Quantitative cone contrast threshold testing in patients with differing pathophysiological mechanisms causing retinal diseases.

BACKGROUND: Cone contrast threshold testing (CCT) provides quantitative measurements of color and contrast function to reveal changes in vision quality that are not standard endpoints in clinical trials. We utilize CCT to measure visual function in patients with multiple sclerosis (MS), age-related macular degeneration (AMD), epiretinal membrane (ERM), and retinal vein occlusion (RVO). METHODS: Retrospective data was gathered from 237 patients of the Gavin Herbert Eye Institute. Subjects included 17 patients with MS, 45 patients with AMD, 41 patients with ERM, 11 patients with RVO, and 123 healthy controls. Patients underwent the primary measurement outcome, CCT testing, as well as Sloan visual acuity test and spectral domain optical coherence tomography during normal care. RESULTS: Color and contrast deficits were present in MS patients regardless of history of optic neuritis. AMD with intermediate or worse disease demonstrated reduced CCT scores. All 3 stages of ERM demonstrated cone contrast deficits. Despite restoration of visual acuity, RVO-affected eyes demonstrated poorer CCT performance than unaffected fellow eyes. CONCLUSIONS: CCT demonstrates color and contrast deficits for multiple retinal diseases with differing pathophysiology. Further prospective studies of CCT in other disease states and with larger samples sizes is warranted.

Quantifying Color Vision Changes Associated With Cataracts Using Cone Contrast Thresholds.

Purpose: To evaluate effects of age and simulated and real cataractous changes on color vision as measured by the high-definition cone contrast test (CCT). Methods: Twenty-four healthy volunteers from two cohort studies performed CCT using best-corrected visual acuity, filters, mydriasis, and pinhole correction. Retrospective cross-sectional study of patients seen in eye clinics evaluated the relationship between age and color vision, and age and lens status in 355 eyes. Last, 25 subjects underwent CCT before and after cataract surgery. Results: CCT scores were most reliable in the nonmydriatic condition without pinhole correction. Progressively dense brown filters produced small decreases in S-cone sensitivity. Linear regression analysis of phakic subjects showed a decline for all cone classes with age. Rate of decline was greater for S-cones (slope = -1.09; 95% confidence interval [CI], -1.30 to 0.86) than M-cones (slope = -0.80; 95% CI, -1.03 to -0.58) and L-cones (slope = -0.66; 95% CI, -0.88 to -0.44). CCT scores increased for S-cones but reduced for L- and M-cones in pseudophakic subjects compared with phakic patients. CCT scores after cataract surgery increased for S-cones, M-cones, and L-cones by 33.0 (95% CI, 8.6 to 57.4), 24.9 (95% CI, 3.8 to 46.0), and 22.0 (95% CI, -3.2 to 47.3), respectively. Conclusions: CCT assessment allows for clinically practical quantitation of color and contrast vision improvement after cataract surgery and aging patients who note poor vision despite good visual acuity. Translational Relevance: CCT testing, which quantifies hereditary and acquired color deficiency, can also quantify the degree of cataract severity and, combined with other parameters, can provide more precise guidance for cataract extraction to optimize patient care.

A two-step method for identifying photopigment opsin and rhodopsin gene sequences underlying human color vision phenotypes.

Purpose: To present a detailed, reliable long range-PCR and sequencing (LR-PCR-Seq) procedure to identify human opsin gene sequences for variations in the long wavelength-sensitive (OPN1LW), medium wavelength-sensitive (OPN1MW), short wavelength-sensitive (OPN1SW), and rhodopsin (RHO) genes. Methods: Color vision was assessed for nine subjects using the Farnsworth-Munsell 100 hue test, Ishihara pseudoisochromatic plates, and the Rabin cone-contrast threshold procedure (ColorDX, Konan Medical). The color vision phenotypes were normal trichromacy (n = 3), potential tetrachromacy (n = 3), dichromacy (n = 2), and unexplained low color vision (n = 1). DNA was isolated from blood or saliva and LR-PCR amplified into individual products: OPN1LW (4,045 bp), OPN1MW (4,045 bp), OPN1SW (3,326 bp), and RHO (6,715 bp). Each product was sequenced using specific internal primer sets. Analysis was performed with Mutation Surveyor software. Results: The LR-PCR-Seq technique identified known single nucleotide polymorphisms (SNPs) in OPN1LW and OPN1MW gene codons (180, 230, 233, 277, and 285), as well as those for lesser studied codons (174, 178, 236, 274, 279, 298 and 309) in the OPN1LW and OPN1MW genes. Additionally, six SNP variants in the OPN1MW and OPN1LW genes not previously reported in the NCBI dbSNP database were identified. An unreported poly-T region within intron 5(c.36+126) of the rhodopsin gene was also found, and analysis showed it to be highly conserved in mammalian species. Conclusions: This LR-PCR-Seq procedure (single PCR reaction per gene followed by sequencing) can identify exonic and intronic SNP variants in OPN1LW, OPN1MW, OPN1SW, and rhodopsin genes. There is no need for restriction enzyme digestion or multiple PCR steps that can introduce errors. Future studies will combine the LR-PCR-Seq with perceptual behavior measures, allowing for accurate correlations between opsin genotypes, retinal photopigment phenotypes, and color perception behaviors.

Quantitative approach for defining basic color terms and color category best exemplars.

A new method is presented that identifies basic color terms (BCTs) from color-naming data. A function is defined that measures how well a term is understood by a communicating population. BCTs are then separated from other color terms by a threshold value applied to this function. A new mathematical algorithm is proposed and analyzed for determining the best exemplar associated with each BCT. Using data provided by the World Color Survey, comparisons are made between the paper's methods and those from other studies. These comparisons show that the paper's new definition of "basicness" mostly agrees with the typical definition found in the color categorization literature, which was originally due to Kay and colleagues. The new definition, unlike the typical one, has the advantage of not relying on syntactic or semantic features of languages or color lexicons. This permits the methodology developed to be generalizable and applied to other category domains for which a construct of "basicness" could have an important role.

Overcoming clinical inertia in the management of postoperative patients with diabetes.

OBJECTIVE: To assess the impact of an intervention designed to increase basal-bolus insulin therapy administration in postoperative patients with diabetes mellitus. METHODS: Educational sessions and direct support for surgical services were provided by a nurse practitioner (NP). Outcome data from the intervention were compared to data from a historical (control) period. Changes in basal-bolus insulin use were assessed according to hyperglycemia severity as defined by the percentage of glucose measurements >180 mg/dL. RESULTS: Patient characteristics were comparable for the control and intervention periods (all P≥.15). Overall, administration of basal-bolus insulin occurred in 9% (8/93) of control and in 32% (94/293) of intervention cases (P<.01). During the control period, administration of basal-bolus insulin did not increase with more frequent hyperglycemia (P = .22). During the intervention period, administration increased from 8% (8/96) in patients with the fewest number of hyperglycemic measurements to 60% (57/95) in those with the highest frequency of hyperglycemia (P<.01). The mean glucose level was lower during the intervention period compared to the control period (149 mg/dL vs. 163 mg/dL, P<.01). The proportion of glucose values >180 mg/dL was lower during the intervention period than in the control period (21% vs. 31% of measurements, respectively, P<.01), whereas the hypoglycemia (glucose >70 mg/dL) frequencies were comparable (P = .21). CONCLUSION: An intervention to overcome clinical inertia in the management of postoperative patients with diabetes led to greater utilization of basal-bolus insulin therapy and improved glucose control without increasing hypoglycemia. These efforts are ongoing to ensure the delivery of effective inpatient diabetes care by all surgical services.

A quantitative theory of human color choices.

The system for colorimetry adopted by the Commission Internationale de l'Eclairage (CIE) in 1931, along with its subsequent improvements, represents a family of light mixture models that has served well for many decades for stimulus specification and reproduction when highly controlled color standards are important. Still, with regard to color appearance many perceptual and cognitive factors are known to contribute to color similarity, and, in general, to all cognitive judgments of color. Using experimentally obtained odd-one-out triad similarity judgments from 52 observers, we demonstrate that CIE-based models can explain a good portion (but not all) of the color similarity data. Color difference quantified by CIELAB ΔE explained behavior at levels of 81% (across all colors), 79% (across red colors), and 66% (across blue colors). We show that the unexplained variation cannot be ascribed to inter- or intra-individual variations among the observers, and points to the presence of additional factors shared by the majority of responders. Based on this, we create a quantitative model of a lexicographic semiorder type, which shows how different perceptual and cognitive influences can trade-off when making color similarity judgments. We show that by incorporating additional influences related to categorical and lightness and saturation factors, the model explains more of the triad similarity behavior, namely, 91% (all colors), 90% (reds), and 87% (blues). We conclude that distance in a CIE model is but the first of several layers in a hierarchy of higher-order cognitive influences that shape color triad choices. We further discuss additional mitigating influences outside the scope of CIE modeling, which can be incorporated in this framework, including well-known influences from language, stimulus set effects, and color preference bias. We also discuss universal and cultural aspects of the model as well as non-uniformity of the color space with respect to different cultural biases.

An outpatient-based clinical program for diabetes prevention: an update.

OBJECTIVE: To update outcomes of the Diet-Exercise-Activity-Lifestyle (DEAL) program, a clinic-based diabetes prevention intervention. METHODS: Changes in weight, fasting blood glucose, and 2-hour glucose after a 75-g oral glucose tolerance test were evaluated in patients who enrolled in the DEAL program between January 2007 and August 2009. RESULTS: The 221 qualified participants had a mean age of 62 years, weight of 87.4 kg, body mass index of 31.2 kg/m², fasting glucose level of 109 mg/dL, and 2-hour glucose value of 138 mg/dL. Among the program participants, 67% were women and 88% were white; 56% had isolated impaired fasting glucose, 5% had impaired glucose tolerance only, and 39% had both. The 6-month follow-up medical appointment was kept by 72% of program participants, but only 56% attended the 12-month visit. By 6 months after baseline, 59% had significantly lower fasting glucose concentrations, 59% had improvement in 2-hour glucose levels, and 61% had weight loss. Nearly 40%, however, were nonresponders and had increased fasting glucose, 2-hour glucose, and weight by 6 months. By the 12-month visit, significant declines in fasting glucose (P<.001), 2-hour glucose (P<.001), and weight (P = .008) occurred in comparison with baseline values; however, no significant changes occurred in these measures between the 6- and 12-month visits (P>.30 for all). CONCLUSION: Most DEAL participants showed improvement in glucose levels and weight, but some patients exhibited worsening glucose intolerance. Factors underlying nonresponse need to be identified. Ongoing experience and analysis should help revise the DEAL program so that outcomes for all participating patients will improve.

Diabetes in the desert: what do patients know about the heat?

BACKGROUND: This study aims to identify self-management strategies used by patients with diabetes in hot weather, examine knowledge of safe temperatures and exposure times, and evaluate comprehension of weather data. METHODS: Patients attending an endocrinology clinic in southwestern United States were surveyed. RESULTS: One hundred fifty-two surveys completed from November 30 to December 31, 2009 were analyzed. Mean patient age was 64 years; diabetes duration e analyzed 15 years; 51% were women 83% had type 2 diabetes, 58% were non Hispanic white, and 77% were on insulin injections. Mean hemoglobin A1c was 7.9%; 38% had hemoglobin A1c values of 8.0% or higher. Patients used an array of personal protective measures during hot weather, and 71% limited heat exposure to less than one hour. Respondents typically took steps to protect their diabetes medication and supplies, but 37% chose to leave medications and supplies at home. Although 73% of respondents had received information regarding the effect of heat on insulin, only 39% had received information about the effect of heat on oral medications, 41% on glucose meters, and 38% on glucose test strips. The temperature at which patients took protective measures varied. Only 55% knew the definition of the heat index. CONCLUSION: Most survey participants took measures to protect themselves from the heat, although gaps in knowledge were evident. Many patients had suboptimal glycemic control, placing them potentially at risk for dehydration during the hottest months. Increased public awareness of this topic is needed, and diabetes education programs should include information about the heat where appropriate.

An outpatient-based clinical program for type 2 diabetes prevention.

OBJECTIVE: To review first-year results of a clinic-based type 2 diabetes prevention program. METHODS: From January through December 2007, patients with a diagnosis of prediabetes participated in the Diet-Exercise-Activity-Lifestyle program for instruction in lifestyle changes. Physical therapy assessments were retrospectively reviewed to search for symptoms or findings of physical impairments. Changes in weight and 2-hour glucose tolerance test results were assessed at 6 months. Patient satisfaction with the program was evaluated. RESULTS: Ninety-two patients qualified for the program. Mean baseline fasting glucose concentration was 108 mg/dL, and 2-hour glucose concentration was 134 mg/dL. Mean age was 62 years, and 66% were women. Review of physical therapy assessments demonstrated gait/balance disturbances in 47% of patients, peripheral neuropathy in 43%, and musculoskeletal problems in 63%. Among 47 patients who had 6-month follow-up visits, 72% lost weight. Fasting glucose levels improved in 58% in persons with impaired fasting glucose, and 2-hour glucose values decreased in patients who had impaired glucose tolerance. Seventy-eight percent graded the program as either "very good" or "excellent." CONCLUSIONS: Programs geared toward type 2 diabetes prevention can be feasibly implemented on an outpatient basis. Preliminary data suggest that improvements in weight and glucose values can be achieved. As the prevalence of prediabetes increases, health care systems must gain further experience with effective outpatient diabetes prevention strategies.

Evolutionary models of color categorization. I. Population categorization systems based on normal and dichromat observers.

The evolution of color categorization is investigated using artificial agent population categorization games, by modeling observer types using Farnsworth-Munsell 100 Hue Test performance to capture human processing constraints on color categorization. Homogeneous populations of both normal and dichromat agents are separately examined. Both types of populations produce near-optimal categorization solutions. While normal observers produce categorization solutions that show rotational invariance, dichromats' solutions show symmetry-breaking features. In particular, it is found that dichromats' local confusion regions tend to repel color category boundaries and that global confusion pairs attract category boundaries. The trade-off between these two mechanisms gives rise to population categorization solutions where color boundaries are anchored to a subset of locations in the stimulus space. A companion paper extends these studies to more realistic, heterogeneous agent populations [J. Opt. Soc. Am. A26, 1424-1436 (2009)].

Evolutionary models of color categorization. II. Realistic observer models and population heterogeneity.

The evolution of color categorization is investigated using computer simulations of agent population categorization games. Various realistic observer types are implemented based on Farnsworth-Munsell 100 Hue Test human performance data from normal and anomalous trichromats, dichromats, and humans with four retinal photopigments. Results show that (i) a small percentage of realistically modeled deficient agents greatly affects the shared categorization solutions of the entire population in terms of color category boundary locations; (ii) for realistically modeled populations, dichromats have the strongest influence on the color categorization; their characteristic forms of color confusion affect (i.e., attract or repel) color boundary locations and accord with our findings for homogeneous dichromat populations [J. Opt. Soc. Am. A26, 1414-1423 (2009)]; (iii) adding anomalous trichromats or trichromat "experts" does not destabilize the solutions or substantially alter solution structure. The results provide insights regarding the mechanisms that may constrain universal tendencies in human color categorization systems.

Perceptions of resident physicians about management of inpatient hyperglycemia in an urban hospital.

BACKGROUND: Information regarding practitioner beliefs about inpatient diabetes care is limited. OBJECTIVE: To assess resident physician attitudes about inpatient hyperglycemia and determine perceived barriers to optimal glycemic control in an urban hospital setting. DESIGN: A previously developed questionnaire was modified and administered. Residents were asked about the importance of inpatient glucose control, desirable glucose ranges, and problems encountered when managing hyperglycemia. SETTING: Urban teaching hospital. RESULTS: Of 85 resident physicians, 66 completed the survey (mean age, 31 years; 47% men; 33% in first residency year). Most respondents categorized glucose control as "very important" in critically-ill and perioperative patients but only "somewhat important" in non-critically-ill patients. Most residents said they would target a therapeutic glucose range within the recommended levels. Most residents (88%) also said they felt "very comfortable" or "somewhat comfortable" using subcutaneous insulin therapy, whereas some were "not at all comfortable" with either subcutaneous (11%) or intravenous (18%) administration. In general, respondents were not very familiar with existing institutional policies and preprinted order sets. The most commonly reported barrier to management of inpatient hyperglycemia was lack of knowledge about appropriate insulin regimens and their use. Anxiety about hypoglycemia was only the third most frequent concern. CONCLUSION: Most residents acknowledged the importance of good glucose control in hospitalized patients and chose target glucose ranges consistent with existing guidelines. Lack of knowledge about insulin treatment options was the most commonly cited barrier to ideal management. Educational programs should emphasize inpatient treatment strategies for glycemic control.

Population heterogeneity and color stimulus heterogeneity in agent-based color categorization.

Investigating the interactions between universal and culturally specific influences on color categorization across individuals and cultures has proven to be a challenge for human color categorization and naming research. The present article simulates the evolution of color lexicons to evaluate the role of two realistic constraints found in the human phenomenon: (i) heterogeneous observer populations and (ii) heterogeneous color stimuli. Such constraints, idealized and implemented as agent categorization and communication games, produce interesting and unexpected consequences for stable categorization solutions evolved and shared by agent populations. We find that the presence of a small fraction of color deficient agents in a population, or the presence of a "region of increased salience" in the color stimulus space, break rotational symmetry in population categorization solutions, and confine color category boundaries to a subset of available locations. Further, these heterogeneities, each in a different, predictable, way, might lead to a change of category number and size. In addition, the concurrent presence of both types of heterogeneity gives rise to novel constrained solutions which optimize the success rate of categorization and communication games. Implications of these agent-based results for psychological theories of color categorization and the evolution of color naming systems in human societies are discussed.

Beliefs about hospital diabetes and perceived barriers to glucose management among inpatient midlevel practitioners.

PURPOSE: The purpose of this study is to explore attitudes among inpatient midlevel practitioners about hospital hyperglycemia and to identify perceived barriers to care. METHODS: A questionnaire previously applied to resident physicians was administered to midlevel providers (physician assistants and nurse practitioners) to determine their beliefs about the importance of inpatient glucose control, their perceptions about what glucose ranges were desirable, and the problems they encountered when trying to manage hyperglycemia in the hospital. Barriers to care reported in this study were also combined with responses from the prior resident survey. RESULTS: Most respondents indicated that glucose control was very important in critically ill, noncritically ill, and perioperative patients. However, most felt only somewhat comfortable treating hyperglycemia and hypoglycemia and with using subcutaneous insulin; respondents expressed the least amount of confidence with using insulin infusions and insulin pumps. Respondents were not familiar with existing institutional polices and preprinted order sets relating to glucose management. The most commonly reported barrier to hyperglycemia management in the hospital was lack of familiarity with how to useinsulin, a finding that persisted after analyzing composite resident and midlevel responses. CONCLUSIONS: Most midlevel providers acknowledged the importance of good glucose control in the hospital. Lack of familiarity with how to use insulin in the hospital was the most commonly cited barrier to care. Educational programs should heavily emphasize inpatient treatment strategies.

Understanding and improving management of inpatient diabetes mellitus: the Mayo Clinic Arizona experience.

We present an overview of strategies our institution has taken to understand the state of its inpatient diabetes management. We first describe how we utilized information systems to assess inpatient glycemic control and insulin management in noncritically ill patients and discuss our findings regarding mean bedside glucose levels, the prevalence and frequency hypoglycemic and hyperglycemic events, the patterns of insulin therapy, and evidence of inpatient clinical inertia. We also review the development of a survey to determine practitioner attitudes and beliefs about inpatient diabetes. Results of this survey study found that, in general, practitioners believed in the importance of controlling hyperglycemia but were not comfortable with many aspects of inpatient diabetes care, particularly with the use of insulin. Finally, we suggest steps to follow in developing a quality-improvement program for hospitals.

Management of inpatient hyperglycemia: assessing perceptions and barriers to care among resident physicians.

OBJECTIVE: To develop insight into resident physician attitudes about inpatient hyperglycemia and determine perceived barriers to optimal management. METHODS: As part of a planned educational program, a questionnaire was designed and administered to determine the opinions of residents about the importance of inpatient glucose control, their perceptions about what glucose ranges were desirable, and the problems they encountered when trying to manage hyperglycemia in hospitalized patients. RESULTS: Of 70 resident physicians from various services, 52 completed the survey (mean age, 31 years; 48% men; 37% in first year of residency training). Most respondents indicated that glucose control was "very important" in critically ill and perioperative patients but only "somewhat important" in non-critically ill patients. Most residents indicated that they would target a therapeutic glucose range within the recommended levels in published guidelines. Most residents also said they felt "somewhat comfortable" managing hyperglycemia and hypoglycemia and using subcutaneous insulin therapy, whereas most residents (48%) were "not at all comfortable" with use of intravenous administration of insulin. In general, respondents were not very familiar with existing institutional policies and preprinted order sets relating to glucose management. The most commonly reported barrier to management of inpatient hyperglycemia was lack of knowledge about appropriate insulin regimens and how to use them. Anxiety about hypoglycemia was only the third most frequent concern. CONCLUSION: Most residents acknowledged the importance of good glucose control in hospitalized patients and chose target glucose ranges consistent with existing guidelines. Lack of knowledge about insulin treatment options was the most commonly cited barrier to ideal management. Educational programs should emphasize inpatient treatment strategies for glycemic control.

Color coding information: assessing alternative coding systems using independent brightness and hue dimensions.

Can independent dimensions of brightness and hue be used in a combined digital information code? This issue was addressed by developing 2 color-coding systems and testing them on informed and naive participants in signal beam detection and classification experiments for simulated sonar displays. Each coding system's results showed both groups efficiently used encoded information that varied simultaneously along the 2 dimensions of brightness and hue. Findings support the proposed procedures for developing color information codes and the validity of such information codes across different populations. Applied significance of these results is provided by the test of principled methods of color-code construction and the demonstration that extending the information content of user interfaces beyond 1 dimension is feasible in practice.