Tuberculosis and risk of acute myocardial infarction: a propensity score-matched analysis.

Several pathogens have been associated with increased cardiovascular disease (CVD) risk. Whether this occurs with Mycobacterium tuberculosis infection is unclear. We assessed if tuberculosis disease increased the risk of acute myocardial infarction (AMI). We identified patients with tuberculosis index claims from a large de-identified database of ~15 million adults enrolled in a U.S. commercial insurance policy between 2008 and 2010. Tuberculosis patients were 1:1 matched to patients without tuberculosis claims using propensity scores. We compared the occurrence of index AMI claims between the tuberculosis and non-tuberculosis cohorts using Kaplan-Meier curves and Cox Proportional Hazard models. Data on 2026 patients with tuberculosis and 2026 propensity-matched patients without tuberculosis were included. AMI was more frequent in the tuberculosis cohort compared with the non-tuberculosis cohort, 67 (3·3%) vs. 32 (1·6%) AMI cases, respectively, P < 0·01. Tuberculosis was associated with an increased risk of AMI (adjusted hazard ratio (HR) 1·98, 95% confidence intervals (CI) 1·3-3·0). The results were similar when the analysis was restricted to pulmonary tuberculosis (adjusted HR 2·43, 95% CI 1·5-4·1). Tuberculosis was associated with an increased risk of AMI. CVD risk assessment should be considered in tuberculosis patients. Mechanistic studies of tuberculosis and CVD are warranted.

[Adherence to recommendations to reduce the risk of Sudden infant Death Syndrome]. / Evaluación de la adherencia a las recomendaciones para disminuir el riesgo de Síndrome de Muerte Súbita del lactante.

INTRODUCTION: Recommendations for Sudden Infant Death Syndrome (SIDS) are available, although it is uncertain the degree of adherence to these measures. The aim of the study is to assess the adherence to recommendations to reduce the risk of SIDS, seeking factors associated to the noncompliance with these recommendations. PATIENTS AND METHOD: 468 infants were enrolled in two maternity hospitals, one public and one private. Postpartum and 4-month assessments were performed. A questionnaire was used adapting a model validated by the International Child Care Practices Study. RESULTS: Adherence to obstetric recommendations was higher (75.4%) than to pediatric recommendations (53.3%). Regarding pediatric recommendations, a compliance decrease was detected after 4 months. Follow-ups showed decrease in breastfeeding (p < 0.001 84.9% vs 48.6%) and supine position (61.2% vs 21.2%, p < 0.001). CONCLUSIONS: The decreased adherence to recommendations for SIDS prevention was mainly observed in younger and less educated women, who were not in a relationship and living in poor housing quality and crowded environments.

Inflammation and oxidative stress are lower in physically fit and active adults.

The objective of this study was to determine if the inverse relationship between perceived physical fitness (pFIT) and exercise frequency (ExFreq) levels and chronic inflammation and oxidative stress exists after making statistical adjustments for confounders including body mass index (BMI), age, gender, and cigarette smoking. Study participants (60% female and 40% male; n = 998) varied widely in age (18-85 years) and BMI (16.7-52.7 kg/m(2)) completed an extensive medical/health and lifestyle questionnaire, and data were used to establish pFIT and ExFreq tertiles. Biomarkers included serum C-reactive protein (CRP), total blood leukocytes, five plasma cytokines [interleukin (IL)-6, IL-10, tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP1), and granulocyte colony-stimulating factor (GCSF)], F2 -isoprostanes, ferric reducing ability of plasma (FRAP), and oxygen radical absorbance capacity (ORAC). A general linear model was used to examine relationships between pFIT and ExFreq with inflammation and oxidative stress while controlling for age, gender, BMI, and smoking. Benjamini-Hochberg method for false discovery rate correction was used for multiple testing corrections. Significant tests (P < 0.05) for trend were found for the effect of pFIT and ExFreq on CRP, white blood cell, IL-6, TNF-α, GCSF, and F2 -isoprostanes, but not MCP1, IL-10, FRAP, and ORAC, after adjustment for confounders. These data indicate that an inverse relationship exists among chronic inflammation, oxidative stress, and pFIT and ExFreq at the community level even after adjustment for important confounders.

Relationship between salivary IgA secretion and upper respiratory tract infection following a 160-km race.

AIM: The relationship between salivary IgA secretion rate and upper respiratory tract infection (URTI) was studied in 155 ultramarathoners (126 males, 29 females, mean age 46.5+/-0.7 y) who had qualified to run the 160-km 2003 Western States Endurance Run. METHODS: Subjects provided saliva samples during registration, held the morning before the race, and within 5-10 minutes postrace (mean race time, 26.2+/-0.3 h). Unstimulated saliva was collected by expectoration for 4 minutes into 15-mL plastic, sterilized vials. Runners finishing the race and providing pre- and postrace saliva samples (n=106) turned in a health log specifying URTI episodes and severity of symptoms for the 2-week period following the race. RESULTS: The total volume of saliva that the runners was able to expectorate during sample collection decreased 51% postrace compared to prerace values (P<0.001). Saliva protein concentration increased 20% (P<0.001) while the saliva protein IgA concentration decreased 10% (P<0.05). Salivary IgA secretion rate decreased 46% when comparing pre- to postrace values (P<0.001). Twenty-four percent of the runners finishing the race and providing salivary samples reported an URTI episode lasting 2 days or longer during the 2-week period following the race (mean number of days with symptoms was 5.4+/-0.6 days). The decrease in salivary IgA secretion rate (pre- to postrace) was 53% greater in the 25 runners reporting URTI (-355+/-45 microg/min) compared to the 81 runners not reporting URTI (-232+/-37 microg/min), (P=0.04). CONCLUSIONS: In summary, nearly 1 in 4 runners reported an URTI episode during the 2-week period following a 160-km race, and the decrease in salivary IgA secretion rate was significantly greater in these runners compared to those not reporting URTI.

Malignant mesothelioma following radiation exposure.

Mesothelioma developed in proximity to the field of therapeutic radiation administered 10-31 years previously in four patients. In three, mesothelioma arose within the site of prior therapeutic radiation for another cancer. Mesothelioma in the fourth patient developed adjacent to the site of cosmetic radiation to a thyroidectomy scar. None of these four patients recalled an asbestos exposure or had evidence of asbestosis on chest roentgenogram. Lung tissue in one patient was negative for ferruginous bodies, a finding considered to indicate no significant asbestos exposure. Five other patients with radiation-associated mesothelioma have been reported previously, suggesting that radiation is an uncommon cause of human mesothelioma. Problems in the diagnosis of radiation-associated mesotheliomas are considered.

The sensation of dyspnea during exercise is not determined by the work of breathing in patients with heart failure.

OBJECTIVES: The present study sought to investigate whether the work of breathing was reduced after heart transplantation. Accordingly, the tension time index of the diaphragm was measured in patients with heart failure and in transplant recipients. BACKGROUND: Patients with heart failure are frequently limited by exertional dyspnea that may be due to the increased work of breathing. After heart transplantation, exertional dyspnea is markedly diminished. Whether work of breathing is reduced in posttransplant recipients is unknown. METHODS: Nine patients with heart failure, six normal subjects and six heart transplant recipients were studied. Transdiaphragmatic pressure was measured throughout exercise. Accessory respiratory muscle oxygenation was assessed using near-infrared spectroscopy. Peak oxygen consumption, time in inspiration, time per breath and maximal inspiratory and expiratory pressures were measured in all subjects. RESULTS: The tension time index remained markedly abnormal after heart transplantation both at rest ([mean +/- SD] normal group 0.01 +/- 0.006, heart failure group 0.026 +/- 0.018, transplant group 0.058 +/- 0.015, p < 0.004) and at peak exercise (normal group 0.03 +/- 0.02, heart failure group 0.10 +/- 0.03, transplant group 0.10 +/- 0.04, p < 0.0001). Accessory respiratory muscle deoxygenation was present only in patients with heart failure (near-infrared absorbency changes [arbitrary units]: normal group -3 +/- 6, heart failure group 28 +/- 5, transplant group -3.5 +/- 4.4, p < 0.0001). CONCLUSIONS: Although heart transplantation alleviates dyspnea in patients with heart failure, the work of breathing as assessed by the tension time index of the diaphragm is not decreased. Amelioration of exertional dyspnea is achieved by other mechanisms, such as improved respiratory muscle perfusion.

Evidence of reduced respiratory muscle endurance in patients with heart failure.

OBJECTIVES: We sought to investigate whether reduced respiratory muscle endurance contributes to increased dyspnea and decreased exercise capacity in patients with chronic heart failure. BACKGROUND: In patients with heart failure, the sensation of dyspnea may be related to abnormalities of respiratory muscle function, such as diminished strength or endurance, or both. METHODS: Respiratory muscle endurance was assessed by measuring maximal sustainable ventilatory capacity in 15 patients with congestive heart failure and 8 normal subjects using progressive isocapnic hyperpnea. Near-infrared spectroscopy of an accessory respiratory muscle, Borg scale recordings of perceived dyspnea, time in inspiration, time per breath and minute ventilation were measured. Exercise testing with measurement of oxygen consumption was also performed. RESULTS: Maximal voluntary ventilation (normal subjects 167 +/- 40, heart failure group 89 +/- 31 liters/min) and maximal sustainable ventilatory capacity (normal subjects 90 +/- 23, heart failure group 53 +/- 22 liters/min) were significantly reduced in patients with heart failure (both p < 0.05). No significant accessory respiratory muscle deoxygenation was observed in either group. Borg scale recordings at maximal sustainable ventilatory capacity were comparable in both groups. At rest, the inspiratory duty cycle (i.e., time in inspiration divided by the time per breath) was comparable in the two groups (normal subjects 0.34 +/- 0.09, heart failure group 0.37 +/- 0.12, p = NS). However at maximal sustainable ventilatory capacity, only normal subjects had a significant increase in the inspiratory duty cycle (normal subjects 0.49 +/- 0.04, heart failure group 0.36 +/- 0.10, p < 0.05). This finding suggests obstruction to airflow in patients with congestive heart failure. Values for peak exercise minute ventilation did not differ significantly from values in maximal sustainable ventilatory capacity in either group and were significantly correlated (r = 0.84, p < 0.0001). CONCLUSION: Respiratory muscle endurance as assessed by maximal sustainable ventilatory capacity is reduced in patients with heart failure.

Biomarkers for early detection of colon cancer.

There is an increasing demand for biomarkers in colon cancer for risk assessment, early detection, prognosis, and surrogate end points. A number of biomarkers have been identified for early detection of colon cancer, although the risk factors have not been identified extensively. The major advances in understanding colorectal cancer include the identification and the involvement of APC, p53, and Ki-ras in the development and progression of the disease, the identification of the aberrant crypt foci as an early preinvasive lesion, and its relation to the development of cancer. Detecting malignant neoplasms in the early stages offers clinical advantages; therefore, the National Cancer Institute has established an Early Detection Research NETWORK: The emphasis of the network is on translational research and collaboration among scientists.

New superior-inferior visual field asymmetry indices for detecting POAG and their agreement with the glaucoma hemifield test.

PURPOSE: To describe and measure the discriminatory performance of three new superior-inferior asymmetry indices for detecting primary open angle glaucoma (POAG) and to compare these with the glaucoma hemifield test (GHT). METHODS: In all, 412 control and 247 POAG eyes were selected from a visual field database of patients attending the Manchester Royal Eye Hospital. Age-adjusted defect asymmetries were calculated for each of the 22 vertically mirrored test point pairs used in the GHT. The three new indices, hemifield mean difference (HMD) and hemifield standard deviation (HSD) of the asymmetry values along with the number of test pairs (NP) falling outside the 85% probability limits of the control population, were calculated. ROC curves of the indices and GHT were constructed. Agreement between the indices was explored with a proportional Venn diagram and 3 × 3 contingency tables. Cases of disagreement between the indices were reviewed. RESULTS: The area under the ROC curves were HMD=0.745 (95% confidence interval (CI) 0.705-0.786), HSD=0.864 (95% CI 0.833-0.894), NP=0.863 (95% CI 0.832-0.893) and GHT=0.792 (95% CI 0.754-0.829). The Venn diagram and contingency tables highlighted the good agreement between HSD, NP and GHT. Agreement was 78% (HSD vs. GHT) and 82% (NP vs. GHT) in the control sample and 70% (HSD vs. GHT) and 71% (NP vs. GHT) in the POAG sample. Five cases are presented where disagreement existed between the indices. CONCLUSIONS: The new HSD and NP asymmetry indices perform better than GHT in differentiating between normal and POAG eyes in this data set. GHT can fail to detect significant asymmetry, detected by HSD and NP, when an early defect crosses sector boundaries.

Delayed hypersensitivity in Graves' disease and exophthalmos: identification of thyroglobulin in normal human orbital muscle.

Patients with Graves' disease and exophthalmos demonstrate delayed hypersensitivity to antigens present in extracts of certain normal human tissue; namely,thyroid gland and retroorbital tissue. The delayed hypersensitivity can be assayed in vitro by quantitating the amount of a lymphokine, migration inhibition factor (MIF), which is produced when T lymphocytes of patients with Graves' disease and exophthalmos are exposed to these antigens. In the present report, a partial purification is described for the retro-orbital tissue antigen which is responsible for the positive leucocyte migration inhibition factor assay (MIF assay) exhibited by a sensitized lymphocytes of these patients. The purified retro-orbital tissue antigen preparation demonstrates a 50- to 150-fold higher specific activity over crude homogenates in its ability to act as an antigen in the MIF assay of exophthalmic patients. Immunodiffusion, ultracentrifugation, and disc electrophoretic data indicate that this purified antigen preparation, obtained from normal human, retro-orbital tissue, contains thyroglobulin or a derivative of thyroglobulin; immunofluorescence studies localize the anti-thyroglobulin reactive material to the plasma membranes of extraocular muscle fibers of normal individuals. On the basis of these data it is concluded that thyroglobulin or a derivative of the thyroglobulin molecule is present in the orbital muscle of normal individuals. Since thyroglobulin purified from normal human thyroid glands and the purified retro-orbital tissue preparation are nearly equivalent as antigens in the MIF assay of exophthalmic patients, we conclude that thyroglobulin or an antigenic component of the thyroglobulin molecule is one of the antigens to which patients with Graves' disease and exophthalmos demonstrate delayed hypersensitivity.

Carbohydrate supplementation affects blood granulocyte and monocyte trafficking but not function after 2.5 h or running.

This randomized, double-blind, placebo-controlled study was designed to determine the influence of carbohydrate supplementation on the granulocyte and monocyte response to 2.5 h of high-intensity running [76.7 +/- 0.4% of maximal oxygen consumption (VO2max)]. Thirty experienced marathon runners (VO2max 53.4 +/- 1.0 mL.kg-1.min-1, age 41.5 +/- 1.4 y) were randomly assigned to carbohydrate-supplement (n = 17) and placebo (n = 13) groups. Subjects rested for 10-15 min before a blood sample was taken at 0715, and then ingested 0.75 L carbohydrate beverage or placebo. At 0730 subjects began running at 75-80% of VO2max for 2.5 h, and drank 0.25 L carbohydrate or placebo fluid every 15 min. Immediately after the 2.5-h run (1000), another blood sample was taken, followed by 1.5-h, 3-h, and 6-h recovery samples. Carbohydrate supplementation had a significant effect compared with placebo on the pattern of change in plasma glucose and cortisol, and the blood concentration of neutrophils (F[14, 112] = 5.13, P = 0.001) and monocytes (F[14, 112] = 4.78, P = 0.001), but not on blood granulocyte and monocyte phagocytosis or oxidative burst activity after 2.5 h of intensive running.

Influence of vitamin C supplementation on cytokine changes following an ultramarathon.

The influence of vitamin C supplementation on the pattern of change in plasma cytokine concentrations was measured in 29 runners following a 90-km ultramarathon. The study was based on a 3 (groups) by 4 (blood samples at 16 prerace, postrace, and 24 h and 48 h postrace) repeated measures design. Groups included placebo control (n = 7) and two groups supplementing vitamin C at 500 mg/day (vit C-500, n = 10) or 1500 mg/day (vit C-1500, n = 12) for 7 days before the race, on race day, and for 2 days after the race. All measured plasma cytokine concentrations were significantly elevated immediately postrace, with the magnitude of increase for tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) much smaller than for IL-6, IL-10, IL-8, and IL-1 receptor antagonist (IL-1RA). Cortisol increased in all groups immediately after the race but significantly less in the vit C-1500 group. Group x time interaction statistics were not significant for any of the plasma cytokines. However, when the placebo and vit C-500 groups were combined (n = 17) and compared with the vit C-1500 group (n = 12), immediate postrace plasma concentrations were significantly lower in the vit C-1500 group for IL-1RA (-57%) and IL-10 (-57%), with a trend measured for IL-6 (-27%, p = 0.11) and IL-8 (-26%, p = 0.14). In summary, runners completing the 90-km Comrades Ultramarathon experienced strong increases in concentrations of plasma IL-6, IL-10, IL-1RA, and IL-8. These increases were attenuated in runners ingesting 1500 mg but not 500 mg vitamin C supplements for 1 week prior to the race and on race day.

beta-VLDL and acetylated-LDL binding to pigeon monocyte macrophages.

Blood-derived monocytes are an important source of foam cells in atherosclerotic lesions of White Carneau pigeons. Based upon studies with cultured blood monocytes (monocyte macrophages) and peritoneal macrophages from a variety of mammalian species, it has been proposed that these cells become loaded with cholesteryl esters through the uptake of lipoproteins including beta-migrating very low density lipoproteins (beta-VLDL) and low density lipoproteins that have been chemically modified in a manner analogous to experimental acetylation (Ac-LDL). The purpose of this study was to determine whether similar mechanisms functioned in pigeon monocyte macrophages. Radioiodinated pigeon beta-VLDL and Ac-LDL were incubated with White Carneau pigeon monocyte macrophages that had been maintained in culture for 7 days. Scatchard analysis of the specific binding data revealed the presence of specific and saturable receptors for both beta-VLDL and Ac-LDL. beta-VLDL receptors had both low and high affinity binding components, whereas Ac-LDL receptors displayed a single class of high affinity binding sites. beta-VLDL binding remained relatively constant from 3 to 10 days in culture while Ac-LDL binding increased with time in culture. Competition studies demonstrated a high degree of binding specificity for 125I-Ac-LDL, but less for 125I-beta-VLDL. Binding of 125I-beta-VLDL was not competed for by Ac-LDL, but was by beta-VLDL and by low density lipoproteins from both normal and hypercholesterolemic pigeons. Following binding of beta-VLDL and Ac-LDL, the lipoproteins were rapidly internalized and degraded. Although the majority of degradation was secondary to internalization by the monocyte macrophages, approx. 5% of the degradation resulted from enzymatic activity in the culture medium, presumably due to secretion of proteolytic enzymes by the cells. As measured by esterification of [14C]oleate to cholesterol, it was shown that the cholesterol liberated from the degradation of both beta-VLDL and Ac-LDL stimulated cholesteryl ester synthesis in pigeon monocyte macrophages. These studies confirm the existence of specific beta-VLDL and Ac-LDL receptors on the surface of pigeon monocyte macrophages which facilitate both internalization of the lipoproteins and subsequent stimulation of cholesteryl ester synthesis. This is the first demonstration of beta-VLDL and Ac-LDL receptors on monocyte macrophages from an avian species, and the findings support the potential role for the receptor-mediated uptake of a variety of abnormal lipoproteins in the formation of monocyte-derived foam cells in the arterial wall of White Carneau pigeons during the development of atherosclerosis.

The pathologist as a consultant in cancer patient management: a patterns of care study in pathology.

The Committee on the Pathologist as a Consultant in Cancer Patient Management, a committee of the Cancer Committee of the College of American Pathologists, was formed in response to the demands made on pathologists by other medical specialists to function as consultants. The Committee on the Pathologist as a Consultant in Cancer Patient Management has evolved from the Patterns of Care Steering Committee (1979) which in turn was spawned by the Patterns of Care Study initiated by The American College of Radiology (ACR) in 1973. The objective of the ACR was to improve the quality of care by establishing guidelines for the best current management in radiation oncology through a consensus by peers. Pathology is concerned with establishing a diagnosis, providing a rationale for treatment, estimating prognosis, and evaluating outcome. Consequently, the CAP Patterns of Care Study assumed a different form from that of the ACR, adapting itself to the role of the pathologist as a consultant. Its objective, however, remained the same - to improve the quality of care by providing quality assurance of pathology reports dealing with cancer patients. Three task forces, one for each site, have been established. Each is composed of pathologists and other medical specialists from small and large community hospitals, universities, and private office practice. The primary function of each task force is to develop guidelines for data to be included in routine pathology consultation reports. These guidelines include parameters that document adequate examination of the specimen, and those essential elements which can be used to guide selection of therapy, estimate prognosis, and evaluate outcome, such as the pathologic factors required for staging. Data to help establish these guidelines have been obtained in consultation with medical specialists who are members of the task forces, as well as from the medical literature. This entire process will be discussed. Currently there is great concern about improving the quality of medical care, particularly in a cost effective manner. Assuring the quality of consultation reports is yet another way in which pathology can contribute.

Intestinal-type adenocarcinoma of the gallbladder. A clinicopathologic study of seven cases.

Seven examples of a distinctive morphological variant of well-differentiated adenocarcinoma of the gallbladder with intestinal features are reported. Four tumors were composed predominantly of goblet cells and absorptive columnar cells, two of which had, in addition, a few Paneth cells and neuroendocrine cells. Three neoplasms closely resembled colonic carcinoma, and one of these also contained neuroendocrine cells. Serotonin-immunoreactive cells were demonstrated in three of the seven intestinal-type adenocarcinomas, two of which also had cells that stained for somatostatin pancreatic polypeptide and cholecystokinin. Four adenocarcinomas were associated with cholelithiasis, and three with intestinal metaplasia of the uninvolved mucosa. Despite the well-differentiated character of all neoplasms and the deceptively benign microscopic appearance of two of them, three patients died with extension to the liver and metastasis. Of the two survivors, one had carcinoma in situ and the other had a carcinoma that extended only to the muscle layer of the gallbladder. The various cell phenotypes found in these gallbladder adenocarcinomas can be explained on the basis of intestinal differentiation.

Mucinous cystadenocarcinoma of the pancreas. Morphologic and immunocytochemical observations.

Twenty mucinous cystadenocarcinomas of the pancreas, most of which occurred in the tail of the pancreas in middle-aged women, were examined histologically and by immunohistochemical stains. Thirteen tumors displayed a marked histological heterogeneity and expressed intestinal differentiation as shown by the colonic appearance of the glands both at the light- and electron-microscopic levels. Other intestinal features included varying numbers of goblet cells, argyrophil and argentaffin cells, and even Paneth cells. By immunohistochemistry, endocrine cells were present in 13 of the 20 tumors (65%) and were more numerous in the poorly differentiated than in the well-differentiated epithelial component of the tumors. Serotonin-containing cells were the most common endocrine cells, followed by somatostatin-containing cells and cells that showed immunoreactivity for pancreatic polypeptide and gastrin. However, none of the patients had clinical manifestations of carcinoid, somatostatinoma, or the Zollinger-Ellison syndrome. The findings support the hypothesis that mucinous cystadenocarcinomas of the pancreas arise from an "endodermal stem cell" that differentiates into cells with intestinal phenotypes.

Carcinoma in situ of the gallbladder. A clinicopathologic study of 18 cases.

Eighteen cases of carcinoma in situ of the gallbladder collected over a 7-year period at the General Hospital of Mexico City are reported. All patients were females whose ages ranged from 26 to 83 years with a mean of 55. Their symptoms and signs were related to the presence of stones. Grossly, the in situ carcinomas could not be differentiated from chronic cholecystitis. In only one case was the diagnosis suspected on macroscopic examination. Thirteen lesions were located either in the fundus or body of the gallbladder. Histologically there were two types of in situ carcinoma--papillary (two cases) and nonpapillary (16 cases). Hyperplasia of the antral-type glands was associated with 12 cases and cholecystitis follicularis with four. The atypical changes began on the surface epithelium and extended into the epithelial invaginations and later into the antral-type glands. Four carcinomas in situ exhibited limited invasion into the underlying lamina propria or inner part of the muscle layer. In the 15 cases that were examined, immunoperoxidase stains revealed cytoplasmic staining for carcinoembryonic antigen (CEA). All patients we were able to follow (those who had only carcinoma in situ) are symptom-free after cholecystectomy. One of the four patients with microinvasion died 7 years after cholecystectomy with clinical evidence of liver metastasis.

Oculomotor adaptation to induced heterophoria and anisometropia.

In the first part of the paper we demonstrate that the oculomotor system adapts to prism-induced heterophoria over limited motor fields. In the second part we demonstrate that it can also adapt to an induced anisometropia. When normal subjects are made 3 diopters anisometropic, they initially exhibit a phoria whose magnitude is dependent on eye position. After 21/2 hr of binocular visual experience, this incomitant phoria has largely disappeared.

Micropachometry: a technique for measuring the thickness of the corneal epithelium.

A micropachometer was developed for the measurement of epithelial thickness in the living human cornea. The technique requires no contact with the eye and will be of value in studies of the anterior cornea and the physiological effects of contact lenses. The design is described, and results are presented from measurements of epithelial thickness.

Influence of fixation accuracy on threshold variability in patients with open angle glaucoma.

PURPOSE: To evaluate the contribution that fixation errors make to the overall variability of perimetric responses in patients with glaucoma. METHODS: Frequency of seeing curves were established, with and without fixation error correction, at two locations in each of 14 patients with glaucoma and good visual acuity. One location corresponded to a relatively normal region of the visual field, whereas the second corresponded to a region in which there was a sensitivity deficit. All patients had an acuity of better than 20/63 (except one whose acuity was 20/100). The locations of the first and fourth Purkinje images of a collimated infrared source were used to give a measure of eye position, during each stimulus presentation (accuracy 10 minutes of arc). RESULTS: Considerable variation was found in patient fixation accuracy. In the worst case, fixation was within 30 minutes of the target in only 7% of presentations whereas in the best, it was within this range in more than 60%. No relationship was found between accuracy of fixation and extent of loss. The gradient of the frequency of seeing curve was found to be shallow at regions of reduced sensitivity, a finding that supports the recognized relationship between variability and sensitivity deficit. A recalculation of the frequency of seeing curves, using only those responses in which the patient's fixation was within a specified range ( < 60 minutes of arc), did not show a meaningful reduction in variability at either location. CONCLUSIONS: It is concluded that fixation errors, though contributing to variability, are not the major cause of the increased variability seen at locations with reduced sensitivity.