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Raman Scattering Spectroscopy to Measure Macular Pigment

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00060580
Recruitment Status : Completed
First Posted : May 8, 2003
Last Update Posted : March 4, 2008
Information provided by:
National Institutes of Health Clinical Center (CC)

Brief Summary:

This study will evaluate the ease and reliability of Raman scattering spectroscopy, a new technique to measure the amount of the pigment lutein in the retina, the light-sensitive tissue lining the back of the eye. The highest concentrations of lutein are in the center of the retina, called the macula, which is the area most important for fine, detailed vision. The functions of lutein are not fully known. Besides absorbing blue light, it may help protect against abnormal changes in the retina, such as age-related macular degeneration. Until recently, lutein was measured using long, cumbersome, and difficult tests. This study will evaluate a new instrument that provides faster measurements. It will be tested under different conditions, such as wearing or not wearing glasses or contact lenses, or dilating or not dilating the pupil of the eye.

Healthy normal volunteers between 20 and 65 years of age may be eligible for this study, which involves two visits to the NIH Clinical Center, as follows:

Visit 1 - Screening

  • Medical history and physical examination, including measurement of vital signs (blood pressure, pulse, temperature, and breathing rate), and examination of the head and neck, heart and lungs, and arms and legs.
  • Eye examination, including eye chart test, eye pressure measurement, examination of pupils and eye movements, and examination of the retina (back part of the eye) using a strong light and magnifying lens after dilation of the pupils.
  • Raman scattering spectroscopy to measure lutein. For this test, the subject looks with one eye at a brief, bright flash of bluish light (similar to a flashbulb light) from a laser. This is repeated several times. Subjects who wear glasses or contact lenses for distance vision will be tested without them and then again with a lens in front of the eye. Subjects who do not wear glasses or contact lenses will be tested before and after dilation of the pupil.
  • Contrast sensitivity to assess ability to identify an object from the background and to see everyday objects. The subject looks at and identifies a variety of objects of different shapes and sizes.
  • Color vision to determine the ability to identify different shades of color. The subject arranges a line of colorful discs, similar to checkers, in order of similar shades.

Visit 2 - Repeat Spectroscopy

Subjects return 1 week after the screening visit for a repeat Raman scattering spectroscopy to evaluate the precision of the measurements.

Condition or disease Intervention/treatment Phase
Raman Spectroscopy Procedure: Raman scattering spectroscopy Phase 1

Detailed Description:
The primary objective of this study is to evaluate the degree of variability in retinal measurements of lutein, a carotenoid macular pigment of human retina in normal volunteers, with a new and novel technique of resonant Raman scattering spectroscopy. This technique is generally more objective than psychophysical techniques used for lutein measurements, such as heterochromatic flicker photometry. Raman scattering spectroscopy is non-invasive and the levels of ocular exposure to argon laser light used in this technique are well below the safety limits recommended by the American National Standards Institute.

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Study Type : Interventional  (Clinical Trial)
Enrollment : 40 participants
Primary Purpose: Treatment
Official Title: Measurement of Macular Pigment With Resonant Raman Backscattering Spectroscopy
Study Start Date : May 2003
Study Completion Date : March 2006

Information from the National Library of Medicine

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the contacts provided below. For general information, Learn About Clinical Studies.

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Ages Eligible for Study:   Child, Adult, Older Adult
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes


  1. Men and women between 18 and 75 years of age.
  2. Corrected visual acuity of 20/30 or better.
  3. Ability to understand and sign an informed consent form prior to enrollment.


  1. Ocular disease, including significant explained or unexplained visual field loss.
  2. Ocular media opacities.
  3. History of epilepsy or light-triggered convulsions.
  4. A maximal pupillary dilation of less than 7 mm.

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 identifier (NCT number): NCT00060580

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United States, Maryland
National Eye Institute (NEI)
Bethesda, Maryland, United States, 20892
Sponsors and Collaborators
National Eye Institute (NEI)
Layout table for additonal information Identifier: NCT00060580    
Other Study ID Numbers: 030156
First Posted: May 8, 2003    Key Record Dates
Last Update Posted: March 4, 2008
Last Verified: March 2006
Keywords provided by National Institutes of Health Clinical Center (CC):
Retinal Measurements
Lutein in Vivo
Raman Spectroscopy
Retinal Measurements of Lutein in Vivo in the Human Eye
Healthy Volunteer