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Efficacy of a novel moist cool air device in office workers with dry eye disease

2012; Wiley; Volume: 91; Issue: 8 Linguagem: Inglês

10.1111/j.1755-3768.2012.02485.x

1755-3768

Masatoshi Hirayama, Murat Doğru, Ying Liu, Takashi Kojima, Tetsuya Kawakita, Kazuo Tsubota,

Skin Protection and Aging

Purpose: To evaluate the efficacy and safety of new moist cool air device (MCAD) for ocular symptoms, tear film stability and ocular surface status in office workers with dry eye disease (DED). Methods: In this prospective single-centre clinical trial, 40 eyes of 20 patients with DED were recruited and randomly divided into two groups (group with MCAD exposure and group without MCAD). All subjects are visual display terminals (VDTs) workers spending at least 4 h/day in front of VDTs. Patients using MCAD underwent moist air applications for 4 h/day for a total of five working weekdays during VDT works at their offices. The other group of patients performed their VDT work without moist cool air device exposure. The change in symptoms of ocular surface (OS) dryness, fatigue and discomfort was evaluated using visual analogue scale (VAS) scores. Changes in visual function, tear functions and ocular surface status were evaluated using best-corrected visual acuity (BCVA), the functional visual acuity (FVA) test, blink rate, BUT measurements, strip meniscometry (SM), tear evaporation rate, fluorescein staining and rose bengal staining scores. Tear film lipid layer interferometry was also performed to assess the status of the lipid layer over the tear film. In addition, adverse events were recorded. Results: In group with MCAD, symptoms of OS dryness during VDTs work, and FVA and BUT were significantly improved. SM and tear evaporation rate were significantly improved. There were no statistically significant differences on lipid layer stability and corneal staining scores in both groups. Blink rate was significantly increased in group without MCAD. No adverse events were reported during this trial. Conclusion: Moist cool air device use provided symptomatic relief of ocular dryness and improvement on tear stability in office workers with DED. This new device seems to be a safe and promising alternative in the treatment of DED. Recent epidemiologic studies revealed that dry eye disease (DED) is prevalent among young and middle-aged office workers, and the condition is more prevalent among prolonged visual display terminals (VDT) users (Backman & Haghighat 1999; Reijula & Sundman-Digert 2004; Uchino et al. 2008). Various ocular symptoms were reported by VDT users including eyestrain, tiredness, irritation, ocular pain, burning sensation, redness, reduced visual acuity and double vision (Thomson 1998; Goto et al. 2002, 2003a,b; Wolkoff et al. 2005). Dry eye symptoms can be debilitating and can impact adversely a person's ability to use a VDT and to perform other tasks requiring sustained visual concentration (Miljanovic et al. 2007). Such symptoms also have been reported to have a negative impact on psychological health and overall sense of well-being (Ye et al. 2007; Friedman 2010). DED in VDT workers can result from a decreased rate of blinking and consequent increase in the rate of tear evaporation (Yaginuma et al. 1990; Tsubota & Nakamori 1993), which exacerbates complaints because of environmental factors such as air drafts and low humidity in air-conditioned offices. These factors and conditions progressively increase tear water evaporation and promote faster thinning of the precorneal tear film. Consequently, corneal dry spots can form that damage the ocular surface and inevitably lead to greater tear deficiency (Rolando & Refojo 1983; Nilsson et al. 1983; Chen et al. 2008). During the past decades, the differences between asymptomatic subjects and those with moderate to severe office dry eye with tear deficiency have been well documented (Patel et al. 1991; Uchino et al. 2008; Chen et al. 2008). However, in the clinic, a number of patients with self-reported office dry eye whose eyes are still wet and who have almost no clinical signs of ocular surface damage are founded (Zhang et al. 2011). We previously reported our clinical experience on such patients with short break-up time (sBUT) type of dry eye and no ocular surface inflammation (Kaido et al. 2008). To alleviate their symptoms, patients frequently use artificial teardrops, hyaluron acid containing eye drops or receive punctual plug treatment (Kaido et al. 2008; Doughty & Glavin 2009). However, teardrop therapy requires the workers to interrupt their VDT work and decrease their concentration. In addition, various new instruments such as moist glasses and warm moist air devices improving low-humidity environments have been reported (Tsubota et al. 1994; Matsumoto et al. 2006). These devices operate by reducing tear evaporation from ocular surface and by increasing the humidity of eye surroundings. Therefore, new approaches improving tear functions that can directly deliver the aqueous solutions to the ocular surface and can be used continuously and easily without interruption of VDT work are essential as the use of VDT in the office environments is continuously expanding. In this study, we report the effects of a newly developed moist cool air device on tear functions and ocular surface in patients with VDT-related sBUT dry eye, comparing the results with those from patients not using it. In this prospective single-centre clinical trial, 40 eyes of 20 patients with sBUT dry eyes were recruited and randomly divided into two groups (group with moist cool air device exposure: six women and four men; mean age, 31.2 ± 6.9 years; minimum: 23 years; maximum: 42 years, and group without moist cool air device : four women and six men; mean age, 30.1 ± 4.95 years; minimum: 25 years; maximum: 38 years) to evaluate the tear function and ocular surface effects of the moist cool air device. The demographic data of the patients are shown in Table 1. All subjects are VDT workers spending at least 4 h/day in front of VDTs. None of the patients had a history of severe ocular inflammation such as Stevens–Johnson syndrome, chemical, thermal and radiation injury, or other systemic disorder. Patients undergoing laser in situ keratomileusis (LASIK) or phakic intraocular lens surgery within the last 3 years were excluded. None of the other patients had undergone any ocular surgery or procedure that would cause an ocular surface problem. Eight patients were contact lens users. At ocular examination, particular attention was paid to lids margins, tarsal and bulbar conjunctiva, and corneas. Ocular surface was assessed by careful slit-lamp examination. The examinations were performed by a single investigator (M.H.) who carried out the same examination procedures during the study. Short break-up time type of dry eye was defined as the presence of a short fluorescein tear film break-up time (BUT) and dry eye symptoms without obvious ocular surface epithelial damage. The criteria for the diagnosis of sBUT dry eye were as follows: (i) the presence of dry eye symptoms such as ocular dryness, tiredness or irritation, (ii) a fluorescein BUT scores of 5 mm and (iii) no ocular surface epithelial damage by fluorescein and rose bengal staining (Kaido et al. 2008). Temperature and humidity of the examination room were maintained at a range from 20 to 24°C and 30% to 50%, respectively, during the trials. All patients were recruited in this study with informed consent. The study was approved by Institutional Review Board of Minami-aoyama eye clinic. The study was conducted according to the tenets of Declaration of Helsinki. Patients using moist cool air device underwent moist air applications for 4 h/day for a total of five working weekdays during VDT works at their offices. The other group of patients performed their VDT work without moist cool air device exposure. Application of eye drops such as artificial teardrops or alcohol consumption was discontinued 3 days before the start of the examinations until the end of this study. The change in symptoms of ocular surface dryness, fatigue and discomfort was evaluated using visual analogue scale (VAS) scores. Changes in visual function, tear functions and ocular surface status were evaluated using best-corrected visual acuity (BCVA), the functional visual acuity (FVA) test, blink rate measurement, BUT measurements, strip meniscometry, tear evaporation rate, fluorescein staining and rose bengal staining scores. Tear film lipid layer interferometry (DR-1; Kowa Co., Tokyo, Japan) was also performed to assess the status of the lipid layer over the tear film. Observations and tests were conducted in the following order: BCVA, FVA test, blink rate, DR-1 lipid layer interferometry, tear evaporation test, strip meniscometry, BUT and ocular surface vital staining. BUT measurement and vital staining were performed 15 min after strip meniscometry. Figure 1A shows outline of the new electrospray device. This spray method and its safety were reported previously (Zimlich & Ding 2000). They reported using this new electrospray device to characterize the pulmonary drug delivery for emitted dose uniformity and particle size distribution reproducibility. A sampling apparatus was used to conduct the emitted dose and dose uniformity tests, using a continuous sampling flow rate of 30 l/min for 4-seconds. The drug mass deposited on the sampling apparatus and filter was recovered and quantified analytically. The authors concluded that the particle size distribution of an aerosol could be adjusted with this technology and that in vitro performance could be improved at least 2–3 folds in terms of dose efficiency. This spray device was composed of a main body and liquid cartridge (40ml of water (98.75%), sodium acetylated hyaluronate (0.1%), castor oil (0.05%), butylene glycol (0.1%) and methylparaben (0.1%)) with resin nozzle (Fig. 1B). When the cartridge is inserted and the spray device is turned on, the liquid is lifted up to top of the nozzle by air pressure. At the same time, a high voltage (about 4000–5000 V) is applied to the liquid in the cartridge. By electrical conduction in the liquid, an electrical field was produced at the top of the nozzle. The liquid is pulled out and turned into small positively charged droplets by electrical field strength. Amount of water emission was about 0.3 μl/sec, and droplet size was about 100 μm (Fig. 2). The electrospray device was 30 cm tall and located beside the monitor and 40 cm away from the faces of the subjects. The noise level measured at this setting was 11.8 dB. The movement of the liquid particles from the electrospray device to the corneal surface of the study subjects was recorded by a video camera. New moist cool air device. (A) outline of the new electro spray device. (B) the liquid is pulled out and turned into small positively charged droplets by electrical field strength. Basic characteristics of the electrospray. Dry eye and ocular fatigue symptoms were evaluated with VAS scores. The questionnaire included symptoms of dryness sensation, ocular tiredness and discomfort. Participants checked on the VAS sheets before, during and after moist cool air device application. Subjects were requested to place a check mark on a 10 cm line on a point corresponding to the severity for their subjective symptoms. The length of the marks made by the patients was measured, and the units were given in points. Higher scores on the VAS referred to more severe degrees of symptoms in this study (minimum score: 0 point, maximum score: 10 points). The best-corrected visual acuity (BCVA) was measured by conventional Landolt VA testing. The FVA measurement system (Nidek, Tokyo, Japan) was used to examine the timewise change in continuous VA as reported previously (Goto et al. 2003a,b; Ishida et al. 2005). In brief, the device is made up of three parts: a hard disk, a monitor and a joystick. The Landolt optotypes are presented on the monitor, and their sizes change depending on the correctness of the responses. The optotypes are displayed automatically, starting with smaller ones. If the responses are incorrect, larger optotypes are presented automatically. When there was no response within the set display times, the answer was taken to be an error and the optotype automatically enlarged. VA is continuously measured from the baseline best-corrected Landolt VA. The FVA measurement system can measure VA from 400/200 to 20/2000. The testing distance information is entered into the computer database so that each Landolt optotype presented on the monitor subtended an equivalent angle to the optotype of the same VA level presented from 5 m during the conventional Landolt VA testing. The blink rate was also recorded simultaneously with the FVA measurement by the examiner who made the FVA testing. The examiner pressed a button on FVA device each time he or she noticed a blinking. The blink rate was then calculated automatically by the FVA software. Tear evaporation rates from the ocular surface were measured noninvasively using the TEROS system as reported previously (Goto et al. 2003a,b). Briefly, the evaporimeter consisted of an eye cup in the form of a ventilated chamber having a volume of 20 cm3 that tightly covered the eye; air, which was supplied into the cup as a tear evaporation carrier by an air compressor at a constant flow rate (150 ml/min); and a quartz crystal sensor (9 MHz A-T cut quartz crystal 8 mm in diameter and 0.2 mm in thickness), known as the microbalance, which is highly sensitive to humidity. The frequency of the sensor shifts in response to changes in humidity. Evaporation rates were measured by calculating the difference between the water content of the air entering and exiting the cup. The data sampling rate was four times per second. Real-time changes in the frequency data appeared on the display of a personal computer, synchronous with this sampling rate. For the measurements, the same eye cup was used as reported in a previous study to fix the conditions. Tear evaporation rate measurements were performed by keeping the temperature and humidity settings constant for each trial. The standard tear film BUT measurement was performed after instillation of 2 μl of 1% fluorescein preservative-free solution in the conjunctival sac with a micropipette. The patient was instructed to blink several times for a few seconds to ensure adequate mixing of the dye. The interval between the last complete blink and the appearance of the first corneal black spot in the stained tear film was measured three times, and the mean value of the measurements was calculated. A BUT value of <5 seconds was considered abnormal. For further evaluation of tears, the strip meniscometry test was performed following a previous report (Dogru et al. 2006). The sterilized strips of filter paper (Alcon, Fort Worth, TX, USA) were placed in the lateral canthus away from the cornea and left in place for 5 seconds. Readings were repeated in millimetres of wetting for 5 seconds. Two microlitres of preservative-free solution consisting of 1% fluorescein and 1% rose bengal dye were applied to the conjunctival sac with a micropipette. Fluorescein staining scores of the corneas ranged between 0 and 9 points. Rose bengal staining scores of the corneas and conjunctiva ranged also between 0 and 9 points. Any score above 3 points was regarded as abnormal. DR-1 interferometry observes the specular reflected light from the tear surface. Light from a white light source is reflected by a half-mirror, focused by a lens and used to illuminate the tear surface. The specular reflected light from the tear surface returns through the half-mirror to a charge-coupled device camera that produces an image on the device monitor. Two polarizers and a quarter-wave plate help eliminate unnecessary reflected light from the lens and detect only the specular reflected light from the tear fluid. The camera is focused on a 2.2 × 3.0-mm area of the central cornea such that a circular area 2 mm in diameter is observable. Lipid layer interference images were recorded soon after a complete blink. The classification of tear lipid layer patterns has been described previously elsewhere (Yokoi et al. 1996). The change of the interference pattern from uniform grey colour to many colours of nonuniform distribution indicates expression of lipids into the tear film in DR-1 lipid layer interferometry (Yokoi et al. 1996). The change in VAS score, strip meniscometry, BUT and ocular surface staining scores was assessed by the Wilcoxon test. The changes in DR-1 tear film lipid layer interferometry grading were assessed by Fisher's exact test. The differences were considered statistically significant if the p values were <0.05. spss software (SPSS Inc, Chicago, IL, USA) was used for statistical analysis. Video recording of the spray device application revealed that the liquid particles were drawn to the corneal surface in all subjects. The VAS scores for ocular dryness showed a significant improvement with moist cool air device exposure while doing VDT work (p = 0.037). The VAS scores in the group not exposed to the moist cool air device did not improve at any examination point as shown in Table 2. Mean log MAR BCVA did not significantly change before and after moist cool air device exposure. Mean logMAR FVA scores significantly improved from −0.073 ± 0.10 to −0.12 ± 0.073 with moist cool air device exposure (p = 0.01). On the other hand, no significant change was observed in patients not exposed to the moist cool air device (p = 0.77) as shown in Table 3. The mean blink rate did not change before and after moist cool air device exposure, while it significantly increased in patients without moist cool air device exposure (p = 0.048). The mean tear film BUT improved from 2.7 ± 0.8 to 3.6 ± 0.8 seconds in patients with moist cool air device application (p = 0.0032). The mean tear film BUT did not change significantly in patients not exposed to the moist cool air device (p = 0.30). The mean strip meniscometry test value showed a significant improvement with moist cool air device exposure from 2.3 ± 1.4 to 3.4 ± 1.8 mm (p = 0.020), while no significant change was observed in the group not exposed to moist cool air device (p = 0.55). Fluorescein and rose bengal staining scores did not show significant changes in both groups (Table 4). The mean tear evaporation rates did not show significant changes in the patients with moist cool air device exposure (p = 0.65), while TEROS significantly increased after VDT work in subjects without moist cool air device exposure (p = 0.032) as shown in Table 3. DR-1 severity grades did not show significant changes in subjects with or without moist cool air device application (Table 4). There were no ocular side-effects reported with the use of moist cool air device. Recent years have seen a dramatic increase in the amount of work performed using VDTs. Home use of computers and portable information terminals also has risen steadily, with an estimated 28 million households in the United States having a home computer by 2006 (Romero et al. 2008). These changes in work and leisure activities have been accompanied by an increase in reported symptoms regarding a number of health problems associated with VDT use. A recent study demonstrated a significantly high prevalence of medical comorbidities in patients with DED in Taiwan (Wang et al. 2010). Of VDT-associated ocular comorbidities, eye problems are among the most common reported symptoms (Collins et al. 1990). Clinically diagnosed DED was present in 266 (10.1%) of 2640 male and in 195 (21.5%) of 909 female VDT workers in a recent large-scale epidemiological study performed in Japan. More than 4 h of VDT use was associated with an increased risk of DED (Uchino et al. 2008). Tsubota & Nakamori (1995) demonstrated, in a Japanese population, that the exposed area of the ocular surface increased by 1.8 and 2.5 times from downgaze to straight ahead and from downgaze to upgaze and that evaporation per eye increased by 2.5 and 3.4 times, respectively, in VDT users. Thus, it has been suggested that individuals working at VDT are at a greater risk of dry eye, because their eyes are more widely open while looking straight ahead at a computer screen than they would be when they are directed downwards toward written work. Tsubota and Nakamori (1993) has recommended relocating screens to a lower position in order to counteract this risk. Blink rate has also been suggested as an important factor in ocular surface evaporation. Blink rate has been reported to be reduced in persons working at VDT (Tsubota et al.1996). The alleviation of symptoms in VDT-related DED is the major aim of currently available treatments. The mainstay of current dry eye treatment regimens is the use of artificial teardrops and punctual plugs (Tsubota et al. 2002). To alleviate VDT-related symptomatology, it is not only important to prevent dry eyes, but improve the VDT environment as well. Simple reported recommendations for VDT-related dry eye include lowering the position of VDT monitors and educating the patients on their condition (Tsubota et al. 2002). It is also essential to try to reduce the effect of the dry eye aggravating factors. For example, patients may be counselled to quit smoking, which has been reported to disturb the lipid layer of the tear film and cause tear instability (Altinors et al. 2006), decrease caffeine and alcohol intake, increase the amount of water they drink, and use room humidifiers. It has been reported that the use of small moistened sponges to special side panels of modified eye glasses provides steady evaporation from the sponges and increases the ambient moisture level in front of the eyes (Tsubota et al. 1994). Acupuncture has been reported to increase BUT and treat DED in a randomized placebo-controlled trial (Lan & Tong 2012).The eye steamer device has been reported to be a safe and promising approach in VDT-related evaporative dry eyes with effects similar to the use of warm hot towel applications (Matsumoto et al. 2006). However, most of these treatment regimens require cessation of VDT work. There is a need for treatment modalities that can be employed while doing VDT work. We thus developed a new moist cool air device to fulfil this requirement for busy VDT environments. Electrohydrodynamic aerosolization is a process of disrupting a liquid into a spray of fine droplets using a strong electric field (Zeleny 1901; Zeleny & Faust 1915). The liquid meniscus at the distal end of a capillary column takes on a conical shape under the action of the electric field. The cone tip breaks up into a splay of nearly monodispersed, charged particles (Zeleny 1912). Our results suggest that application of the moist cool air device for 4 h/day for a whole working week was associated with concomitant improvement in tear reservoir volume, tear stability and FVA. We could also observe with real-time video recording that positively charged liquid particles containing hyaluron acid, lipid and water were drawn toward the negatively charged corneal surface by static electricity pull. The liquid particles were drawn to the corneal surface despite head movements during VDT work based on our video recording observations. We presume that the device provided a constant exposure to moisture during VDT work. Indeed, tear reservoir volume, mean strip meniscometry and tear stability scores improved with moist cool air device application. Our device delivered 20 μl/min of cartridge solution to the ocular surface. The transport rate of the solution to the face from the device (40 cm distance) is 70%, which means that about 14 μl/min of solution reached the eyes for 4 h. Previous reports suggest that 7–10 μl of tears are present at any time over the ocular surface and that approximately 5–7.5 μl (75%) of tears are present in the tear meniscus (Norn 1965; Maurice 1973; Holly 1987). We think that the current device provided considerable amount of moisture droplets consisting of water, hyaluronic acid and castor oil, all of which might have contributed to increased tear stability and decrease in dryness symptoms during VDT work. We believe that BUT improvement might have been due to the elevation of tear meniscus level. Decreased ocular symptomatology during VDT work can increase ocular ergonomy, in our belief. While we believe that crossover designed trials studying the duration of the maintenance of the efficacy of the moist cool air device are essential, our study showed that the effects should be short-lived and disappear soon after termination of moist cool air device application. One possible concern in relation to exposure of the ocular surface and the facial skin is the presence of castor oil particles that may be considered as allergic or toxic to the epidermal or mucosal tissues. Castor oil is widely used in cosmetics, skin-conditioning agents, emulsion stabilizers, surfactants, food colouring agents and deodorant aerosols (Wilbur 2007). While rare allergic skin reactions have been described upon acute/chronic exposure to castor oil containing cosmetic products (Sai 1983; Yoshikawa et al. 1985), we did not observe any skin or ocular allergic reactions with new moist cool air device application. Another concern may be the effect of the inhalation of castor oil particles in lung tissues, which has been shown to induce apoptosis in Type II pneumocytes in rats (Brown & White 1997). We observed no respiratory side-effects in any of the subjects in our study. Castor oil has been classified by FDA as safe and effective when ingested up to a level of 0.7 mg/kg of body weight in human (Wilbur 2007). Because of lack of changes in the tear film lipid layer interferometry after electrospray device applications, we presumed that the amount of castor oil reaching the alveoli should be small to induce the significant changes in the alveolar milieu and respiratory functions. Studies testing the efficacy of moist cool air device on a larger population and comparing the efficacy with eye warmer devices would provide very interesting information. Further prospective studies comparing the efficacy of new moist cool air device with conventional humidifiers would also be useful and increase our understanding on its efficacy. In summary, we reported on a new moist air device that could alleviate dry eye symptoms in VDT workers and improve tear reservoir volume and tear stability and could be applied without interruption of the VDT work.