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PURPOSE: To assess the impact of botulinum toxin type A (BTX-A) on signs and symptoms of dry eye (DE) in affected eye of hemifacial spasm (HFS) patients and to compare the prevalence of DE between affected and non-affected eye in HFS patients. PATIENTS AND METHODS: This prospective study included participants with unilateral HFS, who received BTX-A injection as a treatment. The eyes ipsilateral to the spasm side were used as studied eyes and the contralateral eyes were used as controls. The Ocular Surface Disease Index (OSDI) score, tear break-up time (TBUT), corneal fluorescein staining, and Schirmer I test were measured at baseline, 1 and 3 months after BTX-A injection. Fluorescein clearance test (FCT) was evaluated at baseline and at 1 month after BTX-A injection. RESULTS: Thirty-one participants (6 males and 25 females; mean age 61±10 years) were included. The prevalence of DE according to the Asia Dry Eye Society was not significantly different between affected (37.93%) and non-affected eyes (27.6%); P=0.083. At baseline, there was no significant difference in TBUT, Schirmer test, basal tear secretion, presence of delayed tear clearance, and presence of reflex tear secretion between affected and non-affected eyes, while significant difference in Oxford scheme grade was observed (P=0.031). OSDI score, TBUT, Oxford scheme grade, and Schirmer test at 1 month (P=0.817, 0.796, 0.534, 0.556), and 3 months (P=0.803, 0.904, 0.936, 0.684) after BTX-A injection did not significantly change from baseline in affected eyes. FCT results were not significantly different between baseline and at 1-month follow-up in both groups. All findings were corresponding in both naïve and long-term botulinum toxin injection groups. CONCLUSION: We found no significant effect of BTX-A on signs and symptoms of DE in patients with HFS. Moreover, there was no significant association between HFS and DE. However, we found significant corneal surface damage in the affected eyes, which emphasized importance of ocular surface evaluation and prompt treatment in HFS patients.

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BACKGROUND: The fluorescein clearance test (FCT) provides insight into the tear film dynamics. The purpose of this study was to describe an inexpensive and practical method for assessing FCT in dogs, using photography and software analysis, and to assess the retention time of 1 vs. 2 eye drops on the canine ocular surface. METHODS: (i) In vivo - Eight healthy German Shepherd dogs were recruited. Following topical anesthesia with 0.5% proxymetacaine, each eye sequentially received (1 week apart) either 1 drop (35 µL) or 2 drops (70 µL) of 0.5% fluorescein. A Schirmer strip was inserted in the ventral conjunctival fornix for 10 s at the following times: each 10 min for 100 min, 24 h, 48 h and 72 h. (ii) In vitro - Schirmer strips were placed for 10 s in contact with microplate wells containing 1 or 2 drops of 0.5% fluorescein. In both experiments, the fluorescein-impregnated Schirmer strips were immediately imaged, and the area and intensity of fluorescein uptake were analyzed with ImageJ software. For the in vitro experiment, images were evaluated by the same examiner (repeatability) or two examiners (reproducibility). RESULTS: Photography-based FCT was easy to perform and showed high repeatability and reproducibility (coefficients of variation ≤2.75%). In vivo, the area and intensity of fluorescein uptake on Schirmer strips were significantly greater at 30 min and 40 min post- fluorescein instillation in the 2 drops vs. 1 drop groups (p ≤ 0.044). Compared to baseline, the residual fluorescein uptake on Schirmer strips was < 5% at 60 min and 90 min in the 1 drop and 2 drops groups, respectively. CONCLUSIONS: Photography-based FCT is a practical and reliable diagnostic tool with various clinical and research applications in veterinary medicine. Instillation of two drops provided greater amount and longer retention on the anesthetized canine ocular surface than a single drop. Fluorescein clearance time of a single drop in dolichocephalic dogs is 60 min.

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INTRODUCTION: The aim is to provide a summary of methods available for the assessment of tear turnover and tear clearance rates. The review defines tear clearance and tear turnover and describes their implication for ocular surface health. Additionally, it describes main types of techniques for measuring tear turnover, including fluorescein tear clearance tests, techniques utilizing electromagnetic spectrum and tracer molecule and novel experimental techniques utilizing optical coherence tomography and fluorescein profilometry. AREAS COVERED: Internet databases (PubMed, Science Direct, Google Scholar) and most frequently cited references were used as a principal resource of information on tear turnover rate and tear clearance rate, presenting methodologies and equipment, as well as their definition and implications for the anterior eye surface health and function. Keywords used for data-search were as follows: tear turnover, tear clearance, fluorescein clearance, scintigraphy, fluorophotometry, tear flow, drainage, tear meniscus dynamics, Krehbiel flow and lacrimal functional unit. EXPERT COMMENTARY: After decades, the topic of tear turnover assessment has been reintroduced. Recently, new techniques have been developed to propose less invasive, less time consuming and simpler methodologies for the assessment of tear dynamics that have the potential to be utilized in clinical practice.

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PURPOSE: The aim of this study was to determine the normal inter-day and intra-day variations in tear film osmolarity and the tear fluorescein clearance test (T-FCT) in healthy subjects. METHODS: Tear samples from 24 young, healthy adults were collected from 11:00 AM to 1:00 PM (midday) and 5:00 PM to 7:00 PM (evening) on three non-consecutive days. Tear osmolarity measurement and the T-FCT were performed to assess the basal values and inter-day and intra-day variations of the test results. A freezing point depression osmometer was used to analyze the tear osmolarity, and the T-FCT was performed using a fluorophotometer. RESULTS: The mean osmolarity value was 270 ± 4.4 mOsm/l and the mean T-FCT result was 2.97 ± 0.17 fluorescence arbitrary units. The inter-day or intra-day tear osmolarity values did not differ significantly. The T-FCT results varied significantly during the day, with significantly (p = 0.0004) higher results in the evening; no significant differences were found in the inter-day analysis. CONCLUSIONS: Tear osmolarity was unaffected by intra-day variations; however, the T-FCT showed an inter-day variation, which indicated that the time of day when the test is performed must be considered when it is used to evaluate the diagnosis of dry eye disease, disease progression or therapeutic effectiveness.

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On the proposed fluorescein clearance test by Pflugfelder and Tseng, measurements of volume and concentration of instilled fluorescein, being changed by tear secretion, pumping action, during confined time, are able to discern tear turnover rate(tear clearance). We performed TBUT, Schirmer test and modified FCT to the 60 eyes of healthy person, to the 36 eyes of essential blepharospasm patient, and to the 32 eyes of hemifacial spasm patients. We modified the FCT to economize time. Under the topical anesthesia with 0.5% propacaine, test was performed after instilling a 20 microliter of Flucaine(0.25% fluorescein sodium, and 0.5% propacaine) into the conjunctival sac and standard Schirmer strip was then placed for another 10 minutes. The length of the portion was measured and the concentration of tint fluorescein was graded into 5 degrees(photodocumented classification under the cobalt blue light)(FCT 1). Waiting 10 minutes, a standard Schirmer strip was placed into with nasal stimulation and length and concentration was also measured(FCT 2). The agreement of classification was determined with Kappa values for evaluation for reproducibility and and reliability of FCT. The intra-observer agreement(examination repeated twice) was k=0.84 and the inter-observer agreement(two obsevers' examination) was k=0.77, which revealed a consistent result. Patients with blepharospasm was indicated decreased basal secretion compared with normal control(p<0.001) and also showed delayed tear clearance whith represented significant increased concentration(p<0.001). We concluded that FCT was revealed high reproducibility by intra-observer and inter-observer agreement and test may be useful diagnostic method to evaluate delayed tear clearance.

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