persistent (3 -- 12 months) in 7 patients, and chronic (>12 months) in 17 patients. Platelet count at the time of the blood draw was 47 ± 55 x 109/L. The median bleeding score on day of blood draw was 1 (range 0 to 4). By univariate analysis, higher IPF, and lower platelet count were significantly associated with a higher bleeding score (odds ratio [OR] >1, p<0.05) but MPV was not. Multiple measures of platelet function were associated with bleeding scores by univariate analysis: higher levels of platelet FSC (a measure affected by multiple variables including size) surface GPIb on unstimulated, ADP- or TRAP-stimulated platelets, surface P-selectin on unstimulated platelets, and platelet FSC were associated with increased odds for higher bleeding scores (ORs each >1, p<0.05), while higher ADP- and TRAP-stimulated platelet surface activated GPIIb-IIIa and P-selectin were associated with reduced odds of higher bleeding scores (ORs each <1, p<0.05). After adjustment for platelet count, higher levels of platelet surface P-selectin on unstimulated platelets, GPIb on TRAP-stimulated platelets, and FSC remained significantly associated with increased odds for higher bleeding scores (Figure), but IPF did not. Similarly, after adjustment for platelet count, higher TRAP-stimulated percentage of P-selectin and activated GPIIb-IIIa positive platelets remained significantly associated with reduced odds of higher bleeding scores (Figure). These findings were independent of recent ITP-related treatment. [Display omitted] ConclusionsIn this study of pediatric ITP patients, we identified selected platelet function markers which, independent of platelet count, are associated with increased (platelet FSC, platelet surface P-selectin on unstimulated platelets, and GPIb on TRAP-stimulated platelets) or decreased (TRAP-stimulated percent P-selectin and GPIIb-IIIa positive platelets) odds of high bleeding scores. Possible hypotheses to explain these associations are as follows: 1) Increased P-selectin on unstimulated platelets demonstrates in vivo platelet activation, possibly as a consequence of the recent bleeding. 2) Because platelet activation results in a reduction in platelet surface GPIb and increases in platelet surface activated GPIIb-IIIa and P-selectin, the ORs associated with all of these markers could be explained by reduced ability of platelets in patients with higher bleeding scores to respond to agonists. 3) While platelet FSC is partly related to size, the finding that MPV and IPF, adjusted for platelet count, were not associated with bleeding score suggests that factors other than size account for the association of platelet FSC with higher bleeding scores. Further study is required to validate these findings and determine if differences in platelet function are associated with future risk for bleeding. Disclosures:Off Label Use: Eltrombopag was given to WAS/XLT patients for treatment of thrombocytopenia. Neufeld:Shire: Consultancy, Research Funding; Novartis: Consultancy, Research Funding; Apopharma: Consultancy. Michelson:Sysmex: Honoraria.

Particles small angle forward‐scattered light measurement based on photovoltaic cell microflow cytometer

A method is proposed for detecting microparticles in a microflow cytometer by means of small angle forward-scattered light measurements. The proposed cytometer comprises a commercial photovoltaic cell, an adjustable power laser module, and a PDMS microfluidic chip. The detection performance of the proposed device is evaluated using particles with dimensions of 5, 8, 10, and 15 μm, respectively, given forward-light scattering angles of 5 and 8° and laser powers ranging from 15-25 mW. It is shown that for a constant laser power and particle size, the S/N of the detected light signal increases with a reducing forward-scattering angle. Moreover, for a constant forward-scattering angle and particle size, the S/N increases with an increasing laser power. The intensity of the forward-scattered light signal is found to vary linearly with the particle size and has a correlation coefficient of R(2) = 0.967, 0.967, and 0.963 given laser powers of 15, 20, and 25 mW, respectively, and a forward-scattering angle of 5°. Moreover, the CV of the forward-scattered light intensity is found to lie within the range of 20-30% for both forward-scattering angles. Overall, the present results suggest that the proposed device has significant potential for detection applications in the medical, environmental monitoring, and biological science fields.

Randomized Trial of Multifocal Intraocular Lenses versus Monovision after Bilateral Cataract Surgery

To compare spectacle independence in patients randomized to receive bilateral multifocal intraocular lenses (IOLs) or monofocal IOLs with the powers adjusted to produce monovision. Randomized, multicenter clinical trial. A total of 212 patients with bilateral, visually significant cataract. Before bilateral sequential cataract surgery, patients were randomized (allocation ratio 1:1) to receive bilateral Tecnis ZM900 diffractive multifocal lenses (Abbott Medical Optics, Santa Ana, CA) or Akreos AO monofocal lenses (Bausch & Lomb, Rochester, NY) with the powers adjusted to target -1.25 diopters (D) monovision. Outcomes were assessed 4 months after the second eye underwent operation. The primary outcome was spectacle independence. Secondary outcomes included questionnaires (VF-11R, dysphotopsia symptoms, and satisfaction) and visual function measures (near, intermediate, and distance logarithm of minimum angle of resolution [logMAR] visual acuity, stereoacuity, contrast sensitivity, and forward light scatter). A total of 212 patients were randomized, and 187 patients (88%) returned for assessment 4 months after surgery. Uniocular distance refractions in the monovision arm showed a mean spherical equivalent of +0.075 D in the distance eye and -0.923 in the near eye. In the multifocal arm, the mean distance spherical equivalents were -0.279 D and -0.174 D in the right and left eyes, respectively. A total of 24 of 93 patients (25.8%) in the monovision arm and 67 of 94 patients (71.3%) in the multifocal arm reported never wearing glasses (P<0.001, Fisher exact test). The adjusted odds ratio of being spectacle free was 7.51 (95% confidence interval, 3.89-14.47). Binocular uncorrected acuities did not differ significantly for distance (0.058 logMAR for monovision vs. 0.076 for multifocal, P = 0.3774) but were significantly worse in the multifocal arm for intermediate acuity (0.149 vs. 0.221, P = 0.0001) and in the monovision arm for near acuity (0.013 vs. -0.025, P = 0.037). In the first postoperative year, 6 patients (5.7%) in the multifocal arm underwent IOL exchange (4 had a bilateral and 2 had a unilateral exchange). No patients in the monovision arm underwent IOL exchange. Patients randomized to bilateral implantation with the diffractive multifocal Tecnis ZM900 were more likely to report being spectacle independent but also more likely to undergo IOL exchange than those randomized to receive monofocal implants (Akreos AO) with the powers adjusted to give low monovision.

Expression characteristics of differentiation antigens on granulocytes in patients with megaloblastic anemia

This study was aimed to explore the change characteristics of cell differentiation antigen (CD) on bone marrow (BM) granulocytes in patients,with megaloblastic anemia (MA). In combination with BM cell morphology, hemogram, level of blood serum folic acid, level of Vit B(12), cell genetics and biological examination data, the BM granulocytes differentiation antigens in 13 patients with MA were detected by flow cyto metry and analyzed retrospectively, in order to summarize the variation characteristics of CD13, CD33 and CD15 expressed on myeloid cells in patient with MA, including forward scatter light (FSC) and side scatter light (SSC) signal intensity, then these findings were compared with that in normal healthy persons. The results showed that the expression rates of CD13, CD15 and CD33 on granulocytic in patients with MA and normal healthy persons were (44.53 ± 16)%, (96.16 ± 2.67)%, (80.81 ± 14.71)% and (62.33 ± 11.02)%, (99.53 ± 0.46)%, (70.00 ± 7.81)% respectively, in which the expression rate of CD13 and CD15 in patients with MA decreased (P < 0.01), while the expression rate of CD33 increased (P < 0.01). The mean fluorescence intensity (MFI) of CD13, CD15, CD33, SSC and FSC in MA patients and normal healthy persons were 3.39 ± 1.41, 14.29 ± 6.59, 1.95 ± 0.94, 478.78 ± 70.43, 633.46 ± 75.53 and 5.12 ± 1.15, 20.67 ± 5.13, 1.04 ± 0.17, 332.00 ± 38.16, 537.00 ± 16.70 respectively, in which the MFI of CD13 and CD15 on granulocytes in MA patients decreased (P < 0.01),while the MFI of FSC,SSC and CD33 increased (P < 0.01 and P < 0.05). It is concluded that not only the morphology of BM granulocytes in patents with MA shows dysmaturity, but the expressing feature of differentiation antigens on BM granulocytes in MA patients also displays dysmaturity.These findings will contribute to the clinical diagnosis of MA patients.

Effect of Instillation of Eyedrops for Dry Eye on Optical Quality

To investigate the effects of viscosity and suspensibility of eyedrops for dry eye by evaluating an eyedrop with one of the solutions or no solution (0.3% sodium hyaluronate ophthalmic solution, 3% diquafosol ophthalmic solution, and 2% rebamipide ophthalmic suspension) on ocular higher-order aberrations (HOAs) and forward light scatter. We evaluated ocular HOAs and forward light scatter before and 1, 5, and 10 minutes after instillation of three eyedrops for dry eye in 15 healthy subjects. Saline served as the control. The HOAs were measured for a 4-mm pupil using a wavefront sensor. The obtained aberration data were analyzed in the central 4-mm diameter for total HOAs up to the sixth-order Zernike polynomials. Forward light scatter was quantified with a straylight meter. A significant increase was seen in the HOAs 1 minute after instillation of the three eyedrops for dry eye; the HOAs recovered to the baseline level thereafter. When 0.3% sodium hyaluronate was compared with 2% rebamipide and 3% diquafosol, the HOAs increased significantly (P < 0.01 for both comparisons) immediately after instillation. A significant increase in forward light scatter occurred 1 minute after instillation of rebamipide suspension and returned to the preinstillation level 5 minutes after instillation. No significant changes in forward light scatter occurred after instillation of 3% diquafosol or 0.3% sodium hyaluronate. Quantitative serial measurement of HOAs and forward light scatter showed that the temporal reduction in optical quality may be attributed mainly to increased HOAs after instillation of highly viscous 0.3% sodium hyaluronate ophthalmic solution and to increased forward light scatter after instillation of 2% rebamipide ophthalmic suspension in healthy subjects.

A modified Hartmann–Shack aberrometer for measuring stray light in the anterior segment of the human eye

To examine the use of a modified Hartmann-Shack wave front aberrometer (WASCA; Carl Zeiss Meditec AG, Germany) to measure objective stray light caused by forward light scatter from the anterior segment of the human eye. HELIOS Klinikum Erfurt/Institute of Biomedical Engineering and Informatics, Ilmenau University of Technology, Germany. Scatter parameters, including the Michelson contrast and cross-sectional area at half height (CAHM) were examined in Hartmann-Shack images from ten subjects with a cataract in one eye and an intraocular lens (IOL) in the other. The parameters were compared between each eye. Light scatter was then measured in 40 healthy subjects (age range, 23-75 years) with spherical ametropia ranging from -0.25 to 0.25 diopters. The subjects were divided into three age groups; 23-35, 36-50, and 51-75 years. Light scatter was also measured using four alternative methods. CAHM and contrast were significantly different between the eyes with the cataract and the IOL (P = 0.007 and P = 0.004, respectively). CAHM (r = 0.557, P < 0.001) and contrast (r = -0.467, P < 0.001) were both significantly correlated with age. There were significant differences in CAHM and contrast between the age groups. The modified wave front aberrometer can be used to measure stray light, although its diagnostic sensitivity in individual patients must be improved.