Daily rhythm of tear production in normal horse (original) (raw)
Related papers
Daily rhythm of tear production in normal dog maintained under different Light/Dark cycles
Research in Veterinary Science, 2009
This study was conduced to assess the daily rhythm of tear production in clinically healthy dog. For our study eight female purebred Beagles were subjected to three different Light/Dark schedules: 12/12 L/D, 24/0 L/D and 0/24 L/D cycles. In all subjects Schirmer tear test I was performed at 4 h intervals over a 24 h period. A statistical significant effect of photoperiod was observed comparing the three different L/D schedules, and a statistical significant difference was observed comparing left and right eye during the 12/12 L/D schedule. We demonstrated daily variation of tear production in dogs maintained under an L/D cycle. We also provided strong evidence that the rhythm of tear production is endogenously generated because it persisted in constant darkness. Although the range of excursion of the daily/circadian oscillation in STT I (about 2 mm/min) is likely too narrow to be of clinical significance, it is statistically significant and may have physiological implications not yet appreciated.
Results of the Schirmer tear test performed with open and closed eyes in clinically normal horses
Acta Veterinaria Scandinavica, 2017
Background: The Schirmer tear test (STT) is widely used in both human and veterinary ophthalmology. Two types of STTs have been developed: STT I and SST II. The STT I measures the basal and reflex tear production and is the most widely used STT. However, several factors influence the STT results such as the person performing the test and the location of the strip placement within the conjunctival sac. The aim of this study was to measure the basal and reflex tear production (STT I) in clinically normal horses with open versus closed eyes. Results: Forty clinically healthy horses without any ocular diseases were included. On day 1, the STT I was first performed on all the horses with the eyes open followed by an STT I with closed eyes performed 30 min later. On day 2, all horses had their eyes closed during the first STT and the eyes open during the second test performed 30 min later. The mean value of the STTs performed on open eye was significantly less than the STT performed on closed eye on both days of examination. Conclusion: This study showed a small but statistically significant difference between STT values obtained with open versus closed eyes in clinically normal horses.
Pilot evaluation of the circadian rhythm of tear production in a population of healthy adult cats
Veterinary Ophthalmology, 2019
Objectives: The purpose of this study was to determine if a circadian rhythm exists in Schirmer's tear test (STT-1) values in a group of healthy adult cats. Animals studied: Twenty adult neutered Domestic Short-haired cats (DSH) were used in the study. Procedures: Tear production was measured with the Schirmer tear test (STT-1) at 12 different time points over a 48-hour period. Results: A significant difference (approximately 4.3 mm/min) was noted between STT-1 values measured between 4 pm (lowest) and 12 am (highest) on both day 1 (P = 0.02) and day 2 (P = 0.01), and substantial variation in STT-1 values was observed at different times during the 48-hour period. Conclusions: Significant variation in mean STT-1 values demonstrates that there is a circadian rhythm in tear production in cats and thus shows the importance of taking the time of day into account when measuring STT-1 in cats.
Effect of age, gender, weight, and time of day on tear production in normal dogs
Veterinary Ophthalmology, 2006
Objective To investigate the effects of age, weight, gender, and of time of day on tear production in normal dogs. Animals studied One hundred ophthalmoscopically and systemically unremarkable dogs. Procedure Schirmer tear tests (STT) were performed every 2 h during the day on one randomly chosen eye of each of 100 dogs. Results There was a statistically significant effect of time of day and age on the STT measurement. The mean STT decreased by 0.4 mm for every 1 year that age increased (P = 0.007). Mean STT values taken at 10:00 were 0.7 mm lower than values taken at 4:00 (P = 0.04). Conclusions Tear production decreases with age in the normal dog. In this population of dogs the largest difference was between the 10:00 and the 4:00 STT measurements, but this still only amounted to 0.7 mm. This value is unlikely to be of clinical significance in the diagnosis of keratoconjunctivitis sicca (KCS).
Comparative Clinical Pathology, 2012
The current study was undertaken to evaluate the effects of topical 0.5% timolol maleate on tear production in clinically normal horses. Fourteen horses free from clinically relevant ocular abnormalities were used in the study. The 14 horses were randomly assigned to a treatment or control group. The treatment group included seven horses that received 0.25 mL of 0.5% timolol maleate ophthalmic solution in a randomly chosen eye, and the opposite eye served as the untreated control. The control group included seven horses that received no topical medications during the study. Schirmer tear test was performed on both eyes of all horses 1 day prior to treatment (T 0 ) and then at 1, 3, 7, and 14 days of treatment (T 1 , T 3 , T 7 , and T 14 ). In the treatment group, the baseline (T 0 ) Schirmer tear test (STT) values in the treated and non-treated eyes were 25.5±3.8 and 26.1± 6.6, respectively. In the control group, baseline mean±SD STTs were 21.4±3.6 and 24.2±4.4 in the right and left eyes, respectively. Baseline STTs between the treatment and control groups were not significantly different (P≥0.97). There was no statistically significant change in STT values throughout the study period in treatment and control groups (P≥0.15). In Conclusion, twice daily topical application of 0.5% timolol maleate had no significant effect on tear secretion when administered over a 2-week period in clinically normal horses.
Baseline values of canine tear production determined by schirmer tear and phenol red thread tests
2010
Although research on canine tear production and dry eye has been reported in temperate countries in different breeds, there is no Malaysian data. On the average, at least two new cases of dry eye are diagnosed weekly at the University Veterinary Hospital (UVH) of the Faculty of Veterinary Medicine, Universiti Putra Malaysia. Currently in UVH the guidelines for the diagnosis of keratoconjunctivitis (KCS) and monitoring of response to treatment are based on recommendations for temperate countries. Thus the objectives of this study were to determine the Malaysian baseline values for canine tear levels using Schirmer tear test (STT) and phenol red thread test (PRTT), the relationship between and diurnal effect on STT and PRTT in dogs. The average baseline values for canine tear production in healthy local dogs in Malaysia with normal tear film breakup time (TBUT) were within the range of average baseline values reported in temperate countries. The average STT value for both eyes was approximately 22 mm/min and the PRTT was approximately 26 mm/15 s. There was poor relationship between STT and PRTT. This might be due to the presence of one or more confounding factors. The red colour change in PRTT was more intense when STT was performed first followed by PRTT and vice versa. The intensity of red colour change in PRTT was even more when performed in KCS dogs. This is because the intensity of the colour change in the phenol red thread is due to increasing alkalinity. Thus, KCS dogs had more alkaline tears than normal dogs. The lowest tear level was in the afternoon when diurnal study was conducted. Hence, KCS tests should be performed in the afternoon in order to obtain a more accurate measurement of tear level. Tear levels fluctuate when normal dogs were exposed in clinic with air-conditioned environment. Therefore, KCS tests should be performed immediately when dogs arrived at the clinic.
Corneal esthesiometry in the healthy horse
Veterinary Ophthalmology, 2003
Objective To determine corneal sensitivity in healthy adult horses in order to establish reference values. Animals studied One hundred eyes of 50 healthy adult horses. Procedure Corneal sensitivity was determined by evaluating the corneal touch threshold (CTT) in five different corneal regions using a Cochet-Bonnet esthesiometer. Results Comparing CTT values (in mm filament length) of the five prescribed corneal regions revealed regional variations in corneal sensitivity, with the central region (21.15 ± 6.23 mm) being the most sensitive, followed by the nasal (20.75 ± 5.14 mm), temporal (20.70 ± 5.37 mm), ventral (20.15 ± 5.88 mm) and dorsal (15.85 ± 3.70 mm) region. However, differences between the central, nasal, temporal and ventral regions were not statistically significant, whereas the dorsal region was significantly ( P < 0.0001) less sensitive compared to the other regions. Division of the horses into three age groups revealed an insignificant decrease in corneal sensitivity with age in the nasal, temporal, ventral and central region, and an insignificant increase with age in the dorsal region. Correlation of corneal sensitivity with age was statistically significant in the central, ventral and temporal region. No statistically significant difference in the CTT was found between left and right eyes and between males and females.
Evaluation of inter-day and inter-individual variability of tear
2012
To characterize the tear film peptidome and low molecular weight protein profiles of healthy control individuals, and to evaluate changes due to day-today and individual variation and tear collection methods, by using solid phase extraction coupled to matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) profiling. Methods: The tear protein profiles of six healthy volunteers were analyzed over seven days and inter-day and interindividual variability was evaluated. The bilaterality of tear film and the effect of tear collection methods on protein profiles were also analyzed in some of these patients. MALDI-TOF MS analyses were performed on tear samples purified by using a solid phase extraction (SPE) method based on C18 functionalized magnetic beads for peptide and low molecular weight protein enrichment, focusing spectra acquisition on the 1 to 20 kDa range. Spectra were analyzed using principal component analysis (PCA) with MultiExperiment Viewer (TMeV) software. Volunteers were examined in terms of tear production status (Schirmer I test), clinical assessment of palpebral lids and meibomian glands, and a subjective OSD questionnaire before tear collection by a glass micro-capillary. Results: Analysis of peptides and proteins in the 1-20 kDa range showed no significant inter-day differences in tear samples collected from six healthy individuals during seven days of monitoring, but revealed subtle intrinsic interindividual differences. Profile analyses of tears collected from the right and left eyes confirmed tear bilaterality in four healthy patients. The addition of physiologic serum for tear sample collection did not affect the peptide and small protein profiles with respect to the number of resolved peaks, but it did reduce the signal intensity of the peaks, and increased variability. Magnetic beads were found to be a suitable method for tear film purification for the profiling study. Conclusions: No significant variability in tear peptide and protein profiles below 20 kDa was found in healthy controls over a seven day period, nor in right versus left eye profiles from the same individual. Subtle inter-individual differences can be observed upon tear profiling analysis and confirm intrinsic variability between control subjects. Addition of physiologic serum for tear collection affects the proteome and peptidome in terms of peak intensities, but not in the composition of the profiles themselves. This work shows that MALDI-TOF MS coupled with C18 magnetic beads is an effective and reproducible methodology for tear profiling studies in the clinical monitoring of patients.
Veterinary Ophthalmology, 2020
Objective: To investigate the effects of various biological factors on total protein concentration (TPC) and serum albumin levels in canine tears. Animals Studied: 10 healthy beagles (5 female, 5 male) were used. Procedures: Experiments were conducted on separate days, collecting tears with either capillary tubes or Schirmer strips, as follows: (i) Tear collection at 3hr-intervals (from 6AM to 12AM); and (ii) Tear collection before and 20min following topical histamine application (1, 10, 375 mg/mL) to induce mild, moderate and severe conjunctivitis, respectively. TPC and serum albumin were measured with infrared spectroscopy and ELISA, respectively. Results: Tear film TPC and serum albumin ranged from 9.7-26.1 mg/mL and 6.4-1662.6 µg/mL, respectively. Protein levels did not differ significantly among time points (P≥0.080). Median coefficient of variation (CV%) was lower with Schirmer strips compared to capillary tubes for both TPC (12 vs. 15%, P=0.020) and serum albumin (57 vs. 78%, P=0.232). TPC (P < 0.001), but not serum albumin was greater in male vs. female dogs. Serum albumin, but not TPC (P≥0.099), increased significantly with each grade of conjunctivitis severity (P<0.001), with no differences between collection devices (P≥0.322); median increase was 106%, 1389% and 2871% in eyes with mild, moderate and severe conjunctivitis, respectively. Conclusions: There is no apparent diurnal variation in canine tear protein levels. Blood-tear barrier breakdown with conjunctivitis allows serum albumin to leak into the tear film at high concentrations. Schirmer strips compare well with capillary tubes for bioanalytical purposes in healthy and diseased eyes, and this collection method may offer improved reproducibility for protein quantification.