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Interaction between bioactive glasses and human dentin.

This study explores the interaction between bioactive glasses and dentin from extracted human teeth in simulated oral conditions. Bioactive glasses in the Na(2)O-CaO-P(2)O(5)-SiO(2) and MgO-CaO-P(2)O(5)-SiO(2) systems were prepared as polished disks. Teeth were prepared by grinding to expose dentin and etching with phosphoric acid. A layer of saliva was placed between the two, and the pair was secured with an elastic band and immersed in saliva at 37 degrees C for 5, 21 or 42 days. The bioactive glasses adhered to dentin, while controls showed no such interaction. A continuous interface between the bioactive glass and dentin was imaged using cryogenic-scanning electron microscopy (SEM). However, after alcohol dehydration and critical point drying, fracture occurred due to stresses from dentin shrinkage. SEM investigations showed a microstructurally different material at the fractured interface. Chemical analyses revealed that ions from the glass penetrated into the dentin and that the surface of the glass in contact with the dentin was modified. Microdiffractometry showed the presence of apatite at the interface. Bonding appears to be due to an affinity of collagen for the glass surface and chemical interaction between the dentin and glass, leading to apatite formation at the interface.

Journal Article↗

Granule size and composition of bioactive glasses affect osteoconduction in rabbit.

Bioactive glass granules of three different compositions, regarding particularly Si- and Al- content (S53P4, S59.7P2.5, S52P3) and of two different granule sizes (200-250 microm and 630-800 microm) were implanted for 4 and 8 weeks in the distal part of rabbit femur. The effect of glass composition and granule size on bone formation was studied. The results were evaluated using histology, computerized histomorphometry, scanning electron microscopy and energy dispersive X-ray analysis, and used for mathematical description of bone formation. The results showed that both the composition of the glass and the granule size of the granules, have influence on bone growth from the surrounding tissue. Glass S53P4, which from previous observations is known to be an effective bioactive glass and widely used in the Biomaterial Project of Turku, Finland, showed bone bonding and increasing bone growth between the granules. Glass S59.7P2.5 which due to its high Si-content should be inert, showed bone bonding. At 4 weeks the bone growth was significantly more abundant in bone defects filled with large granules (630-800 microm) than in defects filled with small granules (200-250 microm). Glass S52P3 with an alumina content of 3 wt %, showed good bone conduction, possibly even bone bonding for granules of 630-800 microm size. Granules of 200-250 microm with a high alumina content at the surface of the reaction layer, showed hardly any bone contact at all. This data, therefore, gives new information concerning bone bonding and osteoconduction of bioactive glasses with a high silica or alumina content.

Journal Article↗

Classification of secondary relaxation in glass-formers based on dynamic properties.

Dynamic properties, derived from dielectric relaxation spectra of glass-formers at variable temperature and pressure, are used to characterize and classify any resolved or unresolved secondary relaxation based on their different behaviors. The dynamic properties of the secondary relaxation used include: (1) the pressure and temperature dependences; (2) the separation between its relaxation time taubeta and the primary relaxation time taualpha at any chosen taualpha; (3) whether taubeta is approximately equal to the independent (primitive) relaxation time tau0 of the coupling model; (4) whether both taubeta and tau0 have the same pressure and temperature dependences; (5) whether it is responsible for the "excess wing" of the primary relaxation observed in some glass-formers; (6) how the excess wing changes on aging, blending with another miscible glass-former, or increasing the molecular weight of the glass-former; (7) the change of temperature dependence of its dielectric strength Deltaepsilonbeta and taubeta across the glass transition temperature Tg; (8) the changes of Deltaepsilonbeta and taubeta with aging below Tg; (9) whether it arises in a glass-former composed of totally rigid molecules without any internal degree of freedom; (10) whether only a part of the molecule is involved; and (11) whether it tends to merge with the alpha-relaxation at temperatures above Tg. After the secondary relaxations in many glass-formers have been characterized and classified, we identify the class of secondary relaxations that bears a strong connection or correlation to the primary relaxation in all the dynamic properties. Secondary relaxations found in rigid molecular glass-formers belong to this class. The secondary relaxations in this class play the important role as a precursor or local step of the primary relaxation, and we propose that only they should be called the Johari-Goldstein beta-relaxation.

Journal Article↗

Does equilibrium polymerization describe the dynamic heterogeneity of glass-forming liquids?

A significant body of evidence indicates that particles with excessively high or low mobility relative to Brownian particles form in dynamic equilibrium in glass-forming liquids. We examine whether these "dynamic heterogeneities" can be identified with a kind of equilibrium polymerization. This correspondence is first checked by demonstrating the presence of a striking resemblance between the temperature dependences of the configurational entropy s(c) in both the theory of equilibrium polymerization and the generalized entropy theory of glass formation in polymer melts. Moreover, the multiple characteristic temperatures of glass formation are also shown to have analogs in the thermodynamics of equilibrium polymerization, supporting the contention that both processes are varieties of rounded thermodynamic transitions. We also find that the average cluster mass (or degree of polymerization) varies in nearly inverse proportionality to s(c). This inverse relation accords with the basic hypothesis of Adam-Gibbs that the number of particles in the cooperatively rearranging regions (CRR) of glass-forming liquids scales inversely to s(c) of the fluid. Our identification of the CRR with equilibrium polymers is further supported by simulations for a variety of glass-forming liquids that verify the existence of stringlike or polymeric clusters exhibiting collective particle motion. Moreover, these dynamical clusters have an exponential length distribution, and the average "string" length grows upon cooling according to the predictions of equilibrium polymerization theory. The observed scale of dynamic heterogeneity in glass-forming liquids is found to be consistent with this type of self-assembly process. Both experiments and simulations have revealed remarkable similarities between the dynamical properties of self-assembling and glass-forming liquids, suggesting that the development of a theory for the dynamics of self-assembling fluids will also enhance our understanding of relaxation in glass-forming liquids.

Journal Article↗

Balloon dilatation of the sphincter of Oddi facilitates passage of glass beads from the canine biliary tract.

Laparoscopic management of common duct stones is increasing. The most widely used technique involves trans-cystic duct scope placement and stone extraction. Occasionally, stones cannot be retrieved and are allowed to pass spontaneously after manipulation of the sphincter of Oddi. This study examines a model of sphincter of Oddi dilatation in the dog to facilitate passage of glass beads simulating gallstones. In 24 dogs, glass beads of varying sizes (3-8 mm) were implanted in the gallbladder and allowed to pass spontaneously over 1 month. In three separate groups, these animals underwent (1) sham instrumentation of the sphincter of Oddi (control), (2) sphincter dilatation with balloon catheters, or (3) transduodenal sphincterotomy. At the end of 1 month, all the animals were autopsied, and the glass beads were retrieved. Histologic sections of the pancreas were examined for possible pancreatitis. The results of this study show that no animal experienced pancreatitis from sphincter manipulation or the passage of glass beads. The control animals who underwent sham manipulation of the sphincter passed 10% of their glass beads. In contrast, after sphincter dilatation, 52.5% of the 3-mm glass beads passed or 22% of all size beads. Animals with sphincterotomy passed a similar amount of glass beads as those with balloon dilatation. These studies suggest that balloon dilatation is as efficacious as sphincterotomy in facilitating the passage of glass beads from the canine biliary tract.

Animals↗

Glass wool column filtration, an advantageous way of preparing semen samples for intracytoplasmic sperm injection: an auto-controlled randomized study.

The characteristics of the glass wool filtration technique for the preparation of semen samples in an intracytoplasmic sperm injection programme (ICSI) were compared with a two-layer Percoll density gradient procedure. Half of each of 25 semen samples were prepared by each technique. The oocytes from each patient were randomly injected, half with spermatozoa prepared by glass wool filtration and half with Percoll-separated spermatozoa from the same semen sample. The percentage of recovered motile spermatozoa, the total motile sperm count, the percentage of morphologically normal forms, the fertilization rate, the cleavage rate and embryo quality obtained with both preparations were analysed. The 95% confidence intervals obtained through the Altman-Bland analysis showed that the percentage of motile spermatozoa recovered was 3.5-9.9% higher with the glass wool filtration technique, and this was highly correlated (r = 0.92, P = 0.0001) to the method. Similarly, the total number of spermatozoa available for ICSI was 0.18 x 10(6)-2.44 x 10(6) higher with the glass wool column and was highly correlated to the method (r = 0.956, P = 0.0001). Also, the percentage of normal forms was 1.25-3.31% higher after glass wool filtration but was poorly correlated to the method (r = 0.47, P = 0.017). Out of 100 metaphase II oocytes injected with glass wool-extracted spermatozoa, 77 fertilized and 72 cleaved. Out of 97 metaphase II oocytes injected with Percoll-selected spermatozoa, 71 fertilized and 69 cleaved. These results were not statistically different. The mean +/- SEM embryo quality score for the glass wool group (2.90 +/- 0.27) was the same as that for the Percoll group (2.80 +/- 0.24). No fertilization failures occurred and 11 patients (44% per oocyte retrieval) became pregnant. It was concluded that glass wool filtration for semen preparation in an ICSI programme offers higher sperm recovery and sperm morphology of superior quality than with the classic two-layer Percoll gradient method, without affecting the fertilization rate and embryo quality.

Cell Separation↗

Glycogen pseudoground glass change in hepatocytes.

Ground glass cytoplasmic change in hepatocytes is typically associated with chronic hepatitis B infection. We report 12 cases of glycogen pseudoground glass change that closely mimics hepatitis B inclusions. Nine individuals were immunosuppressed secondary to liver or kidney transplant (N=3), bone marrow transplant (N=2), HIV infection (N=2), kidney dialysis (N=1), or chronic inflammatory bowel disease (N=1). Medication history was available in 10 individuals and all were on multiple medications (range 2 to 33). Histologically, the pseudoground glass change was identical to the ground glass change seen in chronic hepatitis B infection, with distinct, circumscribed, gray-glassy inclusions surrounded by a rim of cytoplasm. The background livers showed mild or no inflammation and mild or no fibrosis. All cases were negative for chronic hepatitis B infection. The pseudoground glass change was PAS positive and diastase sensitive. Electron microscopy of the inclusions showed glycogen in 3/3 cases. No evidence for viral particles or significant endoplasmic reticulum proliferation was seen. Three cases had follow-up biopsies (1, 1, and 36 mo), and the pseudoground glass was persistent in 2 cases and showed partial resolution in 1 case (1 mo biopsy interval). We conclude that glycogen pseudoground glass change is typically seen in immunosuppressed individuals on numerous medications. The changes are generally seen in the background of mild chronic hepatitis with mild or no fibrosis. Glycogen pseudoground glass change can resolve, but may also persist for years.

Adult↗

Ideal glass transitions for hard ellipsoids

For hard ellipsoids of revolution we calculate the phase diagram for the idealized glass transition. Our equations cover the glass physics in the full phase space, for all packing fractions and all aspect ratios X0. With increasing aspect ratio we find the idealized glass transition to become primarily driven by orientational degrees of freedom. For needlelike or platelike systems the transition is strongly influenced by a precursor of a nematic instability. We obtain three types of glass transition line. The first one (straight phi((B))(c)) corresponds to the conventional glass transition for spherical particles which is driven by the cage effect. At the second one (straight phi((B'))(c)), which occurs for rather nonspherical particles, a glass phase is formed that consists of domains. Within each domain there is a nematic order where the center of mass motion is quasiergodic, whereas the interdomain orientations build an orientational glass. The third glass transition line (straight phi((A))(c)) occurs for nearly spherical ellipsoids where the orientational degrees of freedom with odd parity, e.g., 180 degrees flips, freeze independently from the positions.

Journal Article↗

Higher-order glass-transition singularities in colloidal systems with attractive interactions.

The transition from a liquid to a glass in colloidal suspensions of particles interacting through a hard core plus an attractive square-well potential is studied within the mode-coupling-theory framework. When the width of the attractive potential is much shorter than the hard-core diameter, a reentrant behavior of the liquid-glass line and a glass-glass-transition line are found in the temperature-density plane of the model. For small well-width values, the glass-glass-transition line terminates in a third-order bifurcation point, i.e., in a A3 (cusp) singularity. On increasing the square-well width, the glass-glass line disappears, giving rise to a fourth-order A4 (swallow-tail) singularity at a critical well width. Close to the A3 and A4 singularities the decay of the density correlators shows stretching of huge dynamical windows, in particular logarithmic time dependence.

Journal Article↗

Self-generated disorder and structural glass formation in homopolymer globules.

We have investigated the interrelation between spin glasses and structural glasses. Spin glasses in this case are p-spin interaction spin glasses (at p>2) or Potts glasses that contain quenched disorder, whereas the structural glasses are here exemplified by a homopolymeric globule, which can be viewed as a liquid of connected units on a nanoscale. It is argued that the homopolymeric globule problem can be mapped onto a disorder field theoretical model whose effective Hamiltonian resembles the corresponding one for the spin glass model. In this sense the disorder in the globule is self-generated (in contrast to spin glasses) and can be related to competing interactions (virial coefficients of different signs) and the chain connectivity. The work is aimed at giving a quantitative description of this analogy. We have investigated in the mean-field approximation the phase diagram of the homopolymeric globule where the transition line from the liquid to glassy globule is treated in terms of the replica symmetry breaking paradigm. The configurational entropy temperature dependence is also discussed.

Journal Article↗

Characterization of poly(ethylene oxide) brushes on glass surfaces and adhesion of Staphylococcus epidermidis.

Poly(ethylene oxide) brushes have been covalently bound to glass surfaces and their presence was demonstrated by an increase in water contact angles from fully wettable on glass to advancing contact angles of 54 degrees, with a hysteresis of 32 degrees. In addition, electrophoretic mobilities of glass and brush-coated glass were determined using streaming potential measurements. The dependence of the electrophoretic mobilities on the ionic strength was analyzed in terms of a softlayer model, yielding an electrophoretic softness and fixed charge density of the layer. Brush-coated glass could be distinguished from glass by a 2-3-fold decrease in fixed charge density, while both surfaces were about equally soft. Adhesion of Staphylococcus epidermidis HBH276 to glass in a parallel plate flow chamber was extremely high and after 4 h, 19.0 x 10(6) bacteria were adhering per cm2. In contrast, the organisms did not adhere to brush-coated glass, with numbers below the detection limit, i.e. 0.1 x 10(6) per cm2. These results attest to the great potential of polymer brushes in preventing bacterial adhesion to surfaces.

Bacterial Adhesion↗

Bronchoalveolar lavage cell differential on microscope glass cover. A simple and accurate technique.

We describe a quick and easy technique to perform cell differentials on bronchoalveolar lavage: the microscope glass cover. Lavage fluids of 72 subjects were analyzed by 3 techniques: glass cover, filter, and cytocentrifuge preparations. Seventy-seven other lavages were analyzed by glass cover and cytocentrifuge preparations alone. Data for the 72 subjects studied by all 3 techniques showed that the cell counts on glass cover and filter preparations were similar, e.g., lymphocytes, 19.2% (range, 0.5 to 94%) and 20.9% (range, 3 to 95%), respectively (Spearman's correlation coefficient, 0.98). However, on cytocentrifuge preparations, lymphocyte counts were lower (8.3%; range, zero to 87%) and macrophage counts were higher (p less than 0.005). Comparison of glass cover and cytocentrifuge preparation mixtures with varying amounts (20 to 80%) of purified blood leukocytes labeled with 51Cr (greater than or equal to 72% lymphocytes) showed that a significant amount of radioactive cells was lost during the cytocentrifuge technique in contrast to the glass cover technique. Because neutrophils represented a low proportion of lavage cells, we also evaluated cell suspensions with known neutrophil contents (10 to 70%); we found no difference in neutrophil counts obtained with the 3 techniques. Lavage data analysis of 40 young nonsmoking volunteers showed that glass cover lymphocyte count was also higher than counts on cytocentrifuge preparations: 16.5% (range, 3 to 45%) and 8.2% (range, 2.5 to 35%), respectively. In this group, the distribution of glass cover lymphocyte percentages was normal (p = 0.21, chi 2 test), and the one-tailed 95% confidence interval was 18.6 to 34.7% (mean plus 1.65 standard deviation).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Expression of Drosophila glass protein and evidence for negative regulation of its activity in non-neuronal cells by another DNA-binding protein.

The glass gene encodes a DNA-binding zinc-finger protein required for the development of Drosophila photoreceptor cells and which appears to regulate a number of genes specifically expressed in photoreceptors. We have generated monoclonal antibodies to Glass and used them to examine Glass distribution during development. Glass is expressed in all cell types of the developing eye and in all other organs that contain photoreceptor cells in Drosophila, including a small number of cells in the brain. We altered the normal pattern of glass expression by placing the gene under the control of the hsp70 promoter. Our results suggest that nonphotoreceptor cells are restricted in their response to Glass expression. In an effort to discover the mechanism of this restriction, we examined the expression of a number of reporter gene constructs. Our results suggest that nonsensory cells are unable to express certain reporter constructs in response to Glass expression because another DNA-binding factor represses Glass activity in nonsensory cells.

Animals↗

Clinical evaluation of bioactive glass in the treatment of periodontal osseous defects in humans.

The purpose of this study was to compare the use of bioactive glass to demineralized freeze-dried bone allograft (DFDBA) in the treatment of human periodontal osseous defects. Fifteen systemically healthy patients (6 males and 9 females, aged 30 to 63) with moderate to advanced adult periodontitis were selected for the study. All patients underwent initial therapy, which included scaling and root planing, oral hygiene instruction, and an occlusal adjustment when indicated, followed by re-evaluation 4 to 6 weeks later. Paired osseous defects in each subject were randomly selected to receive grafts of bioactive glass or DFDBA. Both soft and hard tissue measurements were taken the day of surgery (baseline) and at the 6-month re-entry surgery. The clinical examiner was calibrated and blinded to the surgical procedures, while the surgeon was masked to the clinical measurements. Statistical analysis was performed by using the paired Student's t test. The results indicated that probing depths were reduced by 3.07 +/- 0.80 mm with the bioactive glass and 2.60 +/- 1.40 mm with DFDBA. Sites grafted with bioactive glass resulted in 2.27 +/- 0.88 mm attachment level gain, while sites grafted with DFDBA had a 1.93 +/- 1.33 mm gain in attachment. Bioactive glass sites displayed 0.53 +/- 0.64 mm of crestal resorption and 2.73 mm bone fill. DFDBA-grafted sites experienced 0.80 +/- 0.56 mm of crestal resorption and 2.80 mm defect fill. The use of bioactive glass resulted in 61.8% bone fill and 73.33% defect resolution. DFDBA-grafted defects showed similar results, with 62.5% bone fill and 80.87% defect resolution. Both treatments provided soft and hard tissue improvements when compared to baseline (P < or = 0.0001). No statistical difference was found when comparing bioactive glass to DFDBA; however, studies with larger sample sizes may reveal true differences between the materials. This study suggests that bioactive glass is capable of producing results in the short term (6 months) similar to that of DFDBA when used in moderate to deep intrabony periodontal defects.

Adult↗

Comparison of bioactive glass to demineralized freeze-dried bone allograft in the treatment of intrabony defects around implants in the canine mandible.

BACKGROUND: The purpose of this study was to evaluate and compare the healing of different bone grafting materials adjacent to titanium plasma-sprayed (TPS) endosseous dental implants. METHODS: Implant osteotomy sites were prepared and standardized 3-walled intrabony defects (3 mm x 5 mm x 5 mm) were created at the mesial of each implant site. Thirty-two TPS implants were placed in edentulous mandibular ridges of the 4 dogs. Periodontal dressings were placed in the defect sites so as to create a defect simulating bone loss around an implant. After 3 months, the periodontal dressing was removed, the defect sites debrided and evaluated for size, and intramarrow penetration performed. The graft materials tested were 1) canine demineralized freeze-dried bone allograft (cDFDBA); 2) bioactive glass granules of a broad size range 90 to 710 microns (BRG); and 3) bioactive glass granules of narrow size range 300 to 355 microns (NRG). One site on each side of the mandible was not filled and served as a control. Dogs were sacrificed 4 months after graft placement. RESULTS: Histologically, differences in percent bone-to-implant contact in the defect area were observed between the treatment groups. cDFDBA>control=BRG=NRG with statistical significance found between cDFDBA and control (P = 0.0379), but no statistically significant difference between control or either bioactive glass material. When comparing percent bone height fill of the defect in the grafted area, cDFDBA (65.7%) was significantly better than the control (48.9%; P < or = 0.05) with no statistically significant difference between control, broad range bioactive glass (57.3%) and narrow range bioactive glass (56.6%). When total bone area was measured, the percentage of new bone in the grafted area was cDFDBA (42.1%), broad range glass (33.1%) and narrow range glass (22.6%) with significance found between cDFDBA and NRG (P = 0.0102). The content of residual graft particles in soft tissue was significant (P = 0.0304) between cDFDBA (1.4%) and NRG (11.4%) with no significant difference between graft material for residual particle content in bone tissue. CONCLUSIONS: The results of this study indicate that percent bone-to-implant contact and percent bone height fill in an intrabony defect around titanium plasma-sprayed implants are statistically significantly higher with the use of DFDBA when compared to bioactive glass material.

Alveolar Bone Loss↗

Relationship between particle size of barium glass filler and water sorption of light-cured composite resin.

The reaction of barium glass filler with water was determined by investigation of the effects of the particle size of barium glass filler on the water sorption rate and the mechanical properties of composite resin. Barium glass and quartz were milled to obtain powders with different average particle sizes. These powders were silanized and used as inorganic filler in composite resin. Photoactivated base monomer was loaded at 65% (w/w) with these fillers to prepare the composite resin paste. The water sorption of barium glass filled resin was always more than that of quartz filled resin. The amount of sorbed water obtained by barium glass filled resin increased as the particle size decreased. The particle size of the quartz filler did not affect the water sorption. The flexural strength of barium filled resin decreased after water immersion more than that of the quartz filled resin as the particle size decreased. These results suggest that the water durability of barium glass is low and the surface of barium glass filler is damaged by water. Water would be retained in the interface between the barium glass filler and the matrix resin.

Absorption↗

Bronchoalveolar lavage and transbronchial lung biopsy in alveolar and/or ground-glass opacification.

In order to assess the diagnostic yield of bronchoalveolar lavage (BAL) and transbronchial lung biopsy (TBB) in pulmonary diseases with a ground-glass and/or alveolar pattern on high-resolution computed tomography (HRCT) scan, a prospective study was undertaken. Thirty-six patients (17 males, 19 females), mean age 53 yrs, selected on the basis of the presence of an alveolar and/or ground-glass pattern on chest HRCT scan, were submitted to fibreoptic bronchoscopy. All patients underwent BAL. TBBs were performed in 33 cases. A specific diagnosis was achieved, taking into account data obtained by means of serology, microbiology, cytology and histopathology in appropriate clinical settings. Twelve (33%) patients only had the appearance of a ground-glass opacity, whereas 24 (67%) had associated areas of airspace consolidation. BAL was performed in all cases and gave a definitive diagnosis in 21 (58%). The diagnostic yield of BAL in patients with only ground-glass opacities was no different from that in those patients also showing areas of alveolar consolidation (58 versus 58%). In eight patients (six with ground-glass opacity and two with alveolar consolidation), BAL provided useful but not definitive information. In these patients, a definitive diagnosis was achieved by means of TBB in seven cases and by open lung biopsy in one case. TBB was performed in 33 out of 36 patients and gave positive results in 25 (76%). The diagnostic yield of TBB in patients showing areas of alveolar consolidation was significantly higher than in those with pure ground-glass opacity, i.e. 95% (21 of 22) and 36% (4 of 11) respectively (p < 0.001). BAL and TBB were performed during the same bronchoscopy in 33 patients, and an accurate diagnosis was achieved in 30 (91%). Overall, the diagnostic yield of TBB (76%) and BAL (56%) did not differ significantly in the whole patient group (p = 0.12), or in patients with a ground-glass opacification (58 versus 36%, p = 0.3). However, in patients with areas of alveolar consolidation, the diagnostic sensitivity of TBB (95%) was significantly greater than the diagnostic sensitivity of BAL (54%) (p = 0.03). In conclusion this study shows that high-resolution computed tomography can be helpful in predicting the diagnostic accuracy of bronchological procedures, in particular of bronchoalveolar lavage and transbronchial biopsy, and that alveolar and/or ground-glass are favourable patterns for these diagnostic tools.

Adolescent↗

Improvement of contrast sensitivity with yellow filter glasses.

Yellow filter glasses, often sold as "antifog" or "safety" glasses at department stores and other retail outlets, are claimed to improve contrast sensitivity and the yield of visually perceived objects, particularly under poor conditions (e.g., fog, rain and twilight), by enhancing contrast. These claims were tested in 15 healthy subjects (30 eyes) aged 26 to 58 (mean 42.5) years with the Vision Contrast Test System (VCTS 6500), first with and then without yellow filter glasses. Testing was done with commercial antifog glasses and frame-mounted, hand-held filter glasses of CR (Columbia resin) 39 quality with a yellow tint made by an optician. Contrast sensitivity was found to be significantly improved with yellow filter glasses (p less than 0.0001). The use of yellow filter glasses may safely be recommended to patients who report subjective improvement in contrast vision with such glasses.

Adult↗