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

Environmental Exposure Clinical Trial

Official title:

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

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT01448356
• Other study ID #: R857/52/2011
• Secondary ID: 2011/197/A
• Status: Completed
• Phase: N/A
• First received: October 4, 2011
• Last updated: November 14, 2012
• Start date: January 2012
• Est. completion date: April 2012

Study information

• Verified date: November 2012
• Source: Singapore Eye Research Institute
• Contact: n/a
• Is FDA regulated: No
• Health authority: Singapore: Health Sciences Authority
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 10
• Est. completion date: April 2012
• Est. primary completion date: April 2012
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Both
• Age group: 21 Years to 90 Years

Eligibility

Inclusion Criteria:

• must have undergone screening examination

Exclusion Criteria:

• unable to go to the DSO laboratory or undergo any of the study procedures

Study Design

Endpoint Classification: Efficacy Study, Intervention Model: Single Group Assignment, Masking: Open Label, Primary Purpose: Basic Science

Related Conditions & MeSH terms

• Environmental Exposure

Intervention

Procedure:
• temperature and humidity
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.

Locations

Country	Name	City	State
Singapore	Singapore Eye Research Institute	Singapore

Sponsors (2)

Lead Sponsor	Collaborator
Singapore Eye Research Institute	Singapore National Eye Centre

Country where clinical trial is conducted

Singapore, 

References & Publications (2)

González-García MJ, González-Sáiz A, de la Fuente B, Morilla-Grasa A, Mayo-Iscar A, San-José J, Feijó J, Stern ME, Calonge M. Exposure to a controlled adverse environment impairs the ocular surface of subjects with minimally symptomatic dry eye. Invest Ophthalmol Vis Sci. 2007 Sep;48(9):4026-32. — View Citation

Wolkoff P. Ocular discomfort by environmental and personal risk factors altering the precorneal tear film. Toxicol Lett. 2010 Dec 15;199(3):203-12. doi: 10.1016/j.toxlet.2010.09.001. Epub 2010 Sep 15. Review. — View Citation

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	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	No
Secondary	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	No