Assessment of lipid layer patterns in domestic dogs and rabbits: an observational study.

Background: Maintaining a stable tear film is crucial for having healthy human and animal vision. Animals are expected to have thicker lipid layers than humans due to living in high-temperature and humid environments. Aim: The study aimed to evaluate the lipid layer patterns (LLPs) in Arabian dogs and rabbits using a non-invasive, practical, and easy-to-use device and compare them to humans with healthy eyes. Methods: The study included 75 domestic Arabian dogs (42 males and 33 females; mean ± SD = 6.1 ± 12.7 months) and 75 rabbits (37 males and 38 females; mean ± SD = 3.1 ± 3.4 months). In addition, 75 individuals with healthy eyes (39 males and 36 females; mean ± SD = 25.7 ± 5.0 years) were included for comparison. EASYTEAR View+ assessed the LLP in each animal's and individual's right eye. Results: The median LLP grades significantly differed between dogs and humans (Mann-Whitney U test, p < 0.001). Similarly, the LLP grades differed significantly between rabbits and humans (Mann-Whitney U test, p < 0.001). No significant difference (Mann-Whitney U test) in the LLP grades between dogs and rabbits was found. The analysis indicated that most dogs had either an A (34.7%) or a B grade (37.3%). Similarly, rabbits had predominantly A or 1 (46.7%) and B (30.7%) grades. On the other hand, humans had predominantly D (53.3%) and E (30.7%) grades. Conclusion: The EASYTEAR View+ has been employed to assess LLP in dogs and rabbits, and the measurements were compared to those of humans with normal ocular health. Dogs and rabbits have thinner lipid layers than healthy humans.

Assessment of the Effect of Wearing a Surgical Face Mask on Tear Film in Normal Eye Subjects.

Purpose: To assess the effect of wearing a face mask for a short time on the tear film parameters in normal eye subjects. Methods: Fifty-four normal eye subjects (14 female and 40 male) aged 18-40 years (23.8 ± 4.4 years) were recruited. A standardized patient evaluation of eye dryness was completed first, followed by noninvasive tear break-up time, phenol red thread, and tear ferning tests. A 5-minute gap was allowed between the tests. The subjects were asked to wear a surgical mask for one hour. The measurements were taken both before wearing a face mask and immediately after its removal. Results: Significant (Wilcoxon test) differences were found between the standardized patient evaluation of eye dryness (p=0.002) and the noninvasive tear break-up time scores (p < 0.001) before and after wearing face masks. No significant differences (Wilcoxon test, p > 0.05) were found between the phenol red thread scores and tear ferning grades before and after wearing face masks. Strong correlations (Spearman's rank correlation coefficient, r) were found among the standardized patient evaluation of eye dryness score (r = 0.590; p < 0.001), noninvasive tear break-up time measurements (r = 0.631; p < 0.001), and the tear ferning grades (r = 0.517; p < 0.001) before and after wearing the mask. A medium correlation (r = 0.377; p=0.005) was found between the noninvasive tear break-up time scores and tear ferning grades before wearing the mask. Conclusions: Wearing a surgical face mask for a short duration of one hour has an effect on ocular tear film in normal eye subjects. Dry eye symptoms and tear break-up increased after wearing a face mask compared with those experienced before wearing one.

Assessment of tear film in subjects with a high body mass index.

PURPOSE: The aim of the study was to assess the tear film in subjects with a high body mass index (BMI). METHODS: Twenty male subjects aged 23-42 years (mean ± standard deviation =31.3±5.7 years) with a high BMI [median (interquartile range) =31.8 (5.2) kg/m2] were recruited. An age-matched control group of twenty male subjects aged 22-38 years with a normal BMI [20.5 (2.8) kg/m2] also participated in the study. RESULTS: There were significant (Kolmogorov-Smirnov test; P<0.05) differences in the BMI, non-invasive tear break-up time (NITBUT), and tear ferning (TF) scores between the study and control groups. There were some differences in the ocular surface disease index (OSDI), tear meniscus height (TMH), and phenol red thread (PRT) scores between the study and control groups, but these differences were not significant (Kolmogorov-Smirnov test; P>0.05). For the study group, the NITBUT and TF tests mean scores showed a dry eye condition (8.5±2.8 s and 2.0±1.1, respectively). However, these two tests showed a normal eye condition within the control group (14.7±2.8 s and 0.7±0.6, respectively). The TMH score had strong correlations with the NITBUT (r=0.711; P=0.001) and PRT scores (r=0.566; P=0.009) and strong negative correlations with age (r=-0.503; P=0.024) and the OSDI scores (r=-0.520; P=0.018). The TF score had a strong correlation with age (r=0.579; P=0.007) and strong negtive correlations with the scores from the NITBUT (r=-0.525; P=0.018), TMH (r=-0.575; P=0.008), and PRT (r=-0.773; P=0.001) tests. CONCLUSION: The acquired data suggest a high BMI has an effect on the quality of tears. The quality of tears seems to be lower in subjects with a high BMI compared with normal subjects. On the other hand, the tear volume in subjects with a high BMI was just as high and adequate as for normal eye subjects.

An assessment of the ocular tear film in patients with thyroid disorders.

Objective: To investigate the ocular tear film in patients with thyroid disorders using various tests. Methods: The study involved the assessment of the ocular tear film in 20 patients with thyroid disorders (6 men and 14 women) aged 18-43 years (mean±standard deviation=34.3±3.2 years). An age-matched control group consisting of 20 subjects (8 males and 12 females) ranging in age from 18 to 43 years (31.3±2.9 years) was also examined under similar conditions. All patients completed the Ocular Surface Disease Index questionnaire, followed by the tear ferning test within the right eye. A phenol red thread test was carried out 10 mins later followed by the fluorescein tear break-up test with a 10-min gap between the tests being implemented. Results: The median score for the Ocular Surface Disease Index (P<0.05) showed the condition of mild dry eyes [median (IQR)=15.5 (21.9)] in patients with thyroid disorders compared to the control group [5.6 (3.6)]. The mean score for the phenol red thread test within both the right and left eyes showed acceptable tear volumes of 11.7±8.1 and 10.5±7.4 mm, respectively, but this was much lower (P<0.05) compared to those recorded within the control group (22.2±6.5 and 20.7±5.2 mm, respectively). In addition, the mean for the tear break-up time (P<0.05) scores in both eyes within the patients with thyroid disorders revealed a certain degree of eye dryness (4.9±1.6 and 4.2±1.9 s), while the control group showed normal eye scores (13.2±2.6 and 12.3±2.2 s). The median score for tear ferning grades showed eye dryness [2.0 (2.2)] within the study group and normal eyes [1.2 (0.9)] within the control group. Conclusions: Patients with thyroid disorders have a significant level of eye dryness compared to normal eye subjects.

Assessment of the tear film in normal eye subjects after consumption of a single dose of hot peppermint drink.

Objective: To test the effect of a single dose of hot peppermint consumption on the tear film in normal eye subjects. Methods: Thirty healthy male subjects aged 18-39 years (23.20±2.17 years) were enrolled. Also, an age-matched control group of 30 male subjects (19-39 years, 23.50±0.70 years) was enrolled to test the effect of the hot water. Tear meniscus height (TMH), noninvasive tear breakup time (NITBUT), and tear ferning (TF) tests were performed for each patient 30 mins before and 60 mins after they drank hot peppermint. Results: Mean TMH measurements were higher postintervention (0.32±0.07) than preintervention (0.27±0.04 mm). Similarly, mean TF grades were significantly higher (2.07±1.20) postintervention than preintervention (0.84±0.71). By contrast, mean NITBUT was lower postintervention than preintervention (11.57±3.17 and 15.84±3.36, respectively). TMH measurements increased in 90% of the subjects. Conversely, NITBUT decreased in 96.7% of the subjects. For the control group that tests the effect of drinking hot water, the scores did not differ significantly in the three tests pre- and postintervention (P˂0.05). TF grades increased in 93.3% of the subjects, postintervention. Conclusion: Tear film quality decreases significantly after peppermint beverage consumption. A similar observation has been made on the consumption of hot green tea drink.

Assessment of tear-evaporation rate in thyroid-gland patients.

OBJECTIVE: To assess the tear-evaporation rate in thyroid-gland patients using a VapoMeter. METHODS: Twenty thyroid gland patients aged 18-43 years (mean 34.3±6.3 years) completed the study. Additionally, an age-matched control group of 20 patients aged 18-43 years (32.2±5.1 years) was enrolled in the study for comparison purposes. An Ocular Surface Disease Index dry-eye questionnaire was completed, followed by a test to determine the tear-evaporation rate using the VapoMeter. The test was performed three times per subject by the same examiner. Two readings were obtained each time. RESULTS: Significant differences (P<0.05) were found between mean Ocular Surface Disease Index and tear-evaporation-rate scores within the study and control groups. The average tear-evaporation rate was much higher in the study group (median 41.2 [IQR 41.4] g/m2⋅h) than the control group (15.7 [13.7] g/m2⋅h). Moreover, the average Ocular Surface Disease Index score for thyroid-gland patients was much higher (15.6 [23.4]) compared to the control group (5.5 [7.50]). CONCLUSION: The tear-evaporation rate in thyroid-gland patients was found to be much higher than normal-eye subjects.

Analysis of basal and reflex human tear osmolarity in normal subjects: assessment of tear osmolarity.

PURPOSE: The aim of this study is to evaluate the difference between reflex and basal tear osmolarity among healthy normal subjects. METHOD: The right eyes of 20 healthy normal male subjects aged 20 to 40 years were recruited for this study. The inclusion criteria for the subjects were the Ocular Surface Disease Index questionnaire score of less than 12 and wetting length of the phenol red thread of more than 10 mm. Tear film osmolarity was assessed using TearLab osmometer. Basic tear osmolarity was measured normally without inducing any irritation to the eye. In order to stimulate reflex tear, subjects were asked to open their eye as long as they can till they feel ocular surface irritation (minimum 20 s). RESULTS: The mean score on the Ocular Surface Disease Index questionnaire was 5.5 ± 3. The mean value obtained from the phenol red thread was 21 ± 4.5 mm. There were no statistically significant differences between the osmolarity readings of basal and reflex tear osmolarity (p > 0.05). The mean value was 308 ± 12 and 306 ± 9 mOsm/l for basic and reflex tear osmolarity, respectively. CONCLUSION: This study found that the osmolarity of the basal and reflex tears fell within the same range. The values found in this study are in agreement with published results for normal subjects.

Assessment of Tear Film Quality among Smokers Using Tear Ferning Patterns.

Purpose. To investigate the effect of cigarette smoking on the ocular tear film. Methods. Thirty healthy young male cigarette smokers (20-38 years old) and 30 healthy age matched nonsmokers were enrolled in the study. McMonnies questionnaire, slit lamp, and PRT test were used to screen the subjects. Tear samples were collected from the right eyes and tear ferning patterns were observed and graded. Results. The mean MacMonnies scores and TF grades were significantly higher in the smoker subjects (mean ± SD = 9.83 ± 5.22 and 0.96 ± 0.54, resp.) compared to nonsmokers (mean ± SD = 5.96 ± 3.06 and 0.41 ± 0.38, resp.). The mean values obtained from PRT and TBUT tests were 22.23 ± 6.35 mm and 12.17 ± 3.81 s for smokers and 22.16 ± 5.63 mm and 14.13 ± 2.62 s for nonsmokers, respectively. Strong correlations were found between MacMonnies scores and both PRT (r = 0.596) and TF (r = 0.516). There was statistically significant difference in TF grades (p = 0.00), TBUT (p = 0.036) and McMonnies (p = 0.02) between smokers and nonsmokers. Conclusion. Cigarette smoking could have a significant effect on the tear film quality of the eye.