"Healthy" eye in office-like environments

Efficacy of hydroxypropyl-guar drops in improving tear film index and ocular surface dynamics using two treatment methods under a controlled desiccating environment

AIM

This study aimed to assess the efficacy of hp-guar eye drops on tear film index and ocular surface dynamics under desiccating conditions using protection and relief treatment modalities.

METHODOLOGY

The 12 normal, non-dry eye participants were subjected to adverse environmental conditions using a Controlled Environment Chamber (CEC) where the relative humidity (RH) was 5% and the ambient temperature was 21 °C. The participants were screened for ocular symptoms, tear osmolarity, ocular surface temperature (OST), tear production using the Ocular Surface Disease Index questionnaire (OSDI), OcuSense TearLab Osmometer, FLIR System ThermaCAM P620, and Schirmer strips. Tear production was calculated by the Tear Function Index test (TFI).

RESULTS

The mean tear film osmolarity decreased significantly from 296 mOsm/L at 40% RH to 285 mOsm/L at 5% RH (p = 0.01). Conflicting responses were seen for osmolarity in protection and relief. Mean tear osmolarity was significantly higher in the protection method in comparison to the relief method (p = 0.005). The mean TFI increased from 557 at 40% to 854 at 5% (p = 0.02). A significant increase in TFI was observed in the relief method in comparison with both 40% (p = 0.001) and 5% (p = 0.04). In the relief method, the mean TFI score went up to 1139 when hp-guar was installed. A significant improvement in ocular comfort was experienced in both the protection (p = 0.041) and relief (p = 0.010) methods at 5% RH. The instillation of hp-guar drops in the relief method resulted in a significant reduction in OST. The mean OST dropped to 33.01 ºC, significantly lower than the recorded OST for both normal (p = 0.040) and dry (p = 0.014) environmental conditions.

CONCLUSION

Hp-guar drops significantly improve tear film parameters under a desiccating environment, however, tear film parameters respond differently to the management modalities. In the protection method, tear film osmolarity was protected against a dry environment, while in the relief mode, an improvement in tear production and a decrease in ocular surface temperature were seen. Hp-guar performance could be maximized for the management of exposure to adverse environments by using a treatment protocol that targets the most affected parameters in each group of patients. Using CEC has the potential to provide researchers with a readily available method to evaluate the efficiency of tear supplementation.

Protecting Tear-Film Stability under Adverse Environmental Conditions Using a Mucomimetic with a Non-Newtonian Viscosity Agent

Background and Objectives: Tamarind-seed polysaccharide (TSP) and hyaluronic acid (HA) have mucoadhesive properties that improve drug absorption and delay in drug elimination from the ocular surface. We aimed to evaluate TSP/HA-containing formulation for its efficiency in dry-eye symptoms induced by adverse environments and the interaction between mucomimic polymer and tear-film parameters. Materials and Methods: The participants were exposed to 5% relative humidity (RH) in a Controlled Environment Chamber (CEC) under constant room temperature (21 °C). Tear-film parameters were assessed at 40% RH and 5% RH. Rohto Dry Eye Relief drops were used in the two treatment modalities, protection (drops instilled before exposure to the dry environment) and relief (drops instilled after exposure to the dry environment). The HIRCAL grid, Servomed EP3 Evaporimeter, and Keeler's TearScope-Plus were used to screen for non-invasive tear break-up time (NITBUT), tear evaporation rate, and lipid-layer thickness (LLT) using protection and relief treatment methodology. Results: LLT was found to be significantly thinner at 5% RH compared with at 40% RH (p = 0.007). The median LLT dropped from 50-70 nm (grade 3) at 40% RH to 10-50 nm (grade 2) at 5% RH. TSP/HA eye drops significantly augment LLT in both treatment modalities, protection (p = 0.01) and relief (p = 0.004) at 5% RH. The mean evaporation rate doubled from 40.93 at 40% RH to 82.42 g/m2/h after exposure to 5% RH. In protection mode, the TSP/HA allowed the average evaporation rate to be much lower than when no TSP/HA was used at 5% RH (p < 0.008). No alteration in evaporation rate was recorded when the TSP/HA drop was used after exposure (relief). The mean NITBUT was reduced from 13 s in normal conditions to 6 s in the dry environment. Instillation of TSP/HA eye drops resulted in significant improvement (p = 0.006) in tear stability, where the NITBUT increased to 8 s in both protection (before exposure) and relief (after exposure) (p = 0.001). Although improved, these values were still significantly lower than NITBUT observed at 40% RH. Conclusions: Significant protection of tear-film parameters was recorded post instillation of TSP/HA eye drop under a desiccating environment. Both treatment methods (protection and relief) were shown to be effective. The presence of TSP/HA enhances the effectiveness of teardrops in protecting the tear-film parameters when exposed to adverse environments.

Impact of Exposomes on Ocular Surface Diseases

Ocular surface diseases (OSDs) are significant causes of ocular morbidity, and are often associated with chronic inflammation, redness, irritation, discomfort, and pain. In severe OSDs, loss of vision can result from ocular surface failure, characterised by limbal stem cell deficiencies, corneal vascularisation, corneal opacification, and surface keratinisation. External and internal exposomes are measures of environmental factors that individuals are exposed to, and have been increasingly studied for their impact on ocular surface diseases. External exposomes consist of external environmental factors such as dust, pollution, and stress; internal exposomes consist of the surface microbiome, gut microflora, and oxidative stress. Concerning internal exposomes, alterations in the commensal ocular surface microbiome of patients with OSDs are increasingly reported due to advancements in metagenomics using next-generation sequencing. Changes in the microbiome may be a consequence of the underlying disease processes or may have a role in the pathogenesis of OSDs. Understanding the changes in the ocular surface microbiome and the impact of various other exposomes may also help to establish the causative factors underlying ocular surface inflammation and scarring, the hallmarks of OSDs. This review provides a summary of the current evidence on exposomes in various OSDs.

Evaluation of different treatment modalities on the efficacy of hydroxypropyl Guar (HP-Guar) formulation on tear film stability (TFS) in subjects exposed to adverse environmental conditions

The study aimed to assess the efficacy of hydroxypropyl guar (HP) formulation (Systane) to protect tear film parameters under desiccating environment using protection and relief treatment modalities. The subjects were exposed to adverse environmental conditions using a Controlled Environment Chamber (CEC) where the relative humidity (RH) was 5% and the ambient temperature was 21 °C and screened for Tear break-up time (TBUT), Tear film evaporation rate (TFER) and lipid layer thickness (LLT) using the HIRCAL grid, Servomed EP3 Evaporimeter and Keeler's TearScope-Plus respectively. Significant improvement in LLT was noticed in the protection modality. The mean tear film evaporation rate doubled after exposure to the humidity of 5% to a value of 105.37 g/m²/h (0.29 µl/min). All subjects displayed a significant reduction in non-invasive tear break-up time (NITBUT) with a mean NITBUT of 7.7 s after exposure to a desiccating environment for 15 min. A significant increase in NITBUT after the instillation of the drops was recorded in both methods. The results obtained from this study showed that a solution containing HP-Guar significantly improves tear film parameters under a desiccating environment. Apart from the tear evaporation rate, all tear parameters showed improvement after the use of HP-Guar eye drops. It is evident that tear film parameters respond differently to the management modalities and using CEC has the potential to provide researchers with a readily available method to evaluate the efficiency of tear supplementation.

Humidification of indoor air for preventing or reducing dryness symptoms or upper respiratory infections in educational settings and at the workplace

BACKGROUND

Indoor exposure to dry air during heating periods has been associated with dryness and irritation symptoms of the upper respiratory airways and the skin. The irritated or damaged mucous membrane poses an important entry port for pathogens causing respiratory infections.

OBJECTIVES

To determine the effectiveness of interventions that increase indoor air humidity in order to reduce or prevent dryness symptoms of the eyes, the skin and the upper respiratory tract (URT) or URT infections, at work and in educational settings.

SEARCH METHODS

The last search for all databases was done in December 2020. We searched Ovid MEDLINE, Embase, CENTRAL (Cochrane Library), PsycINFO, Web of Science, Scopus and in the field of occupational safety and health: NIOSHTIC-2, HSELINE, CISDOC and the In-house database of the Division of Occupational and Environmental Medicine, University of Zurich. We also contacted experts, screened reference lists of included trials, relevant reviews and consulted the WHO International Clinical Trials Registry Platform (ICTRP).

SELECTION CRITERIA

We included controlled studies with a parallel group or cross-over design, quasi-randomised studies, controlled before-and-after and interrupted time-series studies on the effects of indoor air humidification in reducing or preventing dryness symptoms and upper respiratory tract infections as primary outcomes at workplace and in the educational setting. As secondary outcomes we considered perceived air quality, other adverse events, sick leave, task performance, productivity and attendance and costs of the intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles, abstracts and full texts for eligibility, extracted data and assessed the risks of bias of included studies. We synthesised the evidence for the primary outcomes 'dry eye', 'dry nose', 'dry skin', for the secondary outcome 'absenteeism', as well as for 'perception of stuffiness' as the harm-related measure. We assessed the certainty of evidence using the GRADE system.

MAIN RESULTS

We included 13 studies with at least 4551 participants, and extracted the data of 12 studies with at least 4447 participants. Seven studies targeted the occupational setting, with three studies comprising office workers and four hospital staff. Three of them were clustered cross-over studies with 846 participants (one cRCT), one parallel-group controlled trial (2395 participants) and three controlled before-and-after studies with 181 participants. Five studies, all CTs, with at least 1025 participants, addressing the educational setting, were reported between 1963 and 1975, and in 2018. In total, at least 3933 (88%) participants were included in the data analyses. Due to the lack of information, the results of the risk of bias assessment remained mainly unclear and the assessable risks of bias of included studies were considered as predominantly high. Primary outcomes in occupational setting:  We found that indoor air humidification at the workplace may have little to no effect on dryness symptoms of the eye and nose (URT). The only cRCT showed a significant decrease in dry eye symptoms among working adults (odds ratio (OR) 0.54, 95% confidence interval (CI) 0.37 to 0.79) with a low certainty of the evidence. The only cluster non-randomised cross-over study showed a non-significant positive effect of humidification on dryness nose symptoms (OR 0.87, 95% CI 0.53 to 1.42) with a low certainty of evidence. We found that indoor air humidification at the workplace may have little and non-significant effect on dryness skin symptoms. The pooled results of two cluster non-RCTs showed a non-significant alleviation of skin dryness following indoor air humidification (OR 0.66, 95% CI 0.33 to 1.32) with a low certainty of evidence. Similarly, the pooled results of two before-after studies yielded no statistically significant result (OR 0.69, 95% CI 0.33 to 1.47) with very low certainty of evidence No studies reported on the outcome of upper respiratory tract infections. No studies conducted in educational settings investigated our primary outcomes. Secondary outcomes in occupational setting: Perceived stuffiness of the air was increased during the humidification in the two cross-over studies (OR 2.18, 95% CI 1.47 to 3.23); (OR 1.70, 95% CI 1.10 to 2.61) with low certainty of evidence. Secondary outcomes in educational setting: Based on different measures and settings of absenteeism, four of the six controlled studies found a reduction in absenteeism following indoor air humidification (OR 0.54, 95% CI 0.45 to 0.65; OR 0.38, 95% CI 0.15 to 0.96; proportion 4.63% versus 5.08%).

AUTHORS' CONCLUSIONS

Indoor air humidification at the workplace may have little to no effect on dryness symptoms of the eyes, the skin and the URT. Studies investigating illness-related absenteeism from work or school could only be summarised narratively, due to different outcome measures assessed. The evidence suggests that increasing humidification may reduce the absenteeism, but the evidence is very uncertain. Future RCTs involving larger sample sizes, assessing dryness symptoms more technically or rigorously defining absenteeism and controlling for potential confounders are therefore needed to determine whether increasing indoor air humidity can reduce or prevent dryness symptoms of the eyes, the skin, the URT or URT infections at work and in educational settings over time.

Factors Affecting Occupants’ Satisfaction in Governmental Buildings: The Case of the Kingdom of Bahrain

Satisfaction is a very important factor in improving productivity and performance in the work environment. This study aims to investigate the levels of occupants’ satisfaction with the indoor environmental quality (IEQ) in the governmental buildings in the Kingdom of Bahrain and to investigate the impact of occupants’ demographics and building attributes (non-IEQ factors) on these levels. For these purposes, the study used a questionnaire that has 17 indoor environmental quality (IEQ) factors in addition to a group of non-IEQ factors. The questionnaire was distributed by hand or using email to 279 employees in the Bahraini governmental sector. The findings of the study revealed that occupants in the Bahraini governmental buildings are not strongly satisfied with IEQ factors, especially with sound privacy, followed by visual privacy and amount of space, and then noise levels. The findings also showed that for most IEQ factors, men are more satisfied than women are, those who work in enclosed private offices are more satisfied than those who work in open-plan offices, and those who have central air-conditioning at their workplace are more than those who have a wall-mounted air conditioner. The impact of age, nature of work, duration of working in the current building and at the current workstation, weekly working hours, and proximity to the window were also investigated. Accordingly, a group of recommendations was suggested aiming to improve the levels of occupants’ satisfaction.

Relationship between ocular surface disease and patient's satisfaction among cataract surgical patients in Nigeria

PURPOSE

To determine the effect of clinical and cytological features of ocular surface disease on patient's satisfaction following small incision cataract surgery at a tertiary eye care centre.

METHOD

This is a prospective observational study of 70 consecutive consenting patients who underwent manual small incision cataract surgery(MSICS) at a tertiary eye care centre. All participants underwent ocular surface profile assessment using Schirmer I test (ST1), tear film break-up time (TBUT), conjunctival impression cytology (CIC) and ocular surface disease index (OSDI) at pre-operative visit, 1-week and 4-week post-operative visit. Patient's satisfaction with surgical outcome was evaluated at 6-week post-operative visit using a rating scale of 1 to 10. Data were analysed using IBM Statistical Package for the Social Sciences (SPSS) version 20.0 (IBM Corp., Armonk, NY USA).

RESULTS

The mean age was 68 ± 9.4 years with a male/female ratio of 1:1.1. The mean OSDI score decreased significantly (p < 0.001) from 33.1 ± 8.4 pre-operatively to 20.8 ± 7.4 four weeks after surgery. The TBUT was 12 ± 4.1 s pre-operatively, but significantly reduced to 11.2 ± 3.9 s (p < 0.001) at 4-week post-operative period. At 6 weeks, patients with normal CIC reduced from 53 (75.8%) pre-operatively to 8 (11.4%) (p < 0.001, z = - 7.24). Fifty percent of patients with severe post-operative ocular surface disease reported dissatisfaction with their surgical outcome (p = 0.024).

CONCLUSION

Manual small incision cataract surgery can significantly impair the ocular surface health profile of patients. The presence of ocular surface disease in patients pre-operatively can negatively impact their level of satisfaction with surgical outcome.

The Influence of Work Environment Factors on the OcularSurface in a One-Year Follow-Up Prospective Clinical Study

The purpose of this study was to assess the effect of environmental working conditions on the symptoms and signs of dry eye disease and to examine whether and how those conditions impact the ocular surface. Methods: This single-center, prospective clinical study with a 1-year follow-up included 150 patients. The following parameters were evaluated: non-invasive keratograph break-up time (NIKBUT), tear meniscus height (TMH), and conjunctival and limbal hyperemia. We also performed staining of the surface of the eye for simulated fluorescein images, Schirmer’s test I, assessment of Meibomian gland dysfunction (MGD), and an Ocular Surface Disease Index (OSDI) questionnaire. Results: In the OW (office workers) group, in people working >4 h at the computer, the NIKBUT before work and the Schirmer test results were statistically significantly lower than in people working <4 h. The conjunctival hyperemia result before work was statistically significantly higher for people working >4 h at a computer in both groups and after work in the MW (medical workers) group. Low relative air humidity in the building and air-conditioned rooms negatively affects the tear film, causing the symptoms of dry eye disease. At the 1-year follow-up, there was a statistically significant reduction in conjunctival and limbal hyperemia in the OW group as well as a statistically significant reduction in TMH at the first examination before and after work, and in the second examination after 1 year in both groups. Conclusions: Environmental factors such as reduced relative air humidity, increased air temperature, and decreased illumination have a negative impact on the ocular surface.

Objective and subjective evaluation of tear film in machine carpet weavers

OBJECTIVES

The present study was conducted to evaluate the status of tear film objectively and subjectively in machine carpet weavers.

METHODS

In this cross-sectional study, machine-made carpet weavers were compared with the controls who were selected from people working in other parts of the factory except for the production. A complete evaluation of ocular health was done for all participants. The blink rate, tear deformation Time (TDT), and ocular staining were evaluated as an objective assessment and the ocular surface disease index (OSDI) was used for a subjective assessment of the tear film status. The results were compared between the two groups using the SPSS software.

RESULTS

The results of 46 weavers (mean age: 38.43 ± 6.10 years) and 46 controls (mean age: 33.20 ± 8.40 years) were analyzed. The mean of blink rate and OSDI score were significantly higher in weavers (Blink rate: 20.67 ± 4.18 blink/min, OSDI: 22.59 ± 9.51) in comparison with controls (Blink rate: 14.00 ± 3.30 blink/min, OSDI: 6.22 ± 4.78, P < .001). The mean TDT value of the weavers was significantly lower compared with the controls (10.27 ± 3.01 and 16.58 ± 4.18 s respectively, P < .001). Ocular surface staining was seen among 60.9% of weavers while there was 6.5% in the controls (P < .001). Based on the TDT test and OSDI results together, the percentage of dry eye in the weavers was 43.5% and that in the non-weavers was 2.2%, which showed that the relationship between weaving and dry eyes was statistically significant (P < .001).

CONCLUSIONS

The results indicate that increased symptoms and decreased tear stability in weavers compared with non-weavers lead to more tear film abnormalities in these individuals.

Use of digital displays and ocular surface alterations: A review

Digital display use has been accepted to be implicated as a contributing factor for dry eye disease (DED). Abnormal blinking during computer operation, including a reduced blink rate and an incomplete eyelid closure, increased palpebral fissure as consequence of high visualization angles, and meibomian gland dysfunction associated to long-term display use, are behind the increased prevalence of dry eye signs and symptoms found in digital display users. Previous research reveals significant reductions in tear volume and stability, alterations in tear film composition, including increased osmolarity, inflammatory cytokines, oxidative stress markers and reduced mucin secretion, eyelid abnormalities and ocular surface damage, encompassing corneal and conjunctival staining and bulbar redness, as a direct consequence of digital display use. In this regard, individual differences in the way that the various digital displays are typically set up and used may account for differences in their effects on induced dryness signs and symptoms. Furthermore, factors such as the use of contact lenses or inappropriate working environments, usually accompanying the use of displays, may significantly increase the prevalence and the severity of induced dry eye. Other factors, such as old age and female gender are also relevant in the appearance of associated alterations. Finally, clinicians should adopt a treatment strategy based on a multidirectional approach, with various treatments being applied in conjunction.

Ocular surface and tear film changes in workers exposed to organic solvents used in the dry-cleaning industry

Workers in the dry-cleaning industry are exposed to organic solvents that may cause eye irritation and tear film changes. Objective To quantify changes in the ocular surface and tear film in dry cleaners exposed to organic solvents and associate these changes with ocular irritation as reported in a symptom questionnaire for dry eye diagnosis. Methods This was a case and control study in which the characteristics and eye-irritation symptoms were compared between two groups of 62 participants that were either exposed or not exposed to organic solvents. A general optometric examination and the following test were performed: lipid interferometry, Lissamine Green Stain, tear breakup time, Schirmer I, conjunctival impression cytology and the Donate dry eye symptoms questionnaire. Results Sixty-five percent of exposed workers obtained a higher score than 13 on the Donate dry eye symptoms questionnaire which indicated the presence of more irritation symptoms than those in the non- exposed group. A Chi-square analysis indicated the exposed group reported significantly higher incidences (P <0.005) for eye irritation symptoms of sandy sensation; tearing eyes sensation; foreign body sensation; tearing; dry eye; dryness; eyestrain and heavy eyelids. A Mann Whitney-U indicated greater severity only for symptoms relating to dry eye; sandy sensation; foreign body sensation, tearing; tearing eyes and dryness. There was a statistically significant difference (P <0.05) for Schirmer I; tear break up time; and the ocular surface assessed with Lissamine green staining and conjunctival impression cytology between groups. A reduction in the thickness of the lipid layer in the exposed group compared to the non-exposed group was observed. Surprisingly, clinical test outcomes were not significantly correlated with dry eye symptoms nor years of exposure. Conclusion Workers in the dry-cleaning industry exposed to organic solvents are associated with changes in ocular surface and tear film generating irritation symptoms commonly present in evaporative dry eye.

Discomfort glare and psychological stress during computer work: subjective responses and associations between neck pain and trapezius muscle blood flow

PURPOSE

Exposure to additional environmental stress during computer work, such as visual and psychological demands, is associated with increased eye and neck discomfort, altered moods, and reduced well-being. The aim of this study is to elucidate further how subjective responses in healthy, young females with normal binocular vision are affected by glare and psychological stress during computer work, and to investigate possible associations between trapezius muscle blood flow and neck pain development.

METHODS

43 females participated in a laboratory experiment with a within-subject design. Four 10-min computer work conditions with exposure to different stressors were performed at an ergonomically optimal workstation, under the following series of conditions: no additional stress, visual stress (induced as direct glare from a large glare source), psychological stress, and combined visual and psychological stress. Before and immediately after each computer work condition, questionnaires regarding different visual and eye symptoms, neck and shoulder symptoms, positive and negative state moods, perceived task difficulty, and perceived ambient lighting were completed. Associations between neck pain and trapezius muscle blood flow were also investigated.

RESULTS

Exposure to direct glare induced greater development of visual/eye symptoms and discomfort, while psychological stress exposure made participants feel more negative and stressed. The perception of work lighting during glare exposure was closely related to perceived stress, and associations between visual discomfort and eyestrain, and neck pain were observed in all conditions. Furthermore, participants with high trapezius muscle blood flow overall reported more neck pain, independent of exposure.

CONCLUSIONS

Exposure to visual and psychological stresses during computer work affects the development of symptoms and negative moods in healthy, young females with normal binocular vision, but in different ways. The results also demonstrate the complex interactions involved in symptom development and lighting appraisal during computer work. When optimizing computer workstations, the complexity of the field must be taken into account, and several factors, including visual conditions, must be considered carefully.

The role of ethnicity versus environment in tear film stability: A pilot study

PURPOSE

Existing literatures suggest a difference in tear film stability between Caucasian and Asian ethnic groups. However, such a finding was compounded by the fact that the comparison was done on subjects living in different environments. Therefore, it is not clear whether such difference is due to ethnicity, environment, or both. The aim of this study is to clarify the roles of these two factors.

METHODS

A total of 88 asymptomatic subjects participated in this present study. For each subject, the tear film break-up time (TBUT), non-invasive TBUT (NITBUT) and tear meniscus height (TMH) were measured. To isolate the effect of ethnicity, the results of 12 American Asian young adults were compared against the results of 23 Caucasian adults. Both groups were recruited from Nova Southeastern University. To elucidate the effect of environment, the results from the same 12 American Asians were compared to that of the 53 Asian young adults recruited from the Tianjin Vocational Institute, China (Tianjin Asian).

RESULTS

The tear film stability did not show significant difference among American Asian subjects and Caucasian subjects in TBUT (10.49 ± 2.86 s vs. 11.06 ± 2.79 s,p =  0.57), NITBUT (11.19 ± 4.89 s vs. 11.14 ± 6.20 s, p =  0.98), and TMH (0.21 ± 0.08 mm vs. 0.22 ± 0.05 mm, p =0.59). However, the tear film stability was significantly better in the American Asian group than the Tianjin Asian group in TBUT (10.49 ± 2.86 s vs. 7.60 ± 3.26 s, p =  0.01), NITBUT (11.19 ± 4.89 s vs. 8.03 ± 3.56 s, p = 0.01), and TMH (0.21 ± 0.08 mm vs. 0.14 ± 0.03 mm, p <  0.01).

CONCLUSIONS

The previously reported difference in Caucasian and Asian populations might be due to the fact that the studied subjects have different living environments.

Visual and psychological stress during computer work in healthy, young females-physiological responses

Purpose

Among computer workers, visual complaints, and neck pain are highly prevalent. This study explores how occupational simulated stressors during computer work, like glare and psychosocial stress, affect physiological responses in young females with normal vision.

Methods

The study was a within-subject laboratory experiment with a counterbalanced, repeated design. Forty-three females performed four 10-min computer-work sessions with different stress exposures: (1) minimal stress; (2) visual stress (direct glare); (3) psychological stress; and (4) combined visual and psychological stress. Muscle activity and muscle blood flow in trapezius, muscle blood flow in orbicularis oculi, heart rate, blood pressure, blink rate and postural angles were continuously recorded. Immediately after each computer-work session, fixation disparity was measured and a questionnaire regarding perceived workstation lighting and stress was completed.

Results

Exposure to direct glare resulted in increased trapezius muscle blood flow, increased blink rate, and forward bending of the head. Psychological stress induced a transient increase in trapezius muscle activity and a more forward-bent posture. Bending forward towards the computer screen was correlated with higher productivity (reading speed), indicating a concentration or stress response. Forward bent posture was also associated with changes in fixation disparity. Furthermore, during computer work per se, trapezius muscle activity and blood flow, orbicularis oculi muscle blood flow, and heart rate were increased compared to rest.

Conclusions

Exposure to glare and psychological stress during computer work were shown to influence the trapezius muscle, posture, and blink rate in young, healthy females with normal binocular vision, but in different ways. Accordingly, both visual and psychological factors must be taken into account when optimizing computer workstations to reduce physiological responses that may cause excessive eyestrain and musculoskeletal load.

Glaucoma therapy: preservative-free for all?

Preservatives used in topical glaucoma medications have a plethora of well-described toxic effects on the ocular surface. Such ocular toxicity is manifest clinically as ocular surface disease (OSD) and has been confirmed in epidemiologic, prospective clinical trials and studies in which patients are switched from preservative-added to preservative-free topical therapy. Such toxicity has implications not only for tolerability, but also for adherence and persistence with therapy that is known to be poor in glaucoma. Glaucoma medication is now widely available in preservative-free formulations, and the question arises as to which patients should receive preservative-free glaucoma therapy in preference to preservative-added medication. A case can be made for several subpopulations of patients who might particularly benefit from preservative-free medication: patients with existing OSD, older patients, younger adult patients, female patients, pediatric and juvenile patients, patients who work in air-conditioned environments or who use electronic screens frequently, patients with medical risk factors for OSD, patients in whom trabecular surgery may become indicated in the future, contact lens users, perhaps patients with Asian ethnicity and patients with severe or treatment-refractory glaucoma. Whilst arguments could be made for selecting patients for preservative-free medication on the basis of their existing risk of OSD, collectively, these patients form a significant proportion of the glaucoma patient population as a whole and, in the absence of any cost premium or positive indication for preservative-added medication, preservative-free glaucoma medication for all patients seems an appropriate strategy.

Impact of environmental adaptation on tear film assessments

PURPOSE

The purpose of this study was to investigate the effect of ocular environmental adaptation on clinical tear film assessment.

METHOD

Thirty subjects (male, mean age 23±2.5) participated in this study. A number of clinical tear film tests were applied, including: fluorescein tear break-up time (FTBUT), Schirmer test and tear prism height test (TPH). The tear physiology of each subject was evaluated twice, once immediately when they arrived from the external environment, and then after 30minutes adaptation in the exam room environment.

RESULTS

The mean values were: Schirmer test A (22.1±2.99), Schirmer test B (24.2±2.63), FTBUT A (8.00±1.94), FTBUT B (9.13±2.04), TPH A (0.179±0.026) and TPH B* (0.187±0.023). Statistical testing using Wilcoxon-signed rank test showed a significant difference between the Schirmer test results measured at the different times (P=0.008). Also, the FTBUT and tear prism height test results showed significant differences between the two evaluation times, (P=0.001, 0.011, respectively) (A: tear assessed when the subject comes from the outside environment, B: tear film assessed after 30min adaptation in the clinical environment).

CONCLUSION

This study showed a significant difference between the tear film test results evaluated when the subjects were assessed immediately from the outside environment and after an adaptation time in the clinic environment. Practitioners must consider the effect of differences between external and clinical environment adaptation on clinical tear film physiology.

Effects of environment pollution on the ocular surface

The twenty-first century is fraught with dangers like climate change and pollution, which impacts human health and mortality. As levels of pollution increase, respiratory illnesses and cardiovascular ailments become more prevalent. Less understood are the eye-related complaints, which are commonly associated with increasing pollution. Affected people may complain of irritation, redness, foreign body sensation, tearing, and blurring of vision. Sources of pollution are varied, ranging from gases (such as ozone and NO₂) and particulate matter produced from traffic, to some other hazards associated with indoor environments. Mechanisms causing ocular surface disease involve toxicity, oxidative stress, and inflammation. Homeostatic mechanisms of the ocular surface may adapt to certain chronic changes in the environment, so affected people may not always be symptomatic. However there are many challenges associated with assessing effects of air pollution on eyes, as pollution is large scale and difficult to control. Persons with chronic allergic or atopic tendencies may have a pre-existing state of heightened mucosal immune response, hence they may have less tolerance for further environmental antigenic stimulation. It is beneficial to identify vulnerable people whose quality of life will be significantly impaired by environmental changes and provide counter measures in the form of protection or treatment. Better technologies in monitoring of pollutants and assessment of the eye will facilitate progress in this field.

Physicochemical risk factors for building-related symptoms in air-conditioned office buildings: Ambient particles and combined exposure to indoor air pollutants

We conducted a cross-sectional epidemiological study to examine the correlation between indoor air quality (IAQ) and building-related symptoms (BRSs) of office workers in air-conditioned office buildings. We investigated 11 offices during winter and 13 offices during summer in 17 buildings with air-conditioning systems in Tokyo, Osaka, and Fukuoka, and we included 107 office workers during winter and 207 office workers during summer. We conducted environmental sampling for evaluating IAQ and concurrently administered self-reported questionnaires to collect information regarding work-related symptoms. Multivariate analyses revealed that upper respiratory symptoms showed a significant correlation with increased indoor temperature [odds ratio (OR), 1.55; 95% confidence interval (CI), 1.11-2.18] and increased indoor concentration of suspended particles released from the ambient air pollution via air-conditioning systems (OR, 1.31; 95% CI, 1.08-1.59) during winter. In particular, smaller particles (particle size>0.3μm), which possibly penetrated through the filter media in air-conditioning systems from ambient air, were correlated with upper respiratory symptoms. The use of high-efficiency particulate air filters in air-conditioning systems and their adequate maintenance may be an urgent solution for reducing the indoor air concentration of submicron particles. Several irritating volatile organic compounds (VOCs) (e.g., formaldehyde, acetaldehyde, ethylbenzene, toluene, and xylenes) that were positively correlated with the indoor air concentration among their VOCs, were associated with upper respiratory symptoms, although their indoor air concentrations were lower than those specified by the indoor air quality guideline. A new approach and strategy for decreasing the potential combined health risks (i.e., additive effect of risks) associated with multiple low-level indoor pollutants that have similar hazardous properties are required.

Evaluating prevalence and risk factors of building-related symptoms among office workers: Seasonal characteristics of symptoms and psychosocial and physical environmental factors

Background

Psychosocial and environmental factors at the workplace play a significant role in building-related symptoms (BRSs). Environmental factors change during summer cooling and winter heating using air-conditioning systems. Thus, significant risk factors in each season need to be clarified.

Methods

A nationwide cross-sectional study was conducted during summer in Japan and seasonal differences between summer and winter were evaluated. Self-administered questionnaires were distributed to 489 offices. Possible risk factors for BRSs associated with the work environment, indoor air quality, and job stressors were examined by multiple regression analyses.

Results

Among people having at least one BRS, the prevalence of BRSs in summer (27.8%) was slightly higher than that in winter (24.9%). High prevalence was observed for eye and nasal symptoms related to dryness and general symptoms related to psychological distress in both seasons. Analyses revealed that dryness of air was an important and significant risk factor associated with BRSs, and job stressors were significantly associated with general symptoms in both seasons. Conversely, humidity was a significant risk factor of general symptoms in summer (odds ratio, 1.20; 95% confidence interval, 1.02–1.43). Carpeting, recently painted walls, and unpleasant chemical odors in summer and noise, dust and dirt, and unpleasant odors such as body or food odors in both seasons were significant risk factors for BRSs.

Conclusions

Improvements in the physical environmental qualities in an office throughout the year are important along with the reduction in psychological distress related to work.

Electronic supplementary material

The online version of this article (doi:10.1186/s12199-017-0645-4) contains supplementary material, which is available to authorized users.

External eye symptoms in indoor environments

Eye irritation, for example dry or irritated eyes, is generally among top three reported symptoms in office-like environments, in particular among workplaces with cognitive demanding visual display unit (VDU) work. The symptoms are especially among middle and advanced ages and particularly among women more than men. The symptoms are also among the most commonly reported complaints in the eye clinic. To be in a position to interpret the high prevalence of eye symptoms, a multidisciplinary and integrated approach is necessary that involves the external eye physiology (separate from internal eye effects), eye diseases (evaporative dry eye (DE), aqueous-deficient DE, and gland dysfunctions), and risk factors that aggravate the stability of precorneal tear film (PTF) resulting in hyperosmolarity and initiation of inflammatory reactions. Indoor environmental, occupational and personal risk factors may aggravate the PTF stability; factors such as age, contact lenses, cosmetics, diet, draft, gender, low humidity and high temperature, medication, outdoor and combustion pollutants, and VDU work. Psychological stressors may further influence the reporting behavior of eye symptoms. The impact of the risk factors may occur in a combined and exacerbating manner.

Ocular symptoms and tear film break up time (BUT) among junior high school students in Penang, Malaysia - Associations with fungal DNA in school dust

BACKGROUND

There are few studies on ocular effects of indoor mould exposure in schools, especially in the tropics OBJECTIVE: To study associations between eye symptoms and tear film break up time (BUT) in students and demographic data and fungal DNA in schools.

METHODS

A school environment study was performed among randomly selected students in eight randomly selected secondary schools in Penang, Malaysia. Information on eye symptoms and demographic data was collected by a standardised questionnaire. BUT was measured by two methods, self-reported BUT (SBUT) and by the non-invasive Tearscope (NIBUT). Dust was collected by vacuuming in 32 classrooms and analysed for five fungal DNA sequences. Geometric mean (GM) for total fungal DNA was 7.31*10⁴ target copies per gram dust and for Aspergillus/Penicillium DNA 3.34*10⁴ target copies per gram dust. Linear mixed models and 3-level multiple logistic regression were applied adjusting for demographic factors.

RESULTS

A total of 368 students (58%) participated and 17.4% reported weekly eye symptoms the last 3 months. The median SBUT and TBUT were 15 and 12s, respectively. Students wearing glasses (OR 2.41, p=0.01) and with a history of atopy (OR=2.67; p=0.008) had more eye symptoms. Girls had less eye symptoms than boys (OR=0.34; p=0.006) Indoor carbon dioxide in the classrooms was low (range 380-720ppm), temperature was 25-30°C and relative air humidity 70-88%. Total fungal DNA in vacuumed dust was associated with shorter SBUT (4s shorter per 10⁵ target copies per gram dust; p=0.04) and NIBUT (4s shorter per 10⁵ target copies per gram dust; p<0.001). Aspergillus/Penicillium DNA was associated with shorter NIBUT (5s shorter per 10⁵ target copies per gram dust; p=0.01).

CONCLUSION

Fungal contamination in schools in a tropical country can be a risk factor for impaired tear film stability among students.

Outdoor air pollution, meteorological conditions and indoor factors in dwellings in relation to sick building syndrome (SBS) among adults in China

Indoor environment is associated with the sick building syndrome (SBS), but little is known about the contribution of outdoor air pollution and meteorological conditions to SBS. We studied associations between outdoor air pollution, meteorological parameters and selected indoor exposure and building characteristics at home and weekly SBS symptoms in a standardized questionnaire study among 3485 randomly selected adults in China. Outdoor factors included particulate matters with diameter <10μm (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), outdoor temperature (T), relative air humidity (RH), and wind speed (WS) during last three months. Multiple logistic regression was applied calculating odds ratios (OR) with 95% confidence interval (95% CI). Asthma or allergic rhinitis (atopy) was associated with all types of SBS symptoms except fatigue. Indoor factors played a major role in SBS symptoms. Mold/dampness on the floor/ceiling was associated with fatigue OR=1.60 (1.11-2.30) and headache OR=1.80 (1.07-3.04). Moldy odor was associated with fatigue OR=1.59 (1.07-2.37) and dermal symptoms OR=1.91 (1.21-3.02). Window pane condensation in winter was associated with fatigue OR=1.73 (1.30-2.31) and throat symptoms OR=1.53 (1.01-2.31). Damp bed clothing was related with throat symptom OR=1.62 (1.09-2.40). Home redecoration was associated with fatigue OR=1.49 (1.07-2.06). Frequent window opening was associated with less nose symptoms OR=0.54 (0.36-0.82) and mechanical ventilation in the bathroom reduced dermal symptoms OR=0.66 (0.44-0.99). Females were more susceptible to redecoration and window pane condensation than men. No associations with SBS were observed for outdoor air pollutants or meteorological parameters in the final models combining indoor and outdoor factors, although SO2, T, and RH were associated with some SBS symptoms (fatigue, eyes and nose symptoms) in the separate outdoor models. In conclusion, indoor mold/dampness, air pollution from redecoration and poorer ventilation conditions in dwellings can be risk factors for SBS symptoms in an adult Chinese population, especially among females.

Prevalence and risk factors associated with nonspecific building-related symptoms in office employees in Japan: relationships between work environment, Indoor Air Quality, and occupational stress

A nationwide cross-sectional study of 3335 employees was conducted in 320 offices in Japan to estimate the prevalence of building-related symptoms (BRSs) and determine the risk factors related to work environment, Indoor Air Quality, and occupational stress. Data were collected through self-administered questionnaires. The prevalences of general symptoms, eye irritation, and upper respiratory symptoms were 14.4%, 12.1%, and 8.9%, respectively. Multiple logistic regression analyses revealed that eye irritation was significantly associated with carpeting [odds ratio (OR), 1.73; 95% confidence interval (CI), 1.24-2.41], coldness perception (OR, 1.28; 95% CI, 1.13-1.45), and air dryness perception (OR, 1.61; 95% CI, 1.42-1.82). General symptoms were significantly associated with unpleasant odors (OR, 1.37; 95% CI, 1.13-1.65), amount of work (OR, 1.24; 95% CI, 1.06-1.45), and interpersonal conflicts (OR, 1.44; 95% CI, 1.23-1.69). Upper respiratory symptoms were significantly associated with crowded workspaces (OR, 1.36; 95% CI, 1.13-1.63), air dryness perception (OR, 2.07; 95% CI, 1.79-2.38), and reported dustiness on the floor (OR, 1.39; 95% CI, 1.16-1.67). Although psychosocial support is important to reduce and control BRSs, maintaining appropriate air-conditioning and a clean and uncrowded workspace is of equal importance.

Desiccating Stress-Induced MMP Production and Activity Worsens Wound Healing in Alkali-Burned Corneas

PURPOSE

To evaluate the effects of dry eye on ocular surface protease activity and sight threatening corneal complications following ocular surface chemical injury.

METHODS

C57BL/6 mice were subjected to unilateral alkali burn (AB) with or without concomitant dry eye for 2 or 5 days. Mice were observed daily for appearance of corneal perforation. Whole corneas were harvested and lysed for RNA extraction. Quantitative real-time PCR was performed to measure expression of inflammation cytokines, matrix metalloproteinases (MMP). Matrix metalloproteinase-9 activity, gelatinase activity, and myeloperoxidase (MPO) activity were evaluated in corneal lysates. Presence of infiltrating neutrophils was evaluated by immunohistochemistry and flow cytometry.

RESULTS

Eyes subjected to the combined model of AB and dry eye (CM) had 20% sterile corneal perforation rate as soon as 1 day after the initial injury, which increased to 35% by 5 days, delayed wound closure and increased corneal opacity. Increased levels of IL-1β, -6, and MMPs-1, -3, -8, -9, and -13, and chemokine (C-X-C motif) ligand 1 (CSCL1) transcripts were found after 2 days in CM compared with AB corneas. Increased MMP-1, -3, -9, and -13 immunoreactivity and gelatinolytic activity were seen in CM corneas compared with AB. Increased neutrophil infiltration and MPO activity was noted in the CM group compared with AB 2 days post injury.

CONCLUSIONS

Desiccating stress worsens outcome of ocular AB, creating a cytokine and protease storm with greater neutrophil infiltration, increasing the risk of corneal perforation.

Traditional and environmentally preferable cleaning product exposure and health symptoms in custodians

BACKGROUND

We investigated the associations between traditional and environmentally preferable cleaning product exposure and dermal, respiratory, and musculoskeletal symptoms in a population of custodians.

METHODS

We analyzed associations between symptoms and exposure to traditional and environmentally preferable cleaning product exposure among 329 custodians.

RESULTS

We observed increased odds of dermal (P < 0.01), upper (P = 0.01) and lower respiratory (P = 0.01), and upper extremity (P < 0.01), back (P < 0.01), and lower extremity (P = 0.01) musculoskeletal symptoms associated with increased typical traditional cleaning product exposure. We observed significant trends for increased odds of dermal (P = 0.03) and back (P = 0.04) and lower (P = 0.02) extremity musculoskeletal symptoms associated with increased typical environmentally preferable cleaning product exposure.

CONCLUSIONS

Fewer positive associations and reduced odds of health symptoms associated with environmentally preferable cleaning product exposure suggest that these products may represent a safer alternative to traditional cleaning products.

Prevalence and risk factors of dry eye disease among a hospital-based population in southeast China

OBJECTIVE

To investigate the prevalence of dry eye disease (DED) and distribution of associated risk factors among a hospital-based population.

METHODS

In this cross-sectional study, we collected detailed information of clinically defined moderate-to-severe patients with dry eye among a consecutive hospital-based population, including age trend, gender structure, frequency of symptoms, and distribution of associated environmental/occupational risk factors.

RESULTS

Of 6,657 consecutive outpatients aged older than 20 years, symptomatic dry eye presented in 635 subjects (9.54%). Five hundred thirty-two of these 635 subjects (7.99%) were clinically diagnosed as defined DED that combined with positive signs. Women (10.41%) were significantly higher than men (5.21%) (P<0.001). Overexposure to visual display terminal was a major risk factor for DED among young men and women (56.2%). Our study also found occupational conditions with the risk of exposure to adverse environment made up over half of all 532 patients with dry eye. The use of contact lenses was closely associated with DED in young women, and history of ocular surgeries might be another factor associated with DED in old people. One hundred sixty-three of 371 female patients with dry eye (43.9%) were associated with hormonal changes. The incidence of meibomian gland dysfunction-related DED increased gradually with age. There were only 10 patients with dry eye (1.9%) associated with Sjögren syndrome, and all of them were women.

CONCLUSIONS

Environmental and occupational factors were strongly associated with DED and constituted the major proportion in a hospital-based population. A classification of DED based on the distribution of risk factors was recommended for clinical use.

Tear film stability: a review

Tear film stability can be assessed via a number of tools designed for clinical as well as research purposes. These techniques can give us insights into the tear film, and allow assessment of conditions that can lead to dry eye symptoms, and in severe cases, to significant ocular surface damage and deterioration of vision. Understanding what drives tear film instability and its assessment is also crucial for evaluating existing and new therapies. This review examines various techniques that are used to assess tear film instability: evaluation of tear break-up time and non-invasive break-time; topographic and interferometric techniques; confocal microscopic methods; aberrometry; and visual function tests. It also describes possible contributions of different tear film components; namely meibomian lipids, ocular mucins and proteins, and factors such as age, contact lens wear, ocular surgery and environmental stimuli, that may influence tear film instability.

Use of personalized ventilation for improving health, comfort, and performance at high room temperature and humidity

The effect of personalized ventilation (PV) on people's health, comfort, and performance in a warm and humid environment (26 and 28°C at 70% relative humidity) was studied and compared with their responses in a comfortable environment (23°C and 40% relative humidity). Thirty subjects participated in five 4-h experiments in a climate chamber. Under the conditions with PV, the subjects were able to control the rate and direction of the supplied personalized flow of clean air. Subjective responses were collected through questionnaires. During all exposures, the subjects were occupied with tasks used to assess their performance. Objective measures of tear film stability, concentration of stress biomarkers in saliva, and eye blinking rate were taken. Using PV significantly improved the perceived air quality (PAQ) and thermal sensation and decreased the intensity of Sick Building Syndrome (SBS) symptoms to those prevailing in a comfortable room environment without PV. Self-estimated and objectively measured performance was improved. Increasing the temperature and relative humidity, but not the use of PV, significantly decreased tear film quality and the concentration of salivary alpha-amylase, indicating lower mental arousal and alertness. The use of PV improved tear film stability as compared to that in a warm environment without PV.

PRACTICAL IMPLICATIONS

In practice, the supply of clean, cool, and less humid air by PV at each workstation will make it possible to raise room temperatures above the upper comfortable limit suggested in the present standards without adversely affecting the occupants' health [Sick Building Syndrome (SBS) symptoms], comfort (thermal and perceived air quality), and performance. This may lead to energy savings.

Indoor air pollutants in office environments: assessment of comfort, health, and performance

Concentrations of volatile organic compounds (VOCs) in office environments are generally too low to cause sensory irritation in the eyes and airways on the basis of estimated thresholds for sensory irritation. Furthermore, effects in the lungs, e.g. inflammatory effects, have not been substantiated at indoor relevant concentrations. Some VOCs, including formaldehyde, in combination may under certain environmental and occupational conditions result in reported sensory irritation. The odour thresholds of several VOCs are low enough to influence the perceived air quality that result in a number of acute effects from reported sensory irritation in eyes and airways and deterioration of performance. The odour perception (air quality) depends on a number of factors that may influence the odour impact. There is neither clear indication that office dust particles may cause sensory effects, even not particles spiked with glucans, aldehydes or phthalates, nor lung effects; some inflammatory effects may be observed among asthmatics. Ozone-initiated terpene reaction products may be of concern in ozone-enriched environments (≥0.1mg/m(3)) and elevated limonene concentrations, partly due to the production of formaldehyde. Ambient particles may cause cardio-pulmonary effects, especially in susceptible people (e.g. elderly and sick people); even, short-term effects, e.g. from traffic emission and candle smoke may possibly have modulating and delayed effects on the heart, but otherwise adverse effects in the airways and lung functions have not been observed. Secondary organic aerosols generated in indoor ozone-initiated terpene reactions appear not to cause adverse effects in the airways; rather the gaseous products are relevant. Combined exposure to particles and ozone may evoke effects in subgroups of asthmatics. Based on an analysis of thresholds for odour and sensory irritation selected compounds are recommended for measurements to assess the indoor air quality and to minimize reports of irritation symptoms, deteriorated performance, and cardiovascular and pulmonary effects.

The prevalence and incidence of sick building syndrome in Chinese pupils in relation to the school environment: a two-year follow-up study

There are few incidence studies on sick building syndrome (SBS). We studied two-year change of SBS in Chinese pupils in relation to parental asthma/allergy (heredity), own atopy, classroom temperature, relative humidity (RH), absolute humidity (AH), crowdedness, CO₂, NO₂, and SO₂. A total of 1993 participated at baseline, and 1143 stayed in the same classrooms after two years. The prevalence of mucosal and general symptoms was 33% and 28% at baseline and increased during follow-up (P < 0.001). Twenty-seven percent reported at least one symptom improved when away from school. Heredity and own atopy were predictors of SBS at baseline and incidence of SBS. At baseline, SO₂ was associated with general symptoms (OR=1.10 per 100 μg/m³), mucosal symptoms (OR=1.12 per 100 μg/m³), and skin symptoms (OR=1.16 per 100 μg/m³). NO₂ was associated with mucosal symptoms (OR=1.13 per 10 μg/m³), and symptoms improved when away from school (OR=1.13 per 10 μg/m³). Temperature, RH, AH, and CO₂ were negatively associated with prevalence of SBS. Incidence or remission of SBS was not related to any exposure, except a negative association between SO₂ and new skin symptoms. In conclusion, heredity and atopy are related to incidence and prevalence of SBS, but the role of the measured exposures for SBS is more unclear.

PRACTICAL IMPLICATIONS

We found high levels of CO₂ indicating inadequate ventilation and high levels of SO₂ and NO₂, both indoors and outdoors. All schools had natural ventilation, only. Relying on window opening as a tool for ventilation in China is difficult because increased ventilation will decrease the level of CO₂ but increase the level of NO₂ and SO₂ indoors. Prevalence studies of sick building syndrome (SBS) might not be conclusive for causal relationships, and more longitudinal studies on SBS are needed both in China and other parts of the world. The concept of mechanical ventilation and air filtration should be introduced in the schools, and when planning new schools, locations close to heavily trafficked roads should be avoided.

Factors regulating eye blink rate in young infants

PURPOSE

The purpose of this work was to investigate whether individual differences in eye surface area are related to the rate of spontaneous eye blinking (SB) in young infants. Rate of SB was also compared with the rate of gaze shifts.

METHODS

Forty-four 4-month-old infants were observed under controlled conditions for 4 to 6 min. SB, eye surface area, gaze shifts, and various background variables were measured.

RESULTS

Individual differences in the rate of SB and in eye surface area were wide. Neither the eye surface area nor the rate of gaze shifting was related to the rate of SB in young infants. However, when SB do occur, they are more likely to coincide with a shift in gaze than immediately precede or follow a shift in gaze.

CONCLUSIONS

Eye surface area does not explain individual differences in the rate of SB in infancy. This and other recent work suggests that central factors may play a more prominent role in the mechanisms of SB early in human development than previously reported and that the mechanisms regulating the rate of SB seem to be developmentally continuous with those of adults. To the extent that the rate and timing of SB reflects developing neurological systems, SB may be useful clinically.

Dampness and 2-ethyl-1-hexanol in floor construction of rehabilitation center: Health effects in staff

The authors evaluated changes of symptoms and biomarkers in health care staff (N = 18) for people with different physical dysfunctions and similarly in an external office control group in a nondamp building (N = 15). The first workplace had verified dampness in the floor construction, with formation of 2-ethyl-1-hexanol from water-based glue. Tear film break up time (BUT), nasal patency, biomarkers in nasal lavage (NAL), and dynamic spirometry were measured. Both buildings had low indoor air levels of CO2 (510 to 630 ppm), low levels of respirable particles (6 to 7 microg/m3) and formaldehyde (<5 microg/m3), and no indication of microbial growth. Pronounced increase of butanols and 2-ethyl-1-hexanol levels were found in the damp floor material samples, but very low air levels of 2-ethyl-1-hexanol. The staff had been previously exposed to floor construction with alkaline degradation of floor glue, as well as formation of 2-ethyl-1-hexanol. This led to an increase in their ocular, nasal, and respiratory symptoms, a decrease in nasal patency, and slight airway obstruction after 2 days of reexposure, possibly related to neutrophilic inflammation, after a 4-month exposure-free period.

Characterization of occupational exposures to cleaning products used for common cleaning tasks--a pilot study of hospital cleaners

BACKGROUND

In recent years, cleaning has been identified as an occupational risk because of an increased incidence of reported respiratory effects, such as asthma and asthma-like symptoms among cleaning workers. Due to the lack of systematic occupational hygiene analyses and workplace exposure data, it is not clear which cleaning-related exposures induce or aggravate asthma and other respiratory effects. Currently, there is a need for systematic evaluation of cleaning products ingredients and their exposures in the workplace. The objectives of this work were to: a) identify cleaning products' ingredients of concern with respect to respiratory and skin irritation and sensitization; and b) assess the potential for inhalation and dermal exposures to these ingredients during common cleaning tasks.

METHODS

We prioritized ingredients of concern in cleaning products commonly used in several hospitals in Massachusetts. Methods included workplace interviews, reviews of product Materials Safety Data Sheets and the scientific literature on adverse health effects to humans, reviews of physico-chemical properties of cleaning ingredients, and occupational hygiene observational analyses. Furthermore, the potential for exposure in the workplace was assessed by conducting qualitative assessment of airborne exposures and semi-quantitative assessment of dermal exposures.

RESULTS

Cleaning products used for common cleaning tasks were mixtures of many chemicals, including respiratory and dermal irritants and sensitizers. Examples of ingredients of concern include quaternary ammonium compounds, 2-butoxyethanol, and ethanolamines. Cleaning workers are at risk of acute and chronic inhalation exposures to volatile organic compounds (VOC) vapors and aerosols generated from product spraying, and dermal exposures mostly through hands.

CONCLUSION

Cleaning products are mixtures of many chemical ingredients that may impact workers' health through air and dermal exposures. Because cleaning exposures are a function of product formulations and product application procedures, a combination of product evaluation with workplace exposure assessment is critical in developing strategies for protecting workers from cleaning hazards. Our task based assessment methods allowed classification of tasks in different exposure categories, a strategy that can be employed by epidemiological investigations related to cleaning. The methods presented here can be used by occupational and environmental health practitioners to identify intervention strategies.

Acute airway effects of ozone-initiated d-limonene chemistry: importance of gaseous products

There are concerns about ozone-initiated chemistry, because the formation of gaseous oxidation products and ultrafine particles may increase complaints, morbidity and mortality. Here we address the question whether the gaseous products or the ultrafine particles from the ozone-initiated chemistry of limonene, a common and abundant indoor pollutant, cause acute airway effects. The effects on the airways by d-limonene, a ca. 16s old ozone/d-limonene mixture, and clean air were evaluated by a mice bioassay, from which sensory irritation of the upper airways, airflow limitation, and pulmonary irritation can be obtained. A denuder was inserted to separate the ultrafine particles from the gaseous products prior to the exposure chamber. Reduction of mean respiratory frequency (>30%) and 230% increase of time of brake were observed without denuder, during 30min exposure, to the ozonolyzed d-limonene mixture, which are indicative of prominent sensory effects. The initial concentrations (ppm) were 40 d-limonene and 4 ozone. The exposure concentrations (ppm) were about 35 d-limonene and 0.05 ozone. Formaldehyde and residual d-limonene, the salient sensory irritants, accounted for up to three-fourth of the sensory irritation. The upper airway effects reversed to baseline upon cessation of exposure. An effect on the conducting airways was also significant, which did not reverse completely upon cessation. Airway effects were absent with the denuder inserted, which did not alter the size distribution of ultrafine particles ( approximately 10mg/m(3)), significantly. The result was statistically indistinguishable from clean dry air. It is concluded that ultrafine particles that are generated from ozone-initiated d-limonene chemistry and denuded are not causative of sensory effects in the airways.