Vitamin D levels in peanut allergic children

Background The prevalence of peanut allergy is increasing. The reasons for this are not entirely known. A factor may be vitamin D (Vit D). Methods This study was performed in a referral allergist’s office in Ontario. Prospectively, all patients (\u3c18 years old) with peanut allergy who were tested for peanut specific IgE (PN IgE) also had Vit D measured. All measurements were done between December 2010 and May 2011. The Vit D measure was 25-hydroxy vitamin D. Patients were divided into three groups: deficient (less than 25 nmol/L), insufficient (25-75 nmol/L) and sufficient (75-250 nmol/L). Vit D levels were compared to PN IgE, sex, age, body mass index (BMI) and other allergies. Results Fifty peanut allergic patients were included. The mean Vit D level of the patients was 73.8 nmol/L and the 95% confidence interval was 69.6 - 75.7 nmol/L. One patient (2%) had deficient and thirty-one (62%) of the patients had insufficient Vit D levels. Nineteen (38%) had Vit D levels in the sufficient range. There was no correlation between Vit D levels and PN IgE or BMI. Generalized linear modeling showed that vit D levels were predicted by age and sex (p=0.04 & p=0.002, respectively). Conclusions Two percent of our patients had deficient Vit D levels while 62% of our patients had insufficient Vit D levels. These levels were statistically associated with age and sex. Insufficiency of Vit D may play a role in peanut allergy

[Photograph 2012.201.B1422.0064]

Photograph used for a newspaper owned by the Oklahoma Publishing Company. Caption: "Danny A. Yarbrough, 17, died Saturday at Oklahoma Children's Memorial Hospital, Oklahoma City, after an extended illness.

Measurement of Bulbar Redness

Purpose: To examine the relationship between physical image characteristics and the clinical grading of images of conjunctival redness; to develop an accurate and efficient predictor of clinical redness from the measurements of these images

Visual and optical performance of silicone hydrogel contact lenses for moderate myopia

Purpose: To compare the short-term visual and optical performance of silicone hydrogel contact lenses for myopia ≥ −3.00D. Methods: This was a short-term, non-dispense, double-masked, randomized study investigating Night&Day (ND), PureVision (PV), O2 Optix (O2), Biofinity (BF), Acuvue Advance (AA) and Acuvue OASYS for myopia ≥ −3.00D. Testing was conducted under scotopic conditions. Measures (one eye only) included: high- and low-contrast visual acuity (HCVA/LCVA), contrast sensitivity, subjective clarity of vision ratings (0-100 scale using reference images, with test image representing grade 50) and ocular aberrations (up to the 4th order, analyzed across individual scotopic pupil sizes). Results: Three males and 27 females participated, with a mean (± SD) age of 24.9 ± 7.7 yrs (range 19 to 53 yrs), sphere of −5.30 ± 1.73D (range −3.00 to −10.75D) and cylinder −0.36 ± 0.23D (range 0 to −0.75D). Mean (± SEM) logMAR HCVA ranged from 0.06 (PV) to 0.10 (AA) (± 0.02), LCVA from 0.33 (BF) to 0.40 (AA) (± 0.02) and contrast sensitivity from 2.33 (BF) to 2.53 (ND) (± 0.15) (differences not statistically significant; all p > 0.05). Subjective ratings for the test image ranged from 59 (PV) to 64 (ND) (± 4) and 56 (AA) to 65 (ND) (± 4), for monochromatic and polychromatic reference images, respectively (all p > 0.05). There was a statistically significant impact on ocular aberrations with all study lenses compared to no lens. Between-lens differences were statistically significant for defocus (Z02), horizontal coma (Z 13) and spherical aberration (Z04). Conclusions: Despite some differences in ocular aberrations, there were no significant differences in HCVA, LCVA, contrast sensitivity or subjective ratings across lenses

Pupil response to noxious corneal stimulation.

PURPOSE:Ocular somatosensory-autonomic reflexes play critical roles in maintaining homeostasis of the eye. The purpose of this study was to investigate the pupil response to nociceptive corneal stimuli. METHODS:A Waterloo-Belmonte pneumatic esthesiometer was used to determine detection thresholds and randomly deliver mechanical and chemical stimuli from levels of detection threshold to twice the threshold in 50% steps to the central cornea of 15 healthy subjects. For each stimulus, imaging of the stimulated/unstimulated eye was performed using two modified/calibrated Logitech c920 digital cameras for 4 seconds each, pre/post stimulus capture. The data were processed with a custom segmentation algorithm to help identify the pupils and pupil diameter was measured using ImageJ software. Pupil dilation response differences between the ipsi- and contralateral eye was analyzed using dependent t-tests. The effect of stimulus intensity, modality and sex of subjects were analyzed using repeated measures. RESULTS:In mechanical and chemical stimulation experiments, there was no difference in pupil responses between the stimulated eye and the unstimulated eye, (all dependent T-test p > 0.05). On average, pupil diameter increased from baseline as the corneal stimulus intensity increased. This happened regardless of whether mechanical or chemical stimulation occurred (ANOVA p < 0.05). At 200% threshold, pupil diameter was greater than at all stimulus intensities (Tukey HSD, all p < 0.05). Based on stimulus intensity, females had greater pupil diameters than males at levels of 150% threshold and 200% threshold (ANOVA p < 0.05, all Tukey HSD p < 0.05). CONCLUSION:This study serves as a basis for the characterization of the local stimulus-response neural circuitry relating nociceptive stimuli to autonomic responses and in combination with our work on completely separate autonomic circuits of bulbar conjunctival vessel dilation and reflex tearing suggests that the monotonic measurements of redness, tearing and pupils provide accurate, separable responses that reflect painful stimulus intensity

Accuracy of Visante and Zeiss-Humphrey Optical Coherence Tomographers and their cross calibration with optical pachymetry and physical references

Purpose: To calibrate the new ZEISS VisanteTM anterior segment optical coherence tomographer (OCT) using references with known physical thickness and refractive index equal to the human cornea and to compare the Visante measures to those from a previous generation OCT (Zeiss-Humphrey OCT II). Methods: Twenty two semi-rigid lenses of specified thicknesses were manufactured using a material with refractive index of 1.376. Central thickness of these lenses was measured using VisanteTM and Zeiss-Humphrey OCT II OCT's (Zeiss, Germany). Two data sets consisting of nominal measures (with a standard pachymeter) of the lenses and one obtained using a digital micrometer was used as references. Regression equations between the new physical and optical (OCT) measures were derived to calibrate the devices. Results: Before calibration, repeated measures ANOVA showed that there were significant differences between mean lens thicknesses from each of the measurement methods (p < 0.01), where Visante measurements were significantly different from the other three (OCT II, MG and OP) methods (p < 0.001). Visante thickness was significantly higher than the microgauge measures (453 ± 37.6 compared to 445.1 ± 38.2) and the OCT II was significantly lower (424.5 ± 36.1 both, p < 0.001). After calibration using the regressions between physical and optical measurements, there were no differences between OCT II and Visante (p < 0.05). Conclusions: Using references lenses with refractive index of the cornea (1.376) allows rapid and simple calibration and cross calibration of instruments for measuring the corneal thickness. The Visante and OCT II do not produce measurements that are equal to physical references with refractive index equal to the human cornea

Objective measurements of corneal light-backscatter during corneal swelling, by optical coherence tomography

To demonstrate that corneal light-backscatter can be measured objectively during corneal swelling by optical coherence tomography (OCT). One eye (randomly selected) of 20 non-contact-lens wearers (10 men and 10 women; mean age, 35.6 +/- 9.6 years) was patched during 3 hours of soft contact lens (SCL) wear. The contralateral eye acted as the control. Central corneal images were captured before and after SCL wear at 20-minute intervals over 100 minutes using optical coherence tomography (OCT) to obtain corneal thickness and light-backscatter profiles. OCT backscattered light of the epithelial layer (decided by the thickness measurements) and 10 equally divided layers of the remaining cornea were analyzed with a custom software program. Two baseline measurements were taken at different visits before lens wear to test the repeatability of light-backscatter measurements. From two baseline measurements, repeated measurements showed good repeatability of normalized backscatter results. Immediately after contact lens removal, total central corneal thickness increased significantly by 13.8% +/- 2.3% (mean +/- SD) compared with baseline (P = 0.0001, paired t-test) and then decreased during the deswelling course. Corneal backscattered light changed significantly (repeated-measures ANOVA [Re-ANOVA]: F((50, 950)) = 2.22, P = 0.0001) after lens wear, and a significant increase in backscatter was found in the epithelial layer (36.4%) and the most posterior corneal layer (35.6%) immediately after lens removal (post hoc test, P = 0.005). There was a strong correlation (r = 0.9375, P < 0.05) between the change in backscatter and corneal swelling during the deswelling period. The backscatter recovery rate was approximately the same for both epithelial and posterior layers after lens removal. Light-backscattering analysis with OCT seems to be a promising and repeatable method of objectively measuring corneal backscatter. This study has demonstrated that corneal backscattered light increased in the anterior and posterior layers of the cornea during corneal swelling induced by contact lens wear and eye closure

Influence of the blink interval on tear meniscus height in soft contact lens and nonlens wearers

Purpose: Tear meniscus height (TMH) is an indirect measurement of tear film volume. This study investigated the temporal changes in the TMH during the blink interval in the morning (8&ndash;9 am) and at the end of the day (5&ndash;6 pm) in both soft contact lens (CL) and nonlens wearers (NLW).Methods: Fifty participants (25 CL; 25 NLW) were evaluated for their subjective symptoms, TMH, noninvasive break up time, and bulbar hyperemia at the am and pm visits on the same day. The TMH was measured at set intervals between 2 and 15 sec during the blink interval, using an optical coherence tomographer.Results: The NLW group revealed no changes in a variety of symptoms during the day, whereas the CL group reported an increase in dryness (P=0.03) and grittiness (P=0.02) over the day. For both groups, the TMH and calculated tear meniscus volume revealed lower values immediately after the blink and increased progressively afterwards, mainly due to reflex tearing. The am tear meniscus volume values tended to be higher than the pm values for both groups, but this was not significant (NLW P=0.13; CL P=0.82). Noninvasive break up time deteriorated during the day for both groups but was only significant for the CL group (P=0.002), whereas bulbar hyperemia revealed no statistically significant change for either group.Conclusions: Reflex tearing may play a substantial role in the TMH differences observed over the blink interval. Standardization of the time when a TMH measurement is performed will be valuable in comparing tear film clinical studies.<br /

Comparison of three different types of rating scales

A study was initiated to compare the validity, reliability and responsiveness of three types of subjective rating scales, referred to as VAS, VAD and LRS. The lenses and scales were presented in random order. Although all three scales can be used to provide measures of lens handling, the VAS provided the least variable, most valid, repeatable and responsive results.</p