Controlled Adverse Environment: A Pilot Study to Evaluate Tear Film Stability and Tear Evaporation

Study Overview
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Brief Summary
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Dry eye and ocular surface disease account for a lot of morbidity and socio-economic burden in Asia and the rest of the world. This is a small pilot study to evaluate tear function under different conditions of humidity and temperature. This data will be useful for designing future trials in ocular surface and dry eye. The data will likely be used to propose a larger national funded project involving clinical trials. This study involves collaboration between engineers, ocular surface clinicians as well as specialists from the defence science organisation. When successfully completed, the project will increase the capability of Singapore Eye Research Institute and Singapore National Eye Centre to support future industry and academic research in the ocular surface.

Detailed Description
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Study Objectives and Purpose: A primary purpose of the study is to evaluate fluorescein tear break up times in participants under different humidity/ temperature conditions. The second aim is to assess the tear evaporation rates in a dynamic fashion over 20 seconds (based on a non-invasive ocular thermography method) after exposure to different humidity/temperature conditions. Study Design: Prospective, non-comparative, clinical study Rationale: The ocular surface research team who is based at the dry eye service of the Singapore National Eye Center is experienced in the assessment of the ocular surface in patients and clinical trial participants. Collaborators from the DSO National laboratory already have experience in conducting human studies in a controlled environment in Singapore that has been proven to be safe and has passed necessary regulatory approval. In addition, recent technological advances have allowed collaborators from NTU and Singapore Polytechnic to perform non-invasive tear evaporimetry in a dynamic way between blinks. Together, this is a strong research team that can address the important question of the influence of temperature and humidity on the tear film stability. Methods: We intend to use 10 volunteer/patients to establish whether tear film stability or tear film function can be altered after exposure to different combinations of humidity and temperature. This involves the assessment of tear film break up time (TBUT) and tear evaporimetry, a non-invasive procedure (like an auto-refractor where the patient places the chin on the chin rest and forehead on the head rest when the measurement is taken) which involves taking serial images with an infra red sensitive video camera. This process is performed at a facility which is closely monitored and proven to be safe for other research participants. Participants and target sample size: Ten participants will be recruited. Workflow: We assume that approximately 45 minutes are required for the chamber to achieve the required temperature and humidity, and about 15 to 20 minutes for participants to adjust to the first environmental setting. Thermography measurement will take 1 minute (20 sec in each eye, with adjustment of camera between eyes). The participants will undergo slit lamp examination where the fluorescein tear break up time will be assessed and digital color image of the break up pattern will be taken. These will require a further 5 minutes. This means 3 participants can have measurements done in approximately 20 minutes. Measurements of 3 participants in a single condition will therefore take up to 20 minutes.In a session that will last up to 3 hours and 20 minutes, the investigators can complete the condition list for 3 participants. Since the overall session is quite long, a toilet break is permitted after each temperature condition. The investigators estimate that 3 sessions with a further 'dry run' for the photography (without participants) before the first session will be necessary. Visit schedules: Volunteers or patients from the Singapore National Eye Center will be informed of this study. Screening will be performed at the regular dry eye clinic at the Singapore National Eye Center. If eligible, the volunteer or patient will sign consent and undergo baseline examination. Subsequent to this, the examination will be performed at the controlled adverse environment at the DSO facility. Assessment of ocular parameters is outlined below: At Screening visit, the investigators perform: Informed consent Subject background Anterior segment findings Tear film break up time At Evaluation visit, the investigators perform: Tear film break up time Photography/Video to document tear break up Tear evaporimetry Duration of study: Four weeks.

Official Title
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Controlled Adverse Environment: A Pilot Study to Evaluate Tear Film Stability and Tear Evaporation

Conditions
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Environmental Exposure

Intervention / Treatment
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* Procedure: temperature and humidity


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: must have undergone screening examination Exclusion Criteria: unable to go to the DSO laboratory or undergo any of the study procedures

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 90 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: temperature and humidity<br>The volunteer is exposed to a controlled environment with a chamber setting of: 25°C and 45% humidity; 25°C and 65% humidity; 30°C and 45% humidity; 30°C and 65% humidity | Procedure: temperature and humidity<br>* The volunteer is exposed to a controlled environment with a chamber setting of: 25°C and 45% humidity; 25°C and 65% humidity; 30°C and 45% humidity; 30°C and 65% humidity After an adaptation period of at least 20 minutes, participants underwent measurements of tear evaporation and tear film break up time. After collection of data, the chamber settings were adjusted to the next condition.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tear Evaporation Rate | The rate of tear evaporation is measured by the use of ocular thermography. For each subject,his/her ocular surface temperature will be recorded twice, one for each eye. The subject at first rests his/her chin on a chin rest, with his/her forehead lean against a metal frame (which is part of the chin rest). Then the recording starts lasting approximately 20seconds for each eye. While recording, the subject needs to look straight into the lens, but can blink naturally. After this, the recording data will be analyzed to derive the evaporation rate using a mathematical model. | 20 minutes after the required temperature and humidity in the chamber is achieved | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Tear Film Break up Time | After instillation of fluorescein, the participant will then be asked to open the eyes, look ahead at the observer's forehead and not blink for as long as possible. The break up time is defined as the time between the lid opening and the first appearance of any dry spot on the cornea. The participant will be requested to close his eyes for few seconds and the procedure will be repeated for the left eye. | 20 minutes after the required temperature and humidity in the chamber is achieved | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Controlled adverse chamber, tear film stability, tear film evaporation, tear film break up time, humidity, temperature