Controlled Adverse Environment: A Pilot Study to Evaluate Tear Film Stability and Tear Evaporation
Condition: Environmental Exposure
Study type: Interventional

Summary: 
      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: 
      Study Objectives and Purpose:

        1. A primary purpose of the study is to evaluate fluorescein tear break up times in
           participants under different humidity/ temperature conditions.

        2. 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.
    

Intervention name(s): temperature and humidity
Intervention type(s): Procedure
Intervention description(s): 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.
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Basic Science
Keywords: Controlled adverse chamber; tear film stability; tear film evaporation; tear film break up time; humidity; temperature