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Using AS-OCT to Assess the Role of Age and Region in the Morphology and Epithelial Thickness of Limbus

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ClinicalTrials.gov Identifier: NCT02500134
Recruitment Status : Unknown
Verified July 2015 by National Taiwan University Hospital.
Recruitment status was:  Active, not recruiting
First Posted : July 16, 2015
Last Update Posted : July 16, 2015
Sponsor:
Information provided by (Responsible Party):
National Taiwan University Hospital

Brief Summary:

The limbus located between the cornea and the conjunctiva tissue, is important for not only providing a barrier frontier to prevent conjunctival tissue invasion into the cornea, containing nerves passing to the cornea, having blood and lymph vasculature for oxygen and nutrient delivery, but also the niche environment of limbal stem cells.

So far, in vivo image systems are not able to visualize or identify the limbal stem cells directly. One alternative practical is to visualize the histological morphology of palisades of Vogt (POV), and to speculate the possible status of the stem cells accordingly. Slit-lamp biomicroscope can be used routinely for clinical examination of the limbal morphology. However, this technology does not allow for high resolution imaging of structural details and only up to 20% of patients can be identified. In vivo confocal microscopy has been used to visualize the POV and can provide cellular level resolution images, but the technique is limited by high magnification that restricts the area of the scan, and requires contact with the eye. Besides, both slit lamp biomicroscopy and in vivo confocal microscopy have the limitation of not being able to give an overall view of the dimension and structure of the whole palisades region.

Anterior segment optical coherence tomography (AS-OCT) is a noninvasive, rapid and reproducible technique to evaluate the anterior segment and can also provide in vivo spatial information. The purpose of the study is to assess the role of aging and regions on the limbus.


Condition or disease Intervention/treatment
Limbus Corneae Other: Optical coherence tomography study on limbus

Detailed Description:

The limbus located between the cornea and the conjunctiva tissue, approximately 1.5 mm wide in adult human eyes, is important for not only providing a barrier frontier to prevent conjunctival tissue invasion into the cornea, containing nerves passing to the cornea, having blood and lymph vasculature for oxygen and nutrient delivery, but also the niche environment of limbal stem cells. The human limbus contains radially oriented fibrovascular rides named palisades of Vogt (POV), a unique tissue first noted in 1866 and were further described in detail in 1921. The POV has unique structure, configuration and dimension which was commonly found in all types of epithelial stem cell niche all over the body, which include the complicated niche area providing a safe place to protect the stem cells from damage or injury. During the past few years, progress in stem cell research and cell therapy has focused attention on the POV as the location of the stem cells that keep the corneal epithelial homeostasis and clarity. The POV also provide the niche environment for limbal stem cells. The niche cells surrounding the limbal stem cells, the stromal environment underneath the limbal epithelial cells, the blood vessels and nerve innervation around the limbal epithelium all help create the unique niche environment for limabl stem cells. Understanding the limbal structure, especially the POV, is necessary for the treatment of limbal damage and the development of stem cell therapies targeted at restoring impaired function of limbal stem cells.

So far, in vivo image systems are not able to visualize or identify the limbal stem cells directly. One alternative practical is to visualize the histological morphology of POV, and to speculate the possible status of the stem cells accordingly. However, the microstructure of POV is not well defined or understood in spite of awareness of it's importance. Slit-lamp biomicroscope can be used routinely for clinical examination of the limbal morphology. However, this technology does not allow for high resolution imaging of structural details and only up to 20% of patients can be identified. In vivo confocal microscopy has been used to visualize the POV and can provide cellular level resolution images, but the technique is limited by high magnification that restricts the area of the scan. In addition, in vivo confocal microscopy requires direct contact with the eye. Although the quality of these images is impressive, the disadvantages existed included the direct contact during examination, the small field of view (~200μm x 200μm), and the limited axial resolution. Besides, both slit lamp biomicroscopy and in vivo confocal microscopy have the limitation of not being able to give an overall view of the dimension and structure of the whole palisades region.

Optical coherence tomography (OCT) is an imaging modality that allows for non-invasive imaging of the morphology of biological tissue with micrometer scale resolution at imaging depths of 1-2mm below the tissue surface. During these few years, OCT has become a useful clinical and research tool for imaging of the ocular surface. In addition to the mostly used application for observing the optic disc and retinal choroidial structure, the usage in the anterior segment, especially cornea, was also widely developed. An anterior segment OCT (Visante; Carl Zeiss Meditec, Dublin, CA), a time-domain OCT, is a commercial available OCT designed for especially for anterior segment. This OCT instrument has been used widely in LASIK, different lamellar keratoplasties, keratoconus screening and evaluation of corneal diseases in different layers. However, its limited resolution does not allow for the observation of the epithelial layer on the ocular surface. Spectral domain OCT with a corneal module can provide much better resolution than time domain OCT for the observation of epithelial layer on ocular surface. It has been used recently to evaluate the corneal epithelial layer with reliable results. In this study, we use a fourier-domain optical coherence tomography OCT (RTvue, Optovue Inc., Fremont, CA), with a corneal-anterior module long lens adapter with low magnification, to observe the limbal structure (POV). The purpose of the study is to assess the role of aging and regions on the limbus.

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Study Type : Observational
Estimated Enrollment : 200 participants
Observational Model: Case-Only
Time Perspective: Cross-Sectional
Official Title: Using AS-OCT to Assess the Role of Age and Region in the Morphology and Epithelial Thickness of Limbus
Study Start Date : March 2014
Estimated Primary Completion Date : August 2015
Estimated Study Completion Date : August 2017

Group/Cohort Intervention/treatment
Normal
Healthy volunteer control without ocular surface disease or prior ophthalmic surgery history
Other: Optical coherence tomography study on limbus
Optical coherence tomography study on limbus




Primary Outcome Measures :
  1. thickness of limbus [ Time Frame: 1 day of inclusion ]
    measure the thickness of limbus from the image of OCT, describe the morphology of limbus (typical pattern was defined as having the easily identified sharp tapering tip of subepithelial stroma pointing to the corneal-limbal junction with the maximum epithelial thickness of palisades of Vogt at least 1.5 X thicker than the central corneal epithelial thickness)



Information from the National Library of Medicine

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Ages Eligible for Study:   6 Years to 90 Years   (Child, Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Sampling Method:   Probability Sample
Study Population
Healthy normal eyes without any ocular surface disease
Criteria

Inclusion Criteria:

  • Healthy volunteer control without ocular surface disease or prior ophthalmic surgery history

Exclusion Criteria:

  • Patients who decline to receive the diagnostic examinations.
  • Patients younger than 6 years old or older than 90 years old.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02500134


Locations
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Taiwan
National Taiwan University Hospital
Taipei, Taiwan, 100
Sponsors and Collaborators
National Taiwan University Hospital
Investigators
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Principal Investigator: Wei-Li Chen, MD National Taiwan University Hospital
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Responsible Party: National Taiwan University Hospital
ClinicalTrials.gov Identifier: NCT02500134    
Other Study ID Numbers: 201406106RINC
First Posted: July 16, 2015    Key Record Dates
Last Update Posted: July 16, 2015
Last Verified: July 2015